Hi, sory my question was'nt on the first post lol, somthing glitched I guess. After dealing with several leaky re-man master cylinders (especially the caps) I ordered a brand new one, the one in the pic that I'm holding is the new one. Will one like this work? It looks like it might fit, but looks completly different externaly. I thought I'd ask you all before I take off the re-man. With my luck it wont fit work and I'll have wasted my time for nuthin. What do ya'll think, anybody else's master cylinder look like my new one?

 

The one in your hand is a standard gasser unit. The bore should be 7/8" to 1" or so. Not sure why the diesel all run the big cast units, my guess is they have a big 1 1/8" to 1 1/4" piston bore, therefore allowing more braking pressure.

The aluminum one will more then likely bolt up and function fine, BUT, I'd guess in an emergency situation there might not be enough jam in the MC to properly lock up the front calipers.

 

Darn it, I was kinda hopeing it would work. I like the idia of the plastic reservior because it looks like it wouldnt leak as bad. The caps keep leaking on the cast iron ones i'v been getting. Look at my I/C pipe in the pic, the brake fluid is peelin the paint on it, brake booster and everything below the MC . That aint the worst part, I'v ran a few red lights cause the fluid runs out. Spooky lol.

 

Heres the peeled paint on the I/C tube from the leaky MC lid. In the pic of the master cylinders, you can see how wet the (3 month old) re-man MC is, the lid on it is only 3 days old and is leaking already. Rediculous aint it?

 

I measured the bore on the new one and its 1 1/8". It should should be suitable for my 1-ton then correct?

 

That looks like a PowerStroke MC!

 

I truly do not know. There must have been a reason they went with the big cast unit for the diesel trucks. I'd pull the cast unit and check the bore on that one, and if they are close then you make the choice if you want to run it or not.

 

I looked up master cylinders for 1992 dodge w350 on ebay and some looked like this one, also my old master cylinder (the cast iron one) is exactly like a '80s chevy 1-ton MC.

 

I'm gonna do some reading on mastercylinders before I install it i guess. Thanks for the reply

 

hey-Hey!!!,
The smaller master cylinder bore will deliver more brake pad pressure per pedal effort than the larger one will. Force at pedal x lever ratio to MC x [brake caliper piston area/MC piston area ] = clamping force...and that does leave out the vacuum booster.

That analysis does leave out stuff like total volume requirements; a small MC could potentially run out of volume.
cheers,
Douglas

 

The new MC I bought has a 1 1/8" bore, what size MC bore do these trucks have?

 

I just installed a re-man master cylinder, and the sealing edge was all dinged up and I figured it might leak, so before i installed it, I flattened it out on a belt sander. Mine doesn't seem to be leaking, maybe that would help?

 

Belt sander on a master cylinder that's really scarry, I wonder how long before it fails. Why didn't you just bring it back and get another one?

 

i took a file to mine to make it nice and smooth.
no leaks
be sure to keep filings out of the master cylinder though

Steve