Brake rotors on C3.

[Clem Z.]

Re: Maybe Bairs reindexes the rotors before riveti

there are companies that sell a tapered shim to place between the hub and the rotor you can use to get the rotor run true. GM uses them in service.

[Dan Tewell]

Re: Maybe Bairs reindexes the rotors before riveti

Clem, do you have any part numbers for those shims?
Thanks, Dan

[Eugene B.]

Re: Never going to understand reindexing

Gents,
This discussion of reindexing, orienting, marking spindles and rotors totally confuses me.

On my '65 rear rotors, there is only ONE way to put the rotors over the spindle lug bolts. I've purposely tried to do it wrong several times and found that there is only one position that allows the lug bolt holes, rivet holes, and both parking brake access holes to be in perfect alignment.

Did it again this afternoon after reading this posting this morning. Still can't do it wrong, so what am I missing? Regarding reviting, the shop manual makes it clear that it is not necessary.

Regards to all,
Gene

[Clem Z.]

the tapered shims are available from

brake align llc 1-800-551-2228

[Clem Z.]

go to google and type in brake align llc *NM*

[Clem Z.]

you can also chuck up the rotor in a lathe

and after indicating the pad surface for runout take a light cut from the surface that mates up with the spindle hub.this will make the rotor run true if the spindle hub is true.

[Joe C.]

Re: Maybe Bairs reindexes the rotors before riveti

Clem:

I had total runout of .008" on the left rear, and was able to reduce it to .002" with judicious and strategic application of small pieces of ALUMINUM FOIL between the rotor and the hub. This did the trick, and is still there after 3 years.

Joe

[Joe C.]

Re: Never going to understand reindexing

Gene:

The indexing issue applies to some aftermarket rear rotors without the 2 ebrake adjuster holes, and all front rotors. You are right about original style rear rotors though--there is only one right way to install them.

Joe

[Joe C.]

How Are The Rear Rotors Surfaced If.............

.....they are rivetted to the spindles. I can live with removing the front rotor/hub assembly for turning, but the rears......now THERE is a major job of tearing down the trailing arms. I have pulled the bearing assemblies without removing the trailing arms, but this is still a huge job. Am I missing something, or can the units be "turned" while still on the car?

BTW: After snapping my right rear spindle after getting rambunctious with my '65 L76, I replaced the rear spindle with a unit from International Axle. This is a very high quality part. After reassembly with bearing end play set to .001", I measured the runout at the outer circumference on the new spindle. It measured an amazing .001" (the old, original GM measured .007"). Runout of rotor, after attachment to spindle (using reversed lugnuts, torqued to 60 ft lbs), measured .003" at the outer circ.
I understand that original GM (and those made today, using original GM tooling) hubs and spindles were/are produced with runouts exceeding .005". That is the reason that the rotors were rivetted to the spindles/hubs, since a "true" rotor would show excessive runout after assembly to the GM hub/spindle. I suppose that one way (albeit time consuming and expensive) to fix the problem, would be to remove your original hubs and spindles, press out the studs, and machine the faces straight and true.

Joe

[John H.]

Re: How Are The Rear Rotors Surfaced If...........

Many "modern" brake shops (not the converted gas station on the corner with the "Billy-Bob's Discount Brakes" sign out front) have the proper equipment to resurface rotors on the car, and do it regularly; many Chevy dealers also have that capability so they don't have to sublet that kind of work.

[Clem Z.]

PS

you can do the same with the spindle hub since they have center holes so the rotor surface can be checked for runout with a dail indicator in a lathe. it pays to have a machinest friend. if you true the spindle flange and the rotor surface you should have no runout on the rotor pad surface.