ABS delete / Proportioning valve bleeder tool / 1988 K1500

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cragar62

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Anyone have any experience with this bleeder tool? Are the threads 1/2-20? I've been chasing the shuttle valve in my distribution block for HOURS and cant get it to remain centered in order to bleed the rear brake circuit. Is this tool effective?
 

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Schurkey

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That "tool" is a total waste of time, money, effort, and enthusiasm. The Safety Switch does not need to be "centered" to bleed the brakes.

Sure the ABS unit hasn't closed-off the rear brakes with a stuck solenoid valve? That's where I'd be looking. That, and a plugged rear brake hose. I've actually seen more plugged hoses than failed ABS units.
 

GM01

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Personally when I deleted ABS, the proportioning valve didn't allow any fluid movement at all to the rear brakes. 88 C1500. I used a very similar thread adapter from local auto parts store. Everything was hooked up right but there just wasn't enough pressure without the ABS unit to actually open the valve to the rear, was our conclusion. YMMV but keeping the ABS is worth it to avoid chasing the headaches you'll encounter trying to get rid of it.
 

HawkDsl

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Personally when I deleted ABS, the proportioning valve didn't allow any fluid movement at all to the rear brakes. 88 C1500. I used a very similar thread adapter from local auto parts store. Everything was hooked up right but there just wasn't enough pressure without the ABS unit to actually open the valve to the rear, was our conclusion. YMMV but keeping the ABS is worth it to avoid chasing the headaches you'll encounter trying to get rid of it.
Agree... The infomus "spongy" brakes is due to air in the system, not the ABS unit. The ABS has a bleeder... people should use it.
 

Schurkey

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when I deleted ABS, the proportioning valve didn't allow any fluid movement at all to the rear brakes. 88 C1500.
The proportioning valve cannot close of fluid flow to the rear brakes.

there just wasn't enough pressure without the ABS unit to actually open the valve to the rear,
The ABS cannot INCREASE pressure to the rear brakes. It can reduce pressure, but not increase it.

keeping the ABS is worth it to avoid chasing the headaches you'll encounter trying to get rid of it.
...as long as there's nothing wrong with the ABS or the electronic controller. There are two solenoid valves in the RWAL anti-lock, if the one that's normally-open gets stuck closed, the rear brakes won't get fluid pressure, the pedal should be high and firm but the stopping power will suck. If the one that's normally-closed is stuck open, the brake pedal will be soft, lots of pedal travel, and crappy stopping power.

Yes, the early (iron body) RWAL ABS should have a single bleeder screw on it. The later aluminum-body RWAL does not have a bleeder screw. And, of course, the later 3-channel ABS units need a scan tool for bleeding.
 

GM01

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Yes, the early (iron body) RWAL ABS should have a single bleeder screw on it. The later aluminum-body RWAL does not have a bleeder screw. And, of course, the later 3-channel ABS units need a scan tool for bleeding.

As always, thank you for your encyclopedic knowledge and correction
 

Schurkey

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Agree... The infomus "spongy" brakes is due to air in the system, not the ABS unit. The ABS has a bleeder... people should use it.
Air in the system is very common, and the bleeder valve is a Godsend. However, if the solenoid valve that closes-off the accumulator is stuck open, it'll act just like the system has air in it.
 

cragar62

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UPDATE: Manually re-centered the shuttle valve and installed the bleeder tool referenced in my opening comment. Rear brakes bled easily and profusely. Brake pedal is firm and consistent with great braking at all four corners (though at times, the rears will lock up upon very hard braking). I'm satisfied.
 

davidsdailey

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UPDATE: Manually re-centered the shuttle valve and installed the bleeder tool referenced in my opening comment. Rear brakes bled easily and profusely. Brake pedal is firm and consistent with great braking at all four corners (though at times, the rears will lock up upon very hard braking). I'm satisfied.
How did you recenter shuttle valve? How did you use Bleeder tool?
 
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