GMT 800 Brake Conversion > Silverado HD 2500

[DieselAmateur]

Thank you @Dustin Zynda. I've had this conversion on the long list of projects and have been leaning towards using the GMT800 LCAs just so I don't run into the same fate of having a GMT400 LCA so worn that ball joints have to be welded in. I'll still probably use the GMT400 UCAs as I seem to go through ball joints quicker than the average user, and welding the upper ball joints in my application would be a more expensive replacement later. And now thanks to your info I know there's an alternative to reaming out the knuckle for the tie rods too

One more question- I see you shared an image of a 3/16" to 1/8" npt adapter. Is this for the front brake hoses? Some folks who have done this conversion have reported that their old brake lines/ hoses bolted right up. Can you provide info on the brake hose size of the GMT800 caliper and how you connected it to the GMT400 platform?

 

[Dustin Zynda]

Np, two things convinced me to use the gmt800 lower control arms.
1) parts stores sell them complete new, with bushings and ball joints installed. No pressing out old then pressing in new, with lifetime warranty.
I have not found a new complete gmt400 lower control arm
2) no buying a reamer and reaming it.
Both of those things take to much time and effort imo.
If you use the gmt400 upper control arms you can use the 6292 ball joints without welding them. Just find one with a large foot print, you can see where the holes are inner holes just barley line up. That part number seems to be a universal part number for that ball joint. Moog, kryptonite, cognito, etc use them in there gmt800 upgrade upper control arms. You could use parts store upper ball joints lifetime, I went with kryptonite because there warranty.
(Kryptonite No Fine Print Lifetime warranty)-Kryptonite steering and suspension components are warrantied for life to their original purchaser. This warranty is against any manufacturer defects, premature wear or breakage. Race it, jump it, off road it, wreck it, lift it, lower it, sled pull it, I think you get it? We don’t care. If you can break it we will replace it.
Which I do all of these lol

 

[Dustin Zynda]

The brake hose from the gmt400 should fit fine as far as I remember. I used the gmt800 ones because I swapped out the rear end for an 02 gasser 14 bolt disc and Russell sells a complete 5 line gmt800 set for less then the gmt400 3 line set.
I did buy a gmt400 3 line set and I think it was short so maybe one for lift trucks may be the way to go if you use gmt400 brake lines.
I will try to get pictures of them both, you will need to figure a way to mount them out of harms way. Either pry the mounting bracket of the original hose or make a tab.
The wheel speed sensor in the gmt800 bearing will work but I preferred the gmt400 ones because the mounting tabs keep it in the stock location. I did have to grind the one closest to the wheel down to fit well.
I also noticed the brake dust shield from the gmt400 did not work with the gmt800 setup.
My first swap I bought junk yard parts, my second I bought all new parts. Spindles off Amazon for less then 2@$150, Detroit axle bearings 10yr warranty 2@$170, lower control arms 2@$300 or less lifetime warranty, upper ball joints moog lifetime warranty 2@$50, rotors 2@$200 3yr warranty and calipers 2@$150 lifetime warranty
Tierods are about $400 for both
I also use supersteer support bracket $250 and th there are idler and pitman arm support brackets too $300

 

[Will L.]

Man, that ball joint sure looks like a hummer/hmmwv unit.

 

[Dustin Zynda]

Could be, I found #6292 to be a gmt400 1500 upper ball joint but it could be, when I found that one I stopped searching and said close enough. So many parts out there I figured something had to be a close fit. Maybe an exact fit out there somewhere

 

[Husker6.5]

Isn't the K2500/3500 upper ball joint a beefier unit with a different P/N than the K1500? I know Moog shows two different P/Ns for K1500 vs K3500 - both with a 6.5TD engine.

 

[Dustin Zynda]

Yes, this is the ball joint that will fit the gmt800 spindle without reaming it and the 2 front holes on the k2500,k3500 upper control arm. Again to avoid reaming out the spindles this is the option I used.
If you research companies that make upper control arms with lift kits on gmt800 2500 & 3500 this is the ball joint they use.

