Brakes Help!! Rear Brakes Won't Bleed After Adj Pv Install

stangboy

Founding Member
Aug 31, 1999
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New Orleans, LA
Hey guys I can't get my rear brakes to bleed after installing a ford Racing adj PV. I gutted the stock PV like I'm supposed to. Am I missing something? I have 96 Cobra brakes up front and drums in the back.
 
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We FINALLY got the system bled. It was slow and methodical but I think I need to hook the vacuum canister that's in the right fender back up because I think the cam may not be producing quite enough vacuum. I'll be doing that today. Hopefully that will give me sufficient braking. Right now I have to pump them to stop good.
 
And did you install the FRPP M-2450-A solid pug in the factory PV? If you didn't air can get in the hole in the factory plug where the PV guts usually seat, and you will tear your hair out trying to figure out why you need to keep bleeding the rear brakes.
 
Have you ever changed the flexible hose to the axel housing?
They can get goofy and close up with age causing pressure problems.
I actually bought a new one but I couldn't get the hard lines off without damaging the fittings...even using a flare wrench. That was gonna be my next move if we wouldn't have gotten the system bled. I had a time flaring the lines where I put the adjustable PV because I had to replace the fittings with longer ones.

I hooked up the vacuum canister last night so I'll see if that helped.
 
Does that canister have anything to do with the brakes?
If you have manifold vac to booster and it works, pumping the brakes would be a line pressure problem.
Well I sure hope the booster isn't bad because I don't have time to change that before I leave tomorrow to go to TX2K17. If I can't get the brakes right today I just won't be able to take the car.
 
Yeah, we finally got the system bled Sunday evening but the pedal is still mushy I have to actually pump the brakes to stop at very low speeds...like 10 mph. So we're think the cam may be pulling too much vacuum.

With the engine off, does the pedal get rock hard within a few pumps? If not, you still have air in the lines somewhere.

You really can't have too much vacuum. There's only so much air you can take out of a space. Usually with a lack of vacuum, you get no assist and the pedal is hard. With a cam pulling good vacuum, once you evacuate the booster, that's it. Any cam should be able to empty it. The wild card is how fast it can do so.

So...mushy pedal requiring a few pumps..i'm suspecting air.

You left the stock MC correct?
 
With the engine off, does the pedal get rock hard within a few pumps? If not, you still have air in the lines somewhere.

You really can't have too much vacuum. There's only so much air you can take out of a space. Usually with a lack of vacuum, you get no assist and the pedal is hard. With a cam pulling good vacuum, once you evacuate the booster, that's it. Any cam should be able to empty it. The wild card is how fast it can do so.

So...mushy pedal requiring a few pumps..i'm suspecting air.

You left the stock MC correct?
Yes the pedal gets rock hard with the car off. I put my buddy's MC out of his 93(he converted to hydroboost) to see if it was possibly the reason the system wouldn't bleed. But I was having the same problem so I'm thinking mc wasn't the problem...yes I bench bled it first.
 
Is his 93 MC the cobra MC? Or a stock disk/drum setup?

I think you said you are running rear drums correct? With that said, you cannot swap the MC to one of the 4 wheel disk MC's as the bore is entirely too large. The result will be an extremely soft pedal.

With the 96 cobra fronts, and rear drums. A stock 3-port MC is what you want to run.
 
Is his 93 MC the cobra MC? Or a stock disk/drum setup?

I think you said you are running rear drums correct? With that said, you cannot swap the MC to one of the 4 wheel disk MC's as the bore is entirely too large. The result will be an extremely soft pedal.

With the 96 cobra fronts, and rear drums. A stock 3-port MC is what you want to run.
THAT, sir, is the million dollar question. It was on the car when he bought it....but it did already have 4-wheel disc brakes. How do I identify the Cobra mc?