I am having brake issue on my 1970 duster

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dancinwulf

dancinwulf

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Have replaced the master cylinder and the vacuum booster bled the lines and still no brakes
could it be something in the brake pedal linkage? Need help[
 
Define no brakes.

Did you bench bleed the master cyl
 
I agree with @Dana67Dart, we need more information. There are several things that could be going on. Do you still have the old master cylinder (MC)? If so, compare them to make sure you got exactly the right one. If the actuating rod does not match the new MC, you likely won't have brakes. Also, were the brakes working before, and the MC failed? Then that would certainly point to the MC. How old are your hoses? You probably have three; two up front and one at the back. Those can fail internally which will cut off brake fluid flow. And my last question is, how did you bleed them. A friend of mine loves the method where you have someone pump, pump, pump the pedal and then you open the bleeder valve. I don't like that method. I don't think it works all that well. I like the method where you open the bleeder valve, the assistant presses pedal to the floor and holds it there, you close the valve, the assistant lets the pedal rise up, and then repeat. I am NOT questioning you brake bleeding ability; I just think there are good and not so good ways to bleed them.
 
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I agree we need more information. I am wondering if you have disc or drums? If you replaced the shoes, they will need to be adjusted out which can be done through the hole in the backing plate, the automatic adjusters will fine tune them if you do a series of forward and backward stops.

With regard to bleeding, I agree with the post from @harrisonm as to how to do it. I would only add what someone else said regarding the need to first bench bleed the new MC and then when you do bleed, do the furthest brake first (passenger rear, then passenger driver, then passenger front and finally driver front). Using a vacuum pump at the bleeder valve can work but air bubbles don't always seem to get "sucked" out in my experience. Or you get a leak on the hose to bleeder valve and it looks like it never bleeds cause of all the in-leakage.
 
Kendog 170 said:
Did you have no brakes before the install? Definitely not enough info.
Click to expand...
we had brakes but they got to where you really had to stand on them to stop
we replaced both the master cylinder and the vacuum booster that came together in a set is it possible that the linkage from inside off the peddle doest match the brake peddle doesn't want to return so the brake lights stay on when you let off the brake peddle
 
harrisonm said:
I agree with @Dana67Dart, we need more information. There are several things that could be going on. Do you still have the old master cylinder (MC)? If so, compare them to make sure you got exactly the right one. If the actuating rod does not match the new MC, you likely won't have brakes. Also, were the brakes working before, and the MC failed? Then that would certainly point to the MC. How old are your hoses? You probably have three; two up front and one at the back. Those can fail internally which will cut off brake fluid flow. And my last question is, how did you bleed them. A friend of mine loves the method where you have someone pump, pump, pump the pedal and then you open the bleeder valve. I don't like that method. I don't think it works all that well. I like the method where you open the bleeder valve, the assistant presses pedal to the floor and holds it there, you close the valve, the assistant lets the pedal rise up, and then repeat. I am NOT questioning you brake bleeding ability; I just think there are good and not so good ways to bleed them.
Click to expand...
so disc brakes front drum in rear both are in good shape and working then it got to where you really had to stand on the peddle to stop.
 
OK, no brakes can mean a few things. Are you saying the brake pedal is LOW? Are you saying the pedal is good but the brakes just won't stop? We need more info here for good help.
 
harrisonm said:
I agree with @Dana67Dart, we need more information. There are several things that could be going on. Do you still have the old master cylinder (MC)? If so, compare them to make sure you got exactly the right one. If the actuating rod does not match the new MC, you likely won't have brakes. Also, were the brakes working before, and the MC failed? Then that would certainly point to the MC. How old are your hoses? You probably have three; two up front and one at the back. Those can fail internally which will cut off brake fluid flow. And my last question is, how did you bleed them. A friend of mine loves the method where you have someone pump, pump, pump the pedal and then you open the bleeder valve. I don't like that method. I don't think it works all that well. I like the method where you open the bleeder valve, the assistant presses pedal to the floor and holds it there, you close the valve, the assistant lets the pedal rise up, and then repeat. I am NOT questioning you brake bleeding ability; I just think there are good and not so good ways to bleed them.
Click to expand...
brake lines and hoses were all replaced when the brakes were put on maybe 5000 miles
 
RustyRatRod said:
OK, no brakes can mean a few things. Are you saying the brake pedal is LOW? Are you saying the pedal is good but the brakes just won't stop? We need more info here for good help.
Click to expand...
brake peddle is very low and doesn't return so the brake lights stay on unless you pull the peddle up by hand
 
dancinwulf said:
brake peddle is very low and doesn't return so the brake lights stay on unless you pull the peddle up by hand
Click to expand...
Ok cool. Now we got somewhere. Did you bench bleed the master cylinder? I did not see an answer to that.
 
dancinwulf said:
it possible that the linkage from inside off the peddle doest match the brake peddle doesn't want to return so the brake lights stay on when you let off the brake peddle
Click to expand...
Brake light switch is adjustable.
 
What specific booster and mc ( part numbers and manufacturer) did you put on the car.

Was the car a power brake car originally
 
So it was a power brake car we did bench bleed to new master cylinder it came with the new vacuum booster. We bled all the brake lines and adjusted the rear brake pads
disc front drum rear it will stop if you are going slow but takes at least 60 ft to stop at 35 mph. The car was stopping ok last year put it up for the winter and the brakes
were marginal when we started it up this spring so I ordered new master and vacuum booster. installed them and still now working right
thanks for all the help we live in snow country so just now getting nice enough to take it out.
 
Kendog 170 said:
If you didn't it's easy enough to do on the car. They also sell an adjustable pushrod IF that is your issue.
Click to expand...
So who can I order the pushrod from that may be the issue I lubricated the linkage at the brake peddle and now it returns so that
the brake lights go off.. But still doesn't stop like it should
 
Have you verified that the rear brakes are actually applying?
 
I installed a new master/booster this year that I bought at the Nats in Columbus a few years ago. All seemed fine until I pushed hard on the brakes. It took a while to figure out that the cheap pushrod that came with it bent 90 degrees with pedal pressure. When we took it out I could straighten it by hand...
 
dancinwulf said:
So who can I order the pushrod from that may be the issue I lubricated the linkage at the brake peddle and now it returns so that
the brake lights go off.. But still doesn't stop like it should
Click to expand...
Dr Diff should have them.
 
RustyRatRod said:
Dr Diff should have them.
Click to expand...
So I ended up sending the original master cylinder and booster to Power Brake Booster in Washington to have them go thru them the replacement set up doesn't work right. So will see what happens with the original repaired and reinstalled thank you for all the advice
 
dancinwulf said:
So I ended up sending the original master cylinder and booster to Power Brake Booster in Washington to have them go thru them the replacement set up doesn't work right. So will see what happens with the original repaired and reinstalled thank you for all the advice
Click to expand...
Cool! Keep us posted. I sure hope it works!
 
Brake issues are a pain, going thru the same thing, brakes fine, sit in the garage all winter, drove around the block, lost the brakes.
Leaking from the back of the master cylinder, easy fix, yeah right.
What the fu** master cylinder is on this thing, third time was a charm at NAPA, the PO put a 440 in the 85 D-150 and used an earlier master/booster.
Hooked everything up, bleed the brakes, the stupid PO had the brake lines backwards, and they are different sizes, so waiting on Thursday to come for adapters to come to switch the lines.
Fun times............
 
I just did an 8 3/4 swap.

I pulled the wheel cylinders, at minimum 1 piston on each side was rusted into the wheel cylinder bore.

it amazes me how that can happen.

They were replaced in 1992 only 22,000 miles on them
 
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