RX-Snake: Axle and Drive Shaft

[Vettezuki]

How much would a built 8.8" cost vs. a built 9"

How much torque/power can a built 8.8" hold vs. a 9"?

What is the approximate weight differential between the 8.8" 9"?


My practical side says go with a built 8.8". It will probably hold forever, be a bit smaller and lighter, and maybe be a bit cheaper.

My red neck side says 9 is bigger than 8.8 so do that.

[94cobra69ss396]

How much would a built 8.8" cost vs. a built 9"

How much torque/power can a built 8.8" hold vs. a 9"?

What is the approximate weight differential between the 8.8" 9"?


My practical side says go with a built 8.8". It will probably hold forever, be a bit smaller and lighter, and maybe be a bit cheaper.

My red neck side says 9 is bigger than 8.8 so do that.

The 8.8 can be just as strong as the 9" plus they are easier to get. Here is a great article that Chevy High Performance did comparring the 9" to a Chevy 12bolt (8.75") which is equal to the 8.8.

http://www.chevyhiperformance.com/techarticles/0304_9_inch_12_bolt_rearend_comparison/index.html

[Vettezuki]

The 8.8 can be just as strong as the 9" plus they are easier to get. Here is a great article that Chevy High Performance did comparring the 9" to a Chevy 12bolt (8.75") which is equal to the 8.8.

http://www.chevyhiperformance.com/techarticles/0304_9_inch_12_bolt_rearend_comparison/index.html


Cool. What's your recommended source for an 8.8?

[94cobra69ss396]

Cool. What's your recommended source for an 8.8?

I thought we were going to run the Mazda rearend at first to see how it held up? If not, wait until I pick up the car and I'll measre the rear axle to see how wide it is. Then I can compare it to the Explorer and the Cobra to see if either would work without narrowing. If one of those is the right width we can just pull one from a wrecked car or truck. If they're both too wide I say we pull one from an Explorer and then narrow it.

What type of rear axle does the RX7 have under it now? Is it a solid axle or is it independent?

[Vettezuki]

I thought we were going to run the Mazda rearend at first to see how it held up? If not, wait until I pick up the car and I'll measre the rear axle to see how wide it is. Then I can compare it to the Explorer and the Cobra to see if either would work without narrowing. If one of those is the right width we can just pull one from a wrecked car or truck. If they're both too wide I say we pull one from an Explorer and then narrow it.

What type of rear axle does the RX7 have under it now? Is it a solid axle or is it independent?

It's an IRS witha wee pumpkin and ity bity half shafts. I've heard the diffs from the Turbo II cars are pretty stout, but obviously the way a turbo rotary delivers power is completely different than a blown V8, but *maybe* that'd work. We'd at least have to beef up the half shafts in that scenario.

After looking at it more closely last night, with sticky tires, I'd expect total destruction in less than ten runs with the stock unit, if not the first one. :huh: I can post some pics later tonight.

[94cobra69ss396]

If you want to measure it tonight and post it I'll measure the Explorer and Cobra. Measure from the wheel mounting surface. Otherwise I can do it when I have the car.

[Vettezuki]

If you want to measure it tonight and post it I'll measure the Explorer and Cobra. Measure from the wheel mounting surface. Otherwise I can do it when I have the car.

Will do. I'm also going to do a little more research on Turbo II diffs and aftermarket half shafts to see what they can hold. There certainly have been JDM RX-7s that put out way more power than we will be, but it's super high revving turbo power, not blown displacement.

[SeanPlunk]

Cool. What's your recommended source for an 8.8?

There is an all Ford junkyard in Placentia. Maybe we could get it out of a wrecked Explorer there?

[Vettezuki]

I'm doing some research with the V8RX7 boys. From what I've found so far, the stock NA unit is "designed for failure behind a V8". However, it seems the Turbo unit is pretty stout, and has a 4.1 ratio as we'd want. More to come. It'd be kind cool to keep the IRS because then we could use it for straight line and single lap AutoX type stuff just for shits and giggles. We'll see. I'd just like to avoid too many complex re-engineering efforts more than anything.

[big2bird]

I would be willing to bet, with the first popped clutch at 3,500RPM, that stock unit will grenade.
For straight line work, a 9" with a spool.............

Street car needs compromising on racing.

Autocross needs compromising on street and straight line.

Straight line needs....................well, you get it.:D

[Vettezuki]

I would be willing to bet, with the first popped clutch at 3,500RPM, that stock unit will grenade.
For straight line work, a 9" with a spool.............

Street car needs compromising on racing.

Autocross needs compromising on street and straight line.

Straight line needs....................well, you get it.:D

Gots'd it. The unit that's in there now will almost certainly go boom on the first launch or shortly thereafter, so it'll get swapped. The Turbo II unit *may* be up to the task. There certainly are RX-7s with more power than we'll have, but they don't "hit" like we will.

One specific question about the spool. I was under the impression the spools were really only necessary on very high HP cars; like way beyond 500hp to thw wheels.

[94cobra69ss396]

Gots'd it. The unit that's in there now will almost certainly go boom on the first launch or shortly thereafter, so it'll get swapped. The Turbo II unit *may* be up to the task. There certainly are RX-7s with more power than we'll have, but they don't "hit" like we will.

One specific question about the spool. I was under the impression the spools were really only necessary on very high HP cars; like way beyond 500hp to thw wheels.

Don't use a spool. They are horrible on the street and not designed for autocrossing. All we need is a good limited slip which will work well in all three. If the car is going to be used a lot for both drag racing and autocrossing then just get two sets of front struts with different spring rates, two sets of rims and tires and adjustable shocks for the rear.

Also, if this is going to be an autocross car we are going to want to keep that independent rear and stay away from the solid axle if at all possible. Then again, if it is going to see a lot of autocrosses and road racing we may want to modify the firewall so the we can set the engine back some to improve the weight balance.

[big2bird]

Don't use a spool. They are horrible on the street and not designed for autocrossing. Yes. They only have one use.All we need is a good limited slip which will work well in all three. If the car is going to be used a lot for both drag racing and autocrossing then just get two sets of front struts with different spring rates, two sets of rims and tires and adjustable shocks for the rear.

Also, if this is going to be an autocross car we are going to want to keep that independent rear and stay away from the solid axle if at all possible. Then again, if it is going to see a lot of autocrosses and road racing we may want to modify the firewall so the we can set the engine back some to inprove the weight balance.

I think as an autocross car, with that weight in front, and that narrow little wheelbase, it will suck.

[94cobra69ss396]

I think as an autocross car, with that weight in front, and that narrow little wheelbase, it will suck.

I read on an V8 RX7 forum that they actually do well with the SBF because the engine sits low in the car but they don't do as well with a SBC. SBF's have thin walls so they are not that heavy. Then again it is going to have the added weight of the blower but like I said we could set it back some by modifying the firewall it's that the direction Ben has in mind.

[BRUTAL64]

Then again, if it is going to see a lot of autocrosses and road racing we may want to modify the firewall so the we can set the engine back some to inprove the weight balance.

This will be a must for good ( or fair ) balance.:)

[Leedom]

This will be a must for good ( or fair ) balance.:)

For the first project car lets just concentrate on going in 1 direction as opposed to many. I vote for straight line.

[BRUTAL64]

For the first project car lets just concentrate on going in 1 direction as opposed to many. I vote for straight line.

I vote for forward!:drink:

[Vettezuki]

For the first project car lets just concentrate on going in 1 direction as opposed to many. I vote for straight line.

It's not a matter of going extreme in one direction, or of having an exquisitely balanced all around performer, but a matter of balancing time, money, and effort requirements for the vehicle's different subsystems and enjoying the result.

Think of it this way:
Swapping out the whole rearend with a narrowed 8.8 is not a trivial matter. Swapping in a Turbo II diff and upgraded half shafts would be considerably easier overall, and possibly plenty stout. Remember we're not talking 1,000hp here, almost certainly well below 500 to the wheels. Anyways, this will be dictated by what the TII rearend can take, which I'm researching now.

[Vettezuki]

This is from a site that does nothing but sell conversion parts for RX-7s.

