Ok, educate me...

On Rockauto they list 7/8", 15/16", and 1" bores for a 1990 w250. Wouldn't a 1" bore make the rear brakes stronger since it would translate into more pressure on the brake shoe?? I almost remember this being an upgrade in the early 90s Ram 1500, upgrading to a GM wheel cylinder with a larger diameter piston?

I'm going to replace the driver's wheel cylinder since I found the passenger so bad off. They are less than $10 from Rockauto for any of the listed bore diameters.

Pros/cons?



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I know a lot of people put the 1 1/16" from the Chevy 3/4 tons. I personally got the 1" Raybestos cylinders from RockAuto and they feel very good. Don't have anything to compare it to, but they engage the RW abs on hard braking.

I find these trucks lock the rear (no weight) very easily. I don't tow often, so I went with the 1" cylinders for a small upgrade.

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2nd gen's upgrade to a chevy dually wheel cylinder. By looking at the pics on RA, most of them have the brake line come into the cylinder at an angle, except for the 15/16.

The Chevy 1 ton cylinders can be used in a first gen just bend the brake line a bit.

Thanks for the responses, I'll pick a set of those 1" bore deals up next week...



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Those sound like the wheel cylinders for 11inch brakes. You have 12 inch bendix. Look at Ford 250 and 350 trucks prior to 97, same 12 inch brakes. Iirc w250 had 1 inch cylinders and 350 have 1.125 inch.

No need to modify anything like with the GM cylinders.

Most upgrade to 1 316 cylinders, look for listing of 94 e250 i think.

First gen diesel d/w250 12” drums with 2.5” wide shoes used 7/8 cylinders d/w350 used 1” cylinders and the same 12” drums with 3” shoes. The one ton stuff bolts directly into a 250 using the same drum. The Chevy cylinder is an even larger 1 1/8”

See that really threw everyone at Advance Auto, their books show a 12x2 and a 12x3 option, no 12x2-1/2. I chose 12x3 since I was confident it was 12x2, so I may just go buy another one of those for the other side and call it a day.

I still need to replace hoses...

What is the bleeding procedure for that ABS? Is it in the FSM?


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The first gen diesel truck is listed wrong in most parts houses computers for anything suspension wise, heck even oreillys lists a spark plug for the diesel. But they also list a radiator cap for a Corvair so you really can’t trust them.

Try looking up a water pump...they hand you a big block Chevy pump...

I assumed 12x2 was a gasser, the reason I went with 12x3.

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I put those 1-1/8" cyls on my dana 60 w/3" shoes. no complaints

I've had really good luck with Rock Auto. Used them a lot for my rebuild. Water pump, radiator cap, suspension, brakes, fan clutch, axle seals, steering links, and more have all been right.

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