Brake Proportioning Valve Questions

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Tdean91491

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What aproportioning valve do I need to bypass the abs on my 96? I’m getting a little confused with everything I’ve read.
 

Awest623

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You'll need a generic adjustable proportioning valve. There isn't a drop in solution so you'll have to adjust it up yourself. It goes on the line leading to the front brakes. You'll also need a T after it.
https://www.amazon.com/dp/B006K8L3JI/ref=cm_sw_r_fm_apa_i_Pe-kCbJQ861MM
https://www.amazon.com/dp/B01KNGVKEA/ref=cm_sw_r_fm_apa_i_xu-kCbMST4B1N

You'll also want a 2lb residual brake pressure check valve for your front brakes and a 10lb check valve for your rears. They aren't necessary but eliminate excessive brake pedal travel.
https://www.amazon.com/dp/B01GVIM8G8/ref=cm_sw_r_fm_apa_i_0h-kCbTW4Q47Q
https://www.amazon.com/dp/B01H7RO6IU/ref=cm_sw_r_fm_apa_i_mj-kCbW3WPXGC

In short. There are two lines coming from your master cylinder. Back line (closest to firewall) will go to the proportioning valve, then a 2lb check, then the T where it'll be sent to the individual front brakes. Front line will go to the 10lb check, then back to the rear brakes. You'll need 3/8" hard brake line, fittings, brake line flare tool, and a 3/8" tube bender as well.




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wheelman

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I seen on eBay.there are valves.for four way disk brakes and one for front disc and drum brakes rear.
 

Ken K

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The answer by Awest623 is correct. With ABS, the residual line pressure and "Hold-off" is in the ABS hydraulic module. Without it, you have normal brakes.
The master cylinder has the residual line pressure rubber valve behind the flare fitting on vehicles W/O ABS, so now your vehicle needs both.

Thus, if your's is disc / drum, purchase that proportioning valve correct for yours, then add the residual line valve. The 10 lbs. for the rear brakes with drum, keep the cups in the wheel cylinders from collapsing allowing air in, plus hold the shoes close to the drum for less travel, at both foot & drum. Same with front, but disc only require 2 lbs. of residual line pressure.

The hold off part of the proportioning valve operation, keeps the rear brake from applying until you hit...100 PSI line pressure (Give or Take), plus if you have a line / hose failure, the internal valve will move the direction of less pressure and turns the light on the dash. This happens right after you realize you have to change your britches.
 

Davadid

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I too want to ditch the factory ABS module as it has stopped working twice now and been replaced once already. I blame the massive amount of rust on the truck but regardless I am not going to sink another $450 into a new module. I drive perfectly fine without ABS, for the most part. I've got a 98 K1500 5.7 with front disc/rear drums and too can't find a proportioning valve made as a factory part from any other vehicle to swap. Is building my own system really the only way? I've had my eye on a
Wilwood 4444/30 260-11179 Proportioning Valve via Amazon for $75 a while now.
 

Gibson

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I've used one of the Willwood adjustable valves, and you have to fiddle with them a bit to get the right adjustment dialed-in, but they work well.
However, the adjustment setting for an empty truck is not the same as if the truck was loaded with a thousand pounds in the bed.
The Willwood products were mainly designed around passenger/sports car vehicle use, in which the weight on the rear wheels doesn't vary all that much,, if your truck is used a lot between being empty and having heavy loads, you need to aware that brake performance will change,, that's why that lever-linkage valve under the beds for the rear brakes was installed in a lot of our trucks, to vary the rears according to load.
Also, they still have some misconceptions in their descriptions for residual valves;
A 10 pound valve does a good job of keeping the wheel cylinder cups expanded in the rear drums,, but it does not keep the return spring from fully retracting the pistons, the return springs have more than enough tension to completely retract the shoes/pistons.
And, the 2 pound residual valves are for use when the master cylinder is below the disc calipers, to prevent drainback of fluid from the caliper,, with our trucks the master is well above the calipers and you don't need to install separate residuals for the front discs.
 

hatzie

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Is there any reason to not use a 78-87 squarebody Combination Valve on the GMT400 Disc/Drum setups when you completely delete the ABS valve mechanism?

I can see using an aftermarket valve on Disc/Disc but Disc/Drum without ABS should be easily within the envelope of those OEM GM parts.
 
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