Rotors for 1970

[Bill C.]

Re: Rotors for 1970

Boy did I get an education in this thread!!!!

I must have been really lucky when I reassembled my rotors and hubs.
I checked them as an assembly and they were in spec.

I do have a question for the group-
if you buy a new hub/rotor rivited assembly and then check the runout, what do you do if it is out of spec?
I guess you can have the assembly turned true ---

[Jim T.]

Re: Rotors for 1970

Thanks guys. Based on responses, I will stay away from the front rotor with the holes in it. I will buy the other front rotor and beadblast and paint it. Will also have it turned (slightly). On the rears, I was planning on going to Bairs to rebuild my trailing arms anyway. I believe I can buy reproduction rears and have them put it on and check runout. Does anyone think I'd be better off buying these rears (measurements on them are 1.25" and 1.23") and giving them to Bairs to install?

Michael, I am replacing mine because I am doing a restoration (hopefully to NCRS specs) and mine were too thin, beyond the 1.215" on both front and rears. Is the spec same for both?

Tom, yes, please do send me the pdf on how to reduce runout! Does that address front and rears? thanks, Steve

Steve you have the right idea/intentions in your post. Take the fronts and rears to Bairs and they will take care of your concerns with runout and rear bearings. They also have good used rotors/or new that will give put your car on the road for trouble free enjoyable driving.

[Mike G.]

Re: Rotors for 1970

i would just send them to bairs and let them install new ones. they are good at what they do. here is a front done by bairs. they look factory. dont have a good pic of the rear but they look good too.

[Tom L.]

Re: Rotors for 1970

Boy did I get an education in this thread!!!!

I must have been really lucky when I reassembled my rotors and hubs.
I checked them as an assembly and they were in spec.

I do have a question for the group-
if you buy a new hub/rotor rivited assembly and then check the runout, what do you do if it is out of spec?
I guess you can have the assembly turned true ---

Bill, I would imagine that whomever you buy the riveted assembly from would have shimmed the rotors out before riveting. If it's out of spec, the only real solution is to drill the rivets out and start over. As Joe Lucia wrote, the factory fresh rotors were riveted prior to final machining and then cut to spec. I'd hate to take a new finished rotor and start cutting it thinner to remove excess runout.

Steve, the shims go around the lugs so there is no deflection when you torque the lug nuts. The shims are available in stainless through McMaster Carr for a few dollars. They look like very thin washers. I used .001",.002" and .003" shims with a 1/2 inch inside diameter. I don't think that any of the four rotors on my car required shims on more than 2 lugs to get them in spec. The flat head screws, also available through McMaster Carr, are 3/8-24x5/8 with a tapered head, like a lug nut, to center the screw. You can put the taper in the rotor with a 3/4" countersink to match the screw. Good luck.

[Joe L.]

Re: Rotors for 1970

One other thing to keep in mind: the NEW thickness on 65-82 Corvette rotors is 1.250". The MINIMUM ALLOWABLE thickness is 1.215". There's only 35 THOUSANDTHS between those 2 numbers. If one has a TIR out of spec by, say, 10 thousandths, it could easily take a 15 thousandths, or more, cut on the disc to correct that. So, in this case and starting with a NEW rotor, one would be about half way to "terminal condition" of the rotor before one had even put a mile on it.