Head Studs vs. Head Bolts

[Vettezuki]

Which is better for strength and reliability? What are the other pros and cons?

[fiveohwblow]

Studs provide more strength and are more applicable for boosted or high HP applications. Bolts are sufficient for stock/stock-ish configurations. I prefer ARP.

[94cobra69ss396]

Studs provide more strength and are more applicable for boosted or high HP applications. Bolts are sufficient for stock/stock-ish configurations. I prefer ARP.

I agree that studs provide more strength but not that bolts aren't sufficient for boosted applications. I'm running ARP bolts on both the Cobra and Chevelle and have never had an issue with a head lifting. The Cobra is pushing 11-12 psi and the Chevelle has 12.25:1 compression and I run a 250 shot of nitrous to it. I'd say bolts will work just fine for RxSnake.

[fiveohwblow]

I agree that studs provide more strength but not that bolts aren't sufficient for boosted applications. I'm running ARP bolts on both the Cobra and Chevelle and have never had an issue with a head lifting. The Cobra is pushing 11-12 psi and the Chevelle has 12.25:1 compression and I run a 250 shot of nitrous to it. I'd say bolts will work just fine for RxSnake.

I'm on your side brother. I never gave HP ratings, I merely stated the studs were for more power. I have about 460 RWHP with 13 lbs on a dyno jet and have arp head bolts. I also think my setup is fairly mild considering... If I were to push 500 rwhp+ I would prefer studs.

[Shaolin Crane]

Just if we're comparing studs to bolts there is no reason to run bolts over studs. We should especially consider the type of blower going on to RXsnake. Carb and a roots style should have studs.

[94cobra69ss396]

Bolts make it easier to remove the heads with the engine in the car. If we already have bolts to use there is no reason to go out and buy a set of studs.

The Chevelle put down 461 rwhp on just the engine. With the 250 shot it should be over 600 rwhp. I have no fear in the bolts not holding up. They have been for the past 6 years. But then again I'm also using a two bolt main block with a cast crank and running 10 flat at 133 with a 12 bolt rearend that still has the original axles in it.

[Shaolin Crane]

The only 2 studs that are the problem is the back 2 on each side. Remove these and there is no reason why they cant be removed in the car.

[Shaolin Crane]

I'm on your side brother. I never gave HP ratings, I merely stated the studs were for more power. I have about 460 RWHP with 13 lbs on a dyno jet and have arp head bolts. I also think my setup is fairly mild considering... If I were to push 500 rwhp+ I would prefer studs.

You dont count, you dont push your car nearly as hard as we do here. :sm_laughing:

SBF is notorious for having head gasket issues with boost.

I'd say Ron's car is a freak but I do know he's been through a few sets of head gaskets

[94cobra69ss396]

The only 2 studs that are the problem is the back 2 on each side. Remove these and there is no reason why they cant be removed in the car.

Not in the Cobra. I leave the headers on so I wouldn't be able to remove them with studs. I'd have to remove all the studs to get them out.

On the Chevelle, I'd be able to remove the passenger side head but not the drivers because the brake booster is in the way.

You dont count, you dont push your car nearly as hard as we do here. :sm_laughing:

SBF is notorious for having head gasket issues with boost.

I'd say Ron's car is a freak but I do know he's been through a few sets of head gaskets

I've replaced the head gaskets once in the Cobra because I was using the stock replacment Felpro and I got a coolant leak. The MLS ones I've had no problem with.

I've also had to replace one set on the Chevelle but that was because the first time I ran the nitrous I forgot to retard the timing and it detonated and reuined the head gaskets.

[Vettezuki]

As fasteners, it's clear studs are objectively superior. The price difference is not really such a big deal when we're talking about an engine system anyway. The benefit of being able to remove heads in car is nice, but in a car that will be as radically stripped as the Snake, pulling the engine may not be much of a big deal really. I'm 99% sure bolts will be adequate as the estimated power <= 500RWHP and I don't see doing much to make it more than that. My onnly slilght concern is that's a big dumb simple roots blower that probably rocks the hell out of the intake and puts a more lateral force on the heads than they'd ever get with NA or Procharger etc. Whether it's enough to subtantively increase risk I don't know. Curious what Joe runs because he's run this combo and related for years.

Guy, for reference what's the price difference bolts vs. studs?

