Speedjester

We have the same system I believe..The cable pulls on tthe caliper which I believe use hydraulic pressure to hold the parking brakes

kalister1

Last night after installing the rotors, pads and Stainless flex lines I get 1700 or 2200 PSI at the caliper depending on who pushes the pedal. The 1700 PSI was Mike, he pushed 1400 PSI with the old hardware. So I can't say for sure, but it looks like the stainless flex lines improved the pressure?
Sean pushed 2200, but he was trying to put the pedal through the floor.

85z51vette

The cable on my '94 pulls on a lever attached to the caliper. There is a small rod that sits under this lever, passes through the caliper body and seats against caliper piston/parking brake assembly. When the parking brake handle is pulled up, the lever rolls back and pushes on the rod, which in turn presses the inboard pad (albiet mostly one side of it) into the rotor. There is no hydraulic action at play.

Rear caliper on later C4s (not exactly sure when they went to this design):


Just FYI.

kalister1

Yesterday I finished the brakes on the 93 (It's a Ruby) Coupe.
New Rotors, Pads, Stainless Flex lines and hardware kits. Bled out all four corners, twice. Bled the solenoid (Bleeder valve on the ABS unit behind the driver). Hooked up a Tech 1 scan tool and found NO CODES in the ABS or ASR system. Ran all tests on the ABS, one test runs the ABS unit for 25 seconds. All test say passed. Drove the car around and tried to bed the pads. From a 10 MPH roll I CAN get the ABS to activate, they would NOT before I started. I want to drive it easy for a while before I try to stop quick from any speed.
Bu tit seems like the brakes are OK?

Brett Tomlin

I replaced the master cylinder. Still my brake peddle is hard, but only slows the car down. should I replace the proportioning valve ? Or the booster ?

kalister1

Did you bleed the unit in the compartment behind the driver seat? Don't just replace things that you are not sure about.
There are test you can do to verify the operation of each component.
Google Power Brake booster.

Cliff Harris

If the brake pedal is hard you might need to do this:

http://forums.corvetteforum.com/c4-t...placement.html

djxib

1992 LTx - Brembo's Front, stock rear, stock booster, SS lines.

So my brake pedal had been pretty hard but brakes are OK (I guess due to the Brembo's). About 18 months ago I got to exercise the ABS a couple of times and they seemed to improve.

Fast forward to now and I start to notice that the pedal is a bit hard again - seemed to need some extra effort for 'normal' stops. (Booster is fine, I can feel the huge difference in pedal between the engine stopped and started). However, a lot has changed in that time - new engine rebuild and a bigger cam - so I have less vacuum at idle.. this is clearly not going to help the situation.

So my buddy just started his own diagnostics business and has a GM Tech2. He came over at the weekend and performed a 'release solenoids' test on all 4 solenoids.. the Tech2 shows that a 1992 has front right, front left, rear right and rear left solenoids. Initially there was a DTC code set.. something to do with communications errors.. so he reset the code.

The test activates the selected solenoid repeatedly while the test button is held (so the operator can decide how long to run the test). We ran each test for about 5-10 seconds, and we could hear each solenoid buzzing. The front solenoids buzzed very rapidly, the rear solenoids sounded lazy, activating more slowly.. although that could have been the test itself.

After the test I took the car for a test drive, and the brakes seem better by about 20%. I will do a longer road test this weekend including to see if I can activate the ABS on a dry (private) road.

This is far from conclusive, especially with the DTC., except that for me it seems to have made a difference and I am encouraged by the name of the test.. 'release solenoids'.

JrRifleCoach