C3 1971 Brakes

**Joe L.** · June 7, 2005, 04:27 PM

Re: C3 1971 Brakes

Tony----

1) The runout problem created by replacing just the rotors can be a problem for BOTH the front and rear rotors. However, the fronts can (or, at least, used to) be replaced as a complete assembly with hub. The rears could never be purchased as a complete assembly with spindle. If the front rotor is replaced with a unit complete with rivetted-on hub, there is NO problem of runout created-----the factory unit has had the rotor finish-machined to the hub centerline.

GM no longer offers the front rotors as a complete assembly with hub and I don't think that the aftermarket does, either (although they may). So, if a front rotor is replaced and the old hub re-used, the same precautions have to be taken regarding runout. For the fronts, though, a runout problem, if one exists after rotor replacement, can be corrected more easily than the rears. What needs to be done is to precision finish the rotor surface to the hub centerline in a brake lathe. If runout on the assembled rotor hub is excessive, it will be necessary to shim the rotor hub interface to avoid excessive thickness reduction of the rotor. However, basically the same runout correction procedures need to be followed for the front as the rears; it's just that the front is a little easier and more straight-forward to correct.

2) Brake rotor runout involves the faces of the rotor moving in more than one plane. A brake rotor with runout will appear to "wobble" as the rotor is turned. A dial indicator placed with the measuring rod 1" from the perimeter of the disc is used to measure the amount and location of runout.

3) I don't know. There is often a wide variation in the prices of a lot of things, depending upon where you purchase them. Such a price difference as you describe implies a quality difference. However, Raybestos and Bendix are 2 of the larger brake parts suppliers and I would not think that they would put their brand on poor quality pieces. It may be that their pieces are of foreign manufacture. That does not automatically make them bad, though.

**Tony Roussos** · June 7, 2005, 04:46 PM

Re: C3 1971 Brakes

Joe,

Upon removing the tires, the front passenger side rotor is rivited to the hub and is in OK shape. However, the driver side rotor is significantly pitted. It is for this reason coupled with installing new calipers and pads that I elect to replace the rotors, too.

This vett is slated to be my main driver when all is said and done.

The replacement rotors look like very good quality calipers, but there are no holes for rivits. I've always had good success with Raybestos products. I believe they have a manufacturing facility just 25 miles to the east of my town, Erie, PA. Although I'm not sure these rotors were made there.

Would a brake shop like Midas or Monroe have the equipment to check and correct runout? Where would you suggest I trust to perform this job?

Thank you.
Tony

**Joe L.** · June 7, 2005, 04:59 PM

Re: C3 1971 Brakes

Tony-----

Many of the replacement rotors these days lack the rivet holes. The rotors do not have to be rivetted to the hub, although it is a good idea. It is very difficult to add the rivet holes and countersinks to rotors not so-equipped. If one wanted the rivet holes and countersinks, it would be better to just purchase the type that have them (these may be the more expensive ones). The rotors can be secured to the hub via the lug nuts while the runout is checked and, if necessary, corrected. Thereafter, the indexing of the rotor to the hub MUST be maintained.

I wouldn't rely on a shop like Midas or Mieneke to do the rotor runout checking. I'd look for a brake shop or general mechanic shop that specializes in Corvettes. Or, send the rotors and hubs to a shop like Bairs. They're located in Linesville, PA. That would be the best idea of all.

The country of origin of the rotors may be printed on the box, although it might be in small letters. Or, it might be cast somewhere on the rotors.

**Tony Roussos** · June 7, 2005, 05:20 PM

Re: C3 1971 Brakes

Thank you, Joe

I rechecked the new rotors and box. They're made somewhere in the USA.

Roughly how much would I expect to pay for this type of job? I suppose they will remove the spindle from the A-frames? Could I wait until I have the A-frame bushings, springs, and shocks replaced to check/correct runout? I'm not driving it much this year until I re-do the front and rear suspension.

Thank you,
Tony

**Joe L.** · June 7, 2005, 06:04 PM

Re: C3 1971 Brakes

Tony-----

I don't know how much they charge for a job like this. You could call them and find out.

For this operation, they do not need the front spindles, at all. An experienced shop like Bairs can do it with just the new rotors and hubs.

