Help: Rotors and pads on GMC Sierra

[Vettezuki]

Installing Rotor Hub
Ok, the front rotors on a sierra have an integrated hub. The rotor hub has a bearing races and the studs are part of it, rather than a just a rotor that slips onto a hub. When you take it off there's a bearing that comes off the spindle, then the rotor/hub comes off. I could not find the correct torque spec for the axle nut that goes over the bearing and holds the the whole thing on the spindle. When I took it off it was pretty loose, I was basically able to take it off by hand. When putting it back on, I put it on hard enough to hold the rotor/hub on the spindle without wobbling. HOWEVER, it was then MUCH harder to spin than before I took it off. WTF?

New Pads, Box of Rocks
The pads were almost completely gone. I put on new pads, when I took it out after putting them on, it sounded like a rock tumbler or crazy grinder. Is this just the new pads breaking in on a new rotor on a truck where the pads were super worn down? I don't remember anything like this with any other car I've done in the past.


Bleeding Breaks
I suck at it. Is there any trick to doing this with a mighty vac? I must still have a crazy amount of air in the system.

[94cobra69ss396]

For the nut, tighten it down snuggly then back it off. Do this a few times to seat the bearing in the race and then snug it down. Were talking only something around 5-10 ft/lbs or so.

Did you tighten the bearing down too tight? You shouldn't have noise from a new rotor and pad.

The easiest way to bleed the brakes is to have someone help you. Have that person pump the brake peddle 3-5 times and then hold pressure on the peddle. Then open the bleeder until the peddle goes to the floor. They need to let you know when it does. Then close the bleeder and let them know to pump the peddle again. Do this until there is no more air in the line. Start at the passenger rear, then driver rear, then passenger front and end with drivers front. Make sure you keep checking the master cylinder so you don't run it dry.

[Vettezuki]

For the nut, tighten it down snuggly then back it off. Do this a few times to seat the bearing in the race and then snug it down. Were talking only something around 5-10 ft/lbs or so.

Did you tighten the bearing down too tight? You shouldn't have noise from a new rotor and pad.

I must be way too tight. Might I have damaged the bearing? Should I replace them now? The reason I went that tight is that if I didn't the rotor assembly would have been a little wobbly on the spindle. But now that I think of it that's before I tightened down the caliper, which probably aids a lot in locating the rotor on the spindle. I only made a couple low speed circuits around the neighborhood. Hopefully I didn't damage the rotors.


The easiest way to bleed the brakes is to have someone help you. Have that person pump the brake peddle 3-5 times and then hold pressure on the peddle. Then open the bleeder until the peddle goes to the floor. They need to let you know when it does. Then close the bleeder and let them know to pump the peddle again. Do this until there is no more air in the line. Start at the passenger rear, then driver rear, then passenger front and end with drivers front. Make sure you keep checking the master cylinder so you don't run it dry.

That's the tricky part, getting another person to help. My wife's physical condition makes it difficult for her to do much strenuous pushing, plus she works late all the time. Mmm, have to be resourceful.

[94cobra69ss396]

I must be way too tight. Might I have damaged the bearing? Should I replace them now? The reason I went that tight is that if I didn't the rotor assembly would have been a little wobbly on the spindle. But now that I think of it that's before I tightened down the caliper, which probably aids a lot in locating the rotor on the spindle. I only made a couple low speed circuits around the neighborhood. Hopefully I didn't damage the rotors.

You'll have to pull them to see. It doesn't take long to ruin a bearing.

That's the tricky part, getting another person to help. My wife's physical condition makes it difficult for her to do much strenuous pushing, plus she works late all the time. Mmm, have to be resourceful.

Just go to Autozone and pick up one of these for $30. You can use it to bleed the brakes by yourself.

http://contentinfo.autozone.com/znetcs/product-info/en/US/grn/25136/image/4/

[Vettezuki]

You'll have to pull them to see. It doesn't take long to ruin a bearing.

What am I looking for? Just poor rolling?



