• If you currently own, previously owned or want to own an Avalanche, we welcome you to become a member today. Membership is FREE, register now!

H2 14 bolt rear axle swap

patgizz

Full Member
Joined
Feb 16, 2014
Messages
16
the project:  2006 H2 rear axle into 1/2 ton avalanche.

the truck:  2005 Z71 with tow package, 4.10 gears, and 140k miles.


777C764E-F159-4CD1-A84E-303B7944E633_zpstumim9ih.jpg



the reason:  passenger side carrier bearing is no longer a bearing, carrier moved to right, gears chewed up, metal in everything.  every reman unit i found was $1800+ and due to the extent of the damage the parts alone were approaching $1500 for the quality i would use. 

10 bolt extracted

A70C0F54-D3D5-4E72-AA92-679AB24F82FE_zps9rv932e8.jpg


the 14 bolt standing on end, fresh off the pallet from some wrecking yard in alabama.

9D25AAFE-69FF-4C12-9986-1C35A4FE6465_zps7r80lhil.jpg



pay no attention to the plymouth gasser project, i sold it as well as my WRX roller to fund all the truck parts.


rear axle out.

78A4751D-86D9-415F-B367-E76D05DD4936_zpsc0shakvn.jpg



good look at the h2 rear.

782A158C-506C-4417-B9DD-68BC1A91F6F1_zpsblxdfp0r.jpg



tried out the new toys to mount and balance the new tires and wheels.

0CEE7E39-F05C-4451-AF7A-B3970277BDD8_zpstyzxjcgg.jpg



 
more lugs!

C3528ECF-E954-4E81-A4CB-11EBD4CC027F_zps1ssncpfg.jpg


E4034911-2428-4E2B-AB8E-B84E1A7E149C_zpsicz3ccfp.jpg


already had installed QA1 track bar when my stock bushings went.

truck done, drove for first time yesterday

196463D6-C7C3-4905-BF6D-951B2E384C73_zps798idebz.jpg
 
the rundown:


upper control arms direct fit.

spring perches same location

lower control arms, same location however the H2 uses a larger bolt and therefore the bushing has a larger hole.  only slightly, but enough that use of the stock bolt will allow for play.  my axle came with the h2 control arms cut at the mount, so i got the bolts with it.  my solution was to drill the bolt hole in the bushing to fit the h2 bolt, as there is plenty of meat to do so.  key is go slow, take breaks, and use lots of lube to not overheat the rubber portion of the bushing.

e-brake cables were a direct fit.

shocks - the h2 shock mounts are about 1/2 a shock farther outward than stock.  solution here was slot the outside hole on the lower shock mount approx 3/16" so the bolt would slide through.  there is more than enough movement in the upper rubber bushing to accommodate the slight angle that the shocks now sit at.

sway bar direct fit.

ABS sensors - the H2 axle uses a female plug at the sensor.  my axle came with a few feet of wire off each pigtail.  this must be attached to the male plug from the avalanche sensors(solder and heat shrink preferred, as it's exposed to all kinds of crap under the truck).  once this is done, you end up with a couple 3 foot long harnesses with a male plug at both ends, one to plug into the sensor and one to plug into the truck's harness at the top of each frame rail.  ABS and stability control function as they should, and no dash lights are on.  

hard brake lines - the H2 lines and rubber hoses attach at 12 o'clock on the cover.  the avalanche ones are closer to 11.  this difference would have put some stress on the rubber hoses.  to keep my stock hoses from frame to diff, i swapped the hard lines over from the 10 bolt.  they required a little bending at each end but the width is correct and they bolt right to the 14 bolt cover, which has a slot in that position for the bracket that holds the lines.

the h2 diff is 4" wider than the stocker.  up front i used some 2" USA made adapters to go from 6 to 8 lug to match the rear.  the plan is to keep an eye out at pull a part for a 2500 and get all the front end from it and switch it over when i need cv's or bearings up front.  i bought stockish flares on amazon and used bedliner in a can on them.  this has worked great for me in the past.

i'll add if i remember anything else.  the only thing not done is to wire the e-locker to a switch on the dash.  

 
(y) (y) Nice job...
 
oh yeah last thing.  conversion u-joint is a Moog 447.  converts the S44 on the driveshaft to the 1350 on the pinion yoke. 

 
Outstanding (y)

Nice write up.
 
Seriously looking into this. It seems like a great swap for me and what I want out of the truck. I would make sure it is all running right first of course. Then swap it in to my 2009. I would get the lower gears that I want without having to swap into my rear axle. For the price of the swap on gears into mine and for maybe a little more I could swap in a bigger stronger axle onto my current suspension and go to 8 bolt like I want to do. I would still have the same great ride. Then I would just run adapters on the front end and be fully 8 bolt. Now I just have to start saving up for it.
 
i have one update that needs mentioned.  you must take your driveshaft to a driveline shop and have it shortened 1.25" to make up for the larger rear axle.  when at ride height things were ok but tight.  when i hooked up a trailer the yoke bottomed out in the transfer case.  we used the original mark and the new line on the yoke made by the seal to determine the difference.  while they were cutting things apart anyway, they installed a 1350 yoke on the rear of the driveshaft so i did not need to run a conversion u-joint.

also, i've got 5k on the swap now, everything is great including the wheel adapters up front.  i was most nervous about those.  at the end of october we pulled the enclosed racecar trailer over 2200 miles to florida and back.  an upgraded rear axle isn't one of those things that you notice when you are driving around, but it's great to know it is there with the amount of towing i do and knowing how bad my 10 bolt exploded.
 
Thanks for the update.. Good to hear everything's working fine after the long haul, literally.
 
Reviving an old thread and I am assuming this owner is no longer around...

