-Vastly improving C3's Emergency/Parking-brake action...

[Vette/Berlina-coupe]

FOR SAFETY SAKE: -perhaps someone with the capability could experiment with drilling hundreds of say 1/4"Radial-holes (try initially on obliquely-staggered 1/2"-centers) in the brake-drum's surface (doing same into the brake-shoes is not the same), in order to thereby effectively increase the binding-friction of the brake-shoes! One would naturally preferably use two C3-Vettes of same weight and identical brake-shoes for comparison, -thus first testing both for braking comparison prior to the perforation-modification at different speeds(shooting video to document the results before/after)! This notion would be somewhat akin to the racers now popular practice of cross-drilling the disk-brake Rotors, as to attain greater friction and enhanced cooling-ventilation. -If it significantly improves performance as seemingly predictable (without drum bell-mouthing), one could indeed have a thriving/nitch-market radially-drilling these inadequate C3/Emergency-brake drums to actually slide one's rear-tires(or even hold on a hill pray tell), particularly useful in emergency situations when the Hydraulic-disks have taken leave (as has happened to many of us without warning). A viable alternative to radial-drilling would be to instead apply a very coarse Metal-spray to the iron-drum's internal-surface, -aluminum-oxide for example having a hardness quotient of 9 (based upon a scale of diamond being 10), maybe giving it a 48-grit/sandpaper like consistancy; --definitely requiring use of tougher Kevlar/brake-shoes. It was irresponsible of GM to have sold a performance car with such a defective emergency-brake; --anybody up for such a worthy enterprising experiment (people as reflected below are complacent, -only getting serious about safety after someone has become tragically maimed, ---so probably nobody will persue this proposal) to surely save some lives, --maybe that of a loved one! (your beloved C3?)... ~Bob VonHeck
;help

Commentary: -the neg.-replys below are not accurate, but Joe makes an excellent suggestion as to scientifically evaluating vital ongoing modification changes on a Brake/Testing-machine (albeit that real-world seat-of-the-pants results nevertheless still being the ultimate test); --however, his expressed skepticism appears erroneous owing he fails to take into account that insufficient brake-drum sweep-area is the very problem! So my "Hyper-friction E-brake"-principle serves to make the existing drum-area much more effective via the "intrusion-effect" of the brake-shoe composition material momentarily actually minutely receeding into the myriad perforations, which resultantly greatly increased-drag is what the skeptic-critiques are failing to comprehend! Special relatively soft Kevlar/brake-shoes would be my recomendation, it can take tremendous abuse, would exhibit desired perforation-intrusion, -but does not have ability to withstand prolonged-heat (as it is still an amerid-fiber derivative of plastic-resin), -but heat-generation is not a major factor in a panic-stop situation, -when you yank on your Emergency-brake at 60mph, or are parked on a steep-driveway for example... ~B.vH

 

[MaineShark]

Drilling holes would reduce the friction provided by the e-brake, because it would reduce the surface area that is contacted by the shoe. In normal brakes, the "cleaning" of the gas and residue from the pad/rotor junction makes up for the reduction in surface area. But the e-brake is not applied in that manner (well, in the odd emergency, maybe, but I doubt the shoes are designed the same as high-performance brake pads).

Still, if someone wanted to test it, a brake dyno would allow it to be tested, without installation on a car.

Joe

 

[JohnZ]

There wouldn't be any "intrusion" of the brake shoe lining material into the "holes" in the drum surface - the lining material is far too hard to be displaced into any holes by mechanical pressure from the linkage.

This system was never designed to be an "Emergency Brake", to stop the car from speed; it was designed to be a "Parking Brake", and is not (and never has been) particularly effective, except when it was new and none of the parts were corroded.

The arc of the GM parking brake shoes is much better matched to the arc of the mating drum surface than the reproduction/replacement shoes are, putting much more of the lining surface in contact with the I.D. of the drum; the aftermarket shoes tend to put the lining in "point-contact", which significantly reduces the friction surface that's trying to stop relative movement. Even with aftermarket shoes/linings, the system's efficiency can be improved quite a bit by having a competent brake shop "re-arc" the shoes/linings to match the I.D. of the drum area in the rotor, as they used to do with a (proper) drum brake job.

Chill out with the "killed and maimed" rhetoric - it's just a Parking Brake, not cross-drilled ceramic composite 8-piston Brembo racing brakes made to haul the car down from 200mph. I'm reminded of a story about "mountains" and "molehills" :eyerole

 

[rpounds]

These are great old cars. Wonderfully designed for their time. And with proper maintenance and setup, the brakes need not be a problem, including the parking brake. Have you ever tried to stop any car with the parking brake? I dare say that if your brakes are not properly maintained, you will be in a world of trouble with any car, not just our C3s.

Drilling holes in the drum would reduce the surface area and would be counter-productive. It's best to rebuild the parking brake, including having the shoes arced to match the drum and then remember to use it as designed . . . for parking. And while it's all apart, fix the four wheel disks, adhereing to proper procedures and then it will be motoring.

 

[Culprit]

John Z,

Can you 're-arc' the parking break pads yourself? For example get up to highway speeds, throw in the clutch and coast then slowly and lightly engage the parking break to wear the pads to the proper shape and curvature of the drums.

Will this work, or would you have to repeat the process too many times for it to be practical?

Thanks,
Culprit

 

[JohnZ]

I think you'd probably glaze the linings over before enough material wore off to begin to match the curvatures better; any good brake shop (not the "Billy-Bob's Discount Brakes" in the building on the corner that used to be a gas station ) has a drum-arcing grinder. However, you have to remove the rotor to measure its I.D., and you DON'T want to drill out the rivets and remove a Corvette rotor unless the rotor is shot and must be replaced - causes many other problems. Best to leave this job to the day when you need new rear wheel bearings and the spindles have to come out (even then, DON'T remove the rotors from the spindles unless the rotors are shot).

 

[Culprit]

Thanks JohnZ. Sounds like a good reason to go with the GM parking break shoes if they fit better in the first place.


Culprit