One thing you might do is take the cylinders to an automotive machine shop and have the bores cleaned up on a Sunnen hone. This would give you true round bores in the cylinders. Unless the original units are damaged or too pitted to hone out I'd rather rebuild them then deal with what is sold for new ones now.
Came back to see what happened but concerned that you addressed the issue incorrectly. You should not have to shave off the shoe body to relocate the piston. This gets back to my initial position that the piston cups lacked lubrication or prior to ***embly some one was playing squeeze the wheel cylinder pistons. The piston puck seal cups float on a surface of lubricant(brake fluid), if they are dry they don't react correctly and stick. There is a small light tension spring that is inserted in the wheel cylinder to keep pressure on these cups. Now if you are finger pushing on the pistons before ***embly it is possible to retract the cup so far that it will fall beyond the bore sleeve and the spring does not have enough pressure to re align it and a leak will develop, especially in stepped cylinder application. This can also be accidentally done during ***embly if you have not aligned the shoe push rod with the slot in the puck or you have rolled the upper brake adjustment cam back so far that it lets the piston puck retract further than necessary when the return spring is installed. Since there is a good amount of pressure applied to get the brake return spring clipped it is possible to retract an empty wheel cylinder further than necessary and pop the piston cup into the fluid cavity of the wheel cylinder. This is what I think has happened in your case. Shaving 3/16" off the shoe has moved the piston further out in the wheel cylinder bore and it is now important to insure that the brake shoe return cam stop is adjusted correctly to prevent the shoes from retracting so far the brake balance from one side to the other is not effected because you have shoes with unequal bosses... I've given you a cross section picture to explain the scenario. You will probably be alright but...
I am fighting this same problem. Anyone know the part numbers for the plungers? Or recommend a rebuild kit? I ordered new wheel cylinders form a shop in California, and they leak like the ones from Oreillys. Thanks
Early Ford brakes don't have separate plungers. If you have the actual same problem as the OP, do as I said and adjust your shoes out to proper position before putting any fluid in the system. The poor new cylinders seem to have their intake port drilled off center, and the lip of one of the inner cups will overlap the hole and leak fluid past. By doing the adjustment first, you hopefully get the cups outside of this hole.
Probably already mentioned somewhere in this resurrected thread; but another option is to mill the slot in the forward piston about 1/8" or so deeper ( a cut off wheel works if you don't have a mill).
Install residual check valves in the line to the brakes. The more pressure in the line, the tighter the seal in the bore of the wheel cylinder. A 10# check will keep your cups pressed against the bore.
A 14 year old thread resurrected, and with good info that is "timeless". Are there two different sized bores within these cylinders? The photo in post #1 seems to indicate so.
Learn something new everyday ... https://www.jalopyjournal.com/forum...d-bore-wheel-cylinders-make-no-sense.1219844/ https://www.speedwaymotors.com/the-toolbox/replacing-a-front-wheel-cylinder-on-an-early-ford/29865 As mentioned, there needs to be a RESIDUAL PRESSURE VALVE (IMO) to maintain some pressure (10#) within the wheel cylinder to prevent the cups from fluttering/leaking on brake release. If available, you might also consider WHEEL CYL KITS w/ cup expanders also - Now I am not familiar with early braking but on later models, it seems all service parts are CHINESIUM and basically junk. IMO, it is best to retain old castings and have sleeved if necessary and just hope the rebuild kits are quality. EDIT - Came across this @ SPEEDWAY under their wheel cylinder listings - Now I wonder why they are not ***embled with brake ***embly lube?
What brand wheel cylinders are you using? I use raybestos brand exclusively for "new" wheel cylinders and never had an issue.
Wouldn't surprise me if all the new early Ford wheel cylinders didn't come from the same factory and were distributed at the wholesale level to the various vendors. Years back when we first had this problem; we had new wheel cylinders from Raybestos, NAPA, BrakeBest, and some unbranded ones from an early Ford parts dealer (couldn't find any new US cylinders). They all had the same miss-drilled hole that was too far out in the bore. Fooled around trying **** S's method of ***y; but finally milled the slot in the piston which addressed the cup overlapping the incorrect hole.
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