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Project Rear Disc Brakes

spdgofast

Active Member
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Florida
Like just the knuckles from this kit....
https://www.suspensionconnection.com/14986-gmc.html
Here's just the knuckle install instructions...
55. Locate the new driver side steering knuckle and stock hub assembly, the stock hardware for the upper control arm ball joint and the lower control arm ball joint that was removed in step # 22. Using the stock hardware, secure the new driver side steering knuckle and stock hub assembly to the stock upper control arm ball joint and the stock lower control arm ball joint. Special note: Do not install the stock outer tie rod to the new steering knuckle at this point. Torque the stock upper ball joint hardware to 74 ft lbs. and the stock lower ball joint hardware to 101 ft lbs. Special note: When installing the new driver side spindle, make sure that the stock brake line is located towards the inside of the vehicle. Make sure to use thread locker or lock tite. Repeat procedure on the passenger side using the passenger side steering knuckle.
 
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Big T

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Thread starter #102
Thanks, I was just looking around to see if any other lift kit companies did their 4 inch lifts with stock control arms upper and lower, lowering just the lower CAs therefore having a 4 inch longer knuckle I could use without the spacer I have now. I doubt any of them will sell me parts if I tell them what I'm trying to do. The sad part is my truck rides perfect much better than a Excursion and all the front end components are new, bushings, bearings, ball joints, rotors, calipers etc. thus the reason I've spent so much time and $ upgrading it. It just doesn't stop well and I'm trying to make it faster. LOL
Yes the GMT 800 van knuckles are taller. Posted them in case you needed taller knuckles to avoid using the adapters.

Aside from appearance the main difference with the forged LCAs is that they use press fit ball joints. Otherwise they should work with your stuff.
 

THEFERMANATOR

FRANKENBURBAN
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Staff #103
You're over thinking this. Get the gmt-800 knickles, drill the hole out in the upper to accept the bolt on spacer, and you're good on top. I know smithville used gmt-800 lower control arms on his and said they bolted in, then all you would have to ream is the tie rod hole if you opted to use the van tie rods instead of adapters to run the crappy gmt-800 tie rod ends.

And for those wanting a bigger master cylinder, I know a BOLT ON solution to get a MASSIVE master cylinder and improved booster for these trucks meant for 4 wheel disc's.
 

spdgofast

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Yea, I realize they may fit. I was just sitting in my lazy boy surfing the net looking at options incase they won't work for some reason. I'd love to hear about the MASSIVE master cylinder.
 

spdgofast

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In my search for parts friday I found a complete 2006 or 07 GMT 800 4x4 front end setup that only the front diff was removed from but the entire front end with upper & lower CAs, axles, knuckles, hubs, brakes, all steering linkage unbolted laying in the bed with just the diff unbolted. I should probably try and get that and maybe use the LCAs of the GMT 800 and not spend the $ for the gmt 400 forged lowers. Do you guys know if the axles are any better? Different? What about the wheel speed sensors? I thought I read that only 00-04 would plug into thee GMT 400 connectors? I can maybe get that complete setup loaded in my dually for 400.00. My body's broke down I opt to pay a puller to pull the GMT 400 LCAs which makes them cost me 200.00 loaded in my truck.
 

THEFERMANATOR

FRANKENBURBAN
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Staff #106
Pretty sure others that have done this had no problems with the gmt-800 abs sensor plugging into there 95+ abs plug. The cv axles are actually the same from around 98-07(but interchange back with 88-97).

As to the master cylinder and booster, buy one for a late 90's 3500HD. It bolts right in, but you'll want to do the booster as well as it provides alot more assist. It uses a 1 9/16" piston vs the 1 7/16" of the gmt-800, or the 1 1/4" our trucks came with.
 

Big T

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Thread starter #110
Pretty sure others that have done this had no problems with the gmt-800 abs sensor plugging into there 95+ abs plug. The cv axles are actually the same from around 98-07(but interchange back with 88-97).

As to the master cylinder and booster, buy one for a late 90's 3500HD. It bolts right in, but you'll want to do the booster as well as it provides alot more assist. It uses a 1 9/16" piston vs the 1 7/16" of the gmt-800, or the 1 1/4" our trucks came with.
You’re over thinking this. I’m using my OEM master cyclinder and hydro boost and the brakes are phenomenal. Pedal height is higher than it was with the GMT 400 brakes and it’s firmer. The stopping power is amazing.
 

THEFERMANATOR

FRANKENBURBAN
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Staff #111
I wonder if you are taking about the same one that is in my truck. I will say my brakes work pretty good.
It is. They came stock with goos sized 4 wheel disc brakes in the later years. I accidentally got one in my Burb. Mine was leaking, picked one up out of a 3500 pickup in a junkyard, it looked different, but was in nice shape, so I resealed it, and swapped it in. Instantly I noticed I had a SOFT/touchy pedal, not excesspedal travel or spongy soft, but that breathe on the pedal and the brakes are THERE! Did some digging and found out it was a 3500hd booster somebody had swapped in. After looking, I discovered the difference in master cylinders, but all the brake line sizes are the same, even use the same abs unit. So there is a drop in replacement for regular pickups to get more assist and a HUGE master cylinder meant for 4 wheel discs.
 

spdgofast

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So you installed a 3500 HD master and hydroboost in your GMT400 Suburban and plumbed it into your ABS module? Which proportioning valve did you use?
 

spdgofast

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You're over thinking this. Get the gmt-800 knickles, drill the hole out in the upper to accept the bolt on spacer, and you're good on top. I know smithville used gmt-800 lower control arms on his and said they bolted in, then all you would have to ream is the tie rod hole if you opted to use the van tie rods instead of adapters to run the crappy gmt-800 tie rod ends.

