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I have been reading the posts on this subject and wanted to clarify a question that I still have regarding bypassing the RABS module. If I remove the hex bung and take the spring out, then replace the hex bung, have I effectively bypassed the RABS? OR, will I need to get two couplings and a section of brake line and hydraulically bypass it?
I am having an issue with the rears dragging and I suspect the RABS is the cause. The truck in a '92 F-250 HD, 351.
Thanks for the input folks! This forum has been priceless in helping me to get my recently found truck back in business.
No, taking that spring out does not bypass the module, all it does is to bypass the dump circuit to possibly solve a sinking pedal problem.
The only way to bypass the RABS module is, as you describe, to just join the two brake lines at the module and leave it out of the brake line altogether.
Have you changed out the rear rubber brake hose (above the axle). If not do that first.
Last edited by Lazy K; Jun 1, 2010 at 09:34 AM.
Reason: Additional info.
My truck came with RABS bypassed. A few years later, i redid all the rear brakes. guess what - they started locking up under hard braking w/ empty bed. I just know about and deal with it, but the module is there for a reason.
on my 93 f250 xlt 460ci there is a connection under the passenger side dash that if you disconnect it your abs will no longer work. i actually learned this from a guy who had a 92 f250 i believe it was and he was having the same issues except his got worse, he said it started like that and got to the point where barely steppng on the brake would lock up his rear tires and he actually hit something because of it. told me he found that connection and unplugged it and hes had no more problems since. i never looked to see if he was right but its easy and worth a shot.
My truck came with RABS bypassed. A few years later, i redid all the rear brakes. guess what - they started locking up under hard braking w/ empty bed. I just know about and deal with it, but the module is there for a reason.
Do they have a separate proportioning valve? If not that sounds like the problem; the RABS module includes the prop valve. I'm following the thread because I'd like to do the same to my truck but someone suggested the loss of the proportioning valve and I haven't been able to find out for sure one way or the other.
IMO you just gotta be smart about your brake application. However, the disc brakes up front are so much stronger than the drum brakes in the back, I have never had a major problem with rear lock-up. The RABS function was way more scary to me than rear lock-up. For me, I only had to **** my pants once from the pedal drop during a panic stop and I jerked the fuse the next day and never looked back. Across 3 trucks, I have been running this way for about 15 years and never had a problem.
IMO you just gotta be smart about your brake application. However, the disc brakes up front are so much stronger than the drum brakes in the back, I have never had a major problem with rear lock-up. The RABS function was way more scary to me than rear lock-up. For me, I only had to **** my pants once from the pedal drop during a panic stop and I jerked the fuse the next day and never looked back. Across 3 trucks, I have been running this way for about 15 years and never had a problem.
i agree, anti-lock has caused more problems for me in my short time driving(im 17) than no anti-lock. if you know how to drive without anti-lock then just disconnect it.
The issue I'm having is not that the rear brakes are locking up when braking, but that the rear shoes are still slightly engaged after releasing the brake pedal. For instance, when accelerating from a stop it is obvious that the rear shoes (primarily the left I believe) are still dragging the drum. I suspect the RABS valve, but have not yet ruled out an over aggressive self adjuster. I was just curious that if the RABS is the culprit, how to best bypass it altogether.
The issue I'm having is not that the rear brakes are locking up when braking, but that the rear shoes are still slightly engaged after releasing the brake pedal. For instance, when accelerating from a stop it is obvious that the rear shoes (primarily the left I believe) are still dragging the drum. I suspect the RABS valve, but have not yet ruled out an over aggressive self adjuster. I was just curious that if the RABS is the culprit, how to best bypass it altogether.
i see, hmm. i couldnt tell you for sure if thats what was causing it. have you tried just adjusting your rear brakes? if so maybe try just disconnecting the rabs wire and see if that does it?
The RABS system would be way down my list of possible causes for that problem. I would suspect something mechanical first. The RABS cannot control the rear brakes individually, anyway.