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Master Cylinder Question

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The Rebel Alliance View Drop Down
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    Posted: May/31/2015 at 10:37pm
I have a 70 rebel sedan 304 with manual drums all around.

I plan to upgrade the front to disks, and have picked up the entire braking system from an 83 concord.

Looking at Rockauto, they list several Master Cylinder options. Some state bore size 15/16", others say nothing. Which one do I want/need?

Also, some have the cylinder ports facing the engine, others away. The factory set up in the car faces towards the engine, and I assume I want a new one (with booster from said concord) the same way?

Lastly, from my experience boosters rarely fail, but given age and all, would it be worth while buying a new booster too? They don't seem nuts expensive, but I thought I'd ask those with AMC experience.

Thanks,
Chris
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Post Options Post Options   Thanks (0) Thanks(0)   Quote farna Quote  Post ReplyReply Direct Link To This Post Posted: Jun/01/2015 at 8:04am
If the booster is known to be working well I think I'd leave it alone. But then again, if I knew I was keeping the car long term I might go ahead and replace it while everything is apart. It's your call there.

You can keep your original master cylinder. Just remove the residual pressure valve from the front brake outlet. Turn a small screw in the small hole in the center of the outlet. You only need 1/2 to one full turn. Then pull with pliers or a claw hammer (like pulling a nail). The tube seat will come out. Behind the seat is a spring and plastic or hard rubber piece. Remove those (that's the "valve"). The bore of the drum MC is either 15/16" or 1", either is fine -- very little difference in pressure.

Side of outlets doesn't matter as long as you have room on the side to run the brake lines. I have a late model MC on my 63 Classic (1" bore 90s Ford Ranger booster and MC, but that took some modification to work, not a straight bolt-on). I ran the stock booster and MC until the booster failed (drum booster). My booster had come from a 65 Classic that sat up a long time, but it still lasted a couple years before failing. One that has been in service and maintained should last a lot longer.  Sitting is a lot harder on car parts than being in constant use!
Frank Swygert
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Post Options Post Options   Thanks (0) Thanks(0)   Quote The Rebel Alliance Quote  Post ReplyReply Direct Link To This Post Posted: Jun/01/2015 at 9:58am
Thanks so much - great information!
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Post Options Post Options   Thanks (0) Thanks(0)   Quote carnuck Quote  Post ReplyReply Direct Link To This Post Posted: Jun/03/2015 at 12:43am
If you go with the lines towards the fenders, the master cylinder is the same as early XJ Cherokees and the booster has a bit more oomph for helping you stop..
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