Holy Crap – that is some serious run-out
A couple of weeks ago I noticed the disk brakes making some noise right at the start of a drive. It would only do it when the brakes were cold and go away after a minute. Yesterday I figured I would finally look into why they have suddenly started making noise. I started with the drivers side wheel in the air and when I spun the tire, I was amazed at how much the caliper was rocking back and forth. I couldn’t believe how warped the rotor was.
I pulled the tire off and then got the rotor off. When I checked the rotor, it wasn’t warped. I then broke out the dial indicator. There was no good place to mount the indicator on the front suspension, luckily the big anvil provided a solid base.
So after getting it set-up, this is what I find:
At this point I thought the hub must be warped. I popped out the spacer that was short and traded places with the one on the other side. When I spun the hub around again, the same spacer in a different location was still coming up low. So now it looks like the spacer is the problem. I pulled all 4 spacers and checked the hub. It looked good.
Taking the spacers to the table saw top, I found that the shoulders weren’t the same.
I don’t have a lathe or a mill, so I improvised with what I do have – a file and a drill press.
After several hours of taking metal off, checking, taking metal off, checking, this was what I ended up with. I am feeling pretty good about this. When I rebuilt two-stroke cranks, the run-out spec was .001″ for most of them. I am really close to that here:
I am kicking myself for not catching this when I installed the brakes. I just didn’t hear anything and definitely didn’t have any vibration or pulsating from the pedal. But now that I look at how the caliper is mounted, I see why.
The passenger side wasn’t nearly as bad, but I spent some time and got the run-out near .001″ as well.