87carl
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Warning this will be long I tend to ramble and want this as detailed and accurate as possible. I'm trying to figure out what all parts are needed to swap Heavy-duty axles into my 07 1500 burb and convert to 8 lug but keep the 1500 suspension. 2500s have torsion bars front and leaf springs rear. 1500 have struts front and 5 link coil in rear. The 1500 suspension rides alot softer and has more articulation which is why I chose to buy a 1500. But I do alot of towing and offroading so I want the added strength of 2500 axles. most threads on internet discussing this have responses that are can't be done, waste of money, to difficult, just use conversion wheel spacers, buy a 2500, do a solid axle swap etc. So researching is difficult sifting through all the dead end threads trying to find the few with actual information. Here's what I found so far. other than cutting a tab on the front diff milling out upper control arms for 2500 upper ball joint and shortening drive shafts and modify rear shock mounts rest of this stuff is mostly direct bolt on and not as difficult as people think it will be.
Rear axle Hummer h2 use the same rear suspension as tahoe and 1500 burb and avalanche. so a full float 9.5 ring gear 14 bolt axle from a h2 is almost a direct bolt in swap. According to people that have swapped them the lower control arm bolt is supposedly slightly larger than on burbs and hoes and avalanches. but the control arms and bolt are same part number. Control arm can be drilled out for larger bolt if it is bigger. Rear shocks are also slightly offset of where the burbs, avalanche and hoes are. There is a couple of ways to fix that. Either stretch bolt holes slightly so shock can sit at slight angle or move shock mount in to correct spot either way works. Will Need to shorten drive shaft about 1.5 inches and either use conversion u joint or convert drive shaft to use h2 u joint while shortening it. everything else on that axle is direct swap. Another benefit of the h2 axle is they use same calipers as fronts so there's big 6 piston calipers that are direct bolt on.
Front diff also is easy 2011+ 2500/3500 9.25 diff uses mounts similar to the GMT900 1500 front differential. the mounts are slightly farther apart side to side but there is enough play in the bushings to bolt that diff to the 1500 diff mounts. You will need to cut off a bolt ear near the pinion that hits 1500 frames crossmember mount. Driveshaft also needs to be shortened. Idk how much yet. cv axles for that diff use a 8 bolt flange and are 36 spline. Need to use a pre 2010 2500/3500 33 spline cv axle and change the inboard flange cup off the cv to the 8 bolt one from a 2011+ and use 8 bolt cv spacers from incognito. If staying 6 lug can use stock hub bearings with these modified cv axles. Also stock gmt900 1500 cv axles are same length as 2011+ 2500 cv axles so they should be able to used without spacers if the 8 bolt cups fit on them. I think they cups will fit but can't confirm yet. Hopefully they do so can eliminate cv spacers and have better cv angles.
The h2 axle is 8 lug so I want 8 lug in front. 2500 wheel bearings are 4 bolt 1500 are 3 bolt. One option is you can use late 90s dodge 2500 wheel bearings they are 3 bolt 8 lug and will bolt on our stock 1500 gm knuckles but they have no abs. And no clue what rotors and caliper spacers would be needed So don't want to do that method.
I do have a link to a thread on pirate most is nonsense but one post a guy posting claims to have bolted 2500 knuckles on a 04 gmt800 1500 truck. The lower ball joint bolted on. He used 2500 outer tie rod with 1500 inner tie rod. the upper control arm had to be milled out to use the 2500 upper ball joint and he needed cv spacers because 1500 upper control arms are slightly longer then 2500 about 1/2 inch and his torsion bars are cranked. That also caused alignment to be slightly off close but not able to bring it in exact. There are adjustable upper control arms that can fix that. Or lifted trucks like mine sometimes need uppers to be slightly longer mine are currently almost to short had to use extended alignment cams and pushed almost all the way out to get it aligned with my current suspension setup huge pain in the butt.
What he did on that 04 should be same as swapping ours. 2500 gmt800 and pre 2010 gmt900 front suspensions are the same. 1500s changed to struts and rack and pinion steering when switching to gmt900. so Idk what all got changed between the GMT900 and gmt800 1500s. But I do know that they both use same knuckles. so ball joints should be the same size. Tie rods definetly changed switching to gmt900 because of using rack and pinion. But 08 and up hybrid gas/electric 1500 trucks use same steering rack as ours (or a 3 turn lock to lock rack I want). there inner tie rods will bolt on our steering rack and those inner tie rods have same shaft size and thread pitch as 15+ 2500 outer tie rods so that's the solution to tie rods. And our lower ball joints are the same as a 2500 so no worries there.
Also 2011 switched to 8x180 lug pattern so after switching knuckles have to use the pre 2010 33 spline hub bearings to have same lug pattern as h2 rear axle. And use a modified cv shaft that has the 8 bolt cup and 33 spline.
What I am still trying to to figure out is if anyone on here knows the upper ball joint specifications for the 1500 and 2500 gmt900s? Or has access to a ball joint specification book to get the measurements. all ball joint books online I have found don't go that new. I am trying to see if the part of the upper ball joint that goes in the control arms is bigger on gmt900 1500s so I can figure out if 2500 upper ball joints can be pressed in or if I will have to mill out the upper control arms like on the gmt800. And how big the upper control arm needs to be milled out to if I have to do that.
