Need assistance with brake problem
Thread Starter
6th Gear
Joined: Oct 2013
Posts: 6
Likes: 0
Need assistance with brake problem
I have a 1984 Coupe, I have replaced the master cylinder, power booster, rebuilt all 4 calipers and replaced the rotors and pads, and replaced the lines to the calipers. I have bled the system several times, and have ensured that the bleeder valve was on the top to get all air out of each caliper. No matter what I have done, the performance of the brakes is not acceptable. I would think that if I were driving the car and hit the brakes as hard as I can press on the pedal that the tires would lock up, it does not happen. I have power bled the system, vacuum bled the system, and bled the system normally. What am I over looking? I am at my wits end HELP!
Safety Car
Joined: Aug 2002
Posts: 3,842
Likes: 230
From: SANTA CRUZ CA
I see no mention of 'bedding' the brakes. Very important.......
http://zeckhausen.com/bedding_in_brakes.htm
http://zeckhausen.com/bedding_in_brakes.htm
Safety Car
Joined: Aug 2002
Posts: 3,842
Likes: 230
From: SANTA CRUZ CA
Just guessing......... maybe a cleaning of the rotor surfaces may help.
It's possible the surfaces were contaminated. If the pads were contaminated,
the contamination would transfer to the rotor surfaces
Just for comparison..... my '92 (with everything new) does not brake
as well as my 04 Expedition, nor my wife's 06 Mustang. I guess that
is why so many vette owners have gone to brake upgrades.
I understand your disappointment, as I had the same feeling with my new
'92 brakes.
It's possible the surfaces were contaminated. If the pads were contaminated,
the contamination would transfer to the rotor surfaces
Just for comparison..... my '92 (with everything new) does not brake
as well as my 04 Expedition, nor my wife's 06 Mustang. I guess that
is why so many vette owners have gone to brake upgrades.
I understand your disappointment, as I had the same feeling with my new
'92 brakes.
Last edited by don hall; Oct 8, 2013 at 03:08 PM.
Thread Starter
6th Gear
Joined: Oct 2013
Posts: 6
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The park brake is also all new and it works great! All new cables and shoes. Since this is an early production 84 it still has the shoes inside the rear rotors. Matbe I am expecting to much, but I would think that with power brakes, if I stomp on the brake pedal it would lock up the tires. I am a bit leary to go out and "play" if the brakes are not 100% 
Thread Starter
6th Gear
Joined: Oct 2013
Posts: 6
Likes: 0
I have considered an upgrade to dual piston calipers and larger rotors but again the park brake is inside the rear rotors and all I see for the rear is the calipers with the park brake built into the caliper. Actually it acts like a bad proportioning valve, as the rear seems not to be as strong as they should be, but that is built into the master cylinder. I have seen an aftermarket spring for the proportioning valve but it is for an 85.
Team Owner
Joined: Dec 1999
Posts: 34,873
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From: Lacey WA RVN 68-69
NCM Sinkhole Donor
The park brake is also all new and it works great! All new cables and shoes. Since this is an early production 84 it still has the shoes inside the rear rotors. Matbe I am expecting to much, but I would think that with power brakes, if I stomp on the brake pedal it would lock up the tires. I am a bit leary to go out and "play" if the brakes are not 100%
Did you clean the surface of the rotors before installing them? Some manufacturers will coat the rotor surface with oil or a solvent to keep them from rusting. If that material got on the pads, you would see poor braking performance.
Bedding the pads to the rotors might help, but most shops don't do that with OEM-style pads. Which brings up the next question, what pads did you install? There are a number of performance pads available that will improve braking performance over stock pads.
FWIW, all 84-87 C4's had a drum-style parking brake. The 88-96 cars used the rear caliper as the parking brake. Then GM went back to a drum-style parking brake on the C5
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Safety Car
Joined: Sep 2004
Posts: 3,953
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From: Mission Viejo CA
I too, have an '84, and when I bought the car I was expecting to be able to lock up the wheels with enough pressure on the brake pedal. I think this expectations would be met if the car didn't have such large tires! These cars can pull 1 g during cornering, so their tire traction is tremendous! Expecting to skid these tires may be unrealistic.
To improve the braking, I installed a dual diaphragm brake booster from Power Brake Service, Long Beach CA, and my brakes are excellent! Unfortunately, they recently closed.
To improve the braking, I installed a dual diaphragm brake booster from Power Brake Service, Long Beach CA, and my brakes are excellent! Unfortunately, they recently closed.
Safety Car
Joined: Aug 2009
Posts: 3,752
Likes: 276
From: Melbourne, Victoria, Australia
Hi
This is a common issue with C4's and standard type brake pads with very little friction compound, you can stand on the brake pedal and it will just slow the car nowhere near locking the brakes.
I has the same issue 16 years ago when i first got my 85, i came across one of the guys who developed the c4 brakes and he said get high metal content brake pads. Sure enough the change was massive, just have to lightly touch the pedal to brake hard, and very easy to lock the wheels.
Corvette central has Hawk brake pads for all models the street ones should do the job, remember to replace front and back at the same time so you have even brake performance.
http://www.parts123.com/parts123/yb....Z5Z5Z50000050F
You will be amazed how good even the early single piston calliper brakes can be with the right brake pads.
This is a common issue with C4's and standard type brake pads with very little friction compound, you can stand on the brake pedal and it will just slow the car nowhere near locking the brakes.
I has the same issue 16 years ago when i first got my 85, i came across one of the guys who developed the c4 brakes and he said get high metal content brake pads. Sure enough the change was massive, just have to lightly touch the pedal to brake hard, and very easy to lock the wheels.
Corvette central has Hawk brake pads for all models the street ones should do the job, remember to replace front and back at the same time so you have even brake performance.
http://www.parts123.com/parts123/yb....Z5Z5Z50000050F
You will be amazed how good even the early single piston calliper brakes can be with the right brake pads.