"...The RX-7's layout and structure is well suited to engine conversions. The rotary engine's eccentric shaft centerline is way up in the center of the rotary engine, dictating a much higher transmission location than that of a piston engine. The net result is that Mazda designed the RX-7 with a HUGE transmission tunnel, big enough to fit even the monster T-56 6 spd manual transmission which was used in the Viper and Corvette. The rotary engine's low torque output required Mazda to use a very heavy flywheel and a high rear gear ratio, a combination of factors that combined induce large amounts of stress on the RX-7's rear axles and hubs. Mazda planned accordingly, and designed plenty of strength into the RX-7's rear differential/axles/and hubs. Experience has shown that the stock NA RX-7 components are strong enough to withstand low 10sec 1/4mi passes, a feat that requires around 500hp. "


Well, that's interesting. . .

[94cobra69ss396]

This is from a site that does nothing but sell conversion parts for RX-7s.

"...The RX-7's layout and structure is well suited to engine conversions. The rotary engine's eccentric shaft centerline is way up in the center of the rotary engine, dictating a much higher transmission location than that of a piston engine. The net result is that Mazda designed the RX-7 with a HUGE transmission tunnel, big enough to fit even the monster T-56 6 spd manual transmission which was used in the Viper and Corvette. The rotary engine's low torque output required Mazda to use a very heavy flywheel and a high rear gear ratio, a combination of factors that combined induce large amounts of stress on the RX-7's rear axles and hubs. Mazda planned accordingly, and designed plenty of strength into the RX-7's rear differential/axles/and hubs. Experience has shown that the stock NA RX-7 components are strong enough to withstand low 10sec 1/4mi passes, a feat that requires around 500hp. "


Well, that's interesting. . .

That's good news.

[Vettezuki]

That's good news.

They should know, but I'm not sure I totally believe it. I guess we could proceed with the stock unit, knowing that it'll probably go boom sooner or later. I want us to use and enjoy this thing. :thumbs_up:

[BRUTAL64]

This is from a site that does nothing but sell conversion parts for RX-7s.

"...The RX-7's layout and structure is well suited to engine conversions. The rotary engine's eccentric shaft centerline is way up in the center of the rotary engine, dictating a much higher transmission location than that of a piston engine. The net result is that Mazda designed the RX-7 with a HUGE transmission tunnel, big enough to fit even the monster T-56 6 spd manual transmission which was used in the Viper and Corvette. The rotary engine's low torque output required Mazda to use a very heavy flywheel and a high rear gear ratio, a combination of factors that combined induce large amounts of stress on the RX-7's rear axles and hubs. Mazda planned accordingly, and designed plenty of strength into the RX-7's rear differential/axles/and hubs. Experience has shown that the stock NA RX-7 components are strong enough to withstand low 10sec 1/4mi passes, a feat that requires around 500hp. "


Well, that's interesting. . .

Kinda surprising. Well, should we test that statement?:confused:

[Vettezuki]

Kinda surprising. Well, should we test that statement?:confused:

Obviously we have no idea what the internal condition of the diff is right now. We have three options.
1 - Stay with the stock unit til it go boom
2 - Replace with T II unit (if I can determine that it's up to the task)
3 - Replace with narrowed 8.8

For now we'll go with 1, research 2, and do basic planning for 3.

[BRUTAL64]

Obviously we have no idea what the internal condition of the diff is right now. We have three options.
1 - Stay with the stock unit til it go boom
2 - Replace with T II unit (if I can determine that it's up to the task)
3 - Replace with narrowed 8.8

For now we'll go with 1, research 2, and do basic planning for 3.

That is a GOOD plan.:bigthumbsup:

[big2bird]

Obviously we have no idea what the internal condition of the diff is right now. We have three options.
1 - Stay with the stock unit til it go boom

For now we'll go with 1, research 2, and do basic planning for 3.

Second or third pass.:pot_stir:

[SeanPlunk]

Second or third pass.:pot_stir:

LOL, I love your cynasism. I say we set the over/under at 3 passes. I'll take the over :D

[Leedom]

I say we test that statement and when/if it blows up we can say for certain it can't handle it.

I will say over, but not by much.

[big2bird]

LOL, I love your cynasism. I say we set the over/under at 3 passes. I'll take the over :D

Under. (If I drive it first, 1 pass);)

Of course, without D/S and Axle Safety Hoops, I won't.:smack:

[big2bird]

I say we test that statement and when/if it blows up we can say for certain it can't handle it.

Ever seen what 350 HP does to a 3 1/2" Vette Halfshaft? I have. Looks like a donut/twist.:judge:

[BRUTAL64]

Under. (If I drive it first, 1 pass);)

Of course, without D/S and Axle Safety Hoops, I won't.:smack:

Pussy!!!:rolling::rolling::rolling::rolling:

[BRUTAL64]

Ever seen what 350 HP does to a 3 1/2" Vette Halfshaft? I have. Looks like a donut/twist.:judge:


That is with slicks. I USED to do 6,000 rpm blast starts with my Vette in the Seventies -on street tires "L60s" and NEVER twisted the 2.5 inch shafts I had then.:judge:


Hey, I talked to Doug last night. He is thinking of going on the Motorgen run Sat. How about you?

[big2bird]

That is with slicks. I USED to do 6,000 rpm blast starts with my Vette in the Seventies -on street tires "L60s" and NEVER twisted the 2.5 inch shafts I had then.:judge:


Hey, I talked to Doug last night. He is thinking of going on the Motorgen run Sat. How about you?

I might. Teri has a yearly migraine. It depends on how she feels.

[big2bird]

That is with slicks. I USED to do 6,000 rpm blast starts with my Vette in the Seventies -on street tires "L60s" and NEVER twisted the 2.5 inch shafts I had then.:judge:


Hey, I talked to Doug last night. He is thinking of going on the Motorgen run Sat. How about you?

Street tires, yes. Stickey Mickeys?

[big2bird]

Pussy!!!:rolling::rolling::rolling::rolling:

Ya ever see Ben's driveshaft on the Vette?

[BRUTAL64]

Street tires, yes. Stickey Mickeys?

Maybe then. Hell, "we won't know till we know" Yogie Beara

[BRUTAL64]

Ya ever see Ben's driveshaft on the Vette?

Yes, but the diff is in the rear. :huh:


Ok, I'll test it. :gatlin:

[Vettezuki]

There will certainly be DS and HS hoops. And I'm strongly leaning towards a fuel cell as well. I want this thing to get driven hard but be safe. I was joking with one of the guys last Sunday, probably Leedom; we could take it to the track, blow up the rear end in the first pass or two. The announcer will go, "well, that's it for them today." Of course, they don't know we'll have a rear end ready to swap, and we come back around two hours later. :drive:

[Vettezuki]

Ron, while you have it, can you measure the rear end so we can have a tentative idea of what might be required for an 8.8? I'm still thinking to the stock unit for now, but it really is, even in a rosey scenario, just a matter of time before it go boom.

I've been reading a lot more anecdotal cases, and it really seems all over the place.

[BRUTAL64]

I've been reading a lot more anecdotal cases, and it really seems all over the place.

Pieces of the rear end or the information?:sm_laughing:

[94cobra69ss396]

Will do. It's been too windy here to work on it but the wind seems to be dying down some today so hopefully I can back back to work on the cage tonight.

[Vettezuki]

Pieces of the rear end or the information?:sm_laughing:

Information, and in some cases, the rear end. :crutches: It ranges from, 300whp on the stock NA rear end seems to be the upper limit, in which case we'll blow it up on the first launch probably, to they handle 500BHP and 10 second passes. I'm guess because we're roots, sticky tires and manual, we'll be at the lower end. I'm considering going straight to the 8.8, that way I can attempt to sell the stock unit and won't have to have two different drive shafts made. Don't have to decide yet, but something to keep rolling around upstairs. Plenty to do for now.


One person did mention an 8.8 IRS. Something like the stock HS and hubs are fine, but the ring and pinion give. :huh: Maybe slotting an 8.8 pumkin in there is in an interesting combination. . .

[94cobra69ss396]

Information, and in some cases, the rear end. :crutches: It ranges from, 300whp on the stock NA rear end seems to be the upper limit, in which case we'll blow it up on the first launch probably, to they handle 500BHP and 10 second passes. I'm guess because we're roots, sticky tires and manual, we'll be at the lower end. I'm considering going straight to the 8.8, that way I can attempt to sell the stock unit and won't have to have two different drive shafts made. Don't have to decide yet, but something to keep rolling around upstairs. Plenty to do for now.


One person did mention an 8.8 IRS. Something like the stock HS and hubs are fine, but the ring and pinion give. :huh: Maybe slotting an 8.8 pumkin in there is in an interesting combination. . .


