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Discussion Starter #1
I have installed new front disc brakes on a 68 with power brake set up. I have a distribution block and proportioning valve that I bougght specifically for a power front disc, rear drum set up. I also have the stock junction block that is bolted to the frame rail under the driver side. My dilema is I can power bleed the rear brakes using my adapted EZE Bleed set up with no problems at all. I hook up the presure go back to the rear and crack the bleeder. The fluid flows and all air bubbles get pushed through no problem. When I set it up to bleed the front brakes I get nothing unles I have someone push the pedal as if bleeding the old fashion way. Why can't I presure bleed the front like the rears? I cracked the lines at the master and got fluid when under preasure and then did the same at the proportioning valve with the same result. But I get nothing at the caliper. Am I missing something here? Any help would be greatly appreciated.
Thanks,
Jeff
 

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I had this issue for months on my 69 GTO Judge I had. It turned out that the round pressure valve under M/C was faulty. A friend had a few that he let me try and the first one worked for about a week and I lost front brakes. I installed another one and brakes worked fine after that. One other thing I was told and I don't really know if this is true but I was told not to fully push the brake pedal down to the floor. Go about half way down and release pressure at the bleeder and old pedal there until bleeder is tightened. I even went to the local dealer and they put it on a lift with a pressure bleeder and they couldn't even tell me what the problem was when they couldn't bleed them. So I just started removing and replacing one component at a time. Just got lucky when I replace the round pressure valve the first time and figured it was the same thing when it went bad after that first week. Give it a try, it may work for you.
 

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Discussion Starter #3
Thanks for the advise. I will look at that hopefully as a last resort since this valve was purchased new. I also get front brakes but have very little of no rear brakes right now. I am going to bleed the entire system one more time to see if there is a change. If not I will take your advise and replace the round pressure valve.
 

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Thanks for the advise. I will look at that hopefully as a last resort since this valve was purchased new. I also get front brakes but have very little of no rear brakes right now. I am going to bleed the entire system one more time to see if there is a change. If not I will take your advise and replace the round pressure valve.
Sounds like your making progress anyway. No front brakes before but you have something now? Could just need more bleeding since it was all air to start with.


If you know someone that has a known good valve go that way first. That is where I started. There is someone else with the same issue you are having that posted a few weeks ago. There was a lot discussed here. http://www.camaros.net/forums/showthread.php?t=184151

From what I have read it could be anything.
 

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My '68 Camaro has discs up front and drums in the rear. The brake pedal would go down about an inch more after 15 seconds sitting at a red light. Figured there was still air in the rear lines. After two more times of bleeding the brakes, the problem didn't go away. I went to Kragen's and purchased SPEED BLEEDERS (one person brake bleeder with built in check valve). Replaced the existing bleed screws with the SPEED BLEEDERS. Followed the instructions: Screw in the SPEED BLEEDERS until it seats. Unscrew the SB 1/4 to 1/2 turn. Slowly pump brake pedal 4-5 times (you do not have to close SB between pumps).A one way check valve lets the air out & closes between pumps preventing new air from entering the system between pumps. Now close the SB. Go to the next furthest wheel until all are bled. I attached a clear hose to the SB and stuck the other end in a closed jar with a hole in the top for the hose to catch the fluid. Brakes work perfect now. $10 per pair of SB's well spent:hurray:
 

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Discussion Starter #6
Well after power bleeding the system 1 more time it appears I now have brakes on all 4 wheels. When bleeding the rears again I found they had a considerable amount of air still in them. When I cracked the right rear I had only clear fluid with no air. When I was about to close and go to the next wheel all of a sudden I got 2 large bubbles followed by a few smaller ones. Then bled a bit more with only fluid no air. The left rear did almost the same thing with only small bubbles for 2 filled fluid catch cups. When I bled the fronts there was no air at all. I still could not power bleed the fronts but had to go with the pump and close method. I still had the presure bleed attached so I did not have to check the fluid levels. Seems now I have a farely stiff pedal. I will check in a few days to see if it holds. Thanks for all the help and suggestions.
Jeff
 

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I still could not power bleed the fronts but had to go with the pump and close method.
That's because the metering valve (the round one, frequently mis-named "proportioning valve") won't pass any fluid to the front system until it sees 30-40 psi of fluid pressure - it's designed that way on purpose. If your power bleeder won't produce that pressure, you have to depress the button on the rearward side of the valve in order to manually open it for bleeding, as shown in the Chassis Service Manual.

:beers:
 
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