1972RedNeck

When I got my truck, the rear ABS valve had been bypassed and the PO said something about a bad module behind the glove box. The brakes are good, but the back locks up very easy on gravel. I was figuring that since I have 3" wide rear brakes with 1 1/8" bore wheel cylinders, if I run 1" bore wheel cylinders, It will take more pressure to lock the rear up, making the braking more even.

How effective would this be?

torquefan

I think it would make somewhat of a difference; if it was mine, I would give it a try before trying to get the RWAL functional at all. My 2nd gen doesn't have functional ABS any more, and I am happy with the way it stops with the OEM 24mm wheel cylinders.

j_martin

The problem is that the difference between no load and full load on that truck is 3 or 4 to 1 on the back axle. If the wheels slide a bit empty, they'll stop well with a load. If they don't slide empty, they won't have much stopping power with a load.

The other part of the problem is that the early Dodge RWAL system draws through a straw. At least without it you can pretty well guess when it's going to try to swap ends on you, instead of experiencing random acts of braking.

It's a truck. Slow down and let it be a truck.

1972RedNeck

The main problem with it is the ice this time of year. I have had over a ton of hay on the back (~ 3500 Lbs.) and the rear still lock up very easy (better than the front locking up though). I will have to give the wheel cylinders a try.

dieselJon

1" cylinders fill up faster though.

I saw a truck with an adjustable rear proportioning valve under the hood. I can't remember where I saw it though...

NE frmhnd

That's the way I'd go. If you really wanted to you could plumb it into the cab. I guess on sprintcars they'll plumb the RF brake line through the cockpit and put a shutoff valve in it.

93flatbed

Is it possible that your front brakes aren't working to their full potential and the rears are just working harder?

Reason I ask is, I've got the 1.25" rear cylinders and 3" shoes and I can stop just fine. Now my abs is all still in tact but I've had maybe 1 ABS event ever in my truck and that was doing stupid stuff on a gravel road.

TheMrAMack

Couldn't you just back the brakes off a little? Might be adjusted too tight.

1972RedNeck

The brakes are new on all four corners. Drum brakes take less pressure and less oil to get the same stopping power as disc brakes.

Do these Cummins trucks have a proportioning valve on them or do they just rely on the ABS (anything but smart)?

Jim5870

That could be me...

Jim5870

I did my front brakes on my D250 recently, I used D350 pads.
Inboard pads are the same but the outboard pads are 3/8 wider.
D250 pad (bottom) is 1.4" D350 pad (top) is 1.75" wide
More pad area = more braking force with the same pressure.
since you have big shoes on the back, might as well put the big pads in front also.

dieselJon

That is the truck.

NE frmhnd

I might have to go back to NAPA.

1972RedNeck

Do the 4X4's have the same difference?