Problem with brake swap.

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71valiant

71valiant

Make fast, break, repeat.
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Ive got a 67 Valiant with a 73-up K member. So, disc on the front and the rear has bigger drums. 11 inch Im assuming, 8.75 rear end. Manual brakes. My issue is I have no front brakes. All this work was done when I bought the car, so i have no idea whats needing done. The brakes lines are being ran through the original dist block. Am I needing to get a adjustable prop valve to increase front pressure?
 
What master cylinder are you using? Is the "dist block" a Proportioning valve? How do you know you have NO front brakes. Pictures of setup, MC And Valve.
 
Stock MC. The rotors on the front are rusty/dirty. I.e. no pad contact. The block has the electric tab for the dash brake light. Im at work right now. Ill get some pics after work.
 
without a proportioning valve the front calipers will never fill with fluid,the back wheel cylinders will fill first because they alot smaller and give you a good pedal,mark
 
moparmarkk said:
without a proportioning valve the front calipers will never fill with fluid,the back wheel cylinders will fill first because they alot smaller and give you a good pedal,mark
Click to expand...

This is not really accurate. The won't ACTUATE first is more accurate. To give the OP the idea that there is no fluid in them is not accurate.

The short answer is you need a prop valve.
 
the backs will lock up before the fronts have enough fluid to actuate,hows that? mark
 
Thats what I assuming. Now..... WHERE would it need placed is my next question? And what would you guys recommend?
 
if you buy a aftermarket one you can put where you want,just put it someplace out of the way and where you can get to it easily to make adjustments mark
 
It seems like you need to read up and look at a factory service manual car for a 73-up brake system, so you can see how the lines are routed. I think you can find it at mymopar.com. Some simple thoughts are, do you have a master cylinder for a 73 A body with disc brakes? Are the bleeder valves at the top of the caliper? If you use an adjustable proportioning valve, it goes in the line to the rear brakes. I personally like a stock style prop valve. Keeps everything the way it was designed from the factory.
 
I like the stock one too,but if you don't have it after market one about 40.00.Like furyus2 said it goes in the rear brake line, mark
 
furyus2 said:
It seems like you need to read up and look at a factory service manual car for a 73-up brake system, so you can see how the lines are routed. I think you can find it at mymopar.com. Some simple thoughts are, do you have a master cylinder for a 73 A body with disc brakes? Are the bleeder valves at the top of the caliper? If you use an adjustable proportioning valve, it goes in the line to the rear brakes. I personally like a stock style prop valve. Keeps everything the way it was designed from the factory.
Click to expand...


Good advice. You can download the 73 manual, which by the way came from the guys on here, and it will show the "as built" 73 factory A body disc setup including the prop valve and routing

Also good point on the bleeder valves. If the calipers are switched side for side, they will end up "down."
 
I think you should first verify that the front calipers aren't seized, as that was a common problem with the "plastic" pistoned calipers.

Jack the front wheels off the ground, apply brakes and see if a wheel can be turned by hand. Spin a wheel and apply brakes and see if the front brakes will stop the wheel, then try the other side.

If the brakes will not apply and stop the wheel, with the brake pedal still applied, crack open a bleeder on either side to see if there is fluid pressure at the caliper.

If there is pressure at the calipers that won't apply and stop the wheels, the caliper is likely seized, and needs replacement.

hope it helps . . cheers
 
furyus2 said:
It seems like you need to read up and look at a factory service manual car for a 73-up brake system, so you can see how the lines are routed. I think you can find it at mymopar.com. Some simple thoughts are, do you have a master cylinder for a 73 A body with disc brakes? Are the bleeder valves at the top of the caliper? If you use an adjustable proportioning valve, it goes in the line to the rear brakes. I personally like a stock style prop valve. Keeps everything the way it was designed from the factory.
Click to expand...

The MC is the stock 67 manual MC. I will have to look at the bleeders once I'm off work. (Bad Memory)
 
inertia said:
I think you should first verify that the front calipers aren't seized, as that was a common problem with the "plastic" pistoned calipers.

