Rear Rotor Runout Rectification
Thread Starter
Racer
Joined: Aug 2014
Posts: 479
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From: Tennessee
Rear Rotor Runout Rectification
I have new complete set of Wilwood rotors and calipers and I have the fronts on and within spec for runout. As someone has already stated in a previous post on another thread, the rears are a whole new ballgame as for correcting any excessive runout. I am getting close to .030 variance runout the the rotor on one side so I'm thinking my issue is internal. Where do I begin?
Last edited by ykf7b0; May 5, 2019 at 09:13 PM.
Safety Car
Joined: May 2004
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From: los altos hills california
I have new complete set of Wilwood rotors and calipers and I have the fronts on and within spec for runout. As someone has already stated in a previous post on another thread, the rears are a whole new ballgame as for correcting any excessive runout. I am getting close to .030 variance runout the the rotor on one side so I'm thinking my issue is internal. Where do I begin?
If both new rotors show the same runout on the same wheel, then likely you are correct in assuming it's the hub. You can try shimming with thin stock.
Last edited by ignatz; May 5, 2019 at 09:33 PM.
Thread Starter
Racer
Joined: Aug 2014
Posts: 479
Likes: 93
From: Tennessee
All is cleaned up really nice. I have .006 shim stock but I'm thinking .030 is a bit much to shim, am I wrong? Also, how do I replace that hub?
Last edited by ykf7b0; May 5, 2019 at 10:31 PM.
Tech Contributor
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From: Connecticut, USA
030" is a lot, the most I have seen is 015" and was able to dial it in.
You must be sure the mating surfaces are flat, a wire brush is not going to deburr a raised area around a rivet hole, the inside of the rotor hat has to be dressed as well. You can measure the runout in the axle flange to see where that is, expect to find up to 010" that is normal, if the car was ever hit hard the axle could be bent but that is not as common to find.
while I can't say for sure without seeing the parts I would look close for burrs again and see what changes if you dress around those holes with a 2" emery wheel
I have been seeing some QC issues with new rotors lately, I had to machine a couple of brand new ones recently but that wasn't a runout issue it was with the rotor hat ID being too small.
You must be sure the mating surfaces are flat, a wire brush is not going to deburr a raised area around a rivet hole, the inside of the rotor hat has to be dressed as well. You can measure the runout in the axle flange to see where that is, expect to find up to 010" that is normal, if the car was ever hit hard the axle could be bent but that is not as common to find.
while I can't say for sure without seeing the parts I would look close for burrs again and see what changes if you dress around those holes with a 2" emery wheel
I have been seeing some QC issues with new rotors lately, I had to machine a couple of brand new ones recently but that wasn't a runout issue it was with the rotor hat ID being too small.
