I've had this vibration when using the brakes and have been feeling my RABS kick in towards the end of a stop. I went to Ford and asked for a new speed sensor and they asked why. I told them that I've heard on here before that if I'm feelin the RABS kick in that a new sensor will fix it right up. They fought me for ten minutes over this since my ABS and Parking brake lights werent lit!! I'm pretty sure that the vibration is from needing new drums anyhow, but that doesnt explain my RABS kicking in. Any thoughts?

 

Also about 10-15k ago I replaced my brake pads. Im pretty sure that I bent the drums since there was a huge lip that had developed and was holding them on. But besides that I'm not sure that the drums would cause my RABS to kick on.

I noticed that CADRIVER posted pretty much the same thing at about the same time so to answer what already has been asked there. Yes my wheels are properly torqued, the problem seems to have become more and more prominent with time, and I followed what little information I could about the breaking-in.

 

I'm not sure what you mean by the RABS "kicking in". RABS works different than 4 wheel ABS. It will only release brake pressure to the rear wheels when the sensor on the differential detects zero rotation, or rather, a skid. I don't think I've ever felt the RABS valve release pressure on mine, but it must have actuated at some point during my driving.

My 92 Explorer (identical brakes with my 94 Ranger) had a problem with contaminated fluid and a rusted/frozen RABS valve. Have you flushed the brake fluid?

 

vibration is a genereic, do they pulsate or is it a grabbing or what? It actually sounds like you may need a complete brake job. rotors and drums turned since you said the rears had a lip on them. I have had the rears grab while braking which was unusual and that will get your attention.

But again I think your whole system may be due a rebuild. bad rotors will cause a vibration, do you hear any metal to metal sounds?

 

Brake pads and shoes are good all the way around. I forgot to specify that I put all new brakes on front AND rear and I did have the lip turned off of the drums, but only turned the drums since the rotors looked perfect.

I just got done giving both my front wheel bearing nuts an 1/8 of a turn since I had some play in it. Doing this seemed to maybe smooth my ride up a little bit but I havent taken a long enough trip to really figure it out.

When I say that I feel my RABS kicking in, I mean that I can feel the puslation that's associated with ABS even though its not as prominent as a full 4 wheel ABS system. I've got new brake drums on the way, premium grade raybestos, that will probably(hopefully) solve part of the problem. I have on occasion heard my rear brakes squeek when just barely rolling at a stop light, but when I hit the brakes and try to duplicate the sound by rolling again it doesnt do it again it. I'm not to sure what to make out of that sound.

 

not sure if you will really feel the rabs as all it does is unbrake the rears if they are slipping while the brakes are applied. Its always good to turn the rotors and drums when work is done. hard spots can occur in both. The front bearings are a pain I replaced mine than ended up replacing the rotors as the problem remained glad parts are not reall $$.

 

Benghetto i know what you are talking about, now what is the solution. My dads 2000 ranger is doing the same thing. Imagine being on an icy road, and hitting your brakes. The brake pedal pulses up and down as its realeasing the pressure in the rear brakes. My dads does this same thing as its coming to a stop.

Are you sure your brakes are not actually locking up? When you had the drums off were your wheel cylinders leaking at all? was there any oil or moisture inside your drums at all? Be sure to inspect the wheel bearing seals and everything to make sure they are not leaking. I doubt any of this is causing your problem, but it never hurts to be sure.

 

Also I forgot to mention that in the middle of my debate with the guys at the Ford Parts desk that they suggested unplugging the RABS unit and see how it feels. I did so and it really did seem to smooth up the brakes even though the rears still seemed to be grabbing more then they ought to be.

One reason I know my rear brakes are grabbing more then they should: Previously before changing all the brakes I could power brake my truck all day long with ease. (I know I know, its not condoned behavior!) Since replacing them and noticing the problem my truck practically wont power brake anymore. Soon as I try get on the brakes to hold me there it boggs my motor down.

 

Did you adjust your rear drums at all after you did the brake job?

 

Yes I adjusted them just to the point that the drums slid on and off and turned easy. They'll adjust themselves after that point, especially since I'm reversing every day out of the garage to leave home. I even went as far as adjusting them way off and within a week they were back to the same point.

 

Well that's good to hear. The problem with those adusters in my experience has been reliability. Especially side to side. One side would adust up and the other side wouldn't causing one side lock up in slippery conditions. If the adjuster arm was bent a little bit or the edge was worn, it would slip off the star wheel without turning it. On my old Volare, it would take me a lot of fiddling to get them working. As a result, I got pretty adept at manually adjusting them.
Sounds like you did everything right. If the RABS are comming on while on dry pavement without one or both rear wheels locking up, then it should be the sensor. If the rears feel like their braking harder than they should, either your fronts have air, master cylinder seal(front brake portion) is gone, or your just used to driving with weak back brakes(least likely ). I've had freinds stand by and watch while I drove up and hammered on the brakes on a dirt road to see if the backs would lock up before the fronts. They should'nt. That's why the industry started with RABS.
Problem with electronics is once you open the box, you can't return them. I don't think the sensor is that much, so if your a bit of a gambin' man......

Oh, if you keep brake torquin' 'er(power braking), you'll probably be posting a transmission broblems thread sooner than later. You can play, but you will pay.

Good luck Ben

Fred

 

Yeah my rear end wants to lock up first on a gravel road. I've experienced that. The sensor was like $26 from Ford and $19 from Advanced Auto. When I did my rear brakes I did find that the bleeder was a complete waste so I couldnt bleed the rears. But even at that seems like I dont have a problem there since they definately work. My fluid level is fine and I checked the front brakes while I was messing with the front bearings. All A-OK. I do have new drums coming some time this week.

As far as the playing and paying I already paid 3 years ago when I lost a couple pins in my shift linkage when I first learned how to power shift. Never again in this truck! lol But besides that I havent had much of a problem besides the rubber plugs on the top. My brake torquin's are few and far between, but when my best friend drives a corvette and we're side by side at a stoplight its quite a show when you're covering 6 lanes with smoke!!