Which master cylinder

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green72

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Ok, I am just learning so be nice. I have a 1972 Plymouth Scamp 225 /6. I am completely going thru the brake system. It has the stock Kelsey Hayes power disc up front and the stock drums on the rear. I have done a lot of searching on here with great results. The booster is going to Booster Dewey for a rebuild. I just need to know the right replacement master cylinder. Napa and other part stores list them but I am unsure of the exact one I need. A part number would be great. Thanks, The info on this sight is unreal!!!
 
When I looked that # up it seemed to be the 1-1/32 bore, for manual discs. Power discs used the 15/16 bore version of the same basic MC.

Yes, that is the part # recommended by Rock Auto, but in my experience, there are a lot of errors in the brake parts listings.

Unfortunately, they don't always show the bore size in the description, and frequently the photo is generic and doesn't show the actual appearance.

What I usually have to do is crosscheck Dodge and Plymouth listings for a few related years, until I come up with something that seems to have the correct attributes.


dusterglenn said:
Raybestos MC36426.
Click to expand...
 
I was at work (auto parts store) when I saw the question, so I quickly looked it up in the computer. Tomorrow, if I'm not too busy, I'll check my old Raybestos catalog from the late 80's. What's on the car now? Have you measured the bore on the existing cylinder? Are you looking to try and change the pedal feel? Or are you shooting for the correct/original style cylinder?
 
Thanks for looking. I am looking for the correct original replacment. Have not measured the bore but will check it this morning. The one that is on it appears to be original, car only has 57,000 miles. It is dual chamber the chamber for the front disk is larger than the one for the rear
 
My old catalog shows 1-1/32" bore for the MC36426 with power disc in 71-72. There's no manual disc master cylinder listed, so no bore diameter listed. The picture looks like the correct style, with the larger res for the front circuit. If it was my car, I'd use the MC36426. In fact, I did... But, I have since switched to the plactic resovoir Aspen/Diplomat cylinder with adapter plate.
 
Big thank you for taking the time to check it out!! Why di you switch to the plastic res? Was the adapter plate something you made or purchased?
 
A friend of mine made a batch of adapter plates from a template we got from bigblockdart.com. I think there's a few vendors that sell them.
Why did I switch to the plastic style? Lots of reasons, but mostly because it looked "cooler" and wasn't rusty. I was also adding a line lock, adjustable proportioning valve and painting the engine and engine compartment at the same time...
 
Several vendors for the 4 hole to 2 hole adapter plates. Cheapest I have seen is ~$35. There are several types depending on if your car (or booster) has 4 studs or 4 holes. Most people use them on the firewall w/ manual brakes. Not sure how they would work on a power booster since it changes the effective rod length.
 
The pushrod hole in the newer master cylinder is about 3/8" shallower, the same as the thickness of the adapter. I'm not sure if it's design or luck.
 
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