Hand Brakes

[Howard Faria]

[Joe L.]

Re: Hand Brakes

Howard----

First of all, the best reference for you is going to be the GM service manual for your particular model year. I strongly suggest that you obtain one if you don't already have it. These manuals are available through the NCRS Cincy office at a discount to NCRS members. The Assembly Information Manual(AIM), which won't be of any use to you in this particular case, and the factory service manual are the two, basic references which every Corvette owner should have available. Everything else is optional and supplementary to these.

As far as the parking brake shoes go, there are two ways to access them. The first method involves removal of the rear rotors, of which the first step is drilling out the rotor retaining rivets. After the rotor is removed, accessing the parking brake shoes is still difficult because the spindle flange will be in your way. You can, however, use an inexpensive special tool available from most of the vendors to enable you to remove the brake shoes, albeit still with a little difficulty. Having said all this, I DO NOT RECOMMEND this method. If your rotors are still rivetted to the spindles, count yourself among the fortunate and leave them that way lest you open up a Pandora's box of additional problems.

The second method of accessing the parking brake shoes, which I do recommend, involves removal of the rotor and spindle AS AN ASSEMBLY. This is the method which GM recommends in later C3 service manuals(after they discovered the problems associated with spindle/rotor seperation recommended in earlier C2 and C3 manuals). However, to do this you really need several special tools which are EXPENSIVE. They can be obtained from Kent-Moore or, somewhat less expensive versions can be obtained from several of the major Corvette vendors. Using these tools you can remove and reinstall the rotor/spindle assemblies. You won't have any problem accessing the parking brake shoes since the spindle will be removed and you'll be able to service the rear wheel bearings at the same time. If your car still has the rotor rivets installed, the chances are that the rear bearings have never been serviced since most shops that perform this work use the inferior rotor seperation technique as part of the process. If your 76 has never had the rear bearings serviced, IT NEEDS IT.

With Corvette rear suspension/brake work, one thing leads to another.

[Joe L.]

Re: Hand Brakes

Howard----

First of all, the best reference for you is going to be the GM service manual for your particular model year. I strongly suggest that you obtain one if you don't already have it. These manuals are available through the NCRS Cincy office at a discount to NCRS members. The Assembly Information Manual(AIM), which won't be of any use to you in this particular case, and the factory service manual are the two, basic references which every Corvette owner should have available. Everything else is optional and supplementary to these.

As far as the parking brake shoes go, there are two ways to access them. The first method involves removal of the rear rotors, of which the first step is drilling out the rotor retaining rivets. After the rotor is removed, accessing the parking brake shoes is still difficult because the spindle flange will be in your way. You can, however, use an inexpensive special tool available from most of the vendors to enable you to remove the brake shoes, albeit still with a little difficulty. Having said all this, I DO NOT RECOMMEND this method. If your rotors are still rivetted to the spindles, count yourself among the fortunate and leave them that way lest you open up a Pandora's box of additional problems.

The second method of accessing the parking brake shoes, which I do recommend, involves removal of the rotor and spindle AS AN ASSEMBLY. This is the method which GM recommends in later C3 service manuals(after they discovered the problems associated with spindle/rotor seperation recommended in earlier C2 and C3 manuals). However, to do this you really need several special tools which are EXPENSIVE. They can be obtained from Kent-Moore or, somewhat less expensive versions can be obtained from several of the major Corvette vendors. Using these tools you can remove and reinstall the rotor/spindle assemblies. You won't have any problem accessing the parking brake shoes since the spindle will be removed and you'll be able to service the rear wheel bearings at the same time. If your car still has the rotor rivets installed, the chances are that the rear bearings have never been serviced since most shops that perform this work use the inferior rotor seperation technique as part of the process. If your 76 has never had the rear bearings serviced, IT NEEDS IT.

With Corvette rear suspension/brake work, one thing leads to another.

[John]

Re: Hand Brakes

Just serviced the parking brakes last weekend. They are a difficult job but far from impossible to do even for the weekend mechanic. I don't suggest removing the spindles just to do the parking brakes. This is a very difficult job and you will need a lift to wrestle the parts in and out. Check to see how much bearing end play there is first. It should be from .001-.008 ". If more than that consider removing and replacing the rear spindles. If less, leave them alone and attack the parking brake assemblies. Stainless steel brakes has a good replacment set available that comes with excellant instructions. No special tools are needed and you should be able to install them in 1 hour per side after the removal of the rotors. My rotors on a 75 C-3 that were never apart until I did them took about 2 hours to drill the rivets and soak with penetrating oil to remove. Leave the better part of the day to complete the job. I had to tap the rotors with a block of wood and a heavy hammer. Mine were in for 23 years.I also replaced the spindles and it was a 9 hour job with a lift and all the proper tools( both sides). Hope this helps. John

