Non Power Disc Brakes

My experience is that once the rod has been clicked into the M/C you ain't never getting it out ....

I went to Autozone and looked at all the different brands they had ... and bought the one that has the rod in the box ... not pre-installed.

 

Clamp the Master Cylinder in a vice. Get the biggest screw driver you have and put it through the hole in the end of the rod. Put a block of wood between the bottom of the screw driver and the vice. Whack screw driver hard with BFH. It will come out.

 

Same here, no problems.

 

i took the ...piston... out and sawed the end off that was holding the rod...

...Frank...

 

Dude I am so digging your comet SAWWEEEETTTT!!!!

 

There is no check valves....

It is a resticter design.....
Pressure goes through but does not allow it to receed fully....

Kinda like a collapsed rubber brake hose....fluid gets through under pressure but doesn't relieve pressure on that the release stroke....

Even the disc brakes have a 2 lbs on the rear....

lets the rears engage first to maintain a stabble stop...

the reason you need 10lbs on the drums is the smaller piston/cup side...

 

Don't know about the 10 lbs.,but the check valve is in the master cyl.,I found out when building my own 4WDBs for my '72 Bronco,if you take the lines off the M/cly.put a #8 sheetmetal screw in the hole that the line goes in a little brass insert will come out and there is your check valve,when converting to rear disc.s everyone took the rear ck.valve out,worked great after that.

 

I have all stock brake,s on my 74 Mav, disc no power. But we did find out that! The softer the better on the disc pads.

 

Quite a few late models just have resticters that run in line from the master cyl or down stream on the brake lines....seen them as far back as close to the rear rubber lines....

 

It takes something like 300-500 lbs of line pressure to actually stop a car, right? I am basing that number off where guys set line locs in drag cars. If so, you ought to be able to drive through 10 lbs of drag.

I had swapped the front discs on my car 12 years ago. With the stock MC and combo valve, etc. it wore out the front disc pads in about 6000 miles. I did some reading, and forget the source that talked about the elevated line pressure. I also knew I needed help at that time and that is when I got a friend involved, who is a pro mechanic, and he took care of installing the MC and adjustable prop valve. He also said he did something to the combo valve. Perhaps there is some misunderstanding about what he told me he did. Also, he is a Chevy guy and the combo valve was a head scratcher for him, so maybe he was covering up for that. The guy was less than 100% honest and is no longer a friend.

After changing out the MC, the car has gone another 20K miles and brake wear was normal. So, that would back up what ActionRPM was saying about modding the MC. Swapping to a later one would also fix it, and you get reservoir bowl sizes that are better suited to disc brakes.

Also, with so many other folks here saying they are using the stock MC without problem, maybe mine was gunked up and sticking somehow. Even if you rode with your left foot on the brake pedal all the time, to wear out a set of new pads in 6000 miles would be a challenge.

So, what do I really know about any of this ... there was a problem, we changed stuff and it's all good now.
Your experiences are probably different than what I went through. Old cars ... gotta' love em'

 

The prop valve is only for the rear brakes anyway. it keeps a LOWER line pressure there as an equal one would cause a rear skid.
Jeff, you could have had crappy pads and a sticking MC. Ive had a few that lock up with brakes on.

 

Use Raybestos # MC36440. Fits mid 70's w/ manual disc. I used this one on mine. I also reused the old pushrod because of pedal height issues. Just use the new clip from your new pushrod.

 

Thanks for the part number, just ordered one from RockAuto and got to use my 5% discount (again).

Russ

 

I have WAY more then 6,000 miles on mine since doing the disc brake swap without touching the prop. valve or master cylinder.. No signs of excessive wear.