Just go to Autozone and pick up one of these for $30. You can use it to bleed the brakes by yourself. . .

GOt one. But apparently my technique ain't so good. Mm, should I build vacuum, crack the bleeder, let the vacuum deplete. Close the bleeder and repeat? I was just opening the bleeder and pumping. :huh:

[94cobra69ss396]

What am I looking for? Just poor rolling?

Check for metal shavings and wear on the bearings. Also check for discoloration (purple/bluish color).




GOt one. But apparently my technique ain't so good. Mm, should I build vacuum, crack the bleeder, let the vacuum deplete. Close the bleeder and repeat? I was just opening the bleeder and pumping. :huh:

I'm not sure because I haven't used mine to do it but I know you can. Amy's a professional assistant at bleeding brakes now. I still have the manual somewhere in the garage so I'll check it and let you know.

[kdracer73]

I just open the bleeder and pump until I fill the cup 1/3 or so. I leave the pump and hose connected until all the vacuum is gone.Then I take the hose off with the bleeder open and let it gravity bleed for a little bit. Make sure the master cylinder doesn't run dry during any part of the process..Wish I saw this before I left Frankie's house !! Would have stopped over and helped.

[Vettezuki]

I just open the bleeder and pump until I fill the cup 1/3 or so. I leave the pump and hose connected until all the vacuum is gone.Then I take the hose off with the bleeder open and let it gravity bleed for a little bit. Make sure the master cylinder doesn't run dry during any part of the process..Wish I saw this before I left Frankie's house !! Would have stopped over and helped.


Any rule of thumb on lubbing up bearings, or just sort of smother real good. I got a new pair, they were only about $38 out the door for both. I figured if the ones I undoubtedly over tightened and have who knows many miles on them, it's a worthwhile replacement.

[jedhead]

I have always smothered them up real good and work the grease into the bearings. The only thing that I have done differently lately is using synthetic grease.

Bob

[kdracer73]

I put the grease in the palm of my hand, then the bearing in other hand. place the bearing in the grease and with pressure pack the grease into the rollers. Just smearing it on the outside is not enough. I will get a picture up soon.

[kdracer73]

http://i925.photobucket.com/albums/ad94/kdracer73/DSC00594.jpg

pack from the wide side of the bearing, until in starts to squeeze out the other side. Rotate until it is packed all around...then coat the outside a little.
http://i925.photobucket.com/albums/ad94/kdracer73/DSC00595.jpg

[kdracer73]

Nut torque is 10ft lbs. ( Just snug, while turning hub. ) It doesn't take much. I will be out that way Friday night , if ya want me to stop over.

[Vettezuki]

Nut torque is 10ft lbs. ( Just snug, while turning hub. ) It doesn't take much. I will be out that way Friday night , if ya want me to stop over.

That'd be great. What time works for you?

[kdracer73]

I should be off at 5pm, and with traffic should be up there 6 ish.

[Vettezuki]

I should be off at 5pm, and with traffic should be up there 6 ish.

You want to go to Frankie's and call me when you get there, then I'll come get ya? Whatever your preference is.

[kdracer73]

I will be coming up Brookhurst, so I will just cruise by. I will call you when I am on my way.

[Vettezuki]

First and foremorst, mega thanks to Paul, without whose help God only knows what would have happened.

New High Score for Dumb!

I was smart enough to realize something was really wrong when I took it out for the first test drive, which is fortunate, because I wasn't smart enough to realize there was supposed to be an inner bearing on the back side of the new rotor and it turns out that's pretty important. Doh!

[94cobra69ss396]

So did you destroy the new rotor? How about the spindle?

[Vettezuki]

So did you destroy the new rotor? How about the spindle?

Spindle is %100 fine. Cut a small grove into the back of the rotor since the grinding was, uh, the rotor rubbing on a bolt. :sm_up_there: Fortunately it was very shallow on a brand new rotor so the pad will probably just "hone" it down. Nothing too tragic, I drove less than a mile at very slow speed. It was so obviously wrong that even Sean would have noticed.