 

[Big T]

Np, two things convinced me to use the gmt800 lower control arms.
1) parts stores sell them complete new, with bushings and ball joints installed. No pressing out old then pressing in new, with lifetime warranty.
I have not found a new complete gmt400 lower control arm
2) no buying a reamer and reaming it.
Both of those things take to much time and effort imo.
If you use the gmt400 upper control arms you can use the 6292 ball joints without welding them. Just find one with a large foot print, you can see where the holes are inner holes just barley line up. That part number seems to be a universal part number for that ball joint. Moog, kryptonite, cognito, etc use them in there gmt800 upgrade upper control arms. You could use parts store upper ball joints lifetime, I went with kryptonite because there warranty.
(Kryptonite No Fine Print Lifetime warranty)-Kryptonite steering and suspension components are warrantied for life to their original purchaser. This warranty is against any manufacturer defects, premature wear or breakage. Race it, jump it, off road it, wreck it, lift it, lower it, sled pull it, I think you get it? We don’t care. If you can break it we will replace it.
Which I do all of these lol

Reaming takes about 20 minutes per hole.

Never had an issue or needed to weld in lower ball joints.

Forged GMT 400 LCAs can be had for $80/pair from a pick-a-part boneyard. Knuckles are about $30 each. Neither of these are wear parts, so they don't need a warranty.

 

[Dustin Zynda]

Reaming takes about 20 minutes per hole.

Never had an issue or needed to weld in lower ball joints.

Forged GMT 400 LCAs can be had for $80/pair from a pick-a-part boneyard. Knuckles are about $30 each. Neither of these are wear parts, so they don't need a warranty.

OK, 20 minutes a hole maybe if you know what your doing that's 2) lower, 2) upper and tie rod? It makes ME uncomfortable to do it so I did not.
I never said anything about welding in the lower ball joint, I tacked the upper one on the inner with the bolts. Price the reamer $100? You may be able to get lca for $80 if they are available they are getting harder to find and then usually you have to pull them if you get them at an affordable price. I paid more then that for my first one from a junk yard and they would only sell me the hole suspension corner minus the caliper. Yes it is not a "wear part" but the old ball joints and bushing are a "wear part" so then buy new ball joints and bushing adding to the cost and time plus a press tool rental and press them out and then into the old arm. The lifetime warranty on the arm includes bushings and ball joints so anything fails I go get a new one and put it in. I did a torsion bar delete so this is not as much as a project as it is for you guys with a torsion bar.
I'm not criticizing or telling anyone what is a better way, just a different way. I'm saying for me after doing a few of these that's the way I decided to do them.

 

[jrsavoie]

OK, 20 minutes a hole maybe if you know what your doing that's 2) lower, 2) upper and tie rod? It makes ME uncomfortable to do it so I did not.
I never said anything about welding in the lower ball joint, I tacked the upper one on the inner with the bolts. Price the reamer $100? You may be able to get lca for $80 if they are available they are getting harder to find and then usually you have to pull them if you get them at an affordable price. I paid more then that for my first one from a junk yard and they would only sell me the hole suspension corner minus the caliper. Yes it is not a "wear part" but the old ball joints and bushing are a "wear part" so then buy new ball joints and bushing adding to the cost and time plus a press tool rental and press them out and then into the old arm. The lifetime warranty on the arm includes bushings and ball joints so anything fails I go get a new one and put it in. I did a torsion bar delete so this is not as much as a project as it is for you guys with a torsion bar.
I'm not criticizing or telling anyone what is a better way, just a different way. I'm saying for me after doing a few of these that's the way I decided to do them.

Time and having parts on hand is worth a lot.
I've never had good luck at junkyards. And junkyard shopping is time consuming

 

[Will L.]

The difference is really what are the junkyards like in your area.
In vegas there was (idk if it is still this way) a truck junkyard where they fully disassemble the trucks, tag parts and shelf them. Getting the parts is like going to any other parts store- just call and ask for part “x” and if they have it they tell the price.
Then other normal junkyards where you wander around and diy it and parts are way cheap.
BigT $80 a pair is higher than here. Its been a year or so since taking a friend to get a set for his truck- My back was hurting so I just drove and relaxed in the rig next to it and just explaining what to pull apart because he never done it before. Came out fairly quickly and a set with knuckles for him was $60 total. No need to replace those bushings, they have many years left in them. No where near Cali prices.
But if the set Dustin shoed would have been a known option, he might have done that instead. So the quality of the rigs that go into your junkyard is a huge factor.
I just think it’s cool there is more options for people- everyone can decide whats their best one.

i wouldn’t think twice of needing to tack weld something because I have a welder, but many guys dont. Y’all boys that don’t need to watch a couple YouTube videos on how to use stick powered by your truck batteries. Really not bad for everyone to learn “just incase”


A lot of things some people see as consumable parts others don’t. I will never own a rig that would need a arms. All my rigs are always bought used-DESERT LIFE- so rust doesn’t exist.
But yesterday was helping a guy whose hummer needs a couple rears. 6 bolts removed from turbo heat sheild, none are worth installing back, 2 we were lucky got removed. A tbolt V band clamp broke and the other nearly broke. I am afraid his exhaust manifold sealing surface rusted and is causing a leak. Yet to my hummer none of that is even a worry -DESERT LIFE = no rust.

