vette75406

Ive got a 75 and have just replaced all of the brake system other that prop valve , i can gravity bleed the front but can get no fluid to the rear, ive read the posts about removing the prop. valve in corvette faq and im considering this , i also have a spare valve but dont know how to check it , ive taken it apart and the internal switch moves fine but i dont know how to remove the internal valve to check to see if its stuck or to clean it, the only thing i have not done yet is put compressed air to it to try to push out the valve, any ideas to get fluid to the rear brakes , just to let you know it sat for 3 days with the bleeders open and no fluid came out at all , im a one man show so gravity bleeding has been the prefered method and i dont have one of the fancy pressure bleeders , but may invest if i cant get fluid flow any other way , thanks for any ideas that you may give.

Skruball73

I don't know for certain about your year model, but with my 73, the only thing a rebuild on the proportioning valve involves is replacing the o rings. the valve in side could be stuck...but you should be able to gravity bleed the the back brakes with no problems....you may want to have the master cylinder checked out, I replaced mine while troubleshooting & turned out that the new MC was bad, it would not gravity bleed the rears for sqwat, I put back on the original & it gravity bled just fine. Also, I built my own pressure bleeder & could pressure bleed both front & back & had solid peddle, but once the car was started, it got mushy again...that's when I switched back to the old MC & had no troubles since then. If you are thinking of a pressure bleeder, you can get one from ebay for about 80 bucks...I built my own & spent about that much but still had an air leak at my pressure gauge, & had a terrible time getting the cover to seal over the MC body...buy the one off ebay.


[Modified by Skruball73, 10:02 AM 6/28/2004]

Ben's75

I don't know this for a fact, but I have heard that you can open both calipers on one side of the car (driver's side front and rear) to equalize the pressure, re-center the valve, and allow flow to the calipers.

Or you could just rip the prop. valve out

Ben

Gordonm

I made my own low cost pressure bleeder. I took a piece of flat steel about 1/4 inch thick that would cover the master cylinder. I drilled and tapped a hole for a fitting for my air compressor. The side that goes on the master cylinder should have some type of flexible covering, a piece of urethane works good. Epoxy the urethane sheet on the steel and have the hole for the fitting go all the way through. Clamp this on to the master cylinder and hook up the air line to the fitting. I only use about 10 to 15 pounds of air pressure. Make sure the master is full of fluid. Once you have the master cylinder and plate clamped with fluid get some air pressure and open the bleeder screw. This will give you a crude but effective pressure bleeder. Just don't run the master cylinder dry or you will be starting over. You have about 15 to 20 seconds of bleed time before the master runs dry. It takes a little time but it works and is cheap to make.