Thread: Brake troubles

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I'm not getting the brakes to work on my 40 Ford p/u.
Have I hooked the lines up wrong from the master cyl. to the proportioning valve ?
I have turned the valve both ways and I can't get the brakes to lock up on the rear.
Never had any trouble bleeding brakes in 45 years of working on cars and this thing is kicking my butt. Rear has disc with emergency brake calipers . I have followed the instructions to the letter from the supplier (speedway). The master cyl faces towards the rear of the truck. Both reservoirs are the same size.

Only a guess here, Maybe the rear disc calipers are not the same size as the front calipers? I beliieve your master cylinder (assuming this is a disc MC and not a drum as you have equal sized reseivors) only can and will move a given amount of fluid to the front and rear, your metering valve and your porportioning valve limit pressure or hold off the timing not volume, if it was to limit volume the fluid would have to be displaced somewhere and its not as the pedal travel remains the same. So if your front calipers are a Wilwood or small volume caliper and your rears are a GM metric or corvette as an example you will never move enough fluid to collapse the GM's as the wilwoods collapse with less volume and once collapsed the pedal can no longer travel anymore to move more volume. This is only true on disc setups as a drum master cylinder moves a different volume for the front and rear. Sorry for the long answer and I hope I explained it enough to either solve or eliminate this as the problem, but I could also tell you how I know this but I am sure you know why! Best of luck

Originally Posted by Matthyj

Only a guess here, Maybe the rear disc calipers are not the same size as the front calipers? I beliieve your master cylinder (assuming this is a disc MC and not a drum as you have equal sized reseivors) only can and will move a given amount of fluid to the front and rear, your metering valve and your porportioning valve limit pressure or hold off the timing not volume, if it was to limit volume the fluid would have to be displaced somewhere and its not as the pedal travel remains the same. So if your front calipers are a Wilwood or small volume caliper and your rears are a GM metric or corvette as an example you will never move enough fluid to collapse the GM's as the wilwoods collapse with less volume and once collapsed the pedal can no longer travel anymore to move more volume. This is only true on disc setups as a drum master cylinder moves a different volume for the front and rear. Sorry for the long answer and I hope I explained it enough to either solve or eliminate this as the problem, but I could also tell you how I know this but I am sure you know why! Best of luck

You may have the answer to my problem, not sure. The calipers on the rear are 1978 to 1988 GM.
The fronts are also GM but maybe different volume is used to operate.
Matthyj: what was your fix ?

Navy, just a question - I see a purple (appears to be) residual valve in the rear line to the proportioning valve block, and then what appears to be two blue residual valves in the lines from the proportioning valve block to the front & rear brakes? Can you explain your hardware as installed?

Originally Posted by rspears

Navy, just a question - I see a purple (appears to be) residual valve in the rear line to the proportioning valve block, and then what appears to be two blue residual valves in the lines from the proportioning valve block to the front & rear brakes? Can you explain your hardware as installed?

The 2 blue residual valves go to the front brakes and the purple one is for the rear. Should have just put one for the front line near the master but I put one for each line.

Why are they different front to rear if you have disc's all around? The purple one is a 10# valve meant for drum brakes, right?

Originally Posted by rspears

Why are they different front to rear if you have disc's all around? The purple one is a 10# valve meant for drum brakes, right?

Roger: The valves are all 2 psi one is from wildwood and the 2 blue 1's are speedway. I guess they don't talk to each other when designing these things.

Originally Posted by Navy7797

Roger: The valves are all 2 psi one is from wildwood and the 2 blue 1's are speedway. I guess they don't talk to each other when designing these things.

So much for standardized color coding.... How about putting a pressure gauge on the MC outlet ports, one at a time to see how they compare.

Originally Posted by Navy7797

Roger: The valves are all 2 psi one is from wildwood and the 2 blue 1's are speedway. I guess they don't talk to each other when designing these things.

according to the Wilwood site []Wilwood High-Performance Disc Brakes - Search Results: residual valves] Roger is correct, the red valve is 10#. Wildwood also stamps the number on their valve bodies, i would check it make sure someone didn't send you the wrong valve.

I had a similar problem on my 46 coupe. In my case it turned out to be air trapped in the rear line. I could not get it out by the traditional pump and bleed method. I finally built a pressure bleeder and that was able to move enough fluid in a steady flow and get all the air out. This might not be your problem, though. Just a thought. Like you, this was the first car I couldn't get to bleed in the normal way

I would have plumbed the residual valves closer to the MC and used only 1 for the front. Also, I have a prop valve in my rear brakes and it is not needed. It is set to max pressure. I have Ford Explorer disc brakes on the rear. Between the smaller disc size than the front, smaller caliper bore and difference in tire size, the bias is built in. As has been said, you may have built in brake bias that simply won't allow the rears to lock. In my case, I know the rears are working because the rotors show wear and the pads appear to be wearing.

there is an issue adjusting those rear disc parking brakes-check an OEM manual, not Speedway--------
get the eze bleeder screws-------you can bleed a whole system by yourself in less than 10 minutes

Originally Posted by jerry clayton

there is an issue adjusting those rear disc parking brakes-check an OEM manual, not Speedway--------
get the eze bleeder screws-------you can bleed a whole system by yourself in less than 10 minutes

Yup I got the eze bleed screws and have bled the piss out out of them, work great but I still have problems .

Here is the absolute best source for factory manuals on the planet....
Faxon | Shop Manuals for Car & Truck Owners | DIY Service, Repair or Maintenance

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Originally Posted by techinspector1

Here is the absolute best source for factory manuals on the planet....
Faxon | Shop Manuals for Car & Truck Owners | DIY Service, Repair or Maintenance

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Thanks for the info on how to educate my self I seem to need all the help I can get.

ALSO_---lots of OEM type master cylinders contain the residual pressure valves where/as aftermarket (Wildwood?etc) do not-and, the valves that have been used in all vehicles since dual brake systems (1960s) have some delay, proportion,etc funstions so I would suggest that you eliminate those parts out of yours