Your truck came from the factory with rear axle only ABS. RABS was standard starting in 1989.

 

Good to know. Any large problems with disabling the rear ABS?

 

The nice thing about RABS is that it helps prevent lockup when the bed is empty. You can set up a simple adjustable proportioning valve for empty or full or anything in between but you can't set it up for all load situations at once. So, having a proportioning valve plus RABS tends to cover more situations better.

Another way that some trucks overcome this problem is by using a prop valve with a linkage to sense ride height. The link tells it how to adjust the proportioning for the load based on how far the supension has settled. To the best of my knowledge, that system was never used on Rangers though.

I would take a quick look at the original RABS prop valve to see if it has an external adjustment. Most stockers don't but a few do.

 

Hmm it might be worth taking a look for an adjustable stock unit then, or possible finding out exactly what they came on.

Would it also be possible to swap a RABS proportioning valve from an Explorer with rear discs on to the Ranger? I'm not sure if it would be the same as a 96ish explorer and whether or not there ABS system is different.

 

All of the 95~2001 Explorers with rear discs also had 4WABS which does not have the Ranger RABS style prop valve.

 

Thanks for all the tech info bob. My last thing to figure out then is should I use the adjustable proportioning valve to help adjust the front brakes or the rear brakes. The one from summit says it can reduce brake pressure by up to 57%. From info earlier in this thread, the rear drums have around 10 PSI of line pressure, and discs on require about 3 to 4 PSI, which is a little less than 57%.

It seems to me that the rear brake pressure should be reduced to get the front and rear proportioned correctly. Then lastly, should the adjustable proportioning valve be used before or after the stock proportioning valve? I'm guessing the rear brakes should have the adjustable proportioning valve before the stock valve since the stock prop valve is used for the RABS. Just doesn't seem right for the RABS to adjust properly during braking and for the brake pressure then to be reduced, thoughts?

This is the Summit Prop Valve.

 

if it was me i would swap in the stuff and see how it works then go from there. you might not need to do anything.

 

The proportioning valve goes in the line to the rear brakes, not the fronts.

Those values quoted for disc and drum brakes are for residual pressure (2~10 PSI), not applied pressure (1000+ PSI), so they have nothing to do with the front/rear split.

I don't know what to tell you about using 2 prop valves in series. It sounds wrong but I've never tried it myself.

I agree with Zach. I would try it first with the stock prop valve to see if it will work as-is.

 

I say just roll with it for now. No need to try and fix a problem you don't have. Since my Exploder disc swap, The only time the rear has tried to lock first is on wet roads, and alot of that could be the reduced amount of tread on the rear tires.

 

Thanks for all the input guys, I appreciate it. Just doing all the research now before I do all the work. Hoping to do everything once and be done!

 

After converting my 2001 Ranger Edge 4x4 to rear discs, the rear has worn pads like crazy, so there's definitely a rear residual pressure valve somewhere in the system. I wish I knew how to remove it. The rear has an incredible amount of drag. The rotors get to well over 450 degrees. Insane!

Messing with the ABS system seems like a huge no-no, since it takes a special machine that Ford no longer has to bleed the ABS system properly..

It's looking like switching back to the factory drums rear brakes is my only option.

 

did you have to swap your master cylinder? Did you have any issues with a soft brake pedal after? How’d you do the brake lines ?