Tired of these bad brakes and need advice

[99xcss4]

if it was my truck I would do the fallowing
get a gmt800 99-06(07 classic) master cylinder and adapter fitting for the one line
get ld 6 lug k2500 rotors (after market ones that are slotted and cross drilled)
get a set of k3500 calipers and pads if they will fit if they do not fit get one for the ld 6 k2500
swap rear end to 6 lug 14 bolt or get the bigest drums and shoes they make for a 10 bolt
get what ever the most strongest booster tank is or if you a huge budget do a hydro-boost swap

 

[GoToGuy]

If you have worn brakes, adjust the drums with everything installed. Spin and turn the star to get a drag to start.
The turn the star till the drum just goes on works best with new shoes, and fresh smooth brake drum or new drums.

 

[Schurkey]

1988 k1500 5.7l with read 10in drums and disc brakes up front and rwal.

Maybe just like mine when I got it. I had a standard cab, not extended cab. Shytty brakes, never REALLY fixed until I upgraded from JN3 to JN6 brake parts. (Change rear axle for 11.x Duo-Servo drums. Change rotors, calipers, master cylinder and booster for bigger/stronger parts like the extended cabs got.) The crowning touch was to replace the restricted rear brake hose.

I even saw a bleeder nipple on the rwal dump valve and got all the old fluid and air out of that.

That was going to be my first suggestion.

Brakes still suck. I do notice that with the truck off the brakes feel okay after a bleed but once the truck is on the pedal is so soft.

Means nothing except that your booster is still working, and the brakes still have problems.

I do have a brake light on sometimes it flashes 1,2,3,4 but when I jump a to h on aldl it is solid then blinks 1,2,3,4. If I unplug the rwal two wiring harnesses the light turns off.

Not "1, 2, 3, 4." Look again. I bet there's a long flash, followed by other flashes. May be signifying a "Code 5".

The single, red "Brake" light provides info on three different systems. Be sure you're fixing the correct system.

The light comes on with the park-brake.
The light comes on with the safety-switch on the combination valve, when there's a failure in one hydraulic circuit but not the other. (This also causes a low brake pedal.)
The light comes on when triggered by the RWAL module.

The early years of RWAL, checking codes when there isn't a code already set can trigger a false "Code 9". This was fixed in...'90, maybe.

 

[88sclb350]

Maybe just like mine when I got it. I had a standard cab, not extended cab. Shytty brakes, never REALLY fixed until I upgraded from JN3 to JN6 brake parts. (Change rear axle for 11.x Duo-Servo drums. Change rotors, calipers, master cylinder and booster for bigger/stronger parts like the extended cabs got.) The crowning touch was to replace the restricted rear brake hose.


That was going to be my first suggestion.


Means nothing except that your booster is still working, and the brakes still have problems.


Not "1, 2, 3, 4." Look again. I bet there's a long flash, followed by other flashes. May be signifying a "Code 5".

The single, red "Brake" light provides info on three different systems. Be sure you're fixing the correct system.

The light comes on with the park-brake.
The light comes on with the safety-switch on the combination valve, when there's a failure in one hydraulic circuit but not the other. (This also causes a low brake pedal.)
The light comes on when triggered by the RWAL module.

The early years of RWAL, checking codes when there isn't a code already set can trigger a false "Code 9". This was fixed in...'90, maybe.

I wrote that 1,2,3,4 stuff out wrong. It’s one solid then 4 fast so code 14 right?

I’m wondering maybe with the pedal feel and you mention that the brake light can be on due to a failure in the combination valve possibly that’s where the pedal and light issue comes

 

[blackdeathmessenger]

I unplugged the rwal system a year ago and have better brakes now then when I bought my truck

 

[Schurkey]

I wrote that 1,2,3,4 stuff out wrong. It’s one solid then 4 fast so code 14 right?

One long plus four short = five flashes = Code 5.

I’m wondering maybe with the pedal feel and you mention that the brake light can be on due to a failure in the combination valve possibly that’s where the pedal and light issue comes

Not a "failure" in the combination valve, more likely the safety switch in the combination valve is reacting to unbalanced pressure between the front and rear hydraulic systems.

The "usual" causes of unbalanced pressure between the two systems are
1. Air in one system, or
2. A leak in one system, including an internal leak in the master cylinder.

 

[Erik the Awful]

if it was my truck I would do the fallowing
get a gmt800 99-06(07 classic) master cylinder and adapter fitting for the one line
get ld 6 lug k2500 rotors (after market ones that are slotted and cross drilled)
get a set of k3500 calipers and pads if they will fit if they do not fit get one for the ld 6 k2500
swap rear end to 6 lug 14 bolt or get the bigest drums and shoes they make for a 10 bolt
get what ever the most strongest booster tank is or if you a huge budget do a hydro-boost swap

I wouldn't swap to a GMT800 master cylinder. First, you need to know if you have the quick-take-up master cylinder. If you do, DO NOT swap on a GMT800 master cylinder. Sure, some people have done it and like it, but one bad emergency stop and another driver's insurance company will own you.

If you want to swap to a complete 6-lug setup, that's fine. Drilled and slotted rotors? That's absolutely not a good idea unless you're trying to win the crowd at Cars 'n Coffee. Drilled and slotted rotors are '80s technology, and they crack. Modern pads and rotors don't need holes and slots to vent gases any more.

 

[99xcss4]

I wouldn't swap to a GMT800 master cylinder. First, you need to know if you have the quick-take-up master cylinder. If you do, DO NOT swap on a GMT800 master cylinder. Sure, some people have done it and like it, but one bad emergency stop and another driver's insurance company will own you.

If you want to swap to a complete 6-lug setup, that's fine. Drilled and slotted rotors? That's absolutely not a good idea unless you're trying to win the crowd at Cars 'n Coffee. Drilled and slotted rotors are '80s technology, and they crack. Modern pads and rotors don't need holes and slots to vent gases any more.

I did not know that about the rotors. some one I knew did the gmt800 master cylinder on a 99 k1500 classic he said it was an improvement and when he swaped out the 10 bolt for a 6 lug 14 bolt it got better again. I do not know any thing about the quick take up master cylinder just know what I knew about him if he would put front brakes on from a ld k2500 I would say it made it better. I do not know how much this pays into things but he also had an abs delete.

 

[OutlawDrifter]

if it was my truck I would do the fallowing
get a gmt800 99-06(07 classic) master cylinder and adapter fitting for the one line
get ld 6 lug k2500 rotors (after market ones that are slotted and cross drilled)
get a set of k3500 calipers and pads if they will fit if they do not fit get one for the ld 6 k2500
swap rear end to 6 lug 14 bolt or get the bigest drums and shoes they make for a 10 bolt
get what ever the most strongest booster tank is or if you a huge budget do a hydro-boost swap

Agreed with Erik on this. No on the NBS MC and no on drilled/slotted rotors. An improvement in "pedal feel" is not an improvement in braking necessarily.

Hydroboost is the best option if you have the funds, the time, and the parts.



OP, what is the condition of the front calipers and rubber hoses? Are they the same units that the pickup left the factory with?