Looks like he said the wheels will be 2" further out than those on my avalanche on each side?

Since it looks like the front end can also be converted over to the 8 lug setup reasonably easily it looks like it might not be a bad conversion.

Front end would need to have the bottom control arms machined out to take bigger ball joints but didn't look like was a major ordeal.
Also looks like otherwise the front end from a 2500 pickup would be bolt up other than one mount has to be fabricated.

May just throw this in and pull the front axle shafts for now until I can get the gears changed.
 
So update...

Old axle is out and I compared to the H2 axle sitting here... Everything measures out to matching up fine. Since I plan to do a full upgrade in the near future to the suspension I am just going to reuse the factory parts at this time.

I will be bolting up the H2 rear end after I get off here.  I wanted to reread this thread to see if I was missing anything.

I have an older H2 rear end and the bolt holes line up fine. The holes for the bolts appear to be the same as my stock 1500. Maybe even slightly smaller so I will just be reusing my original bolts. Thanks to the OP I already have a shorter driveshaft sitting here with new 1350 balljoint.

I have included pictures of these rear ends. My 1500 is at the bottom, the H2 is on the top in the first one. In the second one I am taking the picture from the other direction so they are swapped. You can see where the shock mounts on the H2 rear is more under the upper arm mount and is at an angle. I will remove my shocks all together and see how it lines up once mounted. I MAY have to make a bracket to fit the top section of the shock. Since I plan to totally redo the suspension when I retire a year and half from now I don't want to do anything permanent to the frame or to the rear end.

While doing this job I will also be fixing the fluid leak between the transfercase and transmission, repair the leaky transmission lines, pull front cv axles replacing them with stubs in the front hubs.

I have been told conflicting stories on removing the front drive axle. I have been told it can be removed and run without it with no issues. I have also been told this is not the case and I need the axle in place when the truck is running. Since I will be pulling the axle anyhow to do the transfer case gasket If I can leave it off I would rather do that. I would likely end up dropping the front differential out all together for now at that point until i decide what I am doing up front.

My truck came with 3.73 gears and this H2 has 4.10 gears.  So I need to disconnect the front diff until I decide my next step.
 

Attachments

  • 20200519_192254.jpg
    20200519_192254.jpg
    4.5 MB · Views: 18
  • 20200519_193153.jpg
    20200519_193153.jpg
    3.7 MB · Views: 14
So update...

Old axle is out and I compared to the H2 axle sitting here... Everything measures out to matching up fine. Since I plan to do a full upgrade in the near future to the suspension I am just going to reuse the factory parts at this time.

I will be bolting up the H2 rear end after I get off here. I wanted to reread this thread to see if I was missing anything.

I have an older H2 rear end and the bolt holes line up fine. The holes for the bolts appear to be the same as my stock 1500. Maybe even slightly smaller so I will just be reusing my original bolts. Thanks to the OP I already have a shorter driveshaft sitting here with new 1350 balljoint.

I have included pictures of these rear ends. My 1500 is at the bottom, the H2 is on the top in the first one. In the second one I am taking the picture from the other direction so they are swapped. You can see where the shock mounts on the H2 rear is more under the upper arm mount and is at an angle. I will remove my shocks all together and see how it lines up once mounted. I MAY have to make a bracket to fit the top section of the shock. Since I plan to totally redo the suspension when I retire a year and half from now I don't want to do anything permanent to the frame or to the rear end.

While doing this job I will also be fixing the fluid leak between the transfercase and transmission, repair the leaky transmission lines, pull front cv axles replacing them with stubs in the front hubs.

I have been told conflicting stories on removing the front drive axle. I have been told it can be removed and run without it with no issues. I have also been told this is not the case and I need the axle in place when the truck is running. Since I will be pulling the axle anyhow to do the transfer case gasket If I can leave it off I would rather do that. I would likely end up dropping the front differential out all together for now at that point until i decide what I am doing up front.

My truck came with 3.73 gears and this H2 has 4.10 gears. So I need to disconnect the front diff until I decide my next step.
Any updates on your build
 
Other than make sure it has oil in it. Mine didn't and I blew it up in short order. Ended up spending $1000 for another one shipped to a rear end shop and them installing it. They didn't even slot the bracket for the shocks like I did. They said the shocks were a little tight to get in there but they got them in.

I have a set of H2 variable rate springs I will be installing shortly along with 5100 Shocks made for 3" lift. The rear end on its own raised the rear of my truck about an inch. The new springs will raise about another 2 inches. Just waiting for my car to get done. I also need to source a lifted compatible brake line for the rear. The one I have now needs to be replaced and it I might as well go with a longer one. I replaced my original brake lines with stainless and on the H2 rear the drivers side works ok. The passenger side is too long and I need to have it shortened or have a custom one made. The locker works well. I just need to figure out a place to but a switch and run the wire to it. Just need a +12 volt and ground to go to it.

Have the 2 piece spacer/adapter on the front that got me to the 8 lug up front but this one probably requires a special lugnut. I bought short ones to fit but they are too wide. Ended up shaving the sides down on a socket to fit the hole.

Do have the original rims I had on my truck up for sale. Have some that were powder coated black and just trying to get them out of my storage now.

Have engine in the engine shop getting redone. The new one, 6.6L previous Lq9. Truck should have a bit more power with a 6.6L newly built engine over the 300k mile 5.3 currently in needing an O ring. Guy I am talking with would like to put an LSA blower on this engine and see if he can get 1000 hp out of it... WIll be looking at transmissions for that.. Probably 4l80e. Checking on 6l90E.. May need its own controller for the 6l80E. We shall see. Hope to have the engine work done in the next year. Still needs some rust repair to get it back to its old self. Rockers are totally gone. But a decent truck to replace this is $35