The IRS in the T-Birds and Cobra have the same 8.8 ring and pinion as the solid 8.8. The difference is that it uses half shafts that are not as strong as the solids axles.

[Vettezuki]

The IRS in the T-Birds and Cobra have the same 8.8 ring and pinion as the solid 8.8. The difference is that it uses half shafts that are not as strong as the solids axles.

What kind of power is your style IRS known for reliably holding? With slicks, and the right spring/shock combo, hop won't be a problem. What about geometry? I wonder how difficult it would be to slot in an 8.8 IRS vs. Solid. :huh:

[94cobra69ss396]

What kind of power is your style IRS known for reliably holding? With slicks, and the right spring/shock combo, hop won't be a problem. What about geometry? I wonder how difficult it would be to slot in an 8.8 IRS vs. Solid. :huh:

Solid would be easier to install. My Cobra doesn't have the IRS but Seans does and so did my old 94 T-Bird I use to have. Not sure what they take in stock form but Sean hasn't blown his up yet. Then again he launches his car like a grandma and run radials.

[BRUTAL64]

Information, and in some cases, the rear end. :crutches: It ranges from, 300whp on the stock NA rear end seems to be the upper limit, in which case we'll blow it up on the first launch probably, to they handle 500BHP and 10 second passes. I'm guess because we're roots, sticky tires and manual, we'll be at the lower end. I'm considering going straight to the 8.8, that way I can attempt to sell the stock unit and won't have to have two different drive shafts made. Don't have to decide yet, but something to keep rolling around upstairs. Plenty to do for now.


One person did mention an 8.8 IRS. Something like the stock HS and hubs are fine, but the ring and pinion give. :huh: Maybe slotting an 8.8 pumkin in there is in an interesting combination. . .

Darlene's T-bird has a 8.8 IRS....................a thought>:judge:

[Vettezuki]

Solid would be easier to install. My Cobra doesn't have the IRS but Seans does and so did my old 94 T-Bird I use to have. Not sure what they take in stock form but Sean hasn't blown his up yet. Then again he launches his car like a grandma and run radials.

What's a solid 8.8 out of a Ranger go for these days?

[Vettezuki]

Darlene's T-bird has a 8.8 IRS....................a thought>:judge:

Isn't that, uh, Darlene's car . . . :sm_up_there:

[94cobra69ss396]

What's a solid 8.8 out of a Ranger go for these days?

Not sure but we are better off getting one out of an Explorer because it has disc brakes already instead of dumb I mean drum brakes.

[BRUTAL64]

Isn't that, uh, Darlene's car . . . :sm_up_there:

Well, if she had something to drive other than the T-bird than we would have to get rid of the T-bird........................................... hint.:drink:

[BRUTAL64]

Not sure but we are better off getting one out of an Explorer because it has disc brakes already instead of dumb I mean drum brakes.


In drag racing Drum brakes are better. I have 4 wheel drums on my Vette, ask Adam how well they work.:rolling:

[Vettezuki]

In drag racing Drum brakes are better. I have 4 wheel drums on my Vette, ask Adam how well they work.:rolling:

Why, cuz there not actually in friction til engaged? Anywho, I don't think I could handle drum brakes. . . mentally. :smack:

[Vettezuki]

Not sure but we are better off getting one out of an Explorer because it has disc brakes already instead of dumb I mean drum brakes.

I forgot which model you suggested in the past. Explorer. Got it.

[Vettezuki]

Well, if she had something to drive other than the T-bird than we would have to get rid of the T-bird........................................... hint.:drink:

Well, get on it. :sm_laughing:

[BRUTAL64]

Why, cuz there not actually in friction til engaged? Anywho, I don't think I could handle drum brakes. . . mentally. :smack:

Hey, on our little run last sat, I didn't start to get fade until we hit Whittier Bl. on the way back. Actually drum brakes have more surface area for stopping than Disc.:drink:

No rolling fiction until brake shoes touch the drum.:bigthumbsup:

[Leedom]

There will certainly be DS and HS hoops. And I'm strongly leaning towards a fuel cell as well. I want this thing to get driven hard but be safe. I was joking with one of the guys last Sunday, probably Leedom; we could take it to the track, blow up the rear end in the first pass or two. The announcer will go, "well, that's it for them today." Of course, they don't know we'll have a rear end ready to swap, and we come back around two hours later. :drive:

Yeah that was me.

[Leedom]

In drag racing Drum brakes are better. I have 4 wheel drums on my Vette, ask Adam how well they work.:rolling:

Them theres fight'n words partner!! :nutkick:

[big2bird]

Hey, on our little run last sat, I didn't start to get fade until we hit Whittier Bl. on the way back. Actually drum brakes have more surface area for stopping than Disc.:drink:
That doesn't mean shit, and you know it.:nutkick:
No rolling fiction until brake shoes touch the drum.:bigthumbsup:

That part is true

[enkeivette]

If a NA stock diff can take 500hp, why not try it out?

What's a solid 8.8 out of a Ranger go for these days?

I'm with SSCobra, on the exploder diff. Additionally, most Ranger diffs are open. I think only the 4wd Rangers have LSD in the rear.

[Vettezuki]

If a NA stock diff can take 500hp, why not try it out?



I'm with SSCobra, on the exploder diff. Additionally, most Ranger diffs are open. I think only the 4wd Rangers have LSD in the rear.

Didn't know the Ranger diff wasn't and LSD. How bout the TBird IRS?

[big2bird]

How bout the TBird IRS?

Sounds like a big can of worms to me.:rolleyes:

[94cobra69ss396]

Didn't know the Ranger diff wasn't and LSD. How bout the TBird IRS?

I had a 94 T-Bird with the 4.6 V8 and it had a LSD.

[BRUTAL64]

That part is true

Damn Bird.
I had them going until you stepped in. :rolling::rolling:

[BRUTAL64]

Sounds like a big can of worms to me.:rolleyes:

I always heard Birds like worms.:)


Yea, T-bird IRS COULD be a problem, but we won't know until we look in to it further. The T-bird IRS is VERY well built. It looks much stronger than my Vette IRS.:motorsmile:

[BRUTAL64]

Them theres fight'n words partner!! :nutkick:

Hey, I didn't hit you once.:judge::rolling:

[Leedom]

I'm with SSCobra, on the exploder diff. Additionally, most Ranger diffs are open. I think only the 4wd Rangers have LSD in the rear.

I agree as well about the Exploder diff. And Adam I think you could get one with a 3.55 LS in the rear in 4x2 trim. You pretty much had to have the 4.0L motor I believe.

[enkeivette]

Sounds like a big can of worms to me.:rolleyes:

:iagree:

If you want to stick with the IRS, go turbo 2. No reason to fab stuff when a stout bolt in is available.

[Vettezuki]

:iagree:

If you want to stick with the IRS, go turbo 2. No reason to fab stuff when a stout bolt in is available.

I agree, either T2 or narrowed 8.8 solid. Probably solid, but don't need to decide just yet. We'll be using a stout manual probably a fairly grabby clutch and sticky tires. There are some guys running 500HP+ LS1s w/T56 and the T2, but it seems like they still can fail of course.

Also, there is the issue of gearing. For aesthetic reasons I'd like to run a shorter tire (25-26). With our trans and a 4.1 rear (both our stock NA and the T2 are 4.1) we'd pretty much have to run a 28" tire or we'll be redlining at like 115. :smack:

[big2bird]

How about Trans-Warp drive?:D

[BRUTAL64]

How about Trans-Warp drive?:D

What, straight WARP is not enough for you??????????:huh:

[94cobra69ss396]

I haven't measured it yet but I'm sure no matter what we get an 8.8 out of that we will have to have it narrowed because this car is little. It's just about the right size for my 7 year old. I'll just need to teach her how to drive a stick.

[big2bird]

I haven't measured it yet but I'm sure no matter what we get an 8.8 out of that we will have to have it narrowed because this car is little. It's just about the right size for my 7 year old. I'll just need to teach her how to drive a stick.

That's kinda why I said 9". It's been narrowed and used for decades. The parts HAVE to be cheaper and easier to get. Aren't they????????

[94cobra69ss396]

That's kinda why I said 9". It's been narrowed and used for decades. The parts HAVE to be cheaper and easier to get. Aren't they????????