Different ways to skin a cat boys. I skin mine by ordering a hamburger instead and leaving the cats to someone hungrier than me.

 

[Husker6.5]

Many of us already own the tools needed to do the job - ball joint press, 12 ton press, tie rod forks, reamers, air tools, etc. because we either need/use them regularly such as the farmers or professional wrenchers on here, or the home mechanic that has put together 40+ years of tool purchases because spending $75 for the tool then was cheaper than spending $35 (or more with inflation) every time you take it to a shop to have them do it for you over the years.

Plus, there is the factor of the "successful hunt" and "look what I engineered" when you're done, vs the opening the checkbook and just buying somebody else's prefabricated solution.

 

[MrMarty51]

OK, 20 minutes a hole maybe if you know what your doing that's 2) lower, 2) upper and tie rod? It makes ME uncomfortable to do it so I did not.
I never said anything about welding in the lower ball joint, I tacked the upper one on the inner with the bolts. Price the reamer $100? You may be able to get lca for $80 if they are available they are getting harder to find and then usually you have to pull them if you get them at an affordable price. I paid more then that for my first one from a junk yard and they would only sell me the hole suspension corner minus the caliper. Yes it is not a "wear part" but the old ball joints and bushing are a "wear part" so then buy new ball joints and bushing adding to the cost and time plus a press tool rental and press them out and then into the old arm. The lifetime warranty on the arm includes bushings and ball joints so anything fails I go get a new one and put it in. I did a torsion bar delete so this is not as much as a project as it is for you guys with a torsion bar.
I'm not criticizing or telling anyone what is a better way, just a different way. I'm saying for me after doing a few of these that's the way I decided to do them.

What is this torsion bar delete item that You speak of ? ? ? ?
Curious minds is needing to know.

 

[Big T]

The difference is really what are the junkyards like in your area.
In vegas there was (idk if it is still this way) a truck junkyard where they fully disassemble the trucks, tag parts and shelf them. Getting the parts is like going to any other parts store- just call and ask for part “x” and if they have it they tell the price.
Then other normal junkyards where you wander around and diy it and parts are way cheap.
BigT $80 a pair is higher than here. Its been a year or so since taking a friend to get a set for his truck- My back was hurting so I just drove and relaxed in the rig next to it and just explaining what to pull apart because he never done it before. Came out fairly quickly and a set with knuckles for him was $60 total. No need to replace those bushings, they have many years left in them. No where near Cali prices.
But if the set Dustin shoed would have been a known option, he might have done that instead. So the quality of the rigs that go into your junkyard is a huge factor.
I just think it’s cool there is more options for people- everyone can decide whats their best one.

i wouldn’t think twice of needing to tack weld something because I have a welder, but many guys dont. Y’all boys that don’t need to watch a couple YouTube videos on how to use stick powered by your truck batteries. Really not bad for everyone to learn “just incase”


A lot of things some people see as consumable parts others don’t. I will never own a rig that would need a arms. All my rigs are always bought used-DESERT LIFE- so rust doesn’t exist.
But yesterday was helping a guy whose hummer needs a couple rears. 6 bolts removed from turbo heat sheild, none are worth installing back, 2 we were lucky got removed. A tbolt V band clamp broke and the other nearly broke. I am afraid his exhaust manifold sealing surface rusted and is causing a leak. Yet to my hummer none of that is even a worry -DESERT LIFE = no rust.

Different ways to skin a cat boys. I skin mine by ordering a hamburger instead and leaving the cats to someone hungrier than me.

Will L the list price is $30+ for the LCAs and goes down into the $26 range on their 40% off sales. Then when they add 8.25% sales tax, core return charge (who’s going to return cores?) and environmental fee, it gets you into the $70+ range which I rounded to $80.

Agree that it’s good to know there’s another option, but I draw the “don’t go there line” at a $400 set of tie rods (did I read that correctly?). I mean that is 10x the cost of a set of Moog tie rods.