[Shaolin Crane]

Not in the Cobra. I leave the headers on so I wouldn't be able to remove them with studs. I'd have to remove all the studs to get them out.

On the Chevelle, I'd be able to remove the passenger side head but not the drivers because the brake booster is in the way.



I've replaced the head gaskets once in the Cobra because I was using the stock replacment Felpro and I got a coolant leak. The MLS ones I've had no problem with.

I've also had to replace one set on the Chevelle but that was because the first time I ran the nitrous I forgot to retard the timing and it detonated and reuined the head gaskets.

Even removing all the studs isnt that big a deal, they're allen tipped and remove just like a bolt.

Your car is a freak, there are countless guys on corral and yellow bullet who are plagued with HG issues even after studs. SBF are notorious for blowing head gaskets.

[Shaolin Crane]

As fasteners, it's clear studs are objectively superior. The price difference is not really such a big deal when we're talking about an engine system anyway. The benefit of being able to remove heads in car is nice, but in a car that will be as radically stripped as the Snake, pulling the engine may not be much of a big deal really. I'm 99% sure bolts will be adequate as the estimated power <= 500RWHP and I don't see doing much to make it more than that. My onnly slilght concern is that's a big dumb simple roots blower that probably rocks the hell out of the intake and puts a more lateral force on the heads than they'd ever get with NA or Procharger etc. Whether it's enough to subtantively increase risk I don't know. Curious what Joe runs because he's run this combo and related for years.

Guy, for reference what's the price difference bolts vs. studs?
Check summit for ARP stuff. Pro Comp studs are about $44

[Vettezuki]

Check summit for ARP stuff. Pro Comp studs are about $44


Oh hell if the Pro Comp is OE equivalent to ARP and a set of studs <$50, it's a non-issue. Studs it'll be. The engine is outside of the car and will be fully assmebled before dropping. As stated before it will always be stripped (never A/C, heater, etc.) so even IF it has to be removed it won't be near the hassle it is on road cars. Fahget about it.

[joedls]

Curious what Joe runs because he's run this combo and related for years.



I ran ARP bolts. I blew a head gasket almost immediately, but then switched to MLS and never had a problem. Well, at least not with the head gaskets.

[Shaolin Crane]

Oh hell if the Pro Comp is OE equivalent to ARP and a set of studs <$50, it's a non-issue. Studs it'll be. The engine is outside of the car and will be fully assmebled before dropping. As stated before it will always be stripped (never A/C, heater, etc.) so even IF it has to be removed it won't be near the hassle it is on road cars. Fahget about it.

When held in the hand its difficult to tell the difference. ARP is definitely superior but we havnt had issues with the procomp studs.

[Vettezuki]

When held in the hand its difficult to tell the difference. ARP is definitely superior but we havnt had issues with the procomp studs.

Ok, on quality, how about ARP bolts (which apparently you have) vs. Pro Comp studs?

[Shaolin Crane]

Not sure what you mean, I have both procomp and arp studs on various motors. I also have a set of arp head bolts. The spare motor with forged internals has arp head and main studs. No issues with pro comp so far. I'd say they're a good bet.

Give Eddy a call and tell him you want the felpro 1133 head gasket and tell him you're from motorgen that way you pay over the phone.

[enkeivette]

Haha, thats not a biased poll. Why not phrase it: which do you prefer, spending $60 on a product, or $130 on a comparable product?

No one is contesting, nor would anyone contest that studs are better than bolts. Mine was a cost vs. benefit argument. Besides I conceeded that with a ten bolt cyl head design even Id shell out the extra cash.

Heres another idea for a poll, how many of you have PERSONALLY experiened head bolt failure?Doubt we'll have even one member.

[enkeivette]

Btw, just voted on studs.

[enkeivette]

Ben, stay away from pro comp crap. I went through a set of pro comp rockers in 15k miles. We'll be taking the heads off so many times, ARP will save money in the long run.

[enkeivette]

Last post I promise, gotta stop reading backwards.

If we cant take the heads off with the studs, Id go with bolts. Especially because Ron has a more serious version of the same motor thats apparently doing fine.

Id hop on the rotary forums and find out if theres wiggle room in 2nd gens.

