Thinking my current brake issues are related to the master cylinder. Are NEW master cylinders available for my 1972? If available where can I buy one? Very VERY reluctant to go with remanufactured!!!!
New (not remanufactured) master cyl
O'Man
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Many companies sell brand new repro units, even with original style bleeder screws. Try all the normal places like OPGI, Yearone, SS396.com and Inline Tube - take a look at their websites. Also, you should confirm that the master cylinder is the actual culprit and not something else in the system like a caliper or wheel cylinder, etc.
Hello in Upstate! I grew up in Conn, now in Atlanta and I miss the N.E.
Reason I suspect the master is as follows.
Yesterday I was bleeding the brakes after replacing all three of the soft lines in the system. Started by bench bleeding the master. The front chamber bleeds as I would expect....fluid comes thru the clear plastic line that comes with the bleeder kits. A few bubbles then the clear line remains full.
Rear chamber however behaves differently. When pumping the cylinder I can't fully fill that clear line. Pushing on the piston does not fully push fluid up into the reservoir It almost makes it but not all the way. Then if I leave the thing sit for awhile the front chamber and it's hose remain full. The rear reservoir and line however don't do the same thing. If I go back an hour later the rear reservoir clear line is empty while the front reservoir line remains full. Since the bleeding I describe is isolated from the lines and wheel cylinders I gotta believe there is an issue in the master. Maybe something else is hosed but given that the master cyl is standalone in my test it think something is amiss in the cyl.
There might also be other issues elsewhere no doubt about that however!
Appreciate any thoughts ya have about my observations / theory / testing.
THX for responding!
O'Man
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6,021 Posts
When bench bleeding did you tilt the master left, right, up and down and tap with a soft hammer each time ?
I hear it can dislodge trapped air.
If you do this let me know what happens. Several of us have soft pedals.
Rick
I hear it can dislodge trapped air.
If you do this let me know what happens. Several of us have soft pedals.
Rick
Joined
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18,738 Posts
Shouldn't need to. O'Man, i recommend you hone the bore and re-seal the piston in your current MC and DRIVE ON! It ought bleed properly fore and aft then.
I dont know about MCs but some of the replacement WP castings look nothing like the originals. I would definitely hit up the resto parts houses, not NAPA.
I dont know about MCs but some of the replacement WP castings look nothing like the originals. I would definitely hit up the resto parts houses, not NAPA.
I plan to rebleed it this AM just to be sure. Interesting about other guys having soft pedals, right now I have the ultimate soft pedal, aka no pedal. Will advise.
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2,229 Posts
I purchased my current master cylinder, wheel cylinders and calipers from Ground Up 8 years ago and have not had any problems with them.
If I need a new master cyl I really think the search for a new unit is warranted. I think they are available but so far in searching I have seen various labels like "Professional" on the listings. Call me a skeptic but a label like "professional" doesn't necessarily make me feel that the part is the best quality wise. The pessimist in me thinks that maybe "professional" could be a euphemism for "as cheap as possible to maximize profit on the repair job". Just saying!
So far there are units available at $65 / $75 then there are units in the $150 / $160 range. Wonder which one is the reman unit???? Why do I think the low bucks unit might be a reman?
Ok new news...yet AGAIN. I am posting this here and on another thread related to the brake issue.
Looked at the little pushrod that actuates the master cyl when the brake pedal is depressed. Tried to turn it /remove it..it was S-T-U-C-K. Yup stuck. Took a tight grip with a pliers to get it loose. It was not rusty just a lot of for want of a better term "gunk" adhering to the body of the little bas---d!!!! Pulled it out and wire wheeled it clean and now it slides easily without the "o" ring seal. Put the seal back on and it moves a little bit more snugly as I think it should but I think I have found the culprit.
As I think I mentioned the car has been sitting a long while and it gets kinda humid (kinda is an under statement) here in Atlanta. I am thinking this along with the collapse softline is going to get me back on the road.
A question....should there be any sort of lubrication on the little bugger pushrod? Any thoughts on cleaning out the hole in the booster, I am thinking of blowing it out with air but that is all I have for ideas.
mpbrakes.com
Looked at the little pushrod that actuates the master cyl when the brake pedal is depressed. Tried to turn it /remove it..it was S-T-U-C-K. Yup stuck. Took a tight grip with a pliers to get it loose. It was not rusty just a lot of for want of a better term "gunk" adhering to the body of the little bas---d!!!! Pulled it out and wire wheeled it clean and now it slides easily without the "o" ring seal. Put the seal back on and it moves a little bit more snugly as I think it should but I think I have found the culprit.
As I think I mentioned the car has been sitting a long while and it gets kinda humid (kinda is an under statement) here in Atlanta. I am thinking this along with the collapse softline is going to get me back on the road.
A question....should there be any sort of lubrication on the little bugger pushrod? Any thoughts on cleaning out the hole in the booster, I am thinking of blowing it out with air but that is all I have for ideas.
Here is something I found that mentions soft pedal as a side effect of the wrong pushrod between the power brake booster and the master cyl.
Got A Soft Brake Pedal? How to check the Booster Pin to Master Cylinder Gap | Master Power Brakes
Got A Soft Brake Pedal? How to check the Booster Pin to Master Cylinder Gap | Master Power Brakes
mpbrakes.com
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