I stand corrected. This is from Grannysspeedshop.com

'86-'93 Ford Mustang 8.8...
...59-1/2" flange/flange width (exact same as the '86-'91 RX-7)
...4 on 4-1/4" lug pattern, easily re-drilled to RX-7 4 or 5 on 4-1/2" pattern
...came std w/tracloc clutch style diff
...Both L&R axles are 29-1/8" long 28 spline axles
...V8's came with 2.73 or 3.08 ratios

'87-'88 Thunderbird Turbo Coupe...
...61-1/2" flange/flange width
...same housing width as '86-'93 Mustangs, but 1" longer axles to make room for ABS sensors
...4 on 4-1/2" lug pattern (same as the RX-7), easily re-drilled to RX-7 5 on 4-1/2"
...came std w/tracloc clutch style diff
...Both L&R axles are 30-1/8" long 28 spline axles
...5spd cars came with 3.55 gears, automatic cars came with 3.73
...standard w/ disc brakes

'95-'01 Explorer...
...59-1/2" flange/flange width
...5 on 4-1/2" lug pattern
...un-equal length 31 spline axles (2-3/16" pinion offset)
...std disc brakes w/ 7/16" x 11.25 rotors

They also sell a complete torque arm setup to bolt it right in that's just under $1000.

http://members.tripod.com/~grannys/TASA8500w.jpg

[BRUTAL64]

I stand corrected. This is from Grannysspeedshop.com

'86-'93 Ford Mustang 8.8...
...59-1/2" flange/flange width (exact same as the '86-'91 RX-7)
...4 on 4-1/4" lug pattern, easily re-drilled to RX-7 4 or 5 on 4-1/2" pattern
...came std w/tracloc clutch style diff
...Both L&R axles are 29-1/8" long 28 spline axles
...V8's came with 2.73 or 3.08 ratios

'87-'88 Thunderbird Turbo Coupe...
...61-1/2" flange/flange width
...same housing width as '86-'93 Mustangs, but 1" longer axles to make room for ABS sensors
...4 on 4-1/2" lug pattern (same as the RX-7), easily re-drilled to RX-7 5 on 4-1/2"
...came std w/tracloc clutch style diff
...Both L&R axles are 30-1/8" long 28 spline axles
...5spd cars came with 3.55 gears, automatic cars came with 3.73
...standard w/ disc brakes

'95-'01 Explorer...
...59-1/2" flange/flange width
...5 on 4-1/2" lug pattern
...un-equal length 31 spline axles (2-3/16" pinion offset)
...std disc brakes w/ 7/16" x 11.25 rotors

They also sell a complete torque arm setup to bolt it right in that's just under $1000.

http://members.tripod.com/~grannys/TASA8500w.jpg

That is pretty. I put in the first $10.00.:drink:

[big2bird]

That is pretty. I put in the first $10.00.:drink:

That looks like the ticket. I bet I can get that fabbed up for alot less.

The exploder has more splines, but I don't know if the gear carrier difference. My Ford knowledge is VERY weak here.

[BRUTAL64]

My Ford knowledge is VERY weak here.

That's because FORDs need VERY LITTLE repair. No need to know this stuff like on a GM.:laugh:

[big2bird]

That's because FORDs need VERY LITTLE repair. No need to know this stuff like on a GM.:laugh:

I have a Ford too. They just quit making them well about 1932.;)

[94cobra69ss396]

That looks like the ticket. I bet I can get that fabbed up for alot less.

The exploder has more splines, but I don't know if the gear carrier difference. My Ford knowledge is VERY weak here.

The carriers are the same except for spline count unless of course you have a Cobra like mine that came with 31 spline axles.

Joe and I could make something like this if that's the route we want to take.

[Vettezuki]

That looks like the ticket. I bet I can get that fabbed up for alot less.

The exploder has more splines, but I don't know if the gear carrier difference. My Ford knowledge is VERY weak here.

Who can do it? How much? How long?

I'm certainly leaning this way.

[Vettezuki]

I stand corrected. This is from Grannysspeedshop.com

'86-'93 Ford Mustang 8.8...
...59-1/2" flange/flange width (exact same as the '86-'91 RX-7)
...4 on 4-1/4" lug pattern, easily re-drilled to RX-7 4 or 5 on 4-1/2" pattern
...came std w/tracloc clutch style diff
...Both L&R axles are 29-1/8" long 28 spline axles
...V8's came with 2.73 or 3.08 ratios

'87-'88 Thunderbird Turbo Coupe...
...61-1/2" flange/flange width
...same housing width as '86-'93 Mustangs, but 1" longer axles to make room for ABS sensors
...4 on 4-1/2" lug pattern (same as the RX-7), easily re-drilled to RX-7 5 on 4-1/2"
...came std w/tracloc clutch style diff
...Both L&R axles are 30-1/8" long 28 spline axles
...5spd cars came with 3.55 gears, automatic cars came with 3.73
...standard w/ disc brakes

'95-'01 Explorer...
...59-1/2" flange/flange width
...5 on 4-1/2" lug pattern
...un-equal length 31 spline axles (2-3/16" pinion offset)
...std disc brakes w/ 7/16" x 11.25 rotors

They also sell a complete torque arm setup to bolt it right in that's just under $1000.



I didn't quite get it. Was the point that any of those rears can go in without being narrowed and that the 86-93 Mustang 8.8 and 95-01 Explorer are exactly the same as our FC RX-7 (59.5" flange width)?

[94cobra69ss396]

I didn't quite get it. Was the point that any of those rears can go in without being narrowed and that the 86-93 Mustang 8.8 and 95-01 Explorer are exactly the same as our FC RX-7 (59.5" flange width)?

Correct. So we just need to go to a wrecking yard and pull one from an Explorer. Shouldn't be hard to get one. Eric97srad and I went a few months ago to buy some frontend part for his 97 Explorer and the yard we went to had about 30 of them.

[Vettezuki]

Correct. So we just need to go to a wrecking yard and pull one from an Explorer. Shouldn't be hard to get one. Eric97srad and I went a few months ago to buy some frontend part for his 97 Explorer and the yard we went to had about 30 of them.

The explorer shows an unequal length for the axles. Doesn't this create an angle from the tailshaft of the trans to the pumpkin? In our application are there any issues with that geometry?

[94cobra69ss396]

The explorer shows an unequal length for the axles. Doesn't this create an angle from the tailshaft of the trans to the pumpkin? In our application are there any issues with that geometry?

It's only offset a little and no it won't matter. If you look under Phil's FJ40 both the front and rear axles are offset to different sides.

[big2bird]

The explorer shows an unequal length for the axles. Doesn't this create an angle from the tailshaft of the trans to the pumpkin? In our application are there any issues with that geometry?

As long as the opposing U-joint angles are equal, opposing, and 3* or less, to provide proper phase cancellation. It could be a problem with a short D/S.
Is the other carrier "centered?"

[Vettezuki]

As long as the opposing U-joint angles are equal, opposing, and 3* or less, to provide proper phase cancellation. It could be a problem with a short D/S.
Is the other carrier "centered?"

I'm not sure this is the question you asked, but, the trans will be "very" center and the DS would be quite short as I imagine it. So the U joint angles would not be opposing and the DS would be greater than 3* as I imagine it. :huh: The explorer has the advantage of 31 spline axles and already being a 5 lug. However, I don't think at our power levels 28 spline is such a problem (our trans output is 28 spline), and converting the hubs to 5 lug ain't such a big deal. Please to advise. Maybe the Stang is a better starting point, though we'd have to regear. . .

[big2bird]

I'm not sure this is the question you asked, but, the trans will be "very" center and the DS would be quite short as I imagine it. So the U joint angles would not be opposing and the DS would be greater than 3* as I imagine it. :huh: The explorer has the advantage of 31 spline axles and already being a 5 lug. However, I don't think at our power levels 28 spline is such a problem (our trans output is 28 spline), and converting the hubs to 5 lug ain't such a big deal. Please to advise. Maybe the Stang is a better starting point, though we'd have to regear. . .

If the Stag pinion yoke is centered between the wheels, then yes, it would be better. (Short answer):thumbs_up:

[big2bird]

So obviously the Exploder is offset for a transfer case, so the Mustang looks like a good fit. If that means gear change, rather than trying to find a LSD, we can get a spool for $90, a gear set for $150., and set it up killer. Maybe I should take Ben down to Unitrax, and see what they might have laying around. Time to start whooing some venders. They might also provide some good advice/guidence concerning this adventure.
As for brakes, as long as the car stops by the last turn off, they are fine.:sm_laughing:

[joedls]

So obviously the Exploder is offset for a transfer case, so the Mustang looks like a good fit. If that means gear change, rather than trying to find a LSD, we can get a spool for $90, a gear set for $150., and set it up killer. Maybe I should take Ben down to Unitrax, and see what they might have laying around. Time to start whooing some venders. They might also provide some good advice/guidence concerning this adventure.
As for brakes, as long as the car stops by the last turn off, they are fine.:sm_laughing:


I have a set of 3.55 gears for an 8.8 that only have 7000 miles on them. Switched them for 4.10s. That may work better for that 4 speed anyway with a 25" - 26" tire.

