Wheel cylinder size ?

[mikie 1954]

I have a 64 gmc 3/4 ton pu. My ? is that it has 1 1/8'' bore size cylinders on the back now, but the auto parts store only shows 1'' bore size and they say it will work fine. Is this right or will it not work right? I tried NAPA & AUTOZONE both had the same sizes. THANKS MIKE

[padresag]

smaller bore will worka s long as the rest of it is the same size and mounting. this is not what your truck was engineered for though. it will change the frt to back braking ratio. the 1 ton uses 1 1/8 cups on the frt . just get kits and redo them yourself. it isn't brain surgery
ron
they may have been looking it up under chevrolet. GMC did use a different rear axle which could result in different wheel cyls
I do have 2 new 1 1/8 kits which I just bought for the frts on my 1 ton which I won't be using as I am putting newer axles under it

[mikie 1954]

THANKS padresag. I got some kits here locally. No one had any for 1 1/8'' for the rear but they had it for the front so I compared them, same parts. Thanks for the help. MIKE.

[padresag]

that is all you did at one time. you just had boxes of whatever sizes cup that you needed.. you honed out the cyl and installed new one. if the cyls were to badly pitted then you bought a new one at an outrageous price, then.
it is a bit of a ripoff now. for new w/cyl for my 65 1t they wanted 75.00 net. I orderd 2 rear kit and 2 frt. rears-1 1/4 , $14.00ea frt 1 1/8, $6.00 ea. quite a price diff for 1/8" in size, but I guess that they have you by the short ones
ron