Jack the front wheels off the ground, apply brakes and see if a wheel can be turned by hand. Spin a wheel and apply brakes and see if the front brakes will stop the wheel, then try the other side.

If the brakes will not apply and stop the wheel, with the brake pedal still applied, crack open a bleeder on either side to see if there is fluid pressure at the caliper.

If there is pressure at the calipers that won't apply and stop the wheels, the caliper is likely seized, and needs replacement.

hope it helps . . cheers
Click to expand...
I'll check on this as well once i'm home. Appreciate it.
 
inertia said:
I think you should first verify that the front calipers aren't seized, as that was a common problem with the "plastic" pistoned calipers.

Jack the front wheels off the ground, apply brakes and see if a wheel can be turned by hand. Spin a wheel and apply brakes and see if the front brakes will stop the wheel, then try the other side.

If the brakes will not apply and stop the wheel, with the brake pedal still applied, crack open a bleeder on either side to see if there is fluid pressure at the caliper.

If there is pressure at the calipers that won't apply and stop the wheels, the caliper is likely seized, and needs replacement.
Click to expand...
As above... if you have NO front brakes, then you have problems up front. No prop valve in the world will fix that.

If you don't get any pressure at the bleeders, then the rubber lines to the calipers may be plugged. When they get old, the inside liner falls apart and plugs them up internally; the front brakes then either don't work, or they lock on and never release.

The 67 MC was for a drum/drum setup, but should work the front calipers OK, BUT this MC has what is called residual pressure valves in each output, front and rear. These are designed to make sure the fluid does not back out of the wheel cylinders of drum brakes. This needs to be removed/punched out from the rear MC chambers outlet, which feed the new front disc brakes. Otherwise, they will tend to hold the front brakes on lightly all the time.

Another issue with the 67 MC will be as the pads wear out; the back cylinder of the 67 MC (which feeds the front brakes, will not have enough fluid capacity to avoid running out of fluid as the pads wear and the fluid drops. You will have to add brake fluid as the pads wear, and then remove it when you put new pads in. Putting in a 73-76 MC will avoid that.

With the front A-body brakes, and 11" rears, you will need to put in a prop valve eventually to get the rears to not be too strong. And BTW, the prop valve does not increase front pressure; it reduces rear pressure.
 
^^^All of that^^^, plus how long has the car sat, is there actually
any pressure at the port of the MC if you bleed it? Sounds like you
need to pick up the correct MC anyway,and most any OE mopar
metering valve unit from a car will work from the '73& up to the newer(RWD) aluminum MC's . They're not rare yet,get one,be happy.
Assuming 11" drums on an A-body 8.75,why? Just sayin', it's
on the drum for you to read,and it wouldn't come that way OE. If
they are 11', you may be able to step down to a smaller dia. set of
wheel cyls. to help balance the brake bias.
 
Ok, sorry for the delay. I went home last night. First off. The rear reservoir was empty... Last I looked. It was full, theres no fluid on the wheels or on my floor. So, I put fluid in, cracked open the bleeder on the drivers side and bled it. Spun the tire and it grabbed when the pedal was hit. The passenger side bleeder rounded off, (awesome) so, I'll have to get it out and replace it.
 
Killer6 said:
^^^All of that^^^, plus how long has the car sat, is there actually
any pressure at the port of the MC if you bleed it? Sounds like you
need to pick up the correct MC anyway,and most any OE mopar
metering valve unit from a car will work from the '73& up to the newer(RWD) aluminum MC's . They're not rare yet,get one,be happy.
Assuming 11" drums on an A-body 8.75,why? Just sayin', it's
on the drum for you to read,and it wouldn't come that way OE. If
they are 11', you may be able to step down to a smaller dia. set of
wheel cyls. to help balance the brake bias.
Click to expand...
The rear end was out of a B-body I'm assuming. Its been narrowed.
 
No fluid.....mmmmm, that might effect things LOL

So nothing under the carpets or down the firewall? Check carefully...
 
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