My burb has MEVOTECH tough terrain control arms the upper ball joint where it goes through the control arm is alot bigger than the stock upper ball joints so also need to figure those specific control arms ball joint size. I emailed MEVOTECH and am waiting for them to respond.
Also can someone with stock 1500 knuckles measure how tall they are. 2500s are 13 inch tall but can't find that measurement for 1500s. my burb has rc lift knuckles so I can't measure it. Also if someone can get wheel mating surface to wheel mating surface width and distance between ball joints from side to side I could use those measurements on 1500 and 2500. Thank you
Rear axle Hummer h2 use the same rear suspension as tahoe and 1500 burb and avalanche. so a full float 9.5 ring gear 14 bolt axle from a h2 is almost a direct bolt in swap. According to people that have swapped them the lower control arm bolt is supposedly slightly larger than on burbs and hoes and avalanches. but the control arms and bolt are same part number. Control arm can be drilled out for larger bolt if it is bigger. Rear shocks are also slightly offset of where the burbs, avalanche and hoes are. There is a couple of ways to fix that. Either stretch bolt holes slightly so shock can sit at slight angle or move shock mount in to correct spot either way works. Will Need to shorten drive shaft about 1.5 inches and either use conversion u joint or convert drive shaft to use h2 u joint while shortening it. everything else on that axle is direct swap. Another benefit of the h2 axle is they use same calipers as fronts so there's big 6 piston calipers that are direct bolt on.
Front diff also is easy 2011+ 2500/3500 9.25 diff uses mounts similar to the GMT900 1500 front differential. the mounts are slightly farther apart side to side but there is enough play in the bushings to bolt that diff to the 1500 diff mounts. You will need to cut off a bolt ear near the pinion that hits 1500 frames crossmember mount. Driveshaft also needs to be shortened. Idk how much yet. cv axles for that diff use a 8 bolt flange and are 36 spline. Need to use a pre 2010 2500/3500 33 spline cv axle and change the inboard flange cup off the cv to the 8 bolt one from a 2011+ and use 8 bolt cv spacers from incognito. If staying 6 lug can use stock hub bearings with these modified cv axles. Also stock gmt900 1500 cv axles are same length as 2011+ 2500 cv axles so they should be able to used without spacers if the 8 bolt cups fit on them. I think they cups will fit but can't confirm yet. Hopefully they do so can eliminate cv spacers and have better cv angles.
The h2 axle is 8 lug so I want 8 lug in front. 2500 wheel bearings are 4 bolt 1500 are 3 bolt. One option is you can use late 90s dodge 2500 wheel bearings they are 3 bolt 8 lug and will bolt on our stock 1500 gm knuckles but they have no abs. And no clue what rotors and caliper spacers would be needed So don't want to do that method.
I do have a link to a thread on pirate most is nonsense but one post a guy posting claims to have bolted 2500 knuckles on a 04 gmt800 1500 truck. The lower ball joint bolted on. He used 2500 outer tie rod with 1500 inner tie rod. the upper control arm had to be milled out to use the 2500 upper ball joint and he needed cv spacers because 1500 upper control arms are slightly longer then 2500 about 1/2 inch and his torsion bars are cranked. That also caused alignment to be slightly off close but not able to bring it in exact. There are adjustable upper control arms that can fix that. Or lifted trucks like mine sometimes need uppers to be slightly longer mine are currently almost to short had to use extended alignment cams and pushed almost all the way out to get it aligned with my current suspension setup huge pain in the butt.
What he did on that 04 should be same as swapping ours. 2500 gmt800 and pre 2010 gmt900 front suspensions are the same. 1500s changed to struts and rack and pinion steering when switching to gmt900. so Idk what all got changed between the GMT900 and gmt800 1500s. But I do know that they both use same knuckles. so ball joints should be the same size. Tie rods definetly changed switching to gmt900 because of using rack and pinion. But 08 and up hybrid gas/electric 1500 trucks use same steering rack as ours (or a 3 turn lock to lock rack I want). there inner tie rods will bolt on our steering rack and those inner tie rods have same shaft size and thread pitch as 15+ 2500 outer tie rods so that's the solution to tie rods. And our lower ball joints are the same as a 2500 so no worries there.
Also 2011 switched to 8x180 lug pattern so after switching knuckles have to use the pre 2010 33 spline hub bearings to have same lug pattern as h2 rear axle. And use a modified cv shaft that has the 8 bolt cup and 33 spline.
What I am still trying to to figure out is if anyone on here knows the upper ball joint specifications for the 1500 and 2500 gmt900s? Or has access to a ball joint specification book to get the measurements. all ball joint books online I have found don't go that new. I am trying to see if the part of the upper ball joint that goes in the control arms is bigger on gmt900 1500s so I can figure out if 2500 upper ball joints can be pressed in or if I will have to mill out the upper control arms like on the gmt800. And how big the upper control arm needs to be milled out to if I have to do that.
My burb has MEVOTECH tough terrain control arms the upper ball joint where it goes through the control arm is alot bigger than the stock upper ball joints so also need to figure those specific control arms ball joint size. I emailed MEVOTECH and am waiting for them to respond.
Also can someone with stock 1500 knuckles measure how tall they are. 2500s are 13 inch tall but can't find that measurement for 1500s. my burb has rc lift knuckles so I can't measure it. Also if someone can get wheel mating surface to wheel mating surface width and distance between ball joints from side to side I could use those measurements on 1500 and 2500. Thank you
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