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bypassing RABS

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Old Jul 7, 2017 | 06:46 PM
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bypassing RABS

so if any of you have been following my other thread i have been having a soft brake pedal after installing new front calipers.the lines have been bled numerous times ,the master cylinder has since been replaced. i squeezed the rear brake lines and i get a hard pedal,squeezed thr FR caliper line and get a hard pedal but its impossible to isolate the RABS module as it has hard lines.does anyone know how to isolate it with the correct fitting or even better bypass this dinosaur technology all together?
 
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Old Jul 7, 2017 | 06:49 PM
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Just cut the lines and couple together with a 3/16" compression fitting. Leave it wired up and you won't get an abs light.
 
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Old Jul 7, 2017 | 06:58 PM
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Originally Posted by Shawn MacAnanny
Just cut the lines and couple together with a 3/16" compression fitting. Leave it wired up and you won't get an abs light.
why cut the lines if I'm going to put a fitting on them?
 
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Old Jul 7, 2017 | 06:59 PM
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I don't think it wise to defeat the RABS. If you think there is restriction there, simply fashion by-pass lines to test. Unwise to cut brake lines IMO.

Why did you start a new thread? Where is the old thread?
 
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Old Jul 7, 2017 | 07:06 PM
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Are you trying to test it or remove it? There's a company that used to make a kit to thread the existing fittings into. A 3/16" brake line compression coupler is about $3 and there is zero risk of kinking the lines trying to line them up or twisting them off if they are corroded to the fitting

As I understand it the rabs gets its signal from the rear ring gear speed sensor and uses a predetermined normal slow pattern to determine safe braking. There are no front wheel speed sensors or transmission or tc sensors used. the rabs works by dumping the rear brake pressure entirely (not just enough until the rear wheels release) and continues to do so until you release the pedal. Essentially if your rear wheels start to slip, it cuts the rear brakes entirely. This is how I've come to understand the system. It's probably great for an empty crew cab long bed srw truck with a regular bed on rainy and snowy days.
 
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Old Jul 7, 2017 | 07:17 PM
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And have you removed your rear drums to check that your auto adjusters are intact yet?
 
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Old Jul 7, 2017 | 07:18 PM
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Yes I've been through the same inside and out! The only thing I can think about that would be for a soft pedal is the rear ABS module. It's not really a big deal to bypass it all together you just get a harder brake pedal in the rear
 
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Old Jul 7, 2017 | 07:21 PM
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Well i know you had mentioned that you recently did the rear brakes, i just wanted to make sure you still removed them and checked them first. If it's working properly bypassing it isnt going to help your soft pedal.
 
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Old Jul 7, 2017 | 07:22 PM
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Ok... just trying to track down what in the actual hell could be causing this! I am not new to brake systems but I am just at my Wit's End of This soft pedal
 
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Old Jul 7, 2017 | 07:25 PM
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So you have definitely removed the rear drums since you did the rear brakes and double checked everything? Maybe post pictures here and someone could pick up on any issues? There is a part that came on IDI F450s with hydroboost i believe that bypassed this part but still used the same lines


 
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Old Jul 7, 2017 | 07:46 PM
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Originally Posted by Shawn MacAnanny
So you have definitely removed the rear drums since you did the rear brakes and double checked everything? Maybe post pictures here and someone could pick up on any issues? There is a part that came on IDI F450s with hydroboost i believe that bypassed this part but still used the same lines


yes I removed the rear drums and inspected everything and there's no leaks but no I did not replace the rear brakes I replaced the front calipers and that's when the issue started.
 
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Old Jul 7, 2017 | 11:57 PM
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Originally Posted by mudrat025

I replaced the front calipers and that's when the issue started.
Can you post the original thread URL so that we can try to figure it out again?
 
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Old Jul 7, 2017 | 11:59 PM
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Yes let me try...
 
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Old Jul 8, 2017 | 09:40 AM
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Originally Posted by KULTULZ


I don't think it wise to defeat the RABS. If you think there is restriction there, simply fashion by-pass lines to test. Unwise to cut brake lines IMO.

Why did you start a new thread? Where is the old thread?
https://www.ford-trucks.com/forums/1...ke-squeal.html
 
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Old Jul 8, 2017 | 09:51 AM
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could it be the proportioning valve on the master cylinder causing this?i wouldnt think it would but that and the RABS are all thats left.
 
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