New to this forum - hope you guys can help - long

[subman]

Just a quick over-view:
5 or 6 years ago son bought a 91 Explorer - V-6, 4 spd, 2WD.
About a year ago (although I did not know it) the rear wheels would lock up and stay locked.
2 or 3 months ago, he gave the car to his sister and B-I-L. Since I seem to be the wrench in the family, he brought it to me and we have replaced the valve cover gaskets, front rotors and pads, rear shoes, tune up with wires, oil change, general maintanince stuff.
About 3 weeks ago, my son-in-law told me the brakes were sticking when he applied them hard (leaning towards lockup) and he would have bi##h of a time getting them to release.
Today, checked the calipers (OK) and pads. Found the pads riveted backs on both sides were crumpled, so we replaced them. Still have no idea how that happens. Since the truck has about 100K on the clock, I replaced the master cylinder and purged all the fluid (put in SynPower).
Still sticks. So now I start looking an the rears and discover the shoes were backwards. Re-mounted shoes. Still sticks.
I live on a slight incline so he got them to stick in front of the house. I cracked the bleed valve and the brakes released.
So now I'm thinking proportioning valve. Get out the Haynes and read that there is rear only ABS (RABS) and that is controlled by a module under the dash and a electro-hydro valve and has a speed sensor in the differential.
I have done a search here and found this is an all to common problem for the 91-92's
So, now to the questions:
1-How likely is cleaning the speed sensor going to resolve the problem?
2-How likely is replacing the module going to resolve the problem?
3-If I have to replace the valve, how expensive is it (new and/or used)?
4-Will the valve throw codes to identify the problem exactly so I don't just throw money at it?
I appreciate any and all imput regarding this nightmare (I hate brakes almost as much as electrical problems) :fire:
Thanks
Subman

 

[Howard]

Ok well I'm not totally familiar with the 91's but here goes.

1. It might and its a 5 min job and its free so worth doing anyway.
2. It could be the valve or the RABS module behind the dash. Could just be a bad connection as they are electric.
3. Pass
4. I don't think the valve would throw codes but the module might.

Now the best course of action.

1. Clean the rear wheel sensor (free)
2. Check all electrical connections both at the valve and the module. (free)
3. Bypass the valve with some pipe and ditch the abs. (definite fix and cheap)
4. replace the valve and module (if electrical connections are ok will fix but most expensive)

Hope this helps and that others chip in.....

And welcome to the site.

 

[AlaskanJack]

well I just completely ditched my RABS completely when I had problems. Mine was just the opposite. I had no rear brakes and it turned out that the rubber hose going down to the rear diff was expanding inside and bleeding off my brake pressure.

On my 91 I have done the following chasing brake problems.

New master cylinder, new wheel cylinders, removed proportioning valve, disconnected RABS at the rear diff, new hard lines from master cylinder to rear, new hardlines from diff to wheel cylinders and completely rebuilt rear shoes.

Now with all that said you might want to check and make sure that the rear drums aren't warped. I have had a rear drum warped and not even known it. I just decided to check the runout on the drum and discoverd the warping.

I have also had rear shoes stick due to the wheel cylinders being bad. They wouldn't allow the brake pressure to release and flow fluid out.

Now here's a thought. If the RABS module is causing problems you should get an indicator light on the dash. I also hate chasing brake problems and obviously you can see that I replaced just about everything.

 

[subman]

Howard and AlaskanJack - thanks for the replys - bypassing the RABS sound good to , but how?
If you have a tech tip on it, I'd really apperciate it.
Will check the speed sensor and all the electrical connections Tuesday (bowl on Mondays, he'll have to suffer)
Thanks again
Subman