Wheel hub/Brake Rotor runout question
 

Hi,

I just removed and replaced the bearings and brake rotors from my front hubs on my 85 Coupe.

I repacked the hubs with Mobil 1 Synthetic grease and used SKF bearings from Pelican, as well as put on new Zimmerman (Z coated) front rotors.

I check the runout on the new rotors with everything tightened up and installed on the spindles....

One side had a max runout of .004", the other has a max runout of .002". I measured with a dial indicator that has a magnetic base that was stick to the strut and pre-loaded to .010".

My Haynes manual states that the max runout for the rotor is .008", but I'm looking for opinions if current thinking is that my runout is excessive?
Is it so far out that I should index or "clock" the rotors?

Thanks,
Erik.

I am doing the exact same thing to my 1984 Targa right now. New Bearings pads, rotors and stainless lines.

This is my third time doing it on this car, as the prior setup was used on the track.

To be honest, I never check the runout. I snug the adjustment nut, and then spin the assembly by hand to make sure everything is OK.

Maybe someone else on the board measures the runout.

Have fun!

I've never checked it either. Just slap everything together and go.

Always a good idea to go back in and check for play after a 100 miles or so. I've seen races move that I was sure were seated properly. You can loose bearings, rotors, and pad quick if you don't double check at least once.

I would have thought 0.003" should be the maximum for a new rotor.

0.008" would be worn out and give some judder and would need work.

0.002" is OK - 0.004 a bit high and could be some dirt on the mating faces.

Have you checked the hub without the disc? I would expect the hub run out to be around 0.0008" (less than 1 thou).

Thanks for all the responses!

Yes, I checked the tops of the races in the hubs, then checked the tops of the hubs, then rechecked both installed on the spindle, then finally checked the rotor installed.

This is honestly the first time I've ever taken the time to check runout after doing this...my other affliction is British sports cars and I've slapped them together in the past as well, with no ill effect.

I guess I'm worrying this to death....

Thanks again,
Erik.

I would do this. Check for play and re-check the run-out. Let the bearings seat in.

It is a tolerance mentioned in the SC Tech Spec book.

However, lateral runout is 0.1mm "installed" That's 0.004 inches vs. the haynes manual of 0.008 inches.

I am not sure what else lateral runout would mean.

This (0.004") would not worry me one bit.