92' Sport 4x4 - RABS Module Bleeding Procedure - Need Assistance

[d.bright]

Hey Folks,

Got a new issue here.

Background: Brakes were vibrating harshly when braking from 60+ mph, when I checked the rotors I found that they would be under spec after turning, so I went to Advance Auto and bought:

2 - New "Wearever Gold" rotors (3 year warr.).
2 - Reman Loaded Calipers (came with Motorcraft pads).
2 - Front caliper brake lines for good measure.
2 - New front bearings just because I've never replaced them.

After replacing everything last night and taking it for a test drive, I noticed that my pedal seems to go about half-way down to the floor before doing any "real" braking, I can feel it grab a little during the first 50%, but the real braking seems to occur in the last 50% of travel.

After the test drive, I decided to bleed the system once more, by starting rear-right - rear-left - front-right - front-left. Some nasty black looking fluid came out of the rear-left this time and I bled it until it was clear. However, no air came out of any bleed adapters.

I took it for a spin again, and aside from the smoke coming from the front right (I forgot to use brake cleaner on the inside of the rotor to clean the coating off) that scared the crap out of me for a minute, it was still doing the same thing.

I've been reading up on here and it seems that my issue is most likely one of two things, it is either a bad master cylinder, which doesn't seem likely because it looks like the previous owner installed a Bendix unit before I purchased it, it has a date written on it (6/7/2006) in marker and looks pretty new. That leads me to the other thing, this Sport has Rear ABS, and it has the module that is mounted on the frame under the drivers seat. I've been reading, and people suggest bleeding or replacing this unit. Before plopping down money for a new unit, I would like to bleed this sucker and see if it helps. But I can't find any procedure on how to bleed this thing!

Could someone please post the procedure, step by step on how to bleed the RABS unit? Again, 92' Explorer Sport 4x4 if it makes any diff.

Thanks guys!

 

[92exp4x4]

You may want to check and make sure that the master cylinder is not bypassing internally. I had this problem before with a reman unit. If you have to pump the brakes and the pedal slowly goes to the floor, this may be an issue.

My factory service manuals have nothing in them about a special bleeding procedure for the RABS. It says to bleed the system starting with the longest run first. Make sure that your helper is pushing the pedal to its furthest extent and holding it there until you close the bleeder screw.

It is possible that your reman calipers were bored out when overhauled. This change in size may effect the transfer of power from the master cylider. Hydraulics work similarly to gear reduction. Your possibly bigger bored calipers need more fluid transfer to exert the same amount of force, therefor more pedal movement.

Good luck, I hope this helps

 

[d.bright]

Thanks for the info, to update, it's actually been doing this since before I replaced the front calipers/lines so its an ongoing issue. As for the rear ABS module, is it possible that it has an air bubble trapped in it or is possibly clogged? The reason I am asking is that I have driven another explorer side-by-side with mine and when I initially press the pedal I get a nice solid feel and I can tell that the rear drums are binding and then the front rotors, conversly when I press the pedal on mine for the first 50% of travel I feel a slight binding from the rear and then after the 50% I get binding from the front..

I' understand your comment about the bore size of the new calipers, however due to the fact that this issue was occuring previously, I think it is possible that that may have some adverse effect, but is not the cause of my issues. I'm thinking a good thing to do would be to bypass my RABS module and see how it feels then, I could eliminate the RABS module as the problem, any other insights?

Also, I need to find it, but I found another older thread on here that talked about bleeding the RABS module, I haven't crawled up under my truck yet, but I think there is a bleeder valve on the top of it, or near the top, am I wrong?

 

[Tony H]

Thanks for the info, to update, it's actually been doing this since before I replaced the front calipers/lines so its an ongoing issue. As for the rear ABS module, is it possible that it has an air bubble trapped in it or is possibly clogged? The reason I am asking is that I have driven another explorer side-by-side with mine and when I initially press the pedal I get a nice solid feel and I can tell that the rear drums are binding and then the front rotors, conversly when I press the pedal on mine for the first 50% of travel I feel a slight binding from the rear and then after the 50% I get binding from the front..

I' understand your comment about the bore size of the new calipers, however due to the fact that this issue was occuring previously, I think it is possible that that may have some adverse effect, but is not the cause of my issues. I'm thinking a good thing to do would be to bypass my RABS module and see how it feels then, I could eliminate the RABS module as the problem, any other insights?

Also, I need to find it, but I found another older thread on here that talked about bleeding the RABS module, I haven't crawled up under my truck yet, but I think there is a bleeder valve on the top of it, or near the top, am I wrong?

Sounds like you didn't adjust the rear Shoes enough. There should be slight friction on the drums.

 

[92exp4x4]

My bronco had a bleeder on the valve (same system design) but i do not know if there is one on the explorer. I never had to mess with it. I did bypass the one on my bronco. I never liked rear ABS anyway.

Its worth a try, let me know what happens.

 

[d.bright]

Well it's been wet and nasty here the past few days and I haven't had a chance to climb under the Explorer to actually look at the RABS unit to see if it has a bleeder valve or not, I will pull it into the garage and do that later today.

Tony, I also think you may be right, I need to adjust the rears some more, I initally adjusted until I fealt friction and THEN backed off, I should have left it I think..

Last resort will be bypassing the RABS module to see if it helps.

Also, since my front pads have seated on the rotors pretty well now, at least they are biting alot sooner and it feels better in the pedal.. I will keep everyone updated..

ALSO..

I have never bled an ABS module with a bleeder valve, is it as simple as bleeding it like you would a caliper or wheel cylinder? Or do you have to do something like pull a fuse or keep the key turned on?

Thanks in advance!

 

[d.bright]

Sometimes all you need is a little adjustment...

Tony H,

You were right, the rears were completely out, I adjusted them up to where they just had a slight bit of drag and that did the trick, the pedal feels great now, and with my new rotors/calipers/pads up front, it stops straight and true.. now my 80+ mph commute to work wont seem so hazardous..

Thanks again!

 

[Tony H]

Tony H,

You were right, the rears were completely out, I adjusted them up to where they just had a slight bit of drag and that did the trick, the pedal feels great now, and with my new rotors/calipers/pads up front, it stops straight and true.. now my 80+ mph commute to work wont seem so hazardous..

Thanks again!

Glad to hear it.