[94cobra69ss396]

The Explorer center section looks centered. I'll measure mine today and tell you for certain. Also, most Explorers came with 3.73 gears which will be a good gear for the RX-Snake.

[Vettezuki]

The Explorer center section looks centered. I'll measure mine today and tell you for certain. Also, most Explorers came with 3.73 gears which will be a good gear for the RX-Snake.

Assuming 26.1 tires (275/50x15) our transmission and a 6,000rpm shift point/red line, I think we' could take advantage of the taller 3.55 gears.

3.55 = 127mph
3.73 = 121mph

I think we'll have the power to weight to ring out the taller gear and have a faster trap/et.

[BRUTAL64]

Assuming 26.1 tires (275/50x15) our transmission and a 6,000rpm shift point/red line, I think we' could take advantage of the taller 3.55 gears.

3.55 = 127mph
3.73 = 121mph

I think we'll have the power to weight to ring out the taller gear and have a faster trap/et.

Ok, with my 3:55s I hit 119 in third gear. That's with a 27.9 (P275 15 60) inch on the 3,000 pound vette. So.......................I don't see how your math is right. Math and the real world don't always jive. Just not sure about it is all. :drink:

[94cobra69ss396]

Assuming 26.1 tires (275/50x15) our transmission and a 6,000rpm shift point/red line, I think we' could take advantage of the taller 3.55 gears.

3.55 = 127mph
3.73 = 121mph

I think we'll have the power to weight to ring out the taller gear and have a faster trap/et.

Can you run a 28 inch tire with 3.73 gears and tell me what mph you show for 6000rpm?

Also know that a Slick will grow as you go sown the track. So if we use a 26 inch slick it will act like a taller tire further down.

[big2bird]

Ok, with my 3:55s I hit 119 in third gear. That's with a 27.9 (P275 15 60) inch on the 3,000 pound vette. So.......................I don't see how your math is right. Math and the real world don't always jive. Just not sure about it is all. :drink:

Glenn, what do think about raising the duration/retarding the cam, installing really stiff springs, and raising the redline? (Think Beehives)

[Vettezuki]

Ok, with my 3:55s I hit 119 in third gear. That's with a 27.9 (P275 15 60) inch on the 3,000 pound vette. So.......................I don't see how your math is right. Math and the real world don't always jive. Just not sure about it is all. :drink:

The weight is irrelevant, what was your rpm at 119rpm? Your math might be fine. Mine rocks. :penguin:

Here's a nice accurate graph of a wide ratio top loader, 3.55 gears and 275/50x15 tires. The engine turns the trans turns the axle (not a lop of slop there) turns the tires. Pressure and rotational inertia can have some effect on "real" diameter and effect total final "gearing", but the margin of error would be a couple mph at most I would think.

http://motorgen.com/pic/data/500/RX-SnakeTransAxleTire3.jpg

[BRUTAL64]

Glenn, what do think about raising the duration/retarding the cam, installing really stiff springs, and raising the redline? (Think Beehives)

Ok, when I had my 289 Hipo it would run to 7000+ rpms with the solid lifter factory cam and stock valve springs. The problem we have here is the unknown cam. I think a switch to a known cam with soild lifter/roller will allow the 302 to rev more freely. Beehives are a thought, but cost factor will be an issue.:drink:

[big2bird]

If weight is irrelevent, let's make the RX 20,000lbs. Should be good for traction.:smack:

[big2bird]

Ok, when I had my 289 Hipo it would run to 7000+ rpms with the solid lifter factory cam and stock valve springs. The problem we have here is the unknown cam. I think a switch to a known cam with soild lifter/roller will allow the 302 to rev more freely. Beehives are a thought, but cost factor will be an issue.:drink:

That MUST change . The cam is EVERYTHING.

[Vettezuki]

Glenn, what do think about raising the duration/retarding the cam, installing really stiff springs, and raising the redline? (Think Beehives)

What about blower effeciency? I was under the impression these smaller roots blowers will start to fall on their face from 5,500 - 6,000 rpm. :huh:

[BRUTAL64]

The weight is irrelevant, what was your rpm at 119rpm? Your math might be fine. Mine rocks. :penguin:

Here's a nice accurate graph of a wide ratio top loader, 3.55 gears and 275/50x15 tires. The engine turns the trans turns the axle (not a lop of slop there) turns the tires. Pressure and rotational inertia can have some effect on "real" diameter and effect total final "gearing", but the margin of error would be a couple mph at most I would think.

http://motorgen.com/pic/data/500/RX-SnakeTransAxleTire3.jpg

Weight is always a factor:laugh::laugh::laugh:

If I remember correctly it was around 6200 to 6500 rpm. I'm just saying a 3.55 gear MIGHT be too tall in the real world. I remember when I was running the 1/4 I was just shifting into forth just before I hit the light with the 3.55s.


Not saying you are wrong , just stating a little real world testing would help here.:drink:

[Vettezuki]

If weight is irrelevent, let's make the RX 20,000lbs. Should be good for traction.:smack:

Weight is irrelevant for calculating gearing and "potential" speed you silly goose.

[Vettezuki]

Can you run a 28 inch tire with 3.73 gears and tell me what mph you show for 6000rpm?

Also know that a Slick will grow as you go sown the track. So if we use a 26 inch slick it will act like a taller tire further down.

I have to go for a few hours, I'll run this later. But yes, the tire changes in diameter is where the real world differences in speed as a function of gearing changes.

[joedls]

Can you run a 28 inch tire with 3.73 gears and tell me what mph you show for 6000rpm?

Also know that a Slick will grow as you go sown the track. So if we use a 26 inch slick it will act like a taller tire further down.


Without allowing for any growth and/or variances in the tire, a 28" tire with 3.73 gears will be running ~134 MPH @ 6000 RPM in fourth gear.

[BRUTAL64]

I have to go for a few hours, I'll run this later. But yes, the tire changes in diameter is where the real world differences in speed as a function of gearing changes.

Just for shits.:D WEIGHT can limit the rpms the engine is able to turn.:p


What ever could be MORE important than Motorgen??????????:rant:




Hey, I just noticed I have OVER 1000 posts on this site. Damn, what the hell would I have to say that takes that many posts???????:huh::o:suicide:

[Vettezuki]

Just for shits.:D WEIGHT can limit the rpms the engine is able to turn.:p


What ever could be MORE important than Motorgen??????????:rant:



Absolutely.

My implicit assumption was that given our power to weight ratio, the engine would have sufficient power to rapidly reach redline given either a 3.55 or 3.73 axle. I was isolating a single variable in the system. There is basically no cost difference with either axle, but there plausibly could be a few mph and/or couple tenths penalty one way or the other. My hypothesis would be that with the power to weight we're likely to have, the "slightly" taller rear axle, would result in faster ET and Trap in the 1/4. However, it is possible that while the top potential speed is lower with the shorter gear, it may reach that top speed faster enough to result in a faster ET. :huh: To model this properly we'd be changing from simple arithmetic to real math. I'm looking for accumulated experience.

Anyway, this is getting to the kinda splitting hair territory, but I enjoy that, so you have to endure it. :pot_stir: :smack:

[Vettezuki]

. . . .

What ever could be MORE important than Motorgen??????????:rant:

. . . .

Making the scratch that allows me to underwrite this project is pretty important. :bigthumbsup:

[Vettezuki]

Without allowing for any growth and/or variances in the tire, a 28" tire with 3.73 gears will be running ~134 MPH @ 6000 RPM in fourth gear.

A tiny bit slower, but close enough. :bigthumbsup:

6,000rpm (shift/redline)
Wide Ratio Top Loader
3.73 Axle
275/60x15 Tire

If we have enough power to turn this gearing (my guess is around 500 BHP with this much weight, very rough) and make it stick for a wicked 60', and click off clean shifts, this would be a consistent low mid 10 second pass.

http://motorgen.com/pic/data/500/RX-SnakeTransAxleTire4.jpg

[BRUTAL64]

Anyway, this is getting to the kinda splitting hair territory, but I enjoy that, so you have to endure it. :pot_stir: :smack:


You mean endure it....:rolling::rolling::rolling::rolling:like a tooth ache????