And for those wanting a bigger master cylinder, I know a BOLT ON solution to get a MASSIVE master cylinder and improved booster for these trucks meant for 4 wheel disc's.
Ferm or anyone else, can you tell me what the deal is with the van tie rod ends? Is there a thread with these details already that I have missed? Also I went back to get the forged CAs off of the 2000 K3500 crew today and they had crushed it, with the 6.5 minus just the IP, and the intake manifold and one dually fender removed, still had eng, turbo, trans, t case, 14 bolt rear, I couldn't believe it. Any how do any of the 97-99 K1500s have forged lower CAs and are they the same as the 2500 and 3500 forged CAs or do I have to find a 97-99 K2500 truck or Suburban or a 97-2000 K3500 to source these?
 

Big T

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Thread starter #115
Ferm or anyone else, can you tell me what the deal is with the van tie rod ends? Is there a thread with these details already that I have missed? Also I went back to get the forged CAs off of the 2000 K3500 crew today and they had crushed it, with the 6.5 minus just the IP, and the intake manifold and one dually fender removed, still had eng, turbo, trans, t case, 14 bolt rear, I couldn't believe it. Any how do any of the 97-99 K1500s have forged lower CAs and are they the same as the 2500 and 3500 forged CAs or do I have to find a 97-99 K2500 truck or Suburban or a 97-2000 K3500 to source these?
Those forged GMT 400 LCAs only came on ‘98 and later 2500s and above. They are not an easy find. When I found them in a boneyard just laying there already removed, I grabbed them immediately.

Thread on tie rod ends for GMT 800 brake conversion:

https://www.thetruckstop.us/forum/t...00-brake-conversion-tie-rod-discussion.45012/
 

THEFERMANATOR

FRANKENBURBAN
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Staff #116
So you installed a 3500 HD master and hydroboost in your GMT400 Suburban and plumbed it into your ABS module? Which proportioning valve did you use?
Currently I have a 3500hd booster, but my stock 1 1/4" piston master cylinder, hence why I have so much excess power assist. I looked up the 3500hd master and found it uses the same thread size for each position, and I know from scrounging junkyards the 3500hd used the same kelsey hayes abs unit(but a different proportioning valve). The 3500hd proportioning valve was used in it and the 98-99 police tahoes. You can also find it in Dodge trucks iirc from 01-02 when they went 4 wheel discs on the 2500/3500's.
 

Ttoyota

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Im close to ms. Parts yard is gmt400 rich. And its oldschool redneck watch out for snakes spiders and all that good stuff. Bring a weed eater just to work on getting to the truck. Forged cntrl arms galore plus more. So i belive all the stuff i harvested for my gmt 800 front brake conversion was from a 1500 hd classic 8 lugger. Not certain but you do have other options to get the fcas your looking for. I read in gmt400 forum that someone had upgraded to the 2500hd fgd lcas and said there suspension was rockharsd stiff. Someone else said it was due to schock mount location and different geometry between the two trucks. Anyways i could be 100% wrong on everything i posted so dont bash to hard. I do need one thing though. Im still stuck on which tie rod to go with for my brake upgrade. Truck is 2000 k2500 8600gvw. So if there is a van tie rod that makes all this work and you dont have to change factory inner or sleeve, could Someone please throw it out there . I even get yousomething from tbe gmt honey hole next time im out there. Not everyone though. Big t has been helping out big time. Thx man!!
 

Will L.

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Sorry in am no help on the suspension issue.

But if you found a stockpile of 6.5s, couple things to rescue:
The metal 9 blade fan gm part# 15992650
And the rare 96 single stat block off crossover that goes really tight to the driver side a/c compressor. I thought i knew right part number but goofed and bought a wrong one.

If you see these while there, grab them and you can make a few bux. Good luck
 

Ttoyota

New Member
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Yeah sorry i forgot to mention the necks pull all the engines trannies and rear ends before they schuck the carcass in the snake pit. But the carcass still has lotsa meat. Sorry i woulda looked.
 

spdgofast

Active Member
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207
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Location
Florida
Im close to ms. Parts yard is gmt400 rich. And its oldschool redneck watch out for snakes spiders and all that good stuff. Bring a weed eater just to work on getting to the truck. Forged cntrl arms galore plus more. So i belive all the stuff i harvested for my gmt 800 front brake conversion was from a 1500 hd classic 8 lugger. Not certain but you do have other options to get the fcas your looking for. I read in gmt400 forum that someone had upgraded to the 2500hd fgd lcas and said there suspension was rockharsd stiff. Someone else said it was due to schock mount location and different geometry between the two trucks. Anyways i could be 100% wrong on everything i posted so dont bash to hard. I do need one thing though. Im still stuck on which tie rod to go with for my brake upgrade. Truck is 2000 k2500 8600gvw. So if there is a van tie rod that makes all this work and you dont have to change factory inner or sleeve, could Someone please throw it out there . I even get yousomething from tbe gmt honey hole next time im out there. Not everyone though. Big t has been helping out big time. Thx man!!
When you mentioned the stiffer ride was that changing from gmt400 stamped arms to gmt400 forged lower CAs? Or was that installing gmt 800 forged LCAs to a gmt400 truck? I would have thought the geometry would be the same on both of the gmt400 LCAs but maybe there is a difference. I guess we need clarification from someone who has compared the two side by side, I believe BigT installed gmt400 forged lowers when he did his gmt800 upgrade, SmithvilleD used gmt800 forged LCAs. I have to drive to eastern Ky next week from Florida, I wonder if I could find a set of forged LCAs somewhere along the way, I would need them pulled. Any suggestions on junk yards?
 
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