[Vettezuki]

Too late. Bought studs, $55 from Guy's ProComp source. The motor is out and will be assembled on the stand. I *suspect* there will be room in the engine bay as well since it will be all bare bones. Even the vacuum booster is not so large. We'll see. :nuts:

[Shaolin Crane]

Ben, stay away from pro comp crap. I went through a set of pro comp rockers in 15k miles. We'll be taking the heads off so many times, ARP will save money in the long run.

I'm not advocating all pro comp stuff but their studs are great and last. Their heads, rockers and anything that moves are crap. Their pushrods, studs, carb intakes, and lifters are all of decent quality for the money. Shawn at Pacific Engine have been running them for years.

[Shaolin Crane]

Last post I promise, gotta stop reading backwards.

If we cant take the heads off with the studs, Id go with bolts. Especially because Ron has a more serious version of the same motor thats apparently doing fine.

Id hop on the rotary forums and find out if theres wiggle room in 2nd gens.

Hard to compare. Rons motor is a freak, plus a centri is a totally different stress then a roots. Hundreds of guys with sbf's are having head gasket issues with studs. Just not a good deck.

[enkeivette]

$55 for studs is a steal from what Ive seen, ARP wanted 130 for my sbc, but then again its 20 studs not 32

[Shaolin Crane]

Its the same cost for a sbf. ARP is getting a little out of hand.

[enkeivette]

Ps, cyl pressure is cyl pressure. You could make the argument that roots blowers blow hotter air, but I dont think anyone has more boost with a higher inlet temp than Ron

[Shaolin Crane]

If only it was as simple as that, the way the roots puts stress on the heads is completely different then a centri since its constantly stressing them, the KB fox guys have an issue with it, they have even higher inlet temps at lower boost and the threads are a plenty. Like I said, Rons car is a freak. Dan Pina the drift patrol driver has an identical setup to Ron and I and he has always been plagued with head gasket issues. He even has the big daddy boss r block with 1/2" deck hardware and he is still plagued with them.

The SBF sucks monkey dick for boost, n/a they're great, but any power adder has great potential for problems

[enkeivette]

Assuming inlet temps are the same (and theyre usually not, but you make up the difference by running a lower boost) explain to me how roots cylinder pressure is different from centri or turbo cyl pressure?

Once the valve closes with x amount of boost at x temp and the engine mixes and compresses the air on its own from that point. Wheres the difference? Splain it to me lucy?

Hint, its not. The only difference is with the inlet temps.

[Shaolin Crane]

First as far as I know the old roots dont have a bypass, so your theory about once you let off the throttle and the valve closes and everything goes away doesnt work. Second i'm talking about the actual stress of the blower itself. Its alot of paracitic drag to begine with and the fact its directly fastened to the heads makes a HUGE difference from a centri or turbo. Every time boost build(and it builds quick with a roots) it immediately stresses the deck and heads. Not so good for head gaskets. Roots also run hotter then a centri.

[Vettezuki]

From what I can imagine and know about physics, I'm gonna have to agree with Guy. A Centri or Turbo is blowing compressed air into the intake, on a roots, you have a very large spinning mass as part of the intake, it must be torqing into and away from the heads all the time; a kind of ratcheting effect . . . 10s of thousands of times. Mechanically, it seems like a much more violent environment/system.

[Shaolin Crane]

From what I can imagine and know about physics, I'm gonna have to agree with Guy. A Centri or Turbo is blowing compressed air into the intake, on a roots, you have a very large spinning mass as part of the intake, it must be torqing into and away from the heads all the time; a kind of ratcheting effect . . . 10s of thousands of times. Mechanically, it seems like a much more violent environment/system.

That's exactly what happens. Ed Curtis has confirmed this and there is a reason why the NHRA requires blower straps for roots applications.

[enkeivette]

I wasnt thinking physically more stressful, but ya, I could def see that.

Actually Ive seen a roots blower pop off of a motor before, but it popped off at the base plate/ blower intake manifold, not at the heads.

[fiveohwblow]

If only it was as simple as that, the way the roots puts stress on the heads is completely different then a centri since its constantly stressing them, the KB fox guys have an issue with it, they have even higher inlet temps at lower boost and the threads are a plenty. Like I said, Rons car is a freak. Dan Pina the drift patrol driver has an identical setup to Ron and I and he has always been plagued with head gasket issues. He even has the big daddy boss r block with 1/2" deck hardware and he is still plagued with them.

