Brake Master Cylinder Question

[krandall]

When I bought my car, the PO had replaced the master cylinder under the hood with one from something unknown. When I want to apply the brakes, I have to press the peddle down to the floor nearly and even still I can't get the wheels to "lock up". I've gravity bled the brakes at all 4 corners and haven't been able to get any air out of the lines which leads me to believe there's something potentially messed up with the master cylinder.

Any initial thoughts from any of you guys?

Here's some pics of the MC(sorry none are of it directly.. I plan on snapping some pics of it this weekend)

 

[PurpleBeeper]

If you still have the factory proportioning valve/metering valve, did you pull out the little plunger on the metering valve (I think) part before you bled the brakes?

I would be inclined to put a factory master cylinder on it, but I'm no brake expert and I'm aware of people putting "odd ball" master cylinders in their cars, especially track cars, and having good luck.

 

[Mopars & Missiles]

Is this a "front disc conversion" from a factory 4 wheel drum car? If so, its a notorious problem you just bought.

 

[krandall]

Still have 4 wheel drum all around. The PO had stated they had looked at doing front disc but never made it that far.

My fix I'm not ready for is I've been researching doing a front disc conversion (keeping it manual) and along with that, purchasing a new Master Cylinder/Proportioning valve but haven't done anything yet.

 

[69L48Z27]

I don't follow your issue. You said. - I can't get any air out. Right?

How do you know there is any air IN? Soft pedal doesn't necessarily mean it's air bound.

That MC looks like a disc Chrysler unit, they came in a bunch of sizes. There's a good chance the bore is the wrong size and it will never work for that application.

If it was mine, I would search out the correct MC for the car and application, sounds like a stock setup. Bench bleed it and put it on the car, bleed the res the out.

 

[krandall]

Wasn't trying to assume air was in it, I'm pretty green-horn when it goes beyond replacing the stock parts/bleeding the system (hence the post). Kind of looking for validation for my suspicion at the very least

 

[PRND21]

I'm with L48, I'm thinking the master cylinder bore is to small.

 

[69L48Z27]

Wasn't trying to assume air was in it, I'm pretty green-horn when it goes beyond replacing the stock parts/bleeding the system (hence the post). Kind of looking for validation for my suspicion at the very least

No worries, I wanted to make sure I understood. Asking is part of the solution. If your all on drums like you said replacing the MC with a stock unit for a couple bucks might save a lot of headaches.

Let us know what fixes it.