C2 Brake Rotor indexing

[Jim S.]

The time has arrived where my original front rotors are to the point of no return. Turning them will put them below the safe limit.

I really don't want inexpensive rotors from the discount parts store so I am considering Van Steel or Vette Brakes here in Fl.

The question is should I take the ft hubs to them for indexing to reduce runout or is indexing something I can do with a dail indicator. If I take the hubs to them should I have them install the rivets as original.

66 small block driver
manual brakes
Vette Brakes 0 ring calipers
Driven a few thousand miles a year.
Decent but not a Top Flight( or any flight)

Thanks

[Joe L.]

Re: C2 Brake Rotor indexing

Jim-----

You can easily check the rotors by mounting them to the hub, torquing all lug nuts to the specified torque, mounting them on the front spindles with bearing end play adjusted to "0", and dial indicating them. It's not hard, at all. If there is excessive runout, though, correcting it is a bit more complicated. There are 3 wyas to do it for the FRONT brakes:

1) Take the assembly to a brake shop and have them turn the assembly on their brake lathe to get runout within spec. I don't like this approach too much with new rotors. Here you have a set of rotors with full thickness and factory blanchard-ground, and you lose all of it to a field machining. IF you can find a brake shop with the equipment and capability of truing the ROTOR SEAT ON YOUR HUBS, that's a different story. In that case, you have them true the rotor seats to minimum run-out. Then, they install the new rotors on these seats. The rotors, themselves, should be factory-machined to near perfect runout. So, when you bolt the 2 together, it should check out ok;

2) Adjust the runout yourself using washers you can make from very thin brass shim stock. You install these on the appropriate wheel studs between the rotor and the hub to adjust the end -play. It's somewhat of a trial-and-error process and takes some time, but you can get the runout very close. Some folks don't like this method because they think that it might result in a broken rotor sometime down the road. However, I've used this successfully for years and I know other brake shops have used it for years. This method is even specified in some factory shop manuals for runout correction. I have never seen or heard of a case of a broken rotor;

3) Obtain special tapered shims, specific as to runout correction value, and use these to correct runout. You first have to know what correction you need. I don't know of a source to buy these things on a one-at-a-time basis. The company that manufactures them sells them as a kit with many shims in it to brake shops. So, I guess you need to find a shop that uses them and see if they will sell you what you need. These are a better solution than the shimming I described above, but they're not enough better to warrant all the trouble involved in getting them. Plus, after you install one, you may find that it's not quite right, then you need another of different spec (that's the reason the brake shops get the kits). This method is a lot better for brake shops, though, since the correction can be done a lot faster (time is money in a brake shop) than using the shimming method I described above.

Whatever method of correction you use, you don't absolutely need to have the rotors riveted to the hubs. However, you do need to make sure that the rotor can always be re-installed on the hub in the same relative position. So, you mark one of the wheel studs and the appropriate hole in the rotor.

[Terry F.]

http://www.brakealign.com/

These people sell indexing shims. Terry

[Jim S.]

Thanks Joe and Terry *NM*

[Philip C.]

JUST

go to a good parts house and buy a set of rotors, clean and repack your wheeling bearing put them on your car and go down the road, Everything on here is a BIG deal. Just think of all the people with pieces of #$# next to you, are drive on with no prolbems. The car show parking lots are full of them. Phil 8063

[Joe L.]

Re: JUST

phil-----

In most cases, you're right. One can replace the rotors on the front hubs, bolt them up, and the runout will be found to be in spec. However, the procedure I described is what one needs to do if the the rotors don't check out within spec. One does need to check the runout after rotor replacement, though. Excessive rotor runout on the front wheels will cause EXACTLY the same "air pumping" problem in the front brake system as the "air pumping" problem often encountered on the rear. In fact, the problem will be MUCH worse if it occurs on the fronts since about 70% of the car's braking is supplied by the front brake system. So, if one gets air in the front brake system, you might not be able to stop the car, at all.

So, why is it that the vast majority of folks out there can replace their rotors, NEVER bother to check rotor runout, and never have any problems, at all? Well, that's because the VAST, VAST majority of cars out there use a floating caliper brake system. In a floating caliper system, excessive rotor runout causes far fewer problems and does not cause the dreaded "air pumping" problem. So, with the VAST majority of cars out there, rotor runout is pretty much a non-issue (although it can still cause some problems if really excessive).

1965-82 Corvettes are an exception since they use a FIXED caliper system. That's what makes them VERY sensitive to rotor runout tolerances. 1969 Camaros with 4 wheel disc brakes (VERY rare) and some late 60's passenger cars with front disc brakes are the only other GM cars that I can think of that used the fixed caliper system. All C4 and C5 Corvettes use a floating caliper brake system. I believe that C6 does, too, but Z-06 MIGHT use a fixed caliper system.

On other car manufacturer vehicles, fixed calipers are VERY uncommon, too.

[John H.]

Re: JUST

Joe -

All '67 Camaros with disc brakes (J50/J52) used the Corvette fixed calipers, and the Viper uses the same (Brembo) 4-piston fixed calipers used by Porsche and Ferrari. These days, not many cars under $90,000.00 or so use fixed calipers; most "brake shops" have never seen anything but floating calipers.

[Joe L.]

Re: JUST

John-----

I think that you may be thinking about 67-68 Camaros with front wheel disc. Those were fixed calipers like Corvette but not exactly the same parts. I just researched this a bit further because I had always understood that only the 1969 Camaros with 4 wheel discs (i.e. JL-8) used the Corvette fixed piston calipers. From what I can find, the front wheel only disc-equipped calipers for 1969 Camaros were single piston, floating caliper type. Also, the same front disc brakes used for 1969 Camaros with front-only discs were also used for 70-74 Novas with front disc brakes.

Anyway, the 1969 Camaro with front disc brakes used caliper assemblies GM #5469122 and 5469123. Generally, GM calipers for floating piston type calipers are available as an assembly. From what I can tell, these are a Delco-Moraine, single piston floating caliper.

Calipers for 1969 Camaros with 4 wheel disc brakes were serviced only as caliper halves, just like Corvettes.

Actually, I was not aware that 67-68 Camaros with front disc brakes used Corvette-type, fixed calipers. However, it makes sense since most, if not all, of the very early Chevrolet disc brake systems were fixed caliper design.

The very first Chevrolet vehicle to have disc brakes was the 1965 Corvette. After that, disc brakes were next utilized for optional front-only usage for 1967 full size passenger cars, 1967 Chevelles and 1967 Camaros. I knew that the passenger cars used fixed calipers. I didn't know that the Chevelles and Camaros did, too. But, it makes sense.

What brakes do you have on your Z-28?

[Philip C.]

Re: JUST Joe

Everbody on here makes a %$@ mountains out of ant hills! HOW do you think gas station type guys have been repairing this pieces of shi* for years is my point. Phil 8063