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Discussion Starter · #1 ·
I'm about to install a new set of Grob-Till GT Rotors. I'm also planning to install new wheel bearings with the rotors, and have both inner & outer bearings and seals.

Upon inspecting the GT Rotors, it turns out they already have the bearing races in them, and the races are coated with the same gold-colored (zinc?)coating as the rotor. They had the races in them when they treated them.

Question: Should I pull the races from the rotors and install the new ones, or can I just put the new bearings in the races already in the rotors? (The surface of the races in the rotors is NOT as smooth as the new races with the bearings).

If I bought new AutoSpecialties or even GM rotors, would they come with bearing races already installed?

Makes me wonder about the GT's, and why they would have bearing races already in them...

Thanks for any insight.

Tony Hill
 
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Discussion Starter · #2 ·
Tony,

I also have the GT Rotors on my 9c1. I used the races that were already installed on the rotors. I only installed new bearings. It's been a year so far, no problems with the GTs.

Now if only I could find some rear rotors. The raybestos rotors I bought are already warped, already after 8 months! :mad:
 
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Discussion Starter · #3 ·
Thanks Brian. Maybe I'll just steelwool off the coating from the race surface. Then I don't need to go buy a bearing puller and installer.

Tony
 
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Discussion Starter · #4 ·
The yellow stuff is propably cosmoline.

It is sprayed on to protect from rust (mil-spec).

You should wash it off with mineral spirts - DO NOT use steel wool.

The races and bearings are installed so they can turn the rotors to spec before shipping.

The races probably do not match the bearings you bought. Use the new ones.

You should be able to tap them out with a long extension thru the center of the rotor.

The set the new races in - use the old races (upside down) on top of the new races to tap them into place.

A bearing failure at speed would not be much fun for you or the car. Change 'em out.
 
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Discussion Starter · #5 ·
Thanks uwsacf,

That makes sense. Old races out, new races in. That's the right way to go. Thanks again.

Tony Hill
 
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Discussion Starter · #6 ·
I'd definitely suggest new bearings, and use the races that come with the bearings. I made the mistake of using the races that came with the rotors while doing the brakes on the Roadmaster, and now the bearings won't stay tight for more than a couple months at a time :( That'll teach me for getting lazy just because it's cold outside...
 
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Discussion Starter · #7 ·
<BLOCKQUOTE>quote:</font><HR>Originally posted by Eric Bryant:
I'd definitely suggest new bearings, and use the races that come with the bearings. I made the mistake of using the races that came with the rotors while doing the brakes on the Roadmaster, and now the bearings won't stay tight for more than a couple months at a time :( That'll teach me for getting lazy just because it's cold outside...<HR></BLOCKQUOTE>
Eric,

This raises an interesting question. What are the symptoms the bearings are not tight?

The more I think about it, it's possible the wandering problem I have could be related to the bearings. As I did not use the races that came with the bearings.
 
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Discussion Starter · #8 ·
You'll feel a clunk during low-speed turns, such as in a parking lot. Also, the brake pedal may sink rather low upon the first hit, as the rotors wobble enough to push back the pads.

If you want to check the wheel bearings, just jack up the front of the car and gave the tire a little wiggle.
 
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Discussion Starter · #9 ·
<BLOCKQUOTE>quote:</font><HR>Originally posted by Eric Bryant:
You'll feel a clunk during low-speed turns, such as in a parking lot. Also, the brake pedal may sink rather low upon the first hit, as the rotors wobble enough to push back the pads.

If you want to check the wheel bearings, just jack up the front of the car and gave the tire a little wiggle.
<HR></BLOCKQUOTE>
How is the problem rectified? Taking off the rotors and replacing the races and bearings enough? I checked the castle nut for the bearing assembly, I was able to turn a whole revolution in to get it torqued properly. =(
 
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Discussion Starter · #10 ·
New Timken bearings are less than $20 for both sides if you buy them from Autozone. That certainly should cure the problem, unless something is screwed up severely (like the rotors aren't allowing the bearing races to seat "squarely").

Proper grease packing and tightening of the bearings is pretty important. I know of a few good ways to do it, but the FSM method of torquing the nut to a value that I can't remember right now is probably the best way for someone that doesn't have a "feel" for the required preload.
 
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Discussion Starter · #11 ·
My Chiltons told me something like 12 ft/lb. Then back off the nut a 1/4 turn. Then hand tighten.

That is how I have mine right now and they spin fairly freely.

-Tom
 
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Discussion Starter · #12 ·
<BLOCKQUOTE>quote:</font><HR>Originally posted by Spartus:
My Chiltons told me something like 12 ft/lb. Then back off the nut a 1/4 turn. Then hand tighten.

That is how I have mine right now and they spin fairly freely.

-Tom
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I have the Haynes manual, describing how to torque the front bearings is something it fails to show. Like Ed says, it's nothing like a good paper weight or door stop.

Did you have the wheel spinning(counterclockwise) when tightening down the bearing nut? I seem to remember reading that in the FSM.
 
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