bikinkawboy
Well-Known Member
Normally when I overhaul a braek caliper, it's on the vehicle and once the caliper is removed, I just pump the brakes to force the piston out. I lose a bunch of brake fluid, but usually it's the old cruddy stuff that needs to be replaced anyway. Well, I'm working on the calipers on my old truck that has set for about 16 years and the master cylinder doesn't work. And I have one of those plier like tools that supposedly allows you to remove the pistons...yeah sure. What I did was go to Ace Hardware and buy a brass 90 degree fitting that has 3/16" male pipe thread on one end and a female flare but fitting on the other end. I'm not real sure of the size, so don't quote me. The pipe thread end screws into a grease gun where the hose goes and a steel brake line screws into the other end. the steel brake line is then connected to the brake hose in normal fashion. With the bottom of the grease gun removed and it held upside down, I poured some old antifreeze into it and pumped away, which pushed the pistons out. I didn't use some old Dextron tranny fluid because motor oil at least will swell up rubber brake parts and didn't want to mess up anything I might want to reuse. I used it on a couple of calpiers off my parts truck and the pistons were stuck really tight due to rust and an unbelievable amount of sludge. I'd never seen anything so nasty.
I know oil swells rubber brake parts up because I was desperate for brake fluid for the leaking master cylinder on the D300 one time and I found some used stuff in an oil bottle. I knew it was cruddy, but I had plans of replacing the master cylinder anyway so what the heck. After I poured it in, I could see there was some motor oil mixed in with it, but it was too late by then. Guess what? The master cylinder stopped leaking and didn't leak again for about 1-1/2 years! I did replace it at that time, but apparently the motor oil swelled up the offending part. However, I'm certainly not suggesting anyone add motor oil to brake fluid to stop a leak. Had to throw that disclaimer in there.
I know oil swells rubber brake parts up because I was desperate for brake fluid for the leaking master cylinder on the D300 one time and I found some used stuff in an oil bottle. I knew it was cruddy, but I had plans of replacing the master cylinder anyway so what the heck. After I poured it in, I could see there was some motor oil mixed in with it, but it was too late by then. Guess what? The master cylinder stopped leaking and didn't leak again for about 1-1/2 years! I did replace it at that time, but apparently the motor oil swelled up the offending part. However, I'm certainly not suggesting anyone add motor oil to brake fluid to stop a leak. Had to throw that disclaimer in there.
