C2:67 Parking Brake Drum Assembly

[Gerard F.]

Anyone have a picture or assembly drawing of the 67 parking brake setup with the disc/drum removed.

A couple of weeks ago, I tightened up the cable on the bottom because the brake was not holding in the forward direction. As it was still not holding, I pulled the wheels and tried the adjustment through the hole in the hub disk per the service manual. I noticed on the p-side that there seems to be a loose spring near the adjustment wheel. Wondering if I just made the cable too tight or there is something broken inside.

The hub and disc has never been off this car, although the brake calipers are fairly new and work just fine. Going to order a parking brake kit, but just trying to figure out how the parking brake works within the wheel assembly. It seems like a big job to me of drilling out rivets to get the disc and drum off and then putting it back on. Probably should take it to as shop.

Any advice.

Jerry Fuccillo
#42179

[Joe L.]

Re: C2:67 Parking Brake Drum Assembly

Jerry-----

It's a pretty simple mechanism----pretty much like a "miniature" drum brake but without self adjuster mechanisms, etc.

In order to service it, at a minimum, the rotor has to be removed. Even then, it's a bit difficult unless the spindle is also removed. However, it can be done if the spindle remains installed.

The best bet for accessing it and for avoiding the creation of other problems is to remove the rotor and spindle as a unit. GM began to recommend this procedure starting in 1974 (after they figured out that seperation of the rotor from the rear spindle can result in creating other problems). This is how I recommend that the rear rotor be removed IF THE ROTOR RIVETS ARE INTACT. This procedure does require special tools, though, especially for re-installation of the rotor/spindle assembly.

The parking brake adjustment procedure is covered very well in the service manual. You need to follow this procedure assiduously if there is any hope of getting the adjustment right. A 1965-82 Corvette parking brake that is "marginal" is about as good as you're going to get it.

Attached is a diagram of the components.

[Joe R.]

Re: C2:67 Parking Brake Drum Assembly

Hi Jerry:

Those parking brakes are a LOT less complicated than some of the other stuff you have successfully rebuilt and posted on this board. If you use the shop manual process of drilling out the rivets and removing the rotor, it is all very straight-forward work.

I see that Joe Lucia is suggesting that the spindle/rotor assembly be removed, and for that I think you probably should take the car to a shop. I'm not sure what he considers to be the down side of removing the rivets, but perhaps he will elaborate. He may be concerned about increasing the rotor runout.

Runout can be a concern if the rotor is re-installed on the wrong side or in the wrong position, but the rear rotors can only be installed in one position if you line up the access hole for the adjuster. So, as long as you reinstall the rotor on the side it came from, I think the (typically low) factory runout will be maintained.

If you decide to just pull the rotor off and do the work yourself, I have two suggestions that may be helpful:

1) It's okay to use the stainless hardware kit, but I recommend using OEM-style shoes. I installed stainless shoes and they would not stay on the the bumps they rest on on the backing plate. In researching the problem, I learned that this is a common problem with the stainless shoes, reportedly because their arch is slightly off. When I switched to OEM-style shoes, the problem went away.

2) I purchased a "brake spring" tool that looks like a screwdriver with a slot in it. When working in the confined space behind the spindle flange, this tool was a lifesaver for getting the springs removed and installed.

Lastly, be sure that that you need to get in there before you take the brake assembly apart. I would think that if there was a loose spring you would hear it rattling around when you rotate the wheel. There *is* a spring that rests against the star wheel to keep it from turning on its own, so if that is what you are seeing when you look in there is is normal and correct. However, this spring is in tension and should not seem loose if you poke it using a smalll screwdriver through the adjustment hole.

As Joe Lucia said, it is essential to follow the factory procedure when adjusting the parking brake. You must first disconnect the cable that comes from from the parking brake lever to remove ALL tension from that. Then you adjust each wheel until it drags and then you back off a few notches (ten if I recall). Only after doing all that do you reconnect the central cable and adjust that.

[Gerard F.]

Re: C2:67 Parking Brake Drum Assembly

Thanks Joe & Joe for the advice.

What I am seeing through the adjustment hole is the end loop of the #6 spring (in Joe L's picture). Is it possible to reset this spring through the adjustment hole with the spring tool. I'm assuming that the spring end loop goes through a hole in the shoe, is that correct?

If this can be done, I'd like to go through the service manual adjustment procedure, this time in the correct order.

