1 1/8 master cyl kit?

Longknife

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Subject, 1969 Rr with front disc brake conv. and rear stock drums, not power.. with up graded 1 1/8 master cyl. Does anyone make a master cyl rebuild kit for 1 1/8 M cyl???
 

Curiousyellow71

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1 1/8 master cylinder it to large for the manual discs it will push really, really hard with no booster. Most have the best luck with a 15/16. I think oem manual disc may be a 1"? It may seem like a small change but makes a noticable difference.
Oreillys could order kits last time I was looking at rebuilding.
 
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Longknife

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I had this cylinder on my car for 3 years and it worked perfectly. I replaced it with one with a smaller bore when I was trying to diagnose a brake problem and have not been happy with the replacement.
 

Curiousyellow71

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That is great the 1 1/8 worked with out the booster. Makes me wonder what is different on your car...what conversion kit do you have? We are about to switch three of our b bodies from front drums to discs...what brake problem did you run into?
 

Fran Blacker

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This is a list of masters from Mopar Action Disco Tech. They tell you bore size and what car they came on. Might want to buy whole master?
dd3.JPG
Hope it helps?
 

Longknife

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Curious, I have the standard conversion that is sold everywhere, don't know the exact brand as I can't find any markings. It's like this one;
disc brake conversion ki

The problem I am having now is that I am getting air in the calipers! After installing the master cyl and bleeding the pedal felt good but after driving a while, the pedal starts to get lower and softer. I had a heck of a time bleeding them out, bled almost a pint of fluid through the front calipers and keep getting air. I finally gravity bled the system and got the air out. The pedal feels good now but where is the air coming from???

Fran, that list is very interesting, but it does not signify, in a lot of those applications. whether that is a manual or power application, or disc or drum,,,,?
 

Fran Blacker

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This is from the article I posted master cylinders.
db2.JPG
 

Curiousyellow71

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I would agree with your first thought of a bad master cylinder letting fluid past to have the pedal creep down. Unless somehow something is going on with the rear drums? Rear drums that the adjusters are backed off will let the pedal go farther and farther down. It will also feel spongy because the rear brakes aren't getting engaged enough to get a firm feel at the pedal.

I have gotten several master cylinders from rock auto, they have had 1" in stock for manual brakes w front discs. This is the last one I put on:1974 DODGE DART 5.9L 360cid V8 Master Cylinder | RockAuto
On the really difficult brake bleed jobs I have a oil can filled w brake fluid...w a spark plug boot over the end of it and fill the master through the bleeders on the calipers. It takes a pretty heavy duty oil can. I found a 40 year old one that was new at a flea market... works very well for a one man show.
 
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Longknife

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It's not the rear, OK? I am getting air in the calipers. I will start from the beginning; I installed new master cyl. and bled it out two months ago but only about a thousand miles. The pedal felt ok but it started going down and getting softer the more I drove it. I checked the rear adjustment first. it was ok, I then bled the rear, no bubbles, I then went to the front and bled them, BUBBLES!!!!. Pumping the pedal seems to make more bubbles so gravity bleeding worked better. After I get all the air out it works fine.....good pedal now.,,,but where did the air come from?
 
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Curiousyellow71

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If I am recalling correctly the front brakes are the rear compartment towards the firewall. Sounds like it's sucking air through the seal. I think that would be more likely then a caliper. Looking for a 1 1/8 kit all I have found is out of stock. There was a universal kit at speedway. Guessing it's gm...most there stuff is, might work though?
 
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Longknife

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Curios, can you post a link to that kit? They have the exact cylinder I am rebuilding,

 

69ChargerR/TSE

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Are your bleeders on the top of the calipers? If not, you will get air.
 

69ChargerR/TSE

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In the mid-1970s, Chrysler eliminated the rear brake residual pressure valve from the master cylinder. Its function was to prevent any air from sneaking into the system via the rear wheel cylinder cups. In its place, Chrysler substituted “expanders” in the rear wheel cylinders. (Expanders are dish-shaped steel inserts that exert outward pressure on the cups.) If you should decide to use a master cylinder from a 1975-up car, be sure you have the expanders in your rear wheel cylinders. For at least 20 years they have been universal in all replacement wheel cylinders and rebuild kits.
 

Longknife

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In the mid-1970s, Chrysler eliminated the rear brake residual pressure valve from the master cylinder. Its function was to prevent any air from sneaking into the system via the rear wheel cylinder cups. In its place, Chrysler substituted “expanders” in the rear wheel cylinders. (Expanders are dish-shaped steel inserts that exert outward pressure on the cups.) If you should decide to use a master cylinder from a 1975-up car, be sure you have the expanders in your rear wheel cylinders. For at least 20 years they have been universal in all replacement wheel cylinders and rebuild kits.
New rear cylinders installed 5-22. I am not having a problem with the rear, it is the front calipers that are getting full of air....
 

Curiousyellow71

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You may want to take apart yours and see what the internal match up to in appearance. It does appear there is some different valving that was changed on that style master cylinder over the years chrysler used it. It's hard to say what is inside a new replacement one.
I wasn't impressed by the speedway offerings either. I did some looking that might help. Our projects are similiar to what your trying to tackle so I did some searches:
There are a few kit part numbers for that style of master cylinder in 1.125.
Raybestos MK662..everywhere seems out of stock?
OEM Mopar part no. 2808616 or 3420117
Wagner 59052.
Kits seems to be scarce, but I bet someone on this site has one on the shelf. Might want to just replace it... Mancini racing seems to have a variety of master cylinders available, scroll down for 4 bolt ones .Master Cylinders
 
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