Master cylinder swap

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Valiant63

Valiant63

Early A-body Valiants
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This is my first posting under the brake section, but here goes. I have a 64 Dart that already has manual disk brakes on it. The master cylinder is leaking out the back and needs to be replaced (front brakes appear to be dragging, too). What master cylinder do I order? I don't know what car it came off of, which is what they usually ask. After I take the mc off, is there a number they can use? Also, what good quality MC should I get as I don't want to be replacing it in a year or two? Thank you in advance.
 
Assuming it's a '67 and later factory disc brake setup and you don't want to modify anything, I'd use an early 70's disc brake master. If you want to match what you have, bring the old master with you to compare. There are 2 bolt master changeover setups out there also.
 
..when we bore our engines we install larger pistons.This is not usually done with a rebuilt master cylinder.
without knowing what you have an educated guess would be a master cylinder with a 1" bore for manual disc brakes.
buy a new unit as opposed to a rebuilt and although pricy Master Power is very hi quality.
 
I also recommend switching to a 2 bolt aluminum master cylinder, for better choices, future rebuild, and much lighter. Requires an adapter plate (~$70). Haven't read of anyone just drilling holes in the firewall, but maybe. For manual discs, get a small bore diameter. You can find suggestions by searching FABO. You could install power brakes, but requires brackets, adds clutter, and many say unneeded for an A body.
 
Should I just take out the master cylinder and put it on the counter and say, "Gimme one of these?" If it looks the same inside and outt hen I scored. If not, then I take it back or don't leave with it.
 
Most auto parts stores would rather you didn't do it that way. They're setup to look the part up by application. If you find a real good parts guy who's been around a while, you might get lucky but I wouldn't count on it. Post a photo of your master and we'll try to narrow down what you have. At least that will give you a starting point if they ask you.
 
You mentioned manual disk brakes, but you didn't say which bolt pattern? That will make it easier to determine which mc you have.
 
I got your PM. Since it's lbp disk brakes, you should either swap over to the two bolt mc like others have recommended or go with the 73 and later lbp disk brake mc. I've never used the two bolt mc yet, but I have one that I plan to install along with the adapter kit. Good luck.
 
he gave the hint that his front brakes drag... so i bet they didn't even change the master when going from drums to discs... 70's a body master will have the disc/drum valving in it...
 
I am going to pull the leaky dual master cylinder off sometime this week and see what I am come up with. I don't think I am going to go the two bolt design unless I got spare cash hidden in the car. I just want to get it running and driving again with good brakes and the brakes wer fine with the iron master cyinder. I will see what I can get to match what I got. Thanks
 
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