Rotor replacement and Dial In

I touched base on this little job on the Trailing Arm post but I also use it for the fronts as well.
Brief history for you "youngsters" who never thought about a corvette brake job until you had to do it or you were recovering from the shock at what your local guy charged you to do brakes and they still failed a few weeks later.

When the rear spindles were assembled to the rotors they were turned as one and thus the surface was perpendicular to the axle centerline. It didn't matter is the spindle flange ranout .010" the rotor was secure with rivets and faced. The fronts were also riveted to the hub and faced. Leavng the dealership, new vettes had superior brakes in their day and still are pretty good. Taking the car to a road course and standing on them all the time is different, but for a street system they were exceptional.

As time went on, the pads needed replacement and then the story changed. Dealerships and local shops( including some corvette shops) would remove the rotors to turn or replace them. The finish off a lathe could be great but once the rotor was in place on the spindle the centerline was no longer perpendicular to the rotor face and they wobbled( runout).The calipers are 4 piston type using lip seals. Runout over .005 would cause them to turn into air pumps and then your brake pedal turns to nothing but air. Big problem.

30-35 years ago SS lined calipers hit the market and everyone thought they eliminated the vette brake problems. Thing is the calipers didn't resolve the runout and few understood what runout was or how to use an indicator for that matter.

So what you need to do it secure the rotors in place and dial in the runout, I like it under .002 but .003 is ok. Over .003' fix it- you're the one driving the car not the guy that just took your $1,000 and said runout is in spec- if he even said that.

You can re-rivet them- why, to be judged?

You can do as many have and just let the lugnuts hold them on? Not the way I like, although I have done that in years past on my cars.

You can bolt them on and they will stay where you set them. You will also be able to replace or service the PB without drilling out rivets.

Since I did rears on the TA post I'll do the fronts now. Follow along it won't take you long to get it and to have vette brakes that work great WITH lip seals in the calipers!:devil:

Here I have a front rotor off my 72. I center punched the rivet heads and will center drill them. Then use a 1/4" and 5/16 bit to drill just below the head. Use a cold chisel across the head and they will pop off and you can remove the rotor. With the rotor off you can drive out the bodies.




I then tap the holes 3/8-24 and countersink the rotor counterbored holes. If you buy aftermarket rotors be sure they have the rivet holes, not all do. REVISION: I no longer use new rotors with rivet holes. I prefer to drill a new bolt pattern to line up the holes better then relying on predrilled holes.

I paint them now as well.



Be sure to clean up all the mating surfaces. I use a 2" die grinder to touch them up.





The flat heads I use do not come beyond the flange to hit anything.


I have a spindle here that I will use for setup. I'll grease the new Timkens and install them. I setup the endplay for .002 by adjusting the spindle nut and facing it on a surface grinder if needed.




Bolt them on and tighten good. I'm not concerned about a torque rating here just equal and tight.


Setup a 1" dial indicator, set it at zero at the highest reading 360* around the rotor and read what you have for runout. Don't be surprised if you have
.010" See if a different tightening sequence changes the RO. If not then you have to shim the difference at the lowest stud. I use SS shim stock and a hole punch kit.





I witness mark the screws and mark the runout.






Maybe your shop does this, maybe not? You can do it at home with a little time and patience.

Good night Irene!!!