treddel

I just did my front brakes on my 2004 E500 and noticed that the rotor is running unround, meaning at half a rotation it scrapes the left side of the caliper and on the second half of the rotation the right side. What do you guys think, ball bearing, kunckle or ....?

Thanks!

vettdvr

Was this a problem before you did the brake job?

treddel

Yes - there was a scraping noise coming from the left front wheel - I thought it was a warped rotor. I wasn't too bumped about that, one excuse to add some fancy rotors and low dust (Red Suff) pads. Now I have some good looking brakes with the same problem.

paulv

Did you notice any play in the hub when you were replacing the rotors?

Regards,
paul...

JoeVal

Since you changed rotors and had the rotor run-out checked, that's definitely a wobbling rotor fit and in the half axle lays the problem.

treddel

Everything is fine again - just want to close this thread with a final solution.

After I had the same problem on the other side, I got susbitious. I took the rotor off again and built a contraption that would show any problem in the ?? part that you bolt the rotor onto. NOTHING - perfectly straight. I cleaned everything again and took all the copper paste off (even though it was very thin) and re-installed the new disc. After the second attempt (everytime I tightend the one little screw) it ran perfectly straight. I did the same thing with the left side and also got it 95% straight.

I am still not sure what and how it happened. I am especially clueless how this could have happened to the left side while the rotor and wheel were installed - like I said it just started to scrape one day.

Lesson learned - when you install your own breaks make sure everything is extra clean an make double sure everything runs straight.

Thanks again for all the suggestions.

vettdvr

Small amounts of rust/contamination between the mount flange and backside of rotor will cause this problem. You are right ALL must be CLEAN.