[joedls]

A tiny bit slower, but close enough. :bigthumbsup:

6,000rpm (shift/redline)
Wide Ratio Top Loader
3.73 Axle
275/60x15 Tire

[/IMG]

Since we're being nitpicky, your math is a little off. Here's how I calculated it.

MPH= ((RPM/(rear gear ratio*trans gear ratio))*60)/tire revs per mile

RPM = 6000
Rear Gear = 3.73
Trans gear ratio = 1
Tire revs per mile = 720.49
MPH = 133.95708

Thus my earlier posting that it would be ~134 MPH.

[Vettezuki]

Since we're being nitpicky, your math is a little off. Here's how I calculated it.

MPH= ((RPM/(rear gear ratio*trans gear ratio))*60)/tire revs per mile

RPM = 6000
Rear Gear = 3.73
Trans gear ratio = 1
Tire revs per mile = 720.49
MPH = 133.95708

Thus my earlier posting that it would be ~134 MPH.

My sheet does three things a little differently. It calculates circumference exactly on input tire size. A 275/60x15 is slightly less than 28 inches. Additionally for reasons I can't remember and forgot were in there it has built in corrections altering the revs per mile and revs through the transmission. Hence the reduction from your completely accurate pure calculation. I can alter my sheet to remove these built-in corrections and we'll come out to the same numbers exactly. But this would be a totally idealized, perfect circumference, no slop kinda situation. I suspect my sheet may model reality a little more closely, but I certainly can't give you the logical proof for the constants that are used. There, aren't you glad you asked?

[BRUTAL64]

Making the scratch that allows me to underwrite this project is pretty important. :bigthumbsup:

"If" I wanted to donate a buck or two how would SOMEONE do this???:leaving:

[joedls]

My sheet does three things a little differently. It calculates circumference exactly on input tire size. A 275/60x15 is slightly less than 28 inches. Additionally for reasons I can't remember and forgot were in there it has built in corrections altering the revs per mile and revs through the transmission. Hence the reduction from your completely accurate pure calculation. I can alter my sheet to remove these built-in corrections and we'll come out to the same numbers exactly. But this would be a totally idealized, perfect circumference, no slop kinda situation. I suspect my sheet may model reality a little more closely, but I certainly can't give you the logical proof for the constants that are used. There, aren't you glad you asked?


So how many tire revs per mile does your sheet calculate? Because I calculated the revs per mile using the exact circumference of what a 275-60-15 tire should be. I don't allow for any variances and frankly I don't know how your spreadsheet could do that accurately, considering different variances between tire, tranny, and rear-end manufacturers.

Here is my calculation.

(((275/25.4)*.6)*2)+15 = 27.992125 (Tire diameter)

27.992125 * 3.1416 = 87.940059 (Tire circumference in inches)

87.940059/12 = 7.3283382 (Tire circumference in feet)

5280/7.3283382 = 720.49076 (tire revolutions per mile)

[joedls]

BTW. I'll be going to Pomona. Anything you want me to be on the lookout for?

[Vettezuki]

BTW. I'll be going to Pomona. Anything you want me to be on the lookout for?

Don't knwo what all they have there, since I've never been, but:

- Repair Parts for the 174
- Holley 750 CFM Carb with four corner idle set (if on the pretty cheap side relative to new, might give that a whirl first)
- Radiator for an 2nd Gen RX-7, we don't have one
- Alternator w/Bracket
- Starter

These I can get new from Summit, but if you see them cheap:
- Scatter Shield for Top Loader
- Long Tube Swap Headers for SBF

I trust your judgement, send me the bill. :sm_up_there:

[Vettezuki]

So how many tire revs per mile does your sheet calculate? Because I calculated the revs per mile using the exact circumference of what a 275-60-15 tire should be. I don't allow for any variances and frankly I don't know how your spreadsheet could do that accurately, considering different variances between tire, tranny, and rear-end manufacturers.

Here is my calculation.

(((275/25.4)*.6)*2)+15 = 27.992125 (Tire diameter)

27.992125 * 3.1416 = 87.940059 (Tire circumference in inches)

87.940059/12 = 7.3283382 (Tire circumference in feet)

5280/7.3283382 = 720.49076 (tire revolutions per mile)

Here's the Excel Fomula for Revs Per Mile I'm using:
=(63360/(((B9/25.4*(D9/100)*2)+F9)*3.141597)) *0.99

B9 = Section Width
D9 = Aspect Ratio
F9 = Rim Diamter

It's basically the same as yours, EXCEPT for the last multiplication. This actually reduces the number of revs per mile and therefore increase the speed for a given RPM. I believe it was the original desginers intention to account for growth in the tire as a function of heat/pressure and rotational inertia.:huh:

However, my sheet also inlucdes a big reduction when calculating the speed for a given tire/axle/gear @ RPM x.

=((D18/(B21*B28*H9))*60)*0.97

D18= RPM (shift or redline, or whatever you want to put in, I'm assuming 6k)
B21=Gear ratio
B28=Axle ratio
H9=tire revs per mile

The final multiplication is an additional reduction I forgot about. If I had to guess it's for nonlockup auto trans, but that's just a guess. Thanks for the catch. :thumbs_up:

I'll take out these constants for future calculations so we're comparing apples to apples.

[big2bird]

Don't knwo what all they have there, since I've never been, but:

- Repair Parts for the 174
- Holley 750 CFM Carb with four corner idle set (if on the pretty cheap side relative to new, might give that a whirl first)
- Radiator for an 2nd Gen RX-7, we don't have one
- Alternator w/Bracket
- Starter

These I can get new from Summit, but if you see them cheap:
- Scatter Shield for Top Loader
- Long Tube Swap Headers for SBF

I trust your judgement, send me the bill. :sm_up_there:

Alt and starter you can get cheap from the zone rebuilt, and forfeit the $10 core charge.
Radiator, I would hold off on. I may get that REAL cheap from a friend. (He owns Anaheim Radiator). He can probably make us one custom.

[big2bird]

Here's the Excel Fomula for Revs Per Mile I'm using:
=(63360/(((B9/25.4*(D9/100)*2)+F9)*3.141597)) *0.99

B9 = Section Width
D9 = Aspect Ratio
F9 = Rim Diamter

It's basically the same as yours, EXCEPT for the last multiplication. This actually reduces the number of revs per mile and therefore increase the speed for a given RPM. I believe it was the original desginers intention to account for growth in the tire as a function of heat/pressure and rotational inertia.:huh:

However, my sheet also inlucdes a big reduction when calculating the speed for a given tire/axle/gear @ RPM x.

=((D18/(B21*B28*H9))*60)*0.97

D18= RPM (shift or redline, or whatever you want to put in, I'm assuming 6k)
B21=Gear ratio
B28=Axle ratio
H9=tire revs per mile

The final multiplication is an additional reduction I forgot about. If I had to guess it's for nonlockup auto trans, but that's just a guess. Thanks for the catch. :thumbs_up:

I'll take out these constants for future calculations so we're comparing apples to apples.

Quit bench racing. So your off 1mph or so. The traps will tell the truith.:D

[joedls]

Don't knwo what all they have there, since I've never been, but:

- Repair Parts for the 174
- Holley 750 CFM Carb with four corner idle set (if on the pretty cheap side relative to new, might give that a whirl first)
- Radiator for an 2nd Gen RX-7, we don't have one
- Alternator w/Bracket
- Starter

These I can get new from Summit, but if you see them cheap:
- Scatter Shield for Top Loader
- Long Tube Swap Headers for SBF

I trust your judgement, send me the bill. :sm_up_there:

I'll call you if I stumble upon a good deal. Is someone maufacturing headers for this swap?

[Vettezuki]

Quit bench racing. So your off 1mph or so. The traps will tell the truith.:D

We don't have a car to race for real yet. :smack: And this is (theoretically) for choosing the best possible total combo in the first place.

[Vettezuki]

I'll call you if I stumble upon a good deal. Is someone maufacturing headers for this swap?

These (http://store.summitracing.com/partdetail.asp?part=BBK-1569&FROM=MG) appear to be the best candidates for our swap.

[Vettezuki]

Alt and starter you can get cheap from the zone rebuilt, and forfeit the $10 core charge.
Radiator, I would hold off on. I may get that REAL cheap from a friend. (He owns Anaheim Radiator). He can probably make us one custom.

