Just picked up a set of Wilwood rotors and just for giggles checked the runout on one of them. Right out of the wrapper, there was .004 on the rotor itself. Not mounted, not spinning, just sitting there on a flat surface there was .004. Is that acceptable? I know in a real world it should be absolutely true, but is .004 good or will I feel pulsing in the pedal? Not that it matters, but these are the type of rotors that mount to an aluminum hub with 8 bolts on a 7" circle.
I don't think you're going to feel 0.004" runout. Unless you have a pretty sensitive foot and butt. 0.04 would worry me, but not 0.004.
How are you checking this? I suppose you could email Wilwood and see what they deem acceptable.
tr8todd wrote: Not that it matters, but these are the type of rotors that mount to an aluminum hub with 8 bolts on a 7" circle.
But it does matter, when you get it bolted in place it may flex the 0.004 just from the torque on the bolts and/or the flatness of the hub. If you want to really check runout the rotor should be mounted and checked with a dial indicator. Even then you may end up with more than 0.004 runout depending on the tightness of the bearings.
0.004 is accepted max. run out.
I originally checked the run out installed and got .010. Cleaned the hub face in a blast cabinet and reinstalled. That brought the installed runout to .004. Pulled the rotor off and checked the runout of just the rotor face sitting flat on the bridgeport. Got .004. Never had access to tools capable of checking rotors this way, so I was wondering if this was normal or if I should bother to have the trued. At this point, the mock up on the big brake kit is done. Sometime next week I will be able to road test what's there and decide if it's real world acceptable or if something needs to be done. At this point we are just waiting on some more 6061 to make the bracket for the other side.
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