The rear brakes in my '97 F-250HD aren't working (front work fine). I haven't started diagnosing it yet, but I'm pretty sure that when I do I'll end up deleting the RABS. I actually like the system when it works well, and it's worked well for 22 years now. But unless I find a pretty obvious non-RABS cause, I'm thinking I'll simplify the truck.

I know I can bypass the control valve which will get it out of the system. But will that cause it to throw codes, confuse the E4OD or light up the dash? And if so, is there a clean way to remove the module and avoid the electronis issues?

Also will I need to do anything about brake proportioning? I'd guess that the rear brakes would be too strong with an empty bed if all I do is get rid of the RABS. But that's just a guess.

 

What is bad? The controller or the RABS valve itself?

If the valve itself is bad, and you don't want to remove it, but simply keep the brake lines intact, you can remove the 1 1/8th nut, then pull the spring from inside, reinstall the nut, and no more RABS.

 

If i has been working fine I would look at the booster or master cylinder possibly being bad.
What are the symptoms other than "rear brakes don't work" ? any fluid loss? lights coming on?

the RABS on my 93 work just fine but i was losing my mind until I found out it was the proportioning valve on my master cylinder.

I went through the whole system and basically rebuilt it and ran new fluid through the whole system to flush out all the cruddy orange looking stuff that was in there.

 

If need be, you should be able to disconnect the RABS module behind the glove box with no other effects than disabling the RABS. You could even try that as a test to see if anything improves.

Probably just replace the RABS valve with a regular disc/drum proportioning valve from an older truck application.

 

No other symptoms. No ABS light, no brake light, no significant fluid loss (I can't be sure there's none, it's too sloppy here now to look for leaks, but the master cylinder reservoir is full). But there is no braking from the rear brakes now. It came on pretty suddenly.

And I'm not saying that I know the problem is with the RABS. I'm just thinking that I kind of like the idea of a simpler system. Once things warm up and dry out a little I'll crawl under and figure out where my problem is. As I said in my first post, if I find a problem that's not related to the RABS I'll fix it and keep the RABS. But if not, I'm not going to replace anything in the RABS system. I'm also not going to hack it up. If I delete it I want to do it cleanly. I'll completely get rid of the valve (replacing it with a proportioning valve if necessary). So I'm wondering what I'll need to do to cleanly deal with the warning light. And if anyone has specific info on a good proportioning valve I'd appreciate that as well.

 

Don't let fear, ignorance and superstition get the best of you. It's a simple system. There are a lot of threads about deleting it if you can't handle it, can't deal with it.

 

What part of what I said gives you any idea that fear, ignorance or superstition have anything to do with my thoughts here? Or that I'm not able to handle it or deal with it? Insulting people like that is really unhelpful.

And I did look for other threads abut deleting it. All I found was people saying that it didn't work, they deleted it and couldn't be happier (while others told them they were fools for getting rid of such a great system). But no details on whether a new proportioning valve was needed or how do deal with the light on the dash (oh, I take that last part back, some recommended putting a piece of tape over the light). So I'm asking about the details (and if there are other helpful threads that I didn't find, a link to one or two of them would also be very helpful).

 

 

Thanks! Any issues with the electronics to work out? (Or does the '87 not have the same system as the gen 9 trucks?)

 

 

Just to close this out, my RABS got a stay of execution. As I said originally, if I found a clearly non-RABS cause of the lack of rear brakes I wouldn't mess with the RABS. Turns out I had leaking wheel bearing seals on both sides. Hydraulically and mechanically my rear brakes were working fine, but with the shoes being soaked in gear lube there was just no friction.

Last fall I had some work done on the rear end. They replaced the pinion bearing and seal and installed a TrueTrac. I don't recall for sure, but I think they also did the wheel bearings and seals at the same time (they said the debris from the worn pinion bearings had damaged them). So I'm suspecting that might have led to the wheel bearing seal issue now. I remember vaguely from when I did the rear brakes a few years ago that there were inexpensive wheel bearing seals and there were good ones. I used good ones and had no trouble for several years, now these only lasted a few months at best. I ended up having a (different) shop do the brake job and I don't know what they used for seals, so I guess we'll see how it holds up.

(And for what it's worth, I do essentially all my own work on my Bronco, but this truck is my daily driver, I work full-time and have family obligations. I do as much of the work on it as I can, but I end up taking it into a shop if something needs to be done right now, especially if it's in the winter when I won't drive the Bronco while I'm working on the truck. That was the case both with the pinion bearing change last fall and the brake job now. I'd have preferred to tackle either of those jobs myself, but life sometimes gets in the way.)

 

glad you finally found out what was giving you all the headaches Bob.

 

X2....sometimes the path to final resolution is quite a journey.

 

...and sometimes it's frustrating when you start at the wrong end of the problem.
I've done that more than once- "I'm sure it's the driveshaft" when really it's a bent wheel. Or something like that...

Far cheaper, though, when you do it, as opposed to your shop!

t
sometimes takes his commuters to someone else, too- thanks, Matt, for doing all the cruddy jobs!