Join Date: Sep 2008
Location: Novato, Calif.
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I found this quote from MLSC..
We've been discussing that topic over at FTE for a while now, and someone brought up an excellent point - RABS-equipped trucks do not have a proportioning valve, they rely on the RABS to back off the line pressure when the rear wheels can't handle it and start locking up. If you bypass or disable the RABS you're now supplying the rear brakes with full line pressure all the time, meaning they will lock up so easy it's scary. Non-RABS trucks tackle the issue with a proportioning valve that reduce the pressure to the rear brakes, and often a load-sensor on the rear axle to drop the pressure even more when there's little to no weight in the bed. So the correct way elliminate the RABS would be to either install a proportioning valve for a similar GVWR non-ABS truck (requires modification to the front lines as well), or install an aftermarket brake-bias valve between the master cylinder and the rear axle.
I actually ran in that issue with my old Chevy truck, it was a shortbed stepside truck that even with full tank and me and a passenger was still under 4000 lbs, yet the brakes were powered by a 1-ton hydroboost system (both booster and master cylinder), and to top it off my tires were mismatched front to back as well (32x10.5 fronts, 33x12.5 rears) - I used a Willwood manual brake-bias valve to sort out this mess, it took me a while to get it right but in the end the decel was so good it could throw you in the windshield and still not lock up any tires.
So keep that in mind when you go about shutting off the RABS, unless you do something to reduce the line pressure when you run empty your truck will be very much unsafe on low-traction surfaces like wet pavement or snow.
'90 F350 XLT Lariat, reg cab, dually, RWD, 4.10s, factory tow package, and lots of add-on goodies
That was what I was looking for. Good information.
Im going to check on the exact price for the part or maybe try the proportioning valve.
1994 F-350 7.3 IDIT, Dually crew
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