What is the correct master cylinder for manual disc

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Here's the one in my 74.

74 dart 031.jpg


74 dart 032.jpg
 
I am going to assume that since your car is a 71, you are referring to the Kelsey-Hayes 4 piston setup your car should have. On my car I used a manual disc master that is correct in application for a 69 Dart. Included is a picture of it. The manual 4 piston master has 2 equal sized resevoirs, where the newer style single piston calipers need the larger resevoir as shown by greendart72. I'm not saying that you can't use that one, but according to the person who I get my brake stuff through, the correct unit for a Kelsey-Hayes manual disc is the one I have pictured. If you'd like, I'll pass you his number, he really knows old car brakes.His name is Craig Studnick, and his number is (516) 485-1935. He is a little unorthodox, but he really knows his brakes. Hope this helps, Geof

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My is Demon is similar to Pauls340, drum brakes on the rear and Kelsey Hays 4 piston disc up front and my master cylinder is similar to Greendart72's master cylinder. I really got confused after reading Cosgigs reply,which is the proper one?

John
 
Mine is a 71 Duster with the factory KH Manual Disc/rear drum setup. My master cylinder is like the one cosgig has. It is the correct one for those brakes. It is the factory part.
 
This comes up alot, and about 2 years ago I needed to replace my mc on my 67 Barracuda with the KH 4 piston manual brakes.
After alot of research, I bought a power mc for a 71 to 76 Dodge.
It looks more like greendart72's mc.
It bolted directly on, the pedal is much easier, and it stops better than ever.
 
All A-B-E body disc brake MCs were interchangeable thru 72. They all looked the same on the outside, with a wire bale holding the cap, and one large/one small reservoir (the large one being for the front brakes, natch).

The difference was in the bore diameter. A larger bore diameter moves more fluid, and requires more pedal effort. For some reason known only to themselves, the Mopar engineers specified larger bores for manual brake cars than for power brake cars (at least for A-bodies). This is the opposite of what would seem logical.

Bore sizes ranged from 15/16" to 1-1/8" (B-body power brakes). A-bodies used either 15/16" or 1-1/32". The latter is "correct" for manual brakes, and is what I have in my car, but if you have a choice, the 15/16" bore will give you a little less pedal effort (trades off pedal effort for a little more pedal travel).

Unfortunately, most of the sources for brake parts do not even realize that bore sizes are a factor, and do not include them in their listings. So you may not be able to tell what you're ordering. "1972 power discs" should get you the 15/16" bore, assuming they have their stuff together (big assumption).



pauls340 said:
Thanks for the reply's..i'm going with the two different size resv.
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mvh said:
All A-B-E body disc brake MCs were interchangeable thru 72. They all looked the same on the outside, with a wire bale holding the cap, and one large/one small reservoir (the large one being for the front brakes, natch).

The difference was in the bore diameter. A larger bore diameter moves more fluid, and requires more pedal effort. For some reason known only to themselves, the Mopar engineers specified larger bores for manual brake cars than for power brake cars (at least for A-bodies). This is the opposite of what would seem logical.

Bore sizes ranged from 15/16" to 1-1/8" (B-body power brakes). A-bodies used either 15/16" or 1-1/32". The latter is "correct" for manual brakes, and is what I have in my car, but if you have a choice, the 15/16" bore will give you a little less pedal effort (trades off pedal effort for a little more pedal travel).

Unfortunately, most of the sources for brake parts do not even realize that bore sizes are a factor, and do not include them in their listings. So you may not be able to tell what you're ordering. "1972 power discs" should get you the 15/16" bore, assuming they have their stuff together (big assumption).
Click to expand...

I always order them for '73 power brakes. (assuming lbp and single piston calipers) I have always gotten the smaller boar(15/16") when doing so. I then run the '76 + f body calipers with the larger boar and it feels very nice, like a power set up but without the twitchyness.
 
1moparman said:
so what year are the kelsey 4 piston caliper availible for sbp mopar? just 71?
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Kelsey-Hayes 4 piston discs were available on an A body starting in 1965, I believe, 66 for sure. They were used all the way up through 72 when the rim bolt pattern was changed to 4.5". Also available on B body cars through 69 with the large bolt pattern. If you think the A body stuff is hard to find, try finding anything for the B body setup. YIKES!!! Geof
 
cosgig said:
Kelsey-Hayes 4 piston discs were available on an A body starting in 1965, I believe, 66 for sure. They were used all the way up through 72 when the rim bolt pattern was changed to 4.5". Also available on B body cars through 69 with the large bolt pattern. If you think the A body stuff is hard to find, try finding anything for the B body setup. YIKES!!! Geof
Click to expand...

The SBC K-H Abody calipers first appeared in late 1964 on the Barracuda. These remained as the only Abody disc brake option until the end of the 1972 model year, when the LBC '73 discs became available.
 
mvh said:
All A-B-E body disc brake MCs were interchangeable thru 72. They all looked the same on the outside, with a wire bale holding the cap, and one large/one small reservoir (the large one being for the front brakes, natch).

The difference was in the bore diameter. A larger bore diameter moves more fluid, and requires more pedal effort. For some reason known only to themselves, the Mopar engineers specified larger bores for manual brake cars than for power brake cars (at least for A-bodies). This is the opposite of what would seem logical.