If you had the capabilities, you could check it yourself on the car before sending them anything. To do this you'd need to drill out the rivets, remove the old rotors, install the new rotors, and fasten the rotors to the hubs by installing the wheel lug nuts. Next, install the assemblies on the spindles (with wheel bearings). Tighten the spindle nut just until all end-play is removed. Then, dial indicate the surface of the rotor. If it's within spec, you're done. Simply mark one of the lug bolts and the rotor hole it passes through so that you can always re-index it if the rotor is removed for any reason.

If it's out-of-spec (0.005" TIR, MAXIMUM), then you could try re-indexing the rotor to the hub by rotating the rotor to the hub by one lug bolt position. Then, measure the TIR again as described above. Repeat this, if necessary until you get an acceptable runout reading. When you do, you're done. If you never get an acceptable runout reading, then you'll need to send them off to Bairs. But, you just need to send the rotors and hubs. For their purpsoes, the front spindles have nothing to do with the work.

**bruce11495** · June 7, 2005, 10:08 PM

Re: C3 1971 Brakes

Joe....That is "old school"to do it the way you are talking....take the rotor/spindle to a machine shop. Not a brake shop. They can turn the complete assembly on a lathe,even the back spindles, which is where 75% of the brake problems are.
To do the backs to perfection....press all the studs out, face the spindle, replace studs, attach rotor in the correct position, and turn the rotor on the spindle in the lathe. ABSOLUTELY the only way to do it, you'll never wear out the rotors in your lifetime if you drove it every day. It may cost $75 dollars to do it, BUT you'll only do it once.........If you need more info, let me know.

**Patrick H.** · June 7, 2005, 10:14 PM

Re: C3 1971 Brakes

Joe,

FYI, the front rotor and hub assembly is available in the Corvette aftermarket.

Patrick

**Joe L.** · June 8, 2005, 03:59 PM

Re: C3 1971 Brakes

bruce-----

Believe me, I know all about the machine shop route. I once took a pair of rear spindles and rotors to a highly regarded machine shop in the area and the ONLY one that I found that would even take the job (I called/visted about 20 shops before I found one that would even take the job). The work cost me $400 and the finished product was no better than they were when I took them in. Machine shops are just not set up for this sort of thing. At least, they are not in my experience.

While NO brake shops will do the work of taking Corvette rear spindles and rotors and machining them to eliminate runout, they can easily handle the fronts as they do this sort of work all the time. Plus, the brake shop brake lathes are set-up for doing the front hub/rotor but are not set-up, at all, for doing the rear spindles and rotors.

Machine shops, on the other hand, are not set up for any of this work. They can, theoretically, set up for it, but you're going to pay for all the set-up time (as my $400 experience demonstrated and that was YEARS ago).

Personally, I would not even consider using a general or automotive machine shop to true Corvette FRONT or REAR rotors to the hub/spindle. A specialty machine shop (like Bairs, Van Steel, or Carter's Corvette), I would have no problem with, at all. In fact, I recommend that approach. However, I do believe that, for the fronts only, a really competent brake shop could do the job with no problem.

**Joe L.** · June 8, 2005, 04:56 PM

Re: C3 1971 Brakes

Patrick-----

What brand are they? I won't need any, though. I have a 5+ lifetime supply of the GM rotor/hub assemblies [none for sale, of course].

**Patrick H.** · June 8, 2005, 05:32 PM

Re: C3 1971 Brakes

Joe,

That I'm not sure of.
I know that Mid America sells them, but I have never discovered who is their supplier. I highly doubt they do the work themselves (they are refurbished units), but I do not recall seeing them in any other catalogs.

Patrick

**bruce11495** · June 9, 2005, 07:11 AM

Re: C3 1971 Brakes

Joe....There is hardly any setup time required. Take the spindle in with the rotor affixed with your wheel nuts, the spindle has a "pickup" point on it, or they can install it in a Jacobs chuck, and turn it just like the brake lathe, When you're done, they are just as good as GM made them, or even better if you find a good machinist. The runout is hardly measurable. Had a set of rears done last week,$60. It takes less time than a brake lathe

**Tony Roussos** · June 9, 2005, 07:38 AM

Re: C3 1971 Brakes Thanks!

Thank you, all, for the education!

How long running with just replacement rotors (not machined for runout) before problems developed and how severe would those problems be?

Tony

C3 1971 Brakes

C3 1971 Brakes

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