Just acquired an abandoned 92 sierra 2500 with the 7.4L. Looking for info and resources

[TylerSteez]

I replaced the JB6 calipers with the JB7 Calipers and it is a night and day braking distance, however, the pedal still engages fairly low, about half way thru it's travel. I've tried everything at this point besides messing with the ABS or master cylinder. all soft lines replaced, 90% of hard lines replaced, new calipers and pads, new wheel cylinders, rebuilt the drum brakes and adjusted them so the shoes are dragging fairly well on the drum, bled the whole system multiple times. What is the deal with the early OBD1 ABS systems? are they capable of trapping air as well? every google and forum search I do only really gets me results for the later OBD2 trucks

 

[Sean Buick 76]

Sorry I can’t help with your brake issue but I’m eager to hear from someone who knows?? Cool truck project

 

[TylerSteez]

Sorry I can’t help with your brake issue but I’m eager to hear from someone who knows?? Cool truck project

right now the pedal engages at about halfway or a little less through its travel but it is stopping very nicely.

i’ve seen posts about holding a flat object infront of the metering valve stem/hole thing while someone hits the brakes in order to remove trapped air. there’s even a tool made for doing it by yourself. i’m hoping this is the fix.

 

[termite]

I replaced the JB6 calipers with the JB7 Calipers and it is a night and day braking distance, however, the pedal still engages fairly low, about half way thru it's travel. I've tried everything at this point besides messing with the ABS or master cylinder. all soft lines replaced, 90% of hard lines replaced, new calipers and pads, new wheel cylinders, rebuilt the drum brakes and adjusted them so the shoes are dragging fairly well on the drum, bled the whole system multiple times. What is the deal with the early OBD1 ABS systems? are they capable of trapping air as well? every google and forum search I do only really gets me results for the later OBD2 trucks

Sounds like air in the system or loose adustment on drums (you've indicated they are tight). Remamber to bleed from right rear, left rear, right front, then left front.

When adjusting the drums, check for drag after putting drum on and activating the brakes, either service or parking, to center the shoes inside the drum. I've had what I thought was adjusted snug be super loose after one activation.

 

[TylerSteez]

Sounds like air in the system or loose adustment on drums (you've indicated they are tight). Remamber to bleed from right rear, left rear, right front, then left front.

When adjusting the drums, check for drag after putting drum on and activating the brakes, either service or parking, to center the shoes inside the drum. I've had what I thought was adjusted snug be super loose after one activation.

i always bleed brakes rear right, rear left, front right, front left. i’ve bled the daylights out of them as well. they are super firm and work great but just engage rather far into the pedals travel

when the truck was parked, the lines rotted away and the rear master went dry so i’m fairly sure any air left is caught up in the abs.

just as a test, i made them tighter than i’ve ever made any drum brake (hard to turn by hand and won’t free spin) and it still had a low engagement. i typically do it so there’s enough drag to only allow for one freewheel rotation.

i also tried the whole “slam the brakes in reverse thing”. i can’t take the truck down the road and trigger the abs system yet.

i’ve replaced the rear parking brake cables and am currently waiting for the front parking brake cable in the mail so i can do the parking brake adjusting i see mentioned on this forum.

 

[termite]

I've activated the ABS with a truck (with 4wheel abs) on jack stands before, its a bit sketchy and shouldn't be attempted thoughtlessly. Take some steps to make sure you dont run someone over, or plow into the house/shop if you hop off the stands somehow before attempting.

Others here are more well versed in the brakes than I am and will likely chime in.

As a point of reference, my 95 k2500 suburban with hydroboost and the 11x3.5 drums have slow engagement until the pedal is nearly halfway to the floor. Full stop is about even with the throttle pedal unless I stab them hard.

 

[TylerSteez]

I've activated the ABS with a truck (with 4wheel abs) on jack stands before, its a bit sketchy and shouldn't be attempted thoughtlessly. Take some steps to make sure you dont run someone over, or plow into the house/shop if you hop off the stands somehow before attempting.

