Posted by Matt Wilson on Tuesday, August 13, 2002 at 2:35PM :
Well, last night I installed a new master cylinder into my '49 flatfender. I then backed the truck out of the garage and onto the concrete pad behind my house, so I could bleed the brakes without soaking the garage floor.
Before I started bleeding the brakes, I filled up the master cylinder and I told my girlfriend (who was in the driver's seat) to pump the brake pedal repeatedly while I continuously filled the master cylinder. When I thought she had pumped up the brakes sufficiently, I told her to stop while I went around to each wheel to look for leaks, and guess what: 3 out of the 4 wheels had brake fluid coming from inside the drums....bummer. These are brand new wheel cylinders from VPW.
I pulled the truck back into the garage, and removed the right front tire and drum, since this one seemed to have the worst leak. I disassembled the wheel cylinder and found nothing obviously wrong, no rust inside the cylinders, no scratches, pitting or anything. The rubber cups look fine, although they did have some kind of grease in them, presumably a brake-friendly grease to keep the seals fresh and keep the cylinders from rusting.
After finding nothing obvious, I finally came up with a theory: When I had my brake shoes relined locally, the lining material was so thick that I could barely get the drums on, even with the shoes retracted all the way. I had to literally knock the drums on with a rubber mallet and also had to use a large c-clamp to push them on. This didn't concern me, since I knew the shoes would quickly wear in work fine. I figure what happened was that the shoes probably pushed the front cup of each wheel cylinder into the rear cylinder bore (which is a bigger bore than the front) and allowed the leakage. If that's the case, then I guess I'll have to remove some lining material from the shoes, using a file or sandpaper, etc, to allow the cups to position themselves properly within the wheel cylinders.
Does anyone have any other ideas about this? Has this problem ever happened to anyone else? I'm sure I'm not the only person to have their Power Wagon brake shoes relined.
Another question: a little bit of brake fluid got on the shoes and most of it seems to come off with a few strokes of a file, but if I find that some of the shoes are soaked, is there a way to remove the fluid from the shoe lining material? Water? Brake parts cleaner?
Sorry for the long post....
Thanks,
Matt
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