The Stovebolt Site Forums The Shop Area General Truck Talk Rebuilt vs new master cylinders

I am doing the brakes on my '47 1/2 ton and upgrading to a dual master cylinder. Drum, drum and stock. I have purchased the bracket for the m.c. and the vendor suggests a Mustang or Corvette m.c. Is there much difference between rebuilt or new master cylinders? (Apart from price, that is.)Am I going to be any safer buying the new m.c. that is $50 more?

Hy Rusty Shackleford, if the rebuild has been done correctly, there should be no differance in their performance or lifespan. Corvette master cylinders, and a lot of others were designed for disc brakes, at least on the front, these will require an additional residual pressure valve [10 psi] to be installed for the drum brakes to function correctly, hope that helps.

I recommend buying a new master cylinder. With the rebuilt, the key work is "if" it's done correctly. I installed a Corvette master cylinder in my '48 Chevy 1 ton, drum/drum brakes. I used '69-'76 Corvette power brake master cylinder even though I run non power brakes. The push rod hole is deep on these just like a manual master cylinder. I don't use residual valves in my truck and it stops great. When I had the residual valves in, the brake pedal was very hard and the brakes were lousy. I tried 3 different sets of residual valves all with the same poor result. 8,000 miles later it stops great with no residual valves. I have a '74-'76 Mustang II power brake set up in my '54 Chevy Panel with disc/ drum brakes. No residual valves. The truck has been on the road 18 yrs now, with no brake problems.

Not pertaining to these old trucks, Ive replaced several master cylinders in the past. Seems they lasted just about a year or so, long enough to get past the warranty before the seals failed. Ive rebuilt a few and havent had any issues, but Id go new before rebuilt due to past experiences.

Jeff

Another good choice for a donor m/c is the '70s-80s Chevy ½-ton. I bought a new one from Rock for not that much more than a re-built.

I'm with you, Cletis! That is exactly what I'll be using. They are still popular and plentiful, so that means cheaper at the Parts House.

best wishes,

Les

I'm a little late getting in on this one but my 2cents:

I would much prefer a rebuilt if done in my shop with quality rubber parts over a new Chinese version. My experience with imported rubber has not been positive. Even windshield wipers and window seals oxidize in less than a year and crack.

I've rebuilt a lot of wheel and master cylinders over the years and have yet to have a failure.

I ended up with a new Wagner for a '67 full size Chev. The mc is made offshore. Does anyone make an mc in USA?

It also depends on the condition of the master cylinder no matter who is doing it. A lot of rust and pitting in the cylinder will not be acceptable in any case. That is unless the cylinder is going to sleeved, which would then drive up the cost to be much more than buying new.

John