If not, I guess I'll have to bite the bullet, get a kit and drill out the rivets. My concern is not drilling out the rivets, but putting them back in.

How easy is it to do this with the spindle on the car.

Jerry Fuccillo
#42179

[Joe R.]

Re: C2:67 Parking Brake Drum Assembly

Hi Jerry:

I seriously doubt that the spring could be reinstalled by working through the adjustment hole. I suppose there is no harm in attempting it, though. The spring is supposed to hook through the holes in the lower portions of the brake shoes. The holes are *near* the numbers 4 and 10 in the diagram that Joe Lucia posted, but they are not what is indicated by those numbers.

For any chance of success going in via the adjustment hole, I think you would need a tool like I described earlier, which is sort of like a screwdriver with a slot in the blade.

Can you see both ends of the spring through the adjustment hole? I suspect that the reason it is loose is that one end of the spring is broken off.

Regarding the rivets, these have been discussed in the archives. They were used by GM to aid the assembly process, and do not perform any useful function once the lug nuts are installed. As the Service Manual says, they do not need to reinstalled (mine are long gone, as are most rivets on older Corvettes that have had this area serviced during the last 40 years).

If you read the archives you will see that when GM built the cars, the rotor surface was machined *after* the rotor was riveted to the spindle. This resulted in very low runout that is hard to duplicate if you remove the rotor and replace it with another. However, if you put the same rotor back (taking care to line up the adjustment hole as before) you should be able to preserve the factory runout.

Rebuilders such as Bairs and Van Steel offer the option to have new rotors riveted on and the rotor/spindle trued as an assembly the way the factory did it, and some people like to do that. However, when I recently had Bairs rebuild my trailing arms, I kept my rotors and skipped this step. My reasoning was that I wanted to retain easy access to the parking brake if I ever needed to get in there in the future. I did, however, spend some time minimizing the runout that I got with the new rotors that I had purchased.

By the way, the most annoying aspect of this job is that you have to disconnect the rear calipers and pull them out of the way. Plan for this in advance, because brake fluid will continue to drip out of the brake lines as long as that point is below the master cylinder. I used a couple old brake lines to plug the hoses, with the ends folded over and raised above the master cylinder.

Another very useful step was to make a couple blocks of wood that are the thickness of the rotor. I slid these between the pads as I pulled the caliper off the rotor. This keeps the pads and pistons in place and aids reassembly.

[Joe L.]

Re: C2:67 Parking Brake Drum Assembly

Joe and Jerry------

If the rivets are removed, it can be problematic to re-achieve the original runout even if the rotor is re-installed on the spindle in exactly the same relative position as it came off. There are many reasons for this. One of these reasons is that you will note that the rotor can be slightly moved relative to the spindle when the rivets are gone. That's because there is some clearance between the wheel studs and the wheel stud holes in the rotors---not much, but a little. There are other reasons, too, which may affect the runout if the rotor is seperated from the spindle. I believe that this is why, from 1974 on, GM no longer recommended that the rotor rivets be drilled out for most service operations (except, of course, the need to replace either component since assemblies were never available in SERVICE). I believe that drilling out the rear rotor rivets "opens up a can of worms" as far as rear rotor runout is concerned.

There is no practical means of re-riveting the rear rotors to the spindles. The rivets used are very difficult to set without special tooling. The original factory tooling set all 5 rivets at once. In the field, even trying to set one at a time is almost impossible.

[Douglas B.]

Re: C2:67 Parking Brake Drum Assembly

I just completed the same job on my 78. It can be done with the rotor removed, but is is quite a challenge.

[Gerard F.]

Do you mean re-riveting the rotor

to the spindle, Doug? If so how did you do it? I was thinking about clamping it tight with bolts first, then figure out some way to re-rivet one at a time.

Jerry Fuccillo
#42179

[Douglas B.]

Re: Do you mean re-riveting the rotor

I did not put the rivets back in. I was told this was optional. I just made sure to put the rotor back in the same position. I had both springs broken on my park brake and had to replace them working through the holes in the flange. It was quite difficult, but I was able to get it done.

[John H.]

Re: Do you mean re-riveting the rotor

Doug -

You don't need to re-rivet the rotor - it's not necessary for function, and nobody will remove a wheel during judging to see if they're present. As long as you indexed the rotors in the original position when you re-installed them, you'll be fine.