[John]

Re: Hand Brakes

Just serviced the parking brakes last weekend. They are a difficult job but far from impossible to do even for the weekend mechanic. I don't suggest removing the spindles just to do the parking brakes. This is a very difficult job and you will need a lift to wrestle the parts in and out. Check to see how much bearing end play there is first. It should be from .001-.008 ". If more than that consider removing and replacing the rear spindles. If less, leave them alone and attack the parking brake assemblies. Stainless steel brakes has a good replacment set available that comes with excellant instructions. No special tools are needed and you should be able to install them in 1 hour per side after the removal of the rotors. My rotors on a 75 C-3 that were never apart until I did them took about 2 hours to drill the rivets and soak with penetrating oil to remove. Leave the better part of the day to complete the job. I had to tap the rotors with a block of wood and a heavy hammer. Mine were in for 23 years.I also replaced the spindles and it was a 9 hour job with a lift and all the proper tools( both sides). Hope this helps. John

[Joe L.]

Re: Hand Brakes

John----

What you say is generally correct. It is a big job to remove the spindles from the car just to service the parking brake shoes. However,as I mentioned, if Howard's rivets have not been drilled out, the chances are that his rear bearings have never been serviced since, as I say, most shops drill out the rivets to perform this job, for better or worse. After 23+ years, Howard will probably be well advised to service his bearings at the same time that he replaces his parking brake shoes.

As far as the rear rotor rivets go I can tell you this: I've owned my '69 for 2 months short of 30 years now and 200,000 miles. In that period, I have made a good number of mistakes on the car and learned a lot of lessons. However, I've never made any mistake greater than drilling out those rivets. Not by a long shot!

[Joe L.]

Re: Hand Brakes

John----

What you say is generally correct. It is a big job to remove the spindles from the car just to service the parking brake shoes. However,as I mentioned, if Howard's rivets have not been drilled out, the chances are that his rear bearings have never been serviced since, as I say, most shops drill out the rivets to perform this job, for better or worse. After 23+ years, Howard will probably be well advised to service his bearings at the same time that he replaces his parking brake shoes.

As far as the rear rotor rivets go I can tell you this: I've owned my '69 for 2 months short of 30 years now and 200,000 miles. In that period, I have made a good number of mistakes on the car and learned a lot of lessons. However, I've never made any mistake greater than drilling out those rivets. Not by a long shot!

[Richard T.]

Re: Hand Brakes

Joe, For the benifit of myself and other novices regarding the rear rotor rivits , what are the problems that are created or encountered when these rivits are removed ? Rich

[Richard T.]

Re: Hand Brakes

Joe, For the benifit of myself and other novices regarding the rear rotor rivits , what are the problems that are created or encountered when these rivits are removed ? Rich

[Joe L.]

Re: Hand Brakes

Rich-----

As simple as it might seem, this is a very complicated subject. I will try to briefly cover the high points, but you might find more of my or others disertation on this issue in the archives.

The original rotor/spindles used on 65-82 Corvettes were manufactured as an assembly. In this process, a spindle was rivetted to an UNFINISHED rotor. The assembly thus created was then machined so that the FINISHED rotor friction surfaces were TRUE TO THE SPINDLE BEARING SURFACES and other critical rotor finished dimensions and specifications were met. As a result of this manufacturing process, it was not necessary for GM to maintain "tight" machining tolerances on the spindle flange mounting surface or, even, the rotor spindle mating surface---the finished product would meet all requirements and that's all that was practically required. Many GM spindles have total indicated runout(TIR) of .010" or greater on the spindle flange mounting surface. However, this was not a problem for GM since this runout was "cancelled out" in the final machining process for the rotor. I might add, at this point, that many GM SERVICE spindles, to this day, maintain the same excessive runout "tradition" of the original PRODUCTION parts. However, as I described, in PRODUCTION the runout didn't matter, but in SERVICE it does. GM rear rotor/spindle ASSEMBLIES were NEVER available in SERVICE unlike front hub/rotor assemblies which are available(EXPENSIVE, but the only way to go, in my opinion----I have TWO SETS in my collection as a hedge against the day GM stops making them).

