Ok so I've been experiencing some strange brake action when driving and I believed it to be a front rotor issue, but I've read some posts here and it makes me question the ABS system.

While braking I notice a pulsing that I believed to be coming from the front, but the past few days I've realized it's coming from the rear and the rear brakes will actually lock up at very low speed (5>). I also noticed that the ABS light bulb is missing and I'm going to assume that is because it was always on, but from what I can see the controller is still wired up.

This is a truck (work truck), which I don't tow or haul with, and I'm not too worried about ABS working as intended, but I do not want the shimmy I get while braking (feels as if the brakes are grabbing and releasing quickly causing the whole truck to shake).

My question... Will disconnecting the brake controller, electronically, stop the ABS system from operating (allowing normal braking) or does the dump valve need to be pulled out of the equation as well. I will fix this at some point, but right now I have other items that are higher on my list of priorities. Please advise.

 

Yes it does, but the problem may be the valve itself, affecting the system independent of the controller. I wouldn't think that the ABS is causing the shaking. Is it like a death wobble? Maybe wheel balance, bad front U-joints, calipers or maybe even king pins. I had issues with mine for months. Here is what I did...Mark

 

Could be warped rotors. My dad has managed to warp almost every rotor he coms in contact with. He thinks drum brakes are better.

 

Front brakes were warped but they aren't the culprit here (brand new as of yesterday) and the king pins appear to be tight (but they'll be replaced soon as well). With that said the shimmy is still there and it feels like a back to front shimmy if that makes sense. If I could compare it to anything I'd say it's like brake dive (on and off x1000) or like riding down a smooth yet imperfect road (road joints) without shocks on the front

 

I ran my truck with the abs controller unplugged for years (maybe four or five). I then suddenly had trouble with the rear anti-lock valve randomly dumping pressure to the rear brakes, which you could feel in the pedal, but was more like a single event per brake application. That was maybe seven years ago.

I would by-pass the abs valve pretty early on as part of the trouble-shooting process, 'cause the valve can cause trouble, but I don't really see it causing this problem . . . And if your controller isn't unplugged, just do that first.

 

I deleted mine. I Needed predictability, and pedal. Got both.

I went to NAPA and browsed their brass section. picked out:

Brass Inverted Flare 90° Male Elbow 3/16 Tube X 1/8" Npt.
Brass Inverted Flare 90° Male Elbow 5/16 Tube X 1/8" Npt.
Brass 1/8" Npt coupling

Screw them together. Take out the RWAL valve. Screw the brake lines into the home made delete adapter. Bleed the rear brakes. (I'd do the driver's side first judging from the line layout.)

Tape up the connector or block it off with a dummy, either from the valve, or from the tail light wiring of almost any dodge pickup of that era.

Disconnect the controller behind the glove box, and yer done.

 

I did the same as above



Try not to strip anything!

 

I disconnected the ABS controller and noticed a difference. The shimmy is almost completely gone. I will bypass the dump valve this weekend to see if that takes care of the rest. Thanks guys and by all means keep the good info coming.

 

I think this should be in the sticky...As "RWAL Delete assembly"....or something like it.

 

Thank you for the compliment.

BTW, if you have good pedal, you probably don't have to delete the valve itself. About the only fault it can have without the electrics is a leaky accumulator valve, which will manifest as low pedal (bad leak) or pedal creeping down (little leak).

 

The RWAL valve is not likely to cause a shimmy when disconnected electrically. I suspect you might have either a rotor problem in the front, or front suspension problems that shake under braking forces. Maybe as simple as bad bushings on the brake control rods.

 

It can still be your problem. Did you have the new rotors turned???

I haven't bought a new set of rotors in years that didn't need a light turn to true them up.

 

^^^ Like he said.

 

Have you checked out the rear drums for warpage . . . this sounds a lot like warped drums to me.