Others here are more well versed in the brakes than I am and will likely chime in.

As a point of reference, my 95 k2500 suburban with hydroboost and the 11x3.5 drums have slow engagement until the pedal is nearly halfway to the floor. Full stop is about even with the throttle pedal unless I stab them hard.

i could probably park my forklift up to the bumper and give it a shot lol

that reference makes me feel better because that’s pretty much where mine engages, about halfway thru its travel. you feel the brakes start grabbing at about 40% engagement and it’s a super firm pedal and hard stop by 50-60% engagement.

the shear number of people reporting the same engagement point make me wonder if i’m just being too critical of an early 90’s work truck brake system with schoolbus-sized drums in the back. but then you also have the outliers who say theirs engage right at the top.

 

[termite]

i could probably park my forklift up to the bumper and give it a shot lol

that reference makes me feel better because that’s pretty much where mine engages, about halfway thru its travel. you feel the brakes start grabbing at about 40% engagement and it’s a super firm pedal and hard stop by 50-60% engagement.

the shear number of people reporting the same engagement point make me wonder if i’m just being too critical of an early 90’s work truck brake system with schoolbus-sized drums in the back. but then you also have the outliers who say theirs engage right at the top.

Ive been driving mine for 2 years, it doesn't go far from home so low miles, and its not changed even after bleeding.

 

[TylerSteez]

Big progress this past week. Upgraded the 4wd actuator to the late model electric unit and then took it for its first test drive down the road and it did great aside from the worn out suspension. I got on it pretty good in the snow and ice and the 4wd performed perfectly.

I then pulled the dash out due to the original dash being shot and smelling like the absolute definition off "a rat's a**".

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While it was out, I pulled the HVAC box out and then degreased and wiped down every inch of the firewall and wiring harness. I then gave it a quick rattle can black pain job and put on adhesive sound deadener. I'm kicking myself for not grabbing a picture of this.

I then took the hvac box completely apart and thoroughly sanitized every single piece, inside and out. While it was apart, I replaced all three actuators, the heater core, the AC condensor, and the blower motor. I also replaced all the foam seals and made sure that they were thoroughly sealing whatever they needed to be sealing. I did a fine RTV coating before assembling the box back together as well. It was super satisifying to stick my nose inside the hvac box and smell citrus cleaner instead of mouse nest.

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I then put the hvac box back in the truck and got to work on the new dashboard. I'm doing an interior color swap from grey to that burgundy red. I scrubbed the front and back of the new dash, cleaned out the defroster duct, and then installed the dash back into the truck. I also finished off the interior with the sound deadener.

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I need to wipe down the front of the dash again and coat it in some sort of oily dash cleaner seeing as the plastic is pretty dried out. It is still a night and day difference from the cracked, mouse infested, swamp dash prior to this one. I also fired the truck up and let it warm up and tried out the heating, It has fantastic air flow and all blend doors work as intended. Smells like sanitary, clean, warm air as well.

This was definitely not a fun job but it was a super rewarding one, I spaced it out over three afternoons. The First night I pulled the dash. the second day I rebuilt the hvac box and prepped the firewall, painted it, sound deadened it, and reinstalled the hvac box. The third day I prepped and installed the new dash and put the truck back together.

 

[TylerSteez]

Interior is 95% finished. ACC carpet is in along with all of the red panels. I need to fix the seatbelt retractors and get some speaker covers but that's really it.

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I also replaced the driver side door and did the hinge bushings on both doors. I ended up machining my own bronze bushings since the Dorman ones are notorious for not lasting long. I'm considering writing up a program and making a few sets of bushings on my CNC turning center. Figured I could sell just the bushings so people dont have to spend $200+ on the fancy door hinge rebuild kits.

Dorman on the left, quality bearing bronze on the right.

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