 

[Dustin Zynda]

Many of us already own the tools needed to do the job - ball joint press, 12 ton press, tie rod forks, reamers, air tools, etc. because we either need/use them regularly such as the farmers or professional wrenchers on here, or the home mechanic that has put together 40+ years of tool purchases because spending $75 for the tool then was cheaper than spending $35 (or more with inflation) every time you take it to a shop to have them do it for you over the years.

Plus, there is the factor of the "successful hunt" and "look what I engineered" when you're done, vs the opening the checkbook and just buying somebody else's prefabricated solution.

Well that may be true for some not all, I had a press and other tools with a buddy that passed and his family cleared out his garage so sometimes shit happens and sometimes people don't have all the tools or self degreed engineering skills.
I've actually used my press for bearings but I've also broke a spindle or 2. I don't own a reamer nor have any want to try it, I have a hard time getting a broken bolt out so I spray heat spray and take my time not to break them. I'm just a dumb electrician so like I said I DID NOT FEEL COMFORTABLE DOING THIS THE WAY IT WAS ORIGINALLY DONE.
AGAIN Tennessee law prohibits steering system modification so "opening up my check book" I used a credit card BTW to buy an engineered tested warranty backed product seemed like the safest legal way to go. I have a lot to lose if my trucks steering killed someone because I wanted to be the cool kid that made my own parts.
I did the research and bought and tried parts that looked factory or better then factory and last. This was my success of the hunt and my way of self engineering.
I just thought I'd share something with you guys but I'm beginning to remember why I don't share or do forums. Like my dad says opinions are like A holes and there are a lot of them in the world.
If I'm doing something unsafe please let me know but I did not criticize the way you all wanted to do it your way, I just found a better way for me and thought maybe others.

 

[Dustin Zynda]

What is this torsion bar delete item that You speak of ? ? ? ?
Curious minds is needing to know.

BDS makes a coilover conversion for gmt800 2001 to current 2500 & 3500 this is listed as a 4.5 lift. Well I own gmt400 trucks so with this brake upgrade I figured I'd try it on my truck. I called BDS and they said they would sell me the parts I wanted because I didn't want the hole kit. I'm not really a lifted truck kinda guy, I run 33×12.5×20s which doesn't require a big lift, bars are cranked up though.
I bought there lower control arm brackets, bolts, torsion bar filler and lift spindle. I bought the lifted spindle because with a little bit of lift I was hoping this would raise the upper arms to ease the ball joint and cv axle.
Overall I think that I wasted my money, the lca bracket they made hit the bump stop and I would have to cut it off. I used air lift air bag coilovers and they didn't fit into the bracket without binding up. They are built very well but we ended up just using the stock gmt800 lca shock mounts and welded in extensions for the upper shock mounts to bring them out away from the frame centering them in the upper arm. You can then use a coilover, bag, hydraulic or maybe air shock.
I'm trying to figure out sprung weight for coilovers spring rate. BDS uses a FOX 2.5 coilover I'm trying to figure out there spring rate a dampening.
Any of these coilover, bags etc are not cheap at around $500 each, air shock may be more cost effective but I don't know about the weight they are rated for. If you use air bags or hydraulics you will be able to lower and lift the truck around 4 inches but then you need to buy air compressors, tanks, controllers, 4 link and bags for the rear if you want to lower and lift that too.
I bought a 4 corner scale and my big block dually front weights are around 1850 each side which is air lifts max. This is not sprung weight though, I have to study on figuring that out yet. I've driven the truck only about 20 miles but it seemed to ride nice. I'm still working with it and plan on trying coilovers, hydraulics and maybe air shocks. I didn't end up using the spindles for the 4.5 lift because when I lowered the tru6 the upper ball joint was to high. I've found a couple other companies that I believe are shorter but I have not contacted them to see if they would sell just just the spindle.

 

[MrMarty51]