Bore sizes ranged from 15/16" to 1-1/8" (B-body power brakes). A-bodies used either 15/16" or 1-1/32". The latter is "correct" for manual brakes, and is what I have in my car, but if you have a choice, the 15/16" bore will give you a little less pedal effort (trades off pedal effort for a little more pedal travel).

Unfortunately, most of the sources for brake parts do not even realize that bore sizes are a factor, and do not include them in their listings. So you may not be able to tell what you're ordering. "1972 power discs" should get you the 15/16" bore, assuming they have their stuff together (big assumption).
Click to expand...

I needed a new master cylinder and found this thread with the search. I have the factory 4 piston disc set up. Based on the above post I ordered a master cylinder for a '73 Duster 340 with power disc brakes. Its a Raybestos Part Number MC36406 which is a new "Professional Grade". www.rockauto.com has them. What was on my car was a 1 1/16" and it took excessive foot pressure even on moderate stops. I bench bled, installed, then pressure bled the system. I took it for a drive and the pedal does travel a bit more. But it takes way less foot pressure to stop the car. And it can lock up the tires where as before it could not.

It bolted right in and hooked right up to my reproduction brake lines without issue. Notice how the rear is curved and the front is square. Opposite of how the stock '69 ones were.

MasterCylinder1.jpg


MasterCylinder2.jpg


MasterCylinder3.jpg
 
The plated cap, which came with it, is a nice touch too.

One thing I did do was use a small amount of 3M Weatherstrip Adheasive to tack the rubber gasket to the lid. I cleaned both surfaces with Wax and Grease Remover first. I did this because the rubber gasket looked slightly deformed and I thought it might not seal against the body of the master cylinder correctly. Should not have had to do that but I didn't feel like hassling with sending it back. It is nice and dry after the drive and I believe it will stay that way.

The other thing to note is the master cylinder body surface that seals against the gasket is very nicely machined. Nice and smooth for a good seal.
 
340sFastback said:
I needed a new master cylinder and found this thread with the search. I have the factory 4 piston disc set up. Based on the above post I ordered a master cylinder for a '73 Duster 340 with power disc brakes. Its a Raybestos Part Number MC36406 which is a new "Professional Grade". www.rockauto.com has them. What was on my car was a 1 1/16" and it took excessive foot pressure even on moderate stops. I bench bled, installed, then pressure bled the system. I took it for a drive and the pedal does travel a bit more. But it takes way less foot pressure to stop the car. And it can lock up the tires where as before it could not.

It bolted right in and hooked right up to my reproduction brake lines without issue. Notice how the rear is curved and the front is square. Opposite of how the stock '69 ones were.
Click to expand...


glad to hear you like it
 
I also have 7/8" rear wheel cylinders (order for a '72 Dodge D100 2WD truck) which are a direct bolt on. And a Mopar Performance proportioning valve on the rear brake line. Those two things got rid of the famous mopar rear wheel lock up issue.
 
340sFastback said:
I needed a new master cylinder and found this thread with the search. I have the factory 4 piston disc set up. Based on the above post I ordered a master cylinder for a '73 Duster 340 with power disc brakes. Its a Raybestos Part Number MC36406 which is a new "Professional Grade". www.rockauto.com has them. What was on my car was a 1 1/16" and it took excessive foot pressure even on moderate stops. I bench bled, installed, then pressure bled the system. I took it for a drive and the pedal does travel a bit more. But it takes way less foot pressure to stop the car. And it can lock up the tires where as before it could not.

It bolted right in and hooked right up to my reproduction brake lines without issue. Notice how the rear is curved and the front is square. Opposite of how the stock '69 ones were.

View attachment 139144

View attachment 139145

View attachment 139146
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Reading old posts to see if it helps my issues, I remember back in the 80s having a problem coming up with a replacement MC for my 69 KH manual front discs. I think I used one speced for 70 cuda manual discs, anyway, takes a lot of foot pressure to slow down and won't lock up. The lid leaks, probably indicates air in the system. I seem to remember the original being equal with square lid but memory is the first thing that goes. My question: go with the 73 power one or get a original?
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Use the 73 power brake master cylinder which is 15/16 inch bore. Unless you like using two legs to stop your car don't use a larger bore MC on a manual brake car.

Also I recently switched to 13/16 rear wheel cylinders and rebuilt front KH calipers. Still running the same master cylinder. Pressure bled with Motive pressure bleeder. Adjustable prop valve now set to full pressure to rear brakes. Balanced braking with minimum leg effort. Running EBC red pads up front. Car stops great.

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Cover is cad plating
Not sure on part number or casting number. This has been talked about and to me never nailed down for manual disc brake master for 1971 A body

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Dorman Brake Master Cylinders M88787​

Original KH front/drum rear.

If the cap leaks, or before you even bolt it on, flip it over on a piece of sandpaper on a really flat surface, metal or glass, and sand it, then sand it some more, then sand it some more. When done, sand it again.
Mine never leak.
 
matthon said:

Dorman Brake Master Cylinders M88787​

Original KH front/drum rear.

If the cap leaks, or before you even bolt it on, flip it over on a piece of sandpaper on a really flat surface, metal or glass, and sand it, then sand it some more, then sand it some more. When done, sand it again.
Mine never leak.
Click to expand...

That's a big bore, expect to use a lotta muscles to stop relative to the smaller bore posted.
 
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