The SBF sucks monkey dick for boost, n/a they're great, but any power adder has great potential for problems



Wut?? SBF sucks for boost? That's new to me...

[Shaolin Crane]

Wut?? SBF sucks for boost? That's new to me...

Tis true. Talk to me when you run your car as hard as Ron and I do. His car is a freak, venture over to corner carvers and yellow bullet and you'll see how many sbf dudes are having head gaskets issues.

[Vettezuki]

Did factory boosted SBFs (e.g., Cobra) have similar common problems? Maybe it's a common problem of people trying to reach for power on the cheap. I don't think Joe, who has run boosted motors hard has had any kind of unusual HG problems. :huh:

[Shaolin Crane]

Completely different engine OHV vs OHC. The 4.6 in the cobra is good for about 800rwhp on stock internals. Modular motors were meant for boost. Sbf not so much. I definitely think it makes a HUGE difference if you plan out the hardware you're using and use an appropriate cam. I know the boosted road course guys are plagued with problems. There are plenty of dudes (like Justin) who make great power and rarely race and they'll last. Problem is the entire sbf is fighting itself when making power 450+ is where you start rolling the dice every time you race your can cause the block likes to spilt itself in half.

[Vettezuki]

I forget what they're called, but doesn't just a little reinforcement across the pan and valley up that a couple hundred HP?

[Shaolin Crane]

For a sbf? No, girdles just keep all your shit from flying all over the place when it breaks. Maybe 75hp if you have a valley girdle and main girdle, maybe...

[enkeivette]

Tis true. Talk to me when you run your car as hard as Ron and I do. His car is a freak, venture over to corner carvers and yellow bullet and you'll see how many sbf dudes are having head gaskets issues.

Is one of your foxes actually blown and running? Whats your setup? I thought you were just putting stuff together.

And Ive heard girdles are for strength too. Seems like this week you just cant type anything that I dont disagree with. (And yes that was a proper double negative. Suck that high school language arts teachers.)

[Shaolin Crane]

Is one of your foxes actually blown and running? Whats your setup? I thought you were just putting stuff together.

And Ive heard girdles are for strength too. Seems like this week you just cant type anything that I dont disagree with. (And yes that was a proper double negative. Suck that high school language arts teachers.)

not yet. Still tracking down wiring issues. But i was having head gaskets issues on the stock engine (which is part of the reason i pulled it and rebuilt it)

Like i said, girdles help for keeping your shit together when it breaks. Jeff (cobra912) snapped a rod at only 550rwhp (forged btw) and it launched out of the car and just about cut the block in half.

I have a girdle on the spare motor with forged internals, the sbf tends to crack at the front of the block near the cam. There's just not enough material in the block to keep it from going, the caps are small, the crank it 75% exposed its a wonder the block even hols the power it can

[fiveohwblow]

Tis true. Talk to me when you run your car as hard as Ron and I do. His car is a freak, venture over to corner carvers and yellow bullet and you'll see how many sbf dudes are having head gaskets issues.

It's difficult to define "hard", but my car is driven anything but nicely. Last run was over 100 miles and barely under 4k or 80 mph. I run the bitch hard. That's how the damned bumper needed replaced actually. My opinion: proper setup and tune, no need for head gaskets popping.

[94cobra69ss396]

I have about 90,000 miles in 6 years on my engine combo which makes 11-12 psi with a Vortech SQi S-trim and puts down 471rwhp. I drag race, autocross, road race, etc and it sees redline every time I drive it. I also use it as my daily driver and since I have customers in northern Cal and AZ that I drive to it's not unusual for me to put 600-700 miles on it in a day.

But like you said proper tuning is key as is the setup. My tune is safe and redline for me is 5800 because of the E303 cam. I have my rev limiter at the factory 6250 and it only hit it if the tires break loose. Even when I'm showing off doing a burnout I don't floor it so it doesn't hit the rev limiter.

[enkeivette]

It's difficult to define "hard", but my car is driven anything but nicely. Last run was over 100 miles and barely under 4k or 80 mph. I run the bitch hard. That's how the damned bumper needed replaced actually. My opinion: proper setup and tune, no need for head gaskets popping.

I can second that, the only time I blew out a HG it was running super lean. But studs will def make it easier to drop the heads in place. Scratching the bottom of the head trying to get the dowel pin to line up always sucks.

