stevebz06

My C5 has a single caliper with cable activation for the parking brake. My C4 uses the integral drum brake for a parking brake. The C6 that I didn't own but wrenched on had a single caliper that worked pretty much like the C5 does. The only problem I had with any of them was with the C4 system. We were racing all of them, so it's not like they were garage queens. To me, the dual caliper is a solution to a problem that I haven't seen.

Bill Dearborn

84-87 C4s had the parking brake drum in the rotor the same as the C2, C3, C5, C6 and C7. The 88-96 cars had the parking brake implemented through the brake caliper, there was no drum in the rotor. The 88-96 cars used a lever mechanism on the caliper to engage the brake pads separately from the hydraulic system. The problem they had with using a lever on the caliper to engage the rear brake pads is if the mechanism froze (parking brake mechanisms/cables tend to freeze up a lot) with the parking brake engaged slightly the car could be driven and the heat would boil the fluid in the caliper. On a dual diagonal system you could lose rear brake and one front brake and on a front/rear system you would lose the rear brakes. If the main cable froze on a dual diagonal system you could lose all the brakes because both rear calipers would have boiled fluid. This was a common occurrence on the 2004 to 2005 GM B model cars.

This is what the 88-96 rear caliper looked like with the parking brake lever.




Bill

stevebz06

Thanks, Bill, but my C5 didn't have the drum parking brake like my C4 has.

Widgeon5

You are right; in fact in every airplane I have flown, from small to very large, there was no separate parking brake mechanism whatsoever. The function was accomplished by trapping hydraulic pressure to the main brake calipers. Of course, this system is only safe to use for the very short term as that pressure will bleed off (in minutes to possibly hours) and wheel chocks are necessary for extended parking. As you say, aircraft engineers would never allow the weight penalty of a separate parking brake system.

stevebz06

My brother worked for Boeing while the 747 was being designed. I'm sure the process has been speeded up quite a bit now, but back then they had design committees and they would work separately. They would have meetings and start comparing notes and discover that two or three parts were planned for the same space, and parts would have to be moved, but also they would keep track of the weight, and when the weight started increasing above planned parameters, the offending parts or systems would be redesigned or a different, lighter material would be used, and it was done according to an approved budget.

Chevrolet could use us as weight management consultants.

Bill Dearborn

All C5s, C6s and C7s have the drum parking brake inside the rotor. Just like the early C4s.

Bill

stevebz06

Then I must have a really rare C5, it doesn't have this.

Bill Dearborn

The only difference between the early C4 and subsequent C5 is the method of mounting the parking brake shoes. The drum is located in the center of the rotor on both.

Just look at online pictures of both. You will see the drum cast into the rotor on both. Take the rear rotor off either car and you be looking at the parking brake shoes not a drum.

Bill

C6_Racer_X

Every caliper I've seen like that, with a single caliper and a cable activated lever to press the pads for a parking brake, they tend to be very unreliable. It's especially bad in northern climates, where there's road salt to deal with in the winter, and in coastal areas, where there can be a bit of salt in the air from "sea moisture" The shaft for the parking brake actuator tends to corrode and seize on those calipers. If you're lucky, it seizes where you can't set the parking brake. More often, it's corroded where it won't release properly, and you get the boiling fluid issues you described.

I'll also say, the first caliper I saw with that design, on a late 1980's VW GTI, had a tendency to shed inner pads when driven hard (during track sessions). We never figured out why it happened, but at least one session every weekend, the race car with those calipers came back with a torn up caliper and missing the inner pad on that caliper. It happened to both sides of the car (though usually not both at the same time), and it happened a lot.

For street cars, I much prefer the drum in the hub of the rotor design. It's tried and true and has very few reliability issues. It's a little extra weight, but for the bullet proof reliability, on most street cars, it's a good trade off.

For cars that may become race cars, the "super car" approach with a second caliper works best. If the racing rules allow removing the entire parking brake, you just remove the parking brake calipers and associated cables and such. If you have to carry the calipers, just leave them in place. Usually they are placed very low on the rotor to keep the weight low. And it's still lighter for unsprung weight, and a lot lighter for rotating mass to have just the rotor with a lighter weight hub area (no need for a brake drum in that part of the rotor).

stevebz06

I don't need a picture: I've taken it apart countless times and there is no drum brake hiding in my rear rotors on my C5. C4, yes.

Apocolipse

Guess you also put your stick shift into park?