Roger. I've been using Duralast alts and starters on other vehicles for a while, and they seem pretty well made and reasonably priced. BTW, what years was this motor in production, or what car can I use as the reference when buying parts?

[big2bird]

These (http://store.summitracing.com/partdetail.asp?part=BBK-1569&FROM=MG) appear to be the best candidates for our swap.

I have been meaning to ask. What is the latest NHRA on sound? Are open headers still okay? (Dating myself)

[big2bird]

Roger. I've been using Duralast alts and starters on other vehicles for a while, and they seem pretty well made and reasonably priced. BTW, what years was this motor in production, or what car can I use as the reference when buying parts?

Ask the Ford guys. I would guess since 289 and 302 are the same block, 63-86?:smack:(I really don't know Fords like Glenn)

[Vettezuki]

I have been meaning to ask. What is the latest NHRA on sound? Are open headers still okay? (Dating myself)

As far as I know, yes, but something to check. I'll put this in the questions section. I see this car being run at street legal, TNT, private track days and *maybe* PSCA.

[Leedom]

As far as I know, yes, but something to check. I'll put this in the questions section. I see this car being run at street legal, TNT, private track days and *maybe* PSCA.

We could always get some cut-outs. That way we can go either way. We can just get the cheap manual ones, not the electronic ones.

[enkeivette]

Open headers? You wimps. Why not zoomies? I can cut two slots in the hood for each row of tubes.

No I'm not kidding.

[Vettezuki]

Open headers? You wimps. Why not zoomies? I can cut two slots in the hood for each row of tubes.

No I'm not kidding.

That'll match the Rebel Flag theme nicely. . . :sm_up_there:

[enkeivette]

That'll match the Rebel Flag theme nicely. . . :sm_up_there:

No but it will add to the Amerijap car confusion... and horsepower.

[eric97srad]

BUMP


So, as long as you guys can wait until I get back from this deployment (mid-November) AND I can find an IRS for a decent price for the Mustang - the rear-end from her is definitely available for the project...

[94cobra69ss396]

BUMP


So, as long as you guys can wait until I get back from this deployment (mid-November) AND I can find an IRS for a decent price for the Mustang - the rear-end from her is definitely available for the project...

Don't go to an IRS on your car. You can make your car handle just as good with the solid axle and it will be a lot stronger.

Ben, if you want to upgrade to a solid 8.8 I can check with GTR and see if they have one laying around.

[Vettezuki]

Don't go to an IRS on your car. You can make your car handle just as good with the solid axle and it will be a lot stronger.

Ben, if you want to upgrade to a solid 8.8 I can check with GTR and see if they have one laying around.

If you could get a quote, I'd be curious. Currently I have the stock IRS fully dropped and disassembled. I still have a hankering to harden it with Delrin/UVHM/Solid mounts and bushings and use it.

[94cobra69ss396]

If you could get a quote, I'd be curious. Currently I have the stock IRS fully dropped and disassembled. I still have a hankering to harden it with Delrin/UVHM/Solid mounts and bushings and use it.

I just checked and they don't have any.

[Vettezuki]

I just checked and they don't have any.

It's cool, thanks. Once hardened the IRS and stock diff is supposed good for 10s with a V8 which, is about where we'll be so we'll probably just go that route.

I am; however, looking into regearing the unit so we an run a shorter tire.

[enkeivette]

Isn't the best thing to regear the diff numerically higher, run the tallest & widest tire possible, nearing redline in 4th gear at the expected trap speed? Leaving nothing on the table.

Or I guess with enough power it might be better to near redline in 3rd at the trap speed. Right?

My line of thinking, you don't want to waste time shifting right before you finish. And it's best to use the gearing to the cars advantage, up until you make enough power to waste the short gearing. But I don't think we're in that range.

[Vettezuki]

Isn't the best thing to regear the diff numerically higher, run the tallest & widest tire possible, nearing redline in 4th gear at the expected trap speed? Leaving nothing on the table.

Or I guess with enough power it might be better to near redline in 3rd at the trap speed. Right?

My line of thinking, you don't want to waste time shifting right before you finish. And it's best to use the gearing to the cars advantage, up until you make enough power to waste the short gearing. But I don't think we're in that range.

The problem is that the approrpiate sized tire for our gearing presents fitment problems; it's very borderline. When expanding it might rub up into the wheel well. It probably doesn't matter for dragging, but taller gearing and shorter tire means less rotational mass (smaller tire). I'm only entertaining the idea because I have to buy wheels and tires anyway.

[BRUTAL64]

The problem is that the approrpiate sized tire for our gearing presents fitment problems; it's very borderline. When expanding it might rub up into the wheel well. It probably doesn't matter for dragging, but taller gearing and shorter tire means less rotational mass (smaller tire). I'm only entertaining the idea because I have to buy wheels and tires anyway.

What ratio do you have now?

[Vettezuki]

What ratio do you have now?

4.10

We'd have to run something close to a 28" tire to take advantage of the power, winding out to redline and trapping around 130. Which is all fine, except a 28" tire is a damn snug fit, and if it's a race slick it'll probably expand into the well, Which is non-ideal. :smack: Also, I'd prefer the look of a somewhat smaller tire.

[BRUTAL64]

4.10

We'd have to run something close to a 28" tire to take advantage of the power, winding out to redline and trapping around 130. Which is all fine, except a 28" tire is a damn snug fit, and if it's a race slick it'll probably expand into the well, Which is non-ideal. :smack: Also, I'd prefer the look of a somewhat smaller tire.


You know real world and paper specs don't always match. You have a 4.10 use it. It's a good starting ratio and I'm thinking ( not always a good thing ) it could work out good for you. Stick your 26 inch tire on there and let rip. You are going to have wheel spin no mater what you do and that will screw up any paper specs you come up with.:bigthumbsup:

[Vettezuki]

Hey kiddies, picture time. While I'm low on time/cash resources (temporary) to kick this project into high gear, we do what we can to keep it moving.

Death Cult and I droppped, dissasembled and cleaned the IRS last week. Here tis:

Freshly dropped:
http://motorgen.com/pic/data/771/IRS_01.JPG

http://motorgen.com/pic/data/771/IRS_12.JPG

Disassembling, Cleaning
http://motorgen.com/pic/data/771/IRS_16.JPG

http://motorgen.com/pic/data/771/IRS_17.JPG

http://motorgen.com/pic/data/771/IRS_03.JPG

http://motorgen.com/pic/data/771/IRS_06.JPG

http://motorgen.com/pic/data/771/IRS_08.JPG

http://motorgen.com/pic/data/771/IRS_02.JPG

[94cobra69ss396]

I agree with Glen. I think the 4.10 will be close to ideal for the engine combo you have now. Also know that I went 10.45 at 128 in the Chevelle on a 26x8.5x14 tire so I think you can get that car to hook up on a 9 or 9.5 inch tire. Remember when we test fit my Cobra tires on it? They were 26x9.5x17 but on a 8 inch rim they are closer to 27 inches tall and they fit perfect. I launch the Cobra at 6000 rpms on those and they hook with my 3650lbs. so I think they will hook good in a lighter car with a lower rpm launch. If you want to use my tires before buying some just let me know. That way you can see how much tire you'll need and if the gearing will need to be changed.

[Vettezuki]

I agree with Glen. I think the 4.10 will be close to ideal for the engine combo you have now. Also know that I went 10.45 at 128 in the Chevelle on a 26x8.5x14 tire so I think you can get that car to hook up on a 9 or 9.5 inch tire. Remember when we test fit my Cobra tires on it? They were 26x9.5x17 but on a 8 inch rim they are closer to 27 inches tall and they fit perfect. I launch the Cobra at 6000 rpms on those and they hook with my 3650lbs. so I think they will hook good in a lighter car with a lower rpm launch. If you want to use my tires before buying some just let me know. That way you can see how much tire you'll need and if the gearing will need to be changed.

Thanks Ron, I'm grateful for all your help.

My concern with the fitment of your tire would be how much it might expand under heavy acceleration. I rembember there beings something like maybe a 1/2 clearance. No way I'd trust something like a wrinkle wall slick of that approximate size, but maybe a DR or, basic (?) slick, might not expand too much. What do you think?


Second question. Might I be able to bring out the pumpkin to you and you could pop it open and take a look at the gears and maybe the LSD to evaluate it's condition. I figure while things are totally apart, it makes some sense to evaluate their condition.

