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TR2/3/3A New Wheel Cylinder too large

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tr3guy

tr3guy

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I stripped the threads on one of the rear wheel cylinders on TR3A s/n 68000. I bought 2 new cylinders to replace both old ones. The new cylinders (catalog # 580-025, Classic Gold) are .025" larger between the flat piston end and the stationary end than on the old wheel cylinder (old 1.565", new 1.590"). The new, larger cylinders cause the brake shoes to be in full contact with the brake drum, even with the adjuster fully retracted. I am using the same brake shoes and brake drum that were being used with the old cylinders. The shoes are slightly worn, and the drums have been turned. With the old cylinders, the wheels turned freely, even without the adjuster being fully retracted. With the new cylinder, it takes force to turn the wheels. Has anyone had this problem? This is a total brake rebuild, so all lines are dry, and the parking brake disconnected. I would be interested in buying a rebuildable used Girling cylendar, casting #304170, 3/4" piston with flat piston end to use with my one good original cylinder.
 
I just put rear cylinders from Moss last week. No issues although I didn't measure them. Are you sure they are not stuck in the backing plate? They should slide freely. I don't think the .025 would make any difference.
Tom
 
Just a thought, have you tried measuring/swapping pistons?

I've probably got some old ones, but chances are that the bore is corroded. And resleeving will probably cost more than new ones.
 
Shawn, the invoice # is 5-454322. I have a conversation going with Bill, but we haven't resolved the issue. Thanks for checking.
 
Thanks Randall. That's a good idea. The two pistons are the same length so I swapped the new piston into the old cylinder. The new piston's seal rides lower on the piston than seal on the old piston, and the bottom of the bore in the old cylinder is machined a little different than the new cylinder (the old has a little ledge). So the seal on the new piston bottoms out on the little ledge on the old cylinder, leaving the piston sticking out too far. The supplier is working on the problem, but if we can't get it resolved, we may have to strike a deal if you have one of the old cylinders. Thanks, again.
 
Tom, the cylinder slides freely on the backing plate, and the locking plates have been greased. I cleaned the adjusters, and that did make a difference. Before cleaning, the drum wouldn't go on, after cleaning it went on with a tight fit. So far, the .025 difference is the only difference between the two cylinders that I can find. Thanks for your input.

Jims
 
tr3guy said:
Tom, the cylinder slides freely on the backing plate, and the locking plates have been greased. I cleaned the adjusters, and that did make a difference. Before cleaning, the drum wouldn't go on, after cleaning it went on with a tight fit. So far, the .025 difference is the only difference between the two cylinders that I can find. Thanks for your input.

Jims
Click to expand...
Good that you cleaned the adjusters. The wedge on one of mine was frozen. What I don't understand is he .025. Mine took quite a few turns to get the shoes to contact the drums and that was with new shoes. The adjusters move each shoes at least .25 so it would seem that such a small size difference alone is not the issue.
Tom
 
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