measuring rotor runout with dial gauge

[Donald]

I bought a Fowler dial gauge kit to measure the runout on the rotors in my 01 Jeep GC. From Amazon, seems like a decent kit.

A had a shop install the Akebono caliper upgrade kit from Jeep (with rotors). The pulsation was much less, but still there. The shop said they noticed some pulsation still so must be the rears. While a good shop, I assume they seldom measure rotor runout. The vehicle has a couple of thousand miles since new rotors.

Can I measure runout now? Or will there be pad material on the rotor that messes up the measurement.

How to proceed to eliminate the pulsation.

 

[MONKEYMAN]

Donald,

I had a thread on runnout and pretty much was learning as I went. Some info people posted may help:

Rethinking vibration when braking

Shims did make a difference. I wish I would have gotten a bigger shim on my passenger side. My advice is know the proper shim thickness needed.

I used a Harbor Frieght Dial guage and the old and new rotors had similar runnout.

I am just learning. Others will direct you better.

 

[mechtech2]

Forget about brake pad deposits [unless you are competitively racing and have insane pad temps with pilling on the pad edges]

Even a feeler gauge can be used to test rotor run out. Make a stationary point, and use your .001" to .004" feelers - make sure the rotor is bolted clamped down evenly!
Rotating it to correct problems is the second thing to do.
Cleaning the mating surfaces is #1!
Shims? I'd probably cut them before using shims, but a fitted tapered shim would be OK. Good luck.
And at .002", I'd leave things alone.

 

[Donald]

Originally Posted By: mechtech2
Forget about brake pad deposits [unless you are competitively racing and have insane pad temps with pilling on the pad edges]

Even a feeler gauge can be used to test rotor run out. Make a stationary point, and use your .001" to .004" feelers - make sure the rotor is bolted clamped down evenly!
Rotating it to correct problems is the second thing to do.
Cleaning the mating surfaces is #1!
Shims? I'd probably cut them before using shims, but a fitted tapered shim would be OK. Good luck.
And at .002", I'd leave things alone.


So you are saying that there will appreciably be no pad deposit on the rotor that might make the runout measurement non accurate?