No Brakes??? - Team Camaro Tech
Brakes, Suspension & Steering Conversion questions, Steering & Handling

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post #1 of 31 (permalink) Old Feb 25th, 19, 06:40 PM Thread Starter
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No Brakes???

Converted a 69 to power front Disc brakes, 10 bolt to 12 bolt. All components are new. Bench bleed the MC, bled all 4 wheels. Pedal feels good until the engine is running, pedal goes to the floor. Short rod with a shallow MC, good vac to the booster, lines off the MC, distribution block and pressure valve to the front brakes all leak fluid when opened to check for blockage. I am stumped as is my mechanic. Any ideas what to do next?
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post #2 of 31 (permalink) Old Feb 25th, 19, 07:59 PM
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Re: No Brakes???

What bore MC?

Is the rod in the lower hole on the brake pedal?

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post #3 of 31 (permalink) Old Feb 26th, 19, 05:08 AM
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Re: No Brakes???

What kind of front calipers? Is the bleed valve on top of the caliper? If the bleeder is facing down the calipers won't bleed properly. Sounds like you still have air in the system somewhere.
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post #4 of 31 (permalink) Old Feb 26th, 19, 05:32 AM Thread Starter
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Re: No Brakes???

Rod is in the lower hole. Calipers are NAPA remans and the bleeder is on top. Now what? Have bled them 3 times and the flow is good with no apparent air.
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post #5 of 31 (permalink) Old Feb 26th, 19, 05:34 AM Thread Starter
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Re: No Brakes???

MC is a reman from NPD with matching booster. Has a short rod. Bore?
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post #6 of 31 (permalink) Old Feb 26th, 19, 05:41 AM
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Re: No Brakes???

Do you get a firm pedal if you plug the ports on the master? That would be my first troubleshooting step.

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post #7 of 31 (permalink) Old Feb 26th, 19, 05:49 AM Thread Starter
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Re: No Brakes???

The pedal is firm without the engine running, however, the rear brakes are not holding but the front are. As soon as I start the engine the pedal goes to the floor when applied.
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post #8 of 31 (permalink) Old Feb 26th, 19, 06:15 AM
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Your problem is possibly the booster. Either its leaking vacuum, or not enough. The other option could be the rear brakes are not adjusted.

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post #9 of 31 (permalink) Old Feb 26th, 19, 06:16 AM
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Re: No Brakes???

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Originally Posted by The Camaro Guy View Post
The pedal is firm without the engine running, however, the rear brakes are not holding but the front are. As soon as I start the engine the pedal goes to the floor when applied.
Plug the ports and test. Work your way from there to troubleshoot. Otherwise you are just shotgunning it....

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post #10 of 31 (permalink) Old Feb 26th, 19, 06:32 AM
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Re: No Brakes???

Personally I would bleed the brakes the old fashioned way 1st. Starting at the back brakes. MC still full of fluid after bleeding?
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post #11 of 31 (permalink) Old Feb 26th, 19, 07:58 AM
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Re: No Brakes???

Quote:
Originally Posted by The Camaro Guy View Post
All components are new.
Quote:
Originally Posted by The Camaro Guy View Post
The pedal is firm without the engine running, however, the rear brakes are not holding but the front are. As soon as I start the engine the pedal goes to the floor when applied.
Did you also install all new brake lines (including all of the rubber brake hoses)?
You might want to look at the rubber brake hose that is located just above the rear axle (or any other rubber brake hose that is also routed to the rear brakes) while someone else depresses the brake peddle with the engine running. See if any of the rubber brake lines appears to be ballooning as the brakes are applied.

There could be some kind of clog (or defect) in one of the rubber hoses that is blocking the fluid pressure from reaching the rear brakes. A similar situation happened to a friend of mine. It turned out to be that one of his front caliper brake hoses was clogged and would expand like a balloon when he hit the brakes... causing the brake peddle to go to the floor.
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post #12 of 31 (permalink) Old Feb 26th, 19, 10:34 AM Thread Starter
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Re: No Brakes???

The rear end, rebuilt came out of my other car, 1500 miles, and worked fine. All hoses and lines are new. This car was a basket case and everything has been replaced except the roof, 1 door and the subframe! I have being doing this for 40 years and have never had issues as I have had with this one. So I must be missing something. I will take all your advise and go at it again. Maybe it just does not want to be restored! I have 2 weeks to deliver it to the client that I am building it for and the Charlotte autofair car show the first of April. Thanks for all your input. . . let you know the outcome. . . . . .
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post #13 of 31 (permalink) Old Feb 26th, 19, 05:06 PM Thread Starter
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Re: No Brakes???

Update. Replaced the MBC, re bled the brakes. . . . no change. All that is left is the booster.
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post #14 of 31 (permalink) Old Feb 26th, 19, 05:46 PM
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Re: No Brakes???

Quote:
Originally Posted by The Camaro Guy View Post
Update. Replaced the MBC, re bled the brakes. . . . no change. All that is left is the booster.
You never answered these questions.

Quote:
What bore MC?

Is the rod in the lower hole on the brake pedal?
To me it sounds like you have the wrong bore master cylinder. Should be a 1 1/4"
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post #15 of 31 (permalink) Old Feb 26th, 19, 06:29 PM Thread Starter
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Re: No Brakes???

John, I changed the MBC that is 6 months old from a guy that is building a pro street. I got the whole booster,MBC prop valve and pressure valve from him and am changing out piece by piece. The pedal is in the lower hole. What I have left is the prop valve and booster. I re bled the system a half hour ago and 3 wheels are just spitting and the last one the left front pissed about 4 inches, this is after I installed the working MBC, so after I change the prop valve I will bleed the system again. It can only be those things. Well on a positive note I finished the all new interior and it looks great with no real issues. I like the TMI seat covers and foam but not the door panels, I like the PUI better. Oh well you all have a great evening.
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