Well, finally got my car together and i went out for a short jaunt. Was basicly manual brakes the whole way. I have 15# of vaccum on the booster and the brakes were bled shortly before parking it and the tires never came off. All new lines, calipers etc, only thing that is original on it is the master, booster, and the propotioning valve...

Can anyone help me?


David

 

If the bearings on your rear spindles need replacing they can cause air to leak into the system. I installed the VBR O Ring seals. They come as a kit. Real easy to replace and install. This kit comes with new pistons and seals. Well worth the effort. I am running synthetic fluid and my brakes will throw you through the windshied. By the way, I also installed the SS flex lines, all new brake lines and master cylinder. while I was at it I rebuilt the trailing arms as well. Everything being said, the o ring seals will help compensate for less than perfect bearings. Trailing arm removal and installation is not for the inexperienced. It can be done but expect to spend a lot of time on the garage floor.

 

Welcome to the wacky world of Corvette brakes. I would start with another complete bleeding. There are members of this forum that will tell you that multiple brake bleedings are not unusual. In addition, don't forget that the rear calipers have two bleeders and the MC has two (at least on my 72). WHile bleeding the calipers, tap them with a rubber mallet to dislodge any air bubbles. The one thing you don't say is whether or not the brakes are soft. If you have a hard pedal, check all the vacuum lines to and from the engine to the booster. A Mity Vac is great for this.
Gary

 

The suspention is completly rebuilt, new bearings etc etc. They arn't O-rings calipers though. And to the question if my brakes are soft, ummm i wish. It's like when the vaccum line came off my booster. I have full stainless brake lines. brand new maybe 80 miles on them. I can get the trailing arms off in an hour if need be. Any other info that might help out?

 

maybe i'm missing the obvious.... but how do you know your brake booster is working?

 

I found this website that offers trouble shooting tips on brake problems.

http://www.classicperform.com/TechBo...oubleshoot.htm

Here is the section for Rock Hard Pedal. It leads to the Power Brake Booster.

Test Power Brake Booster
If the pedal feels "hard" while the engine is running, the booster isn't operating correctly. If you suspect the booster is defective, do not attempt to disassemble or repair the power booster. Doing so is unsafe and will void your warranty.

Test 1

With the engine off, pump the brake pedal to remove any residual vacuum in the booster.
Hold pressure on the pedal while you start the engine. When the engine starts, the pedal should drop about a 1/4", this indicates that the booster is working properly.
Test 2

Run the engine a couple of minutes.
Turn the engine off and press the pedal several times slowly. The first pump should be fairly low. The second and third should become slightly firmer. This indicates an airtight booster.
Test 3

Start the engine and press the brake pedal, then stop the engine with the pedal still pressed. If the pedal does not drop after holding the pressure on the pedal for 30 seconds, the booster is airtight.
Inspect the Check Valve

Disconnect the vacuum hose where it connects to the intake manifold. Do not disconnect the vacuum line from the booster. Air should not flow when pressure is applied, but should flow when suction is applied. If air flows in both directions or there is no air flow, the valve needs to be replaced.
Verify Enough Vacuum

Check the operating vacuum pressure when the engine is at normal operating temperature. There should be a minimum of 18 in. of vacuum. Vacuum may be increased by properly tuning the engine, checking for vacuum leaks and blockages in vacuum lines.

kdf

 

How do i know it's working? I don't. And i only have 15 inch's of vaccum ... Guess its time to check for leaks. I think its time for some l88 lamps and hydraboost......I hate all these vaccum hoses....

Thanks KDF I will try those steps. I will see if the booster is okay tomorrow (per the steps) and then bleed the brakes if it pass's the tests.

Thanks
David

 

Good to hear your back on the road David.