Brake Trouble on 96 Z71

[wheelman]

So, when I first got the truck the brake pedal was soft ,but it stopped alright. I had the ABS light on ,but I wasn't too worried. The fuse had been pulled so I replaced the fuse and the light was still on. I remember the previous owner saying something about a sensor in the rear that needed to be replaced ,but I have no idea if his word is any good or not. So a couple of months later I went to service the rear diff and noticed that the fill plug was stripped out so a hundred and twenty bucks later I had a Perfect Launch diff cover. I ended up breaking the rear brake in the rear so I decided well, it's probably time to service the drums anyway. So I serviced the drums and put new wheel cylinders in and bled the rear with a one man bleeder. I ended up getting a red brake light. Today my father and I put new calipers on in the front. I did the front brakes with new hardware, rotors, and pads. We bled those and it had an incredible amount of pressure coming from the calipers. It was like a geyser of brake fluid. The pedal felt better ,but I would still occasional get the red brake light and the truck stopped ,but it was a very slow stop. I decided to wait it out at my father's house until around 10 when the roads would be clearer to make my way home. I noticed that the brake light only came on at hard stops and my gas gauge would dip down as well. I'm not sure if those are related ,but hey I figure all the information I can give you guys the better. I crept home and on some back roads close to my house I decided to try and test the brakes some more to see what I've got going on. I did a few hard stops and the brake light that had stayed with me for about 20 miles at this point went away and the pedal felt better ,but it wasn't the rock hard pedal I was used to in my K20 I used to own and my C10. I also noticed that my hazards/brake lights don't work. I'm not sure if the relay has anything to do with my pedal feel. Removing the ABS fuse made no difference either. I'd like to delete the ABS unit (a Kelsey Hayes unit) and use the proportioning valve from a 81 K series truck. Would that be a viable solution for me to try? I heard way too many horror stories about the ABS units acting up in this truck and causing people to get into accidents. I also did try bleeding the ABS unit from that little nipple with the rubber cap ,but no fluid was coming from there.

What's the best course of action here? I'd like a rock hard pedal and I'm not looking for the cheapest option per say ,but I know those ABS units cost quite a bit and I don't have a tool to bleed it if I got a new one. Thank you for looking at my thread.

Change the front brake caliper hoses.bleed the brakes.R rear.L rear.R front.L front.

 

[wheelman]

Change out the front caliper brake hoses.bleed the brakes.R rear L rear .R front L front

 

[Schurkey]

Alright. I'll grab another Kelsey Hayes unit from the junkyard before I go nuclear here and rip out the ABS. Shouldn't be too bad.

Did you ever try bleeding the ABS unit?

Sure, the thing can be defective. Valves stuck open--or closed. Maybe you need to replace it. But I'd try bleeding it first.

Change out the front caliper brake hoses.bleed the brakes.R rear L rear .R front L front

We bled those and it had an incredible amount of pressure coming from the calipers. It was like a geyser of brake fluid.

Unless the hoses are damaged, why change 'em? It's obvious that they're not plugged or restricted.

 

[El Tigre]

I deleted my ABS,and am fine with it. Added an adjustable proportion valve to rear brake circuit for fine tuning....

 

[east302]

Alright. I'll grab another Kelsey Hayes unit from the junkyard before I go nuclear here and rip out the ABS. Shouldn't be too bad.

If you swap it out, you’ll need to have a shop with a scanner run the ABS automated bleed sequence, followed by a bleed at all four corners.

Personally, I’d do that first and make sure that the drums are properly adjusted. While you’re there, ask them to pull the ABS code. It could be something really simple and unrelated to the ABS module (like a front wheel sensor).


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[Bad_Luck_Club]

Did you ever try bleeding the ABS unit?

Sure, the thing can be defective. Valves stuck open--or closed. Maybe you need to replace it. But I'd try bleeding it first.



Unless the hoses are damaged, why change 'em? It's obvious that they're not plugged or restricted.

I tried bleeding it once ,but no fluid came out. Is there a better way to bleed the ABS than holding down that little valve while someone is pushing on the pedal? If there's a tool I could buy that would be great. I don't have a scan tool though to pulse it. That would probably be in the thousands for something like that right?

 

[Bad_Luck_Club]

I deleted my ABS,and am fine with it. Added an adjustable proportion valve to rear brake circuit for fine tuning....

How did you do that? I saw that the adjustable ones don't work on these trucks with drums in the rear and rotors in front. I was going to buy a proportioning valve off an old truck at the junkyard or a new one online.

 

[east302]

Some report being able to get the air out by slamming on the brakes while on gravel...followed, I would think, by bleeding at the four corners as the air, once it leaves the ABS unit, is then held in the downstream brake lines.

A shop charged me $70 or $80 a couple of years ago to do the automated bleed and a bleed at the four wheels. The guy used a Snap-on scanner.

That is probably the best way to do it if you don’t have access to a capable scanner.


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[Schurkey]

My '88 has Kelsey-Hayes Rear Wheel Anti-Lock.

There's a bleeder screw right on the ABS unit. Is that true of yours? Step on the brake pedal, have someone loosen and re-tighten the bleeder screw. Could not be easier.

 

[letitsnow]

How did you do that? I saw that the adjustable ones don't work on these trucks with drums in the rear and rotors in front. I was going to buy a proportioning valve off an old truck at the junkyard or a new one online.

I deleted my abs, replaced all brake lines, and added a willwood prop valve on my truck. The valva says "disc brakes" on the package, but works ok with the valve turned all of the way down for the back brakes. Part of the reason for replacing all of the lines was so that I could use the correct fittings for all of my components, which means flaring your own ends etc.

It is a lot of work, but my brakes now work about as good as your typical 1980's model car. When stock, they worked about as well as a 1960's model car. Brakes are the biggest weak point on these trucks, I think.