BDS makes a coilover conversion for gmt800 2001 to current 2500 & 3500 this is listed as a 4.5 lift. Well I own gmt400 trucks so with this brake upgrade I figured I'd try it on my truck. I called BDS and they said they would sell me the parts I wanted because I didn't want the hole kit. I'm not really a lifted truck kinda guy, I run 33×12.5×20s which doesn't require a big lift, bars are cranked up though.
I bought there lower control arm brackets, bolts, torsion bar filler and lift spindle. I bought the lifted spindle because with a little bit of lift I was hoping this would raise the upper arms to ease the ball joint and cv axle.
Overall I think that I wasted my money, the lca bracket they made hit the bump stop and I would have to cut it off. I used air lift air bag coilovers and they didn't fit into the bracket without binding up. They are built very well but we ended up just using the stock gmt800 lca shock mounts and welded in extensions for the upper shock mounts to bring them out away from the frame centering them in the upper arm. You can then use a coilover, bag, hydraulic or maybe air shock.
I'm trying to figure out sprung weight for coilovers spring rate. BDS uses a FOX 2.5 coilover I'm trying to figure out there spring rate a dampening.
Any of these coilover, bags etc are not cheap at around $500 each, air shock may be more cost effective but I don't know about the weight they are rated for. If you use air bags or hydraulics you will be able to lower and lift the truck around 4 inches but then you need to buy air compressors, tanks, controllers, 4 link and bags for the rear if you want to lower and lift that too.
I bought a 4 corner scale and my big block dually front weights are around 1850 each side which is air lifts max. This is not sprung weight though, I have to study on figuring that out yet. I've driven the truck only about 20 miles but it seemed to ride nice. I'm still working with it and plan on trying coilovers, hydraulics and maybe air shocks. I didn't end up using the spindles for the 4.5 lift because when I lowered the tru6 the upper ball joint was to high. I've found a couple other companies that I believe are shorter but I have not contacted them to see if they would sell just just the spindle.

An excellent explanation. Thank You very much.
I like the looks of those airbag shocks. Now maybe I’ll check around and see if there is a set for stock ride height GMT 400s.

 

[Dustin Zynda]

An excellent explanation. Thank You very much.
I like the looks of those airbag shocks. Now maybe I’ll check around and see if there is a set for stock ride height GMT 400s.

Air lift makes them in different configurations they call them the builder series. They have 3 inches of threaded travel and about 4 inches of air travel. That of coarse depends on weight, air pressure, pumps tanks etc. you can put to them. I am not finished with mine yet, right now they are mounted and I have to jack it up to air it up. I have not hooked up the lines pump and tanks. I'm using accuair which will go to 200psi.

 

[Will L.]

Different people like different things- share what ya got and don’t worry about it. You do your truck your way.

I have done air ride work trucks before. I used to be part owner in a truck equipment shop. I believe you are really going to enjoy the ride. Flip of a switch lo compensate for the load and condition you want is nice. It will take a little playing with it to get used to finding sweet spot quickly. The difference of air ride can be impressive.

One example
On the bigger truck side-there is a global company called PRG, Production Resource Group, With locations in different cities like LA, Vegas, NY, etc. they sell& rent everything for movies, tv shows, live production stuff like lighting, sound equipment,rigging and have the workers that do it all. So many millions in electronic equipment that it is scary. They learned long ago all their equipment ONLY goes in semi trailers that have air ride. The equipment gets beat up in regular spring trailers a lot more. Obviously when a customer rents the stuff and hauls it themselves they can’t control it- but they tell them it’s better to make sure they don’t have a failure from it while touring.

Some people think metal spring has to be safer that rubber air bag... and yes the air bags wear out sooner. But if they were that unsafe there wouldn’t be all these semi trucks using them. I found the air bag systems on semis much less a headache to work on.

 

[Big T]

Well that may be true for some not all, I had a press and other tools with a buddy that passed and his family cleared out his garage so sometimes shit happens and sometimes people don't have all the tools or self degreed engineering skills.
I've actually used my press for bearings but I've also broke a spindle or 2. I don't own a reamer nor have any want to try it, I have a hard time getting a broken bolt out so I spray heat spray and take my time not to break them. I'm just a dumb electrician so like I said I DID NOT FEEL COMFORTABLE DOING THIS THE WAY IT WAS ORIGINALLY DONE.
AGAIN Tennessee law prohibits steering system modification so "opening up my check book" I used a credit card BTW to buy an engineered tested warranty backed product seemed like the safest legal way to go. I have a lot to lose if my trucks steering killed someone because I wanted to be the cool kid that made my own parts.
I did the research and bought and tried parts that looked factory or better then factory and last. This was my success of the hunt and my way of self engineering.
I just thought I'd share something with you guys but I'm beginning to remember why I don't share or do forums. Like my dad says opinions are like A holes and there are a lot of them in the world.
If I'm doing something unsafe please let me know but I did not criticize the way you all wanted to do it your way, I just found a better way for me and thought maybe others.

You need to chill. No one criticizing your approach here. In fact, all of us thanked you for posting the alternative. Some, myself included, defended against misinformation you posted about the other preceeding approaches.

These forums exist to provide information to help others. Your self acknowledged lack of basic machining skills should not dissuade others from attempting the other approach. There are +/- with each approach and that is all we were pointing out.