[enkeivette]

Invite me when you guys go through the diff. That's the one thing I've yet to learn.

[Vettezuki]

Invite me when you guys go through the diff. That's the one thing I've yet to learn.

That's it, then you're all done? :smack:

[94cobra69ss396]

Thanks Ron, I'm grateful for all your help.

My concern with the fitment of your tire would be how much it might expand under heavy acceleration. I rembember there beings something like maybe a 1/2 clearance. No way I'd trust something like a wrinkle wall slick of that approximate size, but maybe a DR or, basic (?) slick, might not expand too much. What do you think?


Second question. Might I be able to bring out the pumpkin to you and you could pop it open and take a look at the gears and maybe the LSD to evaluate it's condition. I figure while things are totally apart, it makes some sense to evaluate their condition.

They fit fine and even if they grow they won't rub. :thumbs_up: However, with the short sidewall on them I doubt they will grow much.

We can take a look at the rearend anytime. All we need to check for is the wear pattern on the ring and pinion and check the bearings and race for pitting and wear. As for checking the limited slip it all depends on what type Mazda used. Did they use a clutch style?

[Vettezuki]

. . . As for checking the limited slip it all depends on what type Mazda used. Did they use a clutch style?


Thy had both in that era and I "believe" ours is a clutch type.

[Vettezuki]

What is the difference betweent he Tbird and Explorer 8.8 Diffs?

It looks like a guy is building a setup to allow mounting an Explorer sourced 8.8 into the stock IRS. Some fab required for axles, but otherwise, looks like a pretty slick solution.

http://www.v8rx7forum.com/v8-rx7-technical/54844-fc-8-8-irs-rear-v2-0-a.html

[Ultraperio]

I'm new here but this sort of project is right up my alley.

As for the diff selection, if your going to be using a blown 302 with 500hp or less there is no point in the time, energy, or cost of doing a solid axle swap. I don't know what model FC you have but ill assume its a GTU based on the 5 lug hubs, LSD, and 4.11. I wouldn't trust the n/a diff much farther than you can throw it. It'll probably hold up... for a bit. I would go with a TII rear, these little diffs have proven to hold up reliably with 600+hp launches(im talking about SBC power here). Hell they actually swap the TII rears into 93+ FD's. If one does happen to grenade they are on ebay all the time for ~$200. As for gearing your pretty much limited to 3.9, 4.11, or 4.33 as far as readily available ratio's go.

Another option you might want to look into is a guy in the 7 community was building subframes to fit an IRS dana 36/44 out of a C4 into the FD and FC. I'll look to see if i can find his page/thread(been a few years since i've heard anything) but this will enable you to keep the IRS and open up all kinds of gearing options. The other, more common way to go would be the cobra 8.8 irs swap. there's guys that make subframes already and you can pick up the complete 8.8 setup for about $1k.

If you do decide to go live axle the most reasonable method would be a '96+ explorer (all over junk yards in good condition for ~$250). the explorers have the higher spline count axles and are stronger than most of the 8.8 ranger and mustang rears. You'd want '96+ because of the disk brakes. There's no reason to go with a 9" as far as i can tell based on projected power. Plus if your stressing over any slight lateral location of the pinion on the 8.8. the 9" pinion is around 2" to the right.

I personally have something against live axle 7's tho, its a good handling car. If you just want a good power to weight with a live axle for the strip there's always the fox body.

Anyway, I'm about a year late for this party so the decision might have already been made. But still, i'd love to help out. Anything you need to know about the FC just let me know.

[Vettezuki]

Another option you might want to look into is a guy in the 7 community was building subframes to fit an IRS dana 36/44 out of a C4 into the FD and FC. I'll look to see if i can find his page/thread(been a few years since i've heard anything) but this will enable you to keep the IRS and open up all kinds of gearing options. The other, more common way to go would be the cobra 8.8 irs swap. there's guys that make subframes already and you can pick up the complete 8.8 setup for about $1k.

Hot damn! Consider yourself volunteered. My current thinking is the 8.8 IRS setup, but I thought total cost pushed $2k, by the time you were done with the half shaft work etc.? I seriously considered the TII diff as it does seem to be strong, but we'll be talking a torque monster on sticky rubber and it seems 450WHP is more the real world break point. At least that's what I found. :huh: Putting the TII is tribial and cheap compared to the 8.8" . . . that's for damn sure.

BTW, This project was put on a kind of back burner as my wife left her gig about a year ago now and we decided now is a great time to start a small business. It's working out ok, and all the foot work is done on that, but still hemorrhaging play money. Nevertheless, I'm hell bent to keep pushing on this as I can and one the play money comes back on line, it'll be totally focused on this project.

[Ultraperio]

Hot damn! Consider yourself volunteered. My current thinking is the 8.8 IRS setup, but I thought total cost pushed $2k, by the time you were done with the half shaft work etc.? I seriously considered the TII diff as it does seem to be strong, but we'll be talking a torque monster on sticky rubber and it seems 450WHP is more the real world break point. At least that's what I found. :huh: Putting the TII is tribial and cheap compared to the 8.8" . . . that's for damn sure.

BTW, This project was put on a kind of back burner as my wife left her gig about a year ago now and we decided now is a great time to start a small business. It's working out ok, and all the foot work is done on that, but still hemorrhaging play money. Nevertheless, I'm hell bent to keep pushing on this as I can and one the play money comes back on line, it'll be totally focused on this project.

Considering the scope of this project, I'd assume $200(cost of a TII diff, less if you can find one in a yard) isn't going to break it. I'm not suggesting throwing money around but if a $200 experiment could save you $1500 in fab work, it might be worth it. That's not so say if the TII rear doesn't work out you couldn't still splurge on a built 8.8.

Depending on your fab skills you might be able to throw together a budget dana 44/8.8 conversion on the cheap.

I feel you on the play money, or lack thereof. >.<

[Vettezuki]

Considering the scope of this project, I'd assume $200(cost of a TII diff, less if you can find one in a yard) isn't going to break it. I'm not suggesting throwing money around but if a $200 experiment could save you $1500 in fab work, it might be worth it. That's not so say if the TII rear doesn't work out you couldn't still splurge on a built 8.8.

Depending on your fab skills you might be able to throw together a budget dana 44/8.8 conversion on the cheap.

It's a good point. If a TII could even work for a while, it might substantially improve our timeline to getting the project on the road for real.

[enkeivette]

That's it, then you're all done? :smack:

For carb cars... yes :)

[kdracer73]

I got the hubs apart, front bearings packed. The studs not the same front to rear. The front studs have a longer spline area, and overall length.

[Vettezuki]

I got the hubs apart, front bearings packed. The studs not the same front to rear. The front studs have a longer spline area, and overall length.

Thanks Paul. :thumbs_up:

[kdracer73]

I have the bearings going together now. Are we using the backing plates/dust shields? I would assume not, being a lighter is better thinker. But before I press the hubs together, they would need to go on.

[94cobra69ss396]

I would say not as well.

[Vettezuki]

I would say not as well.

Nope.

[kdracer73]

Ok, I am a dork when it comes to posting picks in the thread. I don't know how to post them large, like normal people do.

I have a few here that need captions, so I will number my comments.

#1: Safety glasses make me look even cooler !

#2: My 30 ton press

#3: I cut a relief into the bearing race, and then use a chisel to split it. Making
it easier to remove.

#4: The cut in the race.

#5: The cut in my face ! I took one for the team ! Hardened steel can be
brittle, and chip. Sending bits into your nose. Second time in 25 years I
did this to myself (last time left a chunk in my forearm that I can still
stick a magnet to). Next time I will put the safety nose guard on too !

I should have the hubs back to Ben Friday night.

[Vettezuki]

Ok, I am a dork when it comes to posting picks in the thread. I don't know how to post them large, like normal people do.

I have a few here that need captions, so I will number my comments.

#1: Safety glasses make me look even cooler !

#2: My 30 ton press

#3: I cut a relief into the bearing race, and then use a chisel to split it. Making
it easier to remove.

#4: The cut in the race.

#5: The cut in my face ! I took one for the team ! Hardened steel can be
brittle, and chip. Sending bits into your nose. Second time in 25 years I
did this to myself (last time left a chunk in my forearm that I can still
stick a magnet to). Next time I will put the safety nose guard on too !

I should have the hubs back to Ben Friday night.


Awesome! Too bad you didn't bleed near painting, we could have mixed it in. I'll give you a hands on photo lesson. Or maybe I should make a thread.