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1974 corvette brakes

I love my Chevy Chevette!
Posts: 2
Joined: 03/08
Posted: 10/14/12 01:45 AM

I have a problem with my brakes. My brake pedal was touching the floor when I applied my brakes. Thought it was just low on brake fluid, added some, did not fix problem. Upon examination my right rear caliper was leaking. Replaced caliper---did not fix problem. Ended up replacing master cylinder, inspecting the other 3 calipers, bled the brakes not once but 3 times. Brake pedal still not working properly and still almost touches the floor although my brakes seem better. Any ideas on how to get this brake pedal to work properly?? THANKS  

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My first time was in a Chevy
Posts: 181
Joined: 04/12
Posted: 10/14/12 07:03 AM

there are a bunch of things...

tapered brake rotor wear surfaces..

new pads on tapered rotors..

worn or loose wheel bearings ...

trapped air in the system..

leaking caliper piston seals.

seized caliper pistons...

lets talk about tapered rotors.. the outside of the rotor goes farther around the circle than the inside .. this builds up more heat.. more friction.. wears away the metal faster around the outside.. leaving a ridge ...

when new pads get installed on tapered or rotors with a ridge...

the caliper pistons are designed for parallel
the brake pads are designed for parallel.
if the rotors are tapered.. the caliper pistons will push the pads against the inner wear surface first.. then something has to flex to engage the outer thinner part of the rotor..  this requires more volume from the master.. so you get a low pedal...


loose or worn wheel bearings don't keep the rotor at right angles through the caliper...  you end up lifting the weight of the car as you depress the brakes do do the rotor angle through the pad/caliper..


trapped air...

since you have had one caliper failure.. you might need to look at replacing the other calipers..   what happens is when you take your foot off the pedal.. the master cylinder comes up. pressure behind the caliper pistons drops.. but do to the corrosion in the bores.. the pistons do not retract as fast.. air gets pulled around the pistons seals and into the caliper.. this gives you a LOW pedal...

C3 4 piston calipers have a tapered face seal on the piston.. verses a single piston GM caliper that has a rectangular section seal in a groove and the piston slides through.. less likely to leak..  

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V-6 Camaros rule!
Posts: 83
Joined: 01/12
Posted: 10/16/12 08:22 PM

If you pump the brake pedal while coming to a stop does the pedal come back?
  If it comes back up, then there is air in the system.
If your sure there is NO FLUID LEAKS then bleed the brakes again. Thats the only reason a hydraulic system will not function correctly...AIR is trapped somewhere in the system.
  You can either gravity bleed the system or have a helper pump the pedal atleast 4 to 6 times going all the way to the floor with each pump, then hold the pedal while the other person opens the bleeder screw until the pedal goes to the floor. Your helper should not release the pedal until you have closed the bleeder screw. If this doesn't do it get it to a brake shop. Have them bleed the system for you....Good Luck...Let me know how you make out?


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V-6 Camaros rule!
Posts: 83
Joined: 01/12
Posted: 10/19/12 05:12 PM

Have you been able to find the problem with your 1974 Corvette? I like to check back to see if helped or not. Please let us know as we take pride in what we do. We do this on our own time. Wayne sometime will have schematics, and flow charts thats how involved he gets. You can't beat...Thanks... Grin  Cool


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