front brakes DRAGGING

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plymouthdude

plymouthdude

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I have a 1970 plymouth duster that came with front rotors and calipers and no power brakes . I replaced all brake lines rubber hoses , calipers, rotors ,proportioning valve,and master cylinder. I put two new master cylinder on from raybestes . Bench blead both master cylinders and front brakes are dragging .any help
 
Did you have to change your m.cylinder pushrod?Maybe it,s too long and pushing in on the master a tiny bit,enough to make them grab a bit?

New pads will drag abit till worn in.
 
There is no adjustment on the pushrod it is the one that came with the car . To me you should not have to take 2 hands to spin the rotor ?
 
Take the pushrod out and see how it is. That will tell you if it is the pushrod.

If this is a brand new brake job you may need to just drive it around the block, use the brakes a few times and let the calipers and pads find their neutral position.
 
I loosen up the master cylinder to see if it took pressure off the rod and it did not change till i loosened the line
 
is it a aluminum master cyl,went threw that problem on my old 80s cordova.went threw 3 master cyls till i found one that worked like it suppose to.makes a difference on a rebuilt one and a new one.sometimes i think the rebuilt ones arent the way to go on a aluminum master cyl.on my duster i run a cast iron one and never have those problems.
 
Hovis auto parts and rock auto said it is for my car ? The first master look just like the one i took off . The 2 one from rock auto said it was up graded same part number but a bolt on lid
 
When you order the MC are you ordering for "Your Car" or for the Disc Brakes that are on your car?
I ask this because if your setup is original to your car it would be SBP Kelsy-Hayes 4 Piston Calipers.
IF you have Single Piston BBP Rotors it has been upraded.
That will make a big difference on what MC you get.
Also, there should be a Threaded Tip to your Brake Rod so you can adjust the length for the MC.
I ran into this exact issue once before and the Rod Tip needed turn in 2 turns and problem solved.
Of course that was after replacing the Calipers 3 times and 3 sets of Brake Pads.

Hope this helps,
Later,
Bruce B.
 
I had the same problem on a conversion i did and the pads got better after use but were still tight,i changed to a different brand of pads and they worked like they should,you will have a slight drag but not to where you need a lot of pressure to turn the wheel.
wayne
 
if they are dragging, pick them up! sorry couldn't resist...

But maybe it is the pads, what brand are they, and yes, check the wheel bearings, maybe loosen the spindle nut, give it a spin, and snug it back up...
 
The flexible brake hose could be the problem. They can collapse inside and not allow the fluid to leave the caliper. It happened on my 71 Dart.
 
"Remanufactured" master cylinders are junk.

There is no threaded (or other) adjustment on the end of the pushrod -- not with nonpower brakes. And an adjustable pushrod is not needed; every single vehicle Chrysler ever built with nonpower brakes came with a non-adjustable pushrod and they worked (and still work) fine.

A drum brake master cylinder will have a residual pressure valve in both outlets. A disc brake master cylinder will not have a residual pressure valve in the rear outlet (which serves the front disc brakes). If you have an RP valve in the line to the disc brakes, they will drag! Please help us help you: post details about the exact master cylinder you installed. What is the Raybestos number you've been getting and installing?
 
slantsixdan said:
Please help us help you: post details about the exact master cylinder you installed. What is the Raybestos number you've been getting and installing?
Click to expand...


Good advice on this one. (highlighted.)

I also have a question. Just a little diagnostic work. Have you opened a bleeder to see if it spins freely? Just open it and close it again, then spin it. Do this on just one side, but check both sides to see how they both spin. What happens?
 
Firs i wanted to thanks all for the input , but the new reman mc fixed the brake dragging problem . I don't know why raybestes mc would not work but it don,t drag any more with the reman . Now the reman mc leaks between the lid and the body . I just can't get a brake .that is why i replaced the one that came with the car when i got it . Both reservoir are the same size . I would like to up grade to one reservoir bigger then the other . Because i have nothing but problems with this style . Any one know of a different mc that has close to a 1'' bore and the same size brake line fittings
 
plymouthdude said:
firs i wanted to thanks all for the input , but the new reman mc fixed the brake dragging problem . I don't know why raybestes mc would not work but it don,t drag any more with the reman . Now the reman mc leaks between the lid and the body . I just can't get a brake .that is why i replaced the one that came with the car when i got it . Both reservoir are the same size . I would like to up grade to one reservoir bigger then the other . Because i have nothing but problems with this style . Any one know of a different mc that has close to a 1'' bore and the same size brake line fittings
Click to expand...
with out power brakes
 
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