When the rear spindle/rotor assemblies are seperated, the rigid rotor TIR specifications can be easily lost. Of course, if the SAME ROTOR is reinstalled on the SAME SPINDLE and IN THE SAME RELATIVE POSITION TO THE SPINDLE, there is a good chance, but not a certainty, that acceptable rotor TIR will be maintained. However, if the rotor is even SLIGHTLY displaced from its original position(which CAN occur even if reinstalled in the same relative position), or if any substance(like a SPECK OF DIRT OR RUST)finds its way into the spindle/rotor interface upon reinstallation, TIR values on the rotor surface can become excessive. If one component of the original assembly is replaced (rotor or spindle or both), there is a virtual certainty that TIR will be excessive. One must remember that a TIR on the spindle mounting flange of .002" will produce a TIR of .005" or greater on the rotor. .005" TIR on the rotor is the absolute MAXIMUM that can be tolerated on the rotor without producing brake problems("air pumping")in a car with fixed calipers like 65-82 Corvettes. I have NEVER seen a GM spindle, PRODUCTION or SERVICE, that measured .002" or less TIR on the spindle mounting flange. Although less of a safety concern, but greatly annoying, is the other "by-product" of excessive TIR: the incessant, rotational squeeking produced by the rubbing of the ends of the brake pad backing plates on the calipers.

I could go on and on on this subject, but that's all I'm going to say. I have studied it. For years.

[Joe L.]

Re: Hand Brakes

Rich-----

As simple as it might seem, this is a very complicated subject. I will try to briefly cover the high points, but you might find more of my or others disertation on this issue in the archives.

The original rotor/spindles used on 65-82 Corvettes were manufactured as an assembly. In this process, a spindle was rivetted to an UNFINISHED rotor. The assembly thus created was then machined so that the FINISHED rotor friction surfaces were TRUE TO THE SPINDLE BEARING SURFACES and other critical rotor finished dimensions and specifications were met. As a result of this manufacturing process, it was not necessary for GM to maintain "tight" machining tolerances on the spindle flange mounting surface or, even, the rotor spindle mating surface---the finished product would meet all requirements and that's all that was practically required. Many GM spindles have total indicated runout(TIR) of .010" or greater on the spindle flange mounting surface. However, this was not a problem for GM since this runout was "cancelled out" in the final machining process for the rotor. I might add, at this point, that many GM SERVICE spindles, to this day, maintain the same excessive runout "tradition" of the original PRODUCTION parts. However, as I described, in PRODUCTION the runout didn't matter, but in SERVICE it does. GM rear rotor/spindle ASSEMBLIES were NEVER available in SERVICE unlike front hub/rotor assemblies which are available(EXPENSIVE, but the only way to go, in my opinion----I have TWO SETS in my collection as a hedge against the day GM stops making them).

When the rear spindle/rotor assemblies are seperated, the rigid rotor TIR specifications can be easily lost. Of course, if the SAME ROTOR is reinstalled on the SAME SPINDLE and IN THE SAME RELATIVE POSITION TO THE SPINDLE, there is a good chance, but not a certainty, that acceptable rotor TIR will be maintained. However, if the rotor is even SLIGHTLY displaced from its original position(which CAN occur even if reinstalled in the same relative position), or if any substance(like a SPECK OF DIRT OR RUST)finds its way into the spindle/rotor interface upon reinstallation, TIR values on the rotor surface can become excessive. If one component of the original assembly is replaced (rotor or spindle or both), there is a virtual certainty that TIR will be excessive. One must remember that a TIR on the spindle mounting flange of .002" will produce a TIR of .005" or greater on the rotor. .005" TIR on the rotor is the absolute MAXIMUM that can be tolerated on the rotor without producing brake problems("air pumping")in a car with fixed calipers like 65-82 Corvettes. I have NEVER seen a GM spindle, PRODUCTION or SERVICE, that measured .002" or less TIR on the spindle mounting flange. Although less of a safety concern, but greatly annoying, is the other "by-product" of excessive TIR: the incessant, rotational squeeking produced by the rubbing of the ends of the brake pad backing plates on the calipers.

I could go on and on on this subject, but that's all I'm going to say. I have studied it. For years.

[Richard T.]

Re: Hand Brakes

Joe , Thanks for the reply. I never knew that the general assembled the unit that way. I'm really a straight axle guy but have had a few mid years and currently own a 67. In the past I've drilled the rivits and reassembled without any problems but it appears that I was just lucky. Thanks again. Rich

[Richard T.]

Re: Hand Brakes

Joe , Thanks for the reply. I never knew that the general assembled the unit that way. I'm really a straight axle guy but have had a few mid years and currently own a 67. In the past I've drilled the rivits and reassembled without any problems but it appears that I was just lucky. Thanks again. Rich