Does anyone have a good way to tell these master cylinders apart? I did some looking but didn’t find clear answer. I think they have the same shape and mounting pattern. Im also pretty sure the components are different inside! Any help is appreciated!

 

Has to be different piston sizes. Lmc lists two different brake cylinders too. F100 and F250. I would assume brake would have larger piston and F250 larger than F100. I couldn't find rebuild kits but maybe specs out there somewhere. If anyone sells rebuilts maybe they would know.

 

The difference between the two is the residual pressure valve on a brake cylinder, clutch doesn't have one.

 

A residual pressure valve... so they all have to be disassembled to figure it out? Or is there a bench test that can be performed? Visual inspection isn’t obvious for me!

 

It would be best to take them apart.