I redid my manual brakes a couple of years back. Front disk and rear drums. I put in new rubber lines, calipers and pads. The factory master cylinder was not pumping fluid so I needed a new one. I figured bigger is better so I got one with a 1.31 bore size. Too big I know but now I want to go with a 7/8" or maybe a 5/16".

The car stops fine but, if I remember correctly, the outer pads on both sides do not clamp down hard enough. There is more wear on the inner side of the rotor than the outer. NAPA had a 7/8" Bore MC back then but now I don't see one on their site, or anyone else's for that matter.

Where would you recommend finding this MC?

Any info on a rebuilder would work as well.

Thanks

I think the only 15/16" mc you can get is through drdiff here on the site. If the car had a 7/8" on it originally that's what I'd put on it.

The car stops fine but, if I remember correctly, the outer pads on both sides do not clamp down hard enough. There is more wear on the inner side of the rotor than the outer.

this has nothing to do with the master.
I would look at the calipers to see if they can move freely.

What Andrew said. Grab a helper to work the pedal & up on stands/wheels off see what's going on

You said 5/16th, likely mean 15/16. If so this is what I just installed on our Challenger. You do not say what car you have. Challenger was all drum, now converted to front disc. No power brakes. With larger bore MC had very poor front brake performance.

http://www.amazon.com/gp/product/B001PYO1PU/ref=oh_aui_detailpage_o02_s00?ie=UTF8&psc=1

Also just installed ceramic pads. Have high hopes once I sort out a silly Wilwood caliper issue. Has to do with their minuscule non standard bleeder valves.

Sorry about not posting what kind of car. It is in my signature, a 72 340 Cuda. I've been hanging out on Cummins Forum and those guys expect you to have everything in your Sig, including mods, so that they can answer your questions.

Calipers slide pretty good. I've had them on and off a couple of times and relubed them. They are brand new. From another post on Moparts someone said that a larger bore MC would not bring the pressure up high enough for the calipers to properly do their job with manual brakes. Dr. Diff's 15/16" MC states that if you really want a high pressure, then use his MC.

NAPA has a 1" bore MC for under 50 bucks. I may try that one but I know that I saw some for sale that were 7/8" The guy at www.brakeplace.com quoted me $170 to rebuild the factory MC. Plus his book shows that I should have a MC with a 1" bore.

The MC in the Amazon ad doesn't say what size bore it has. I found a lot of ads like that.

edit: It was late when I posted. I googled the Dorman MC and it IS a 15/16" bore. It is listed as a power brake MC. Does the pushrod for a manual brake car fit into a power brake MC?

Thanks

If your car stops fine but the outer pads are not working properly then you have a caliper problem.

The caliper is sticking. If the bolts/sliders are well lubed then your caliper may be rocking a bit and binding up due to the angle.

Forget your MC. Leave it alone. Figure out the problem with your calipers.

Well, if the calipers are rocking what's to be done? These are aftermarket calipers that came with new bolts and sliders. They seem to slide pretty well with just my hands.

I'll have to have someone pump the brake pedal while I'm looking at them.

A larger bore master will displace more fluid BUT Require more pedal effort to generate the same braking pressure /effect. We usually try to stay around 1.00" max on bore dia. Especially with a manual brake application.