Brake Wheel Cylinder Help

NCSUDucker

NCSUDucker

Senior Member
Looking for the correct wheel cylinders for a 39 1 ton truck. Got a little confused looking at the green bible/searching online. I think I have found the front at CW Moss.

https://cwmoss.com/collections/brakes/products/wheel-cylinder-assembly-front-right-1939-48

https://cwmoss.com/collections/brakes/products/front-wheel-cylinder-assembly-1-x-1-3-8

But I'm struggling with finding the correct rear cylinders as most say "except 122" wheelbase"

I can find the rear for a 3/4 ton 122" wheelbase and a 1 ton but it says "except 122".

Truck is at the mechanics right now so a visual reference isn't possible for me, brakes were fading bad last time I drove it. Assuming it is the master cylinder which I already have but wanted to have the parts on hand in case its one or more of the wheel cylinders causing the problem.

Thanks in advance.
Brad
 
If the brakes were "sorta" functioning, maybe the cylinders can just be rebuilt.

Often, there is a wagner part # on the cylinder
 
My experience on the early 122" tonners was that The front brakes were based on the 1/2 ton parts and the rears on the 1 1/2 ton parts. Drums being the exception. Chuck at 'Chuck's Trucks' in Conneticut could confirm this. I can attest to seeing 'except 122"' over and over again in the green bible.
 
cas3 said:
If the brakes were "sorta" functioning, maybe the cylinders can just be rebuilt.

Often, there is a wagner part # on the cylinder
Click to expand...

I have a friend who's very deep into GM big trucks. He has a bunch of them. First thing he does is pull all the wheel cyls and the master and sends them to his favorite machine shop for stainless steel sleeves. Because of this he has never gotten one back that didn't fit his application, and they last a lifetime with no rust pits.
 
Bob C said:
The green book shows 92Y-2261 122" 1 ton truck rear 1939-47.
Click to expand...

GB SISSON said:
My experience on the early 122" tonners was that The front brakes were based on the 1/2 ton parts and the rears on the 1 1/2 ton parts. Drums being the exception. Chuck at 'Chuck's Trucks' in Conneticut could confirm this. I can attest to seeing 'except 122"' over and over again in the green bible.
Click to expand...

Thanks GB, that was my understanding as well.
 
cas3 said:
If the brakes were "sorta" functioning, maybe the cylinders can just be rebuilt.

Often, there is a wagner part # on the cylinder
Click to expand...

That's where I'm leaning, I'm honestly just hoping it's the master cylinder but would like to have the parts on hand just in case.
 
I think the CW Moss listing is wrong. I looked up 92Y-2261
on a couple of other sites and they show 1 3/8" Bore and Moss shows 1"x1 1/8".
 
Since it has to come off anyway, take it off, take apart, the cup size is usually on the rubber cups. If its been moving, its a good chance a hone job and new rubber cups will fix that part. Do the master cyl first, Then with the right rear line disconnected, pump the brake pedal slowly until you get clean fluid. No need to close the bleeders, it will work doing it slow. ( hose connected-dump in a clear jar).

Then, connect the rear lines, and do the same at the front right. Theory is aways start at the cyl furthest from the master.

After you get al the brown icky fluid out, bleed as normal.

Napa I believe still sells the cups only, not a cylinder kit, I always just clean up the pistons and spring.
 
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