I had SS sleeves installed in my cylinders and they came back looking perfect but the rebuild kit pistons won’t go in. I had the parts checked with a CMM and the cylinder bore is 1.376” which seems about perfect but the piston OD is 1.388”.
Does anyone out there know what my problem is, or do you have a fresh part you can measure for comparison?
Is the cylinder bore too small or are the piston ODs too large?
Kit # ME338 from Jim Carter. Cylinders were sleeved by Mark Frappier.
Are you using new pistons, or the original ones that were in the cylinder? A .012" oversize piston isn't going to work at all. I'd suggest turning the pistons down to about a .002" clearance in the cylinder bore. Jerry
"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt! There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway Love your enemies and drive 'em nuts!
Maybe call Jim Carter and ask them about the expectations? It sounds like the pistons might have been made slightly oversized to account for expected wear in the bore when you are rebuilding it.
I would expect that to be called out in the listing if it was true, but maybe not? A measurement of 1.376" for a nominally 1-3/8" bore is what I would expect. Having 0.001" oversize on the bore and 0.001" undersized on the piston is pretty normal and gives you the clearance Jerry mentioned.
Making brake cylinder pistons isn't rocket science. A piece of aluminum round stock, a lathe, and some emery cloth for final sizing is all you really need. After I honed some very scarce wheel cylinders for a big GMC about .010" oversize to eliminate some pits, I just made pistons that fit the new bore size. NAPA open stock cylinder cups had plenty of expansion to fit the slightly bigger bore. New cylinders were available- - - -for $96.00 each- - - -two per hub! Jerry
"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt! There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway Love your enemies and drive 'em nuts!
Interestingly the pistons in my kits are steel and appear to have ben plated. I don't have the ability to make my own. I contacted Jim Carter but was only provided the option to return the kits. Evan was happy to resize the cylinders to fit, so I chose that option. Evan does beautiful work so if you want stainless sleeves in your cylinders you should check him out. Wheel cylinders were $45 each, master cylinder $75.
Well it turned out that only 1 of the 8 pistons was oversized, so the cylinders did not need resized. What a coincidence and ignorance that I only checked one piston and it was the only bad one! Another lesson learned.