PS, girdles help keep the crank from flexing. Not that there will be so much stress on the crank in a normal app that the block needs a girdle to keep it in place, like rocker girdles, but after 100k miles I would imagine there would be less wear. So Id vote no on a block girdle, yes on rocker girdles.

[Shaolin Crane]

I can second that, the only time I blew out a HG it was running super lean. But studs will def make it easier to drop the heads in place. Scratching the bottom of the head trying to get the dowel pin to line up always sucks.

PS, girdles help keep the crank from flexing. Not that there will be so much stress on the crank in a normal app that the block needs a girdle to keep it in place, like rocker girdles, but after 100k miles I would imagine there would be less wear. So Id vote no on a block girdle, yes on rocker girdles.

Ben mentioned adding a couple hundred horsepower capacity to a sbf using valley and main girdles. That mean you're taking a stock block ford from 500rwhp capacity to 700rwhp capacity. No, just no, a stock sbf block will NEVER hold that kind of power for more then a few miles. Not sure how you screwed up a rocker stud but i've never heard of anyone fucking up a sbf rocker/stud with 7/16 studs

[Shaolin Crane]

It's difficult to define "hard", but my car is driven anything but nicely. Last run was over 100 miles and barely under 4k or 80 mph. I run the bitch hard. That's how the damned bumper needed replaced actually. My opinion: proper setup and tune, no need for head gaskets popping.

Its not difficult to define hard if you've seen Ron drive. I treat my car the same way, though I cant seem to just drive something without fucking with it.

Rons car is a freak but also not reving it helps ALOT with a sbf.

[fiveohwblow]

Its not difficult to define hard if you've seen Ron drive. I treat my car the same way, though I cant seem to just drive something without fucking with it.

Rons car is a freak but also not reving it helps ALOT with a sbf.

My point was its just subjective. I run my junk hard too.

I have been told by everyone and their dog that revs kill them also. I take mine to the 6200 redline I have set every time it runs. Not sure if that's considered high by all, but by most I guess it is *shrugs*

[94cobra69ss396]

My point was its just subjective. I run my junk hard too.

I have been told by everyone and their dog that revs kill them also. I take mine to the 6200 redline I have set every time it runs. Not sure if that's considered high by all, but by most I guess it is *shrugs*

Depends on the setup. If that was my Cobra I would consider it high but not with my Chevelle. I shift the Chevelle at 6500 and I've hit valve float at 7200 during a burnout before I installed a limiter chip. Oh, and the Chevelle has a cast crank and 2 bolt mains.

[enkeivette]

Ben mentioned adding a couple hundred horsepower capacity to a sbf using valley and main girdles. That mean you're taking a stock block ford from 500rwhp capacity to 700rwhp capacity. No, just no, a stock sbf block will NEVER hold that kind of power for more then a few miles. Not sure how you screwed up a rocker stud but i've never heard of anyone fucking up a sbf rocker/stud with 7/16 studs

Add 13lbs of boost on a motor setup to produce 450hp NA and youll get a better idea how I screwed up a rocker stud. Plus I spin to 6500, rev limiter is set for 7k, and Ive hit it.

[Shaolin Crane]

Add 13lbs of boost on a motor setup to produce 450hp NA and youll get a better idea how I screwed up a rocker stud. Plus I spin to 6500, rev limiter is set for 7k, and Ive hit it.

3/8 or 7/16"? ARP or standard sbc? Cause ikve never heard of people having issues with studs on a sbf surprisingly.

[Shaolin Crane]

My point was its just subjective. I run my junk hard too.

I have been told by everyone and their dog that revs kill them also. I take mine to the 6200 redline I have set every time it runs. Not sure if that's considered high by all, but by most I guess it is *shrugs*

If you're shifting at or near redline its not high at all. The blue car is nearly indetical to Rons motor so should run as such. The race car however is projected to have a 7500 rpm red line and a 7k shift point. I dont expect 100k out of it

[94cobra69ss396]

Add 13lbs of boost on a motor setup to produce 450hp NA and youll get a better idea how I screwed up a rocker stud. Plus I spin to 6500, rev limiter is set for 7k, and Ive hit it.

The Chevelle put 461 to the wheel NA and I also shift at 6500 and spray a 250 shot with 12.25:1 compression. I've never had an issue with a rocker stud.

[enkeivette]

Dont remember, and now you have ;) Ps, the only GM part on my engine is the block and the dist clamp. Theyre AFR studs, a top of my sexy AFR heads.

[Shaolin Crane]

AFR studs are just standard sbc studs. Nothing special about them.

[enkeivette]

Youre saying AFR studs are OEM for GM? :p

[Damian]

Question, I'm looking at replacing the main bolts. Looking at ARP bolts and studs, they both have the same tensil strength. Why are the studs way more expensive? Is it worth the extra cash if they have the same tensil strength? Common sense tells me no.

[Vettezuki]

Question, I'm looking at replacing the main bolts. Looking at ARP bolts and studs, they both have the same tensil strength. Why are the studs way more expensive? Is it worth the extra cash if they have the same tensil strength? Common sense tells me no.

Guy briefly stated the same thing earlier, but:

Torque Efficiency

During engine assembly or maintenance, a bolt must be installed by torqueing it into place. Due to the head bolt’s design, it has to be rotated into its slot in order to engage the threads and secure it into place. This process creates both twisting force and a vertical clamping force, which means that when the cylinders within the engine’s combustion chamber begin accumulating load, the bolt will both stretch and twist. Because the bolt has to react to two different forces simultaneously, its capacity to secure the head is slightly reduced and it forms a less reliable seal in high-powered engines.

By contrast, a head stud can be tightened into place without any direct clamping force applied through the tightening. A stud can be threaded into a slot up to “finger tightness,” or the degree to which it would be tightened by hand. Afterward, the cylinder head is installed and a nut is torqued into place against the stud. The nut torque provides the clamping force, rather than the torque of the fastener itself, and the rotational force is avoided entirely. Because the stud is torqued from a relaxed state, the pressure from the nut will make it stretch only along the vertical axis without a concurrent twisting load. The result is a more evenly distributed and accurate torque load compared to that of the head bolt. This ultimately translates into higher reliability and a lower chance of head gasket failure.

http://www.thomasnet.com/articles/hardware/head-stud-bolts

[enkeivette]

Starting to get silly, it is a budget motor. Id just reuse the old shit. If ford heads are defunct thats one thing, but bolts for everything else. Id even reuse the HG if it was an MLS. Ive reused mine 3 or 4 times, just copper spray it.

[enkeivette]

Piston rings too, theres really no reason you cant reuse them, especially if you kept them in order.

[Vettezuki]

I don't know what you're talking about? This is a technical discussion of bolts vs. studs, not so much specific application. You're assuming Snake only. The Snake is not so much a budget motor (probably around 500-550BHP with a roots blower) compared to the lemon Fox, for which duct tape would be sufficient if it works. Studs $55 . . .that's free. The rings are already replaced and installed. Done.

This was to answer Damian's specific technical question.

[Shaolin Crane]

Youre saying AFR studs are OEM for GM? :p

I'm saying afr studs are OEM material, nothing upgraded about them. Sbf AFR heads use to have chevy valves. If you want something thats strong you need to use something else.

[enkeivette]

Oops, thought that was you asking... Guess if I had a bigger screen LTE phone I would have known that... Ahhhhhh I hate my iPhone 4!!! Why did I buy such a slow piece of shit?! Sean was right!!! Baaaahhhhhhh!!! :crybaby: :crybaby:

[enkeivette]

I'm saying afr studs are OEM material, nothing upgraded about them. Sbf AFR heads use to have chevy valves. If you want something thats strong you need to use something else.

Hmmm... like stud girdles?

And I know what you meant, I was taunting you. Ha

[Shaolin Crane]

Hmmm... like stud girdles?

And I know what you meant, I was taunting you. Ha

No, like arp studs. The money spent on stud girdles can be spent on the studs.

[Damian]

This was to answer Damian's specific technical question.
Thank you BTW.

[enkeivette]

No, like arp studs. The money spent on stud girdles can be spent on the studs.

AFR studs plus girdles (cheaper, and no risk of deflection) > ARP studs ALONE (geometrically inferior and more than the $30 bucks I spent on AL girdles)

[Shaolin Crane]

Do the girdles come with new poly locks? Btw I paid $22 for my arp 7/16 studs. Which I am not concerned about fucking up

[enkeivette]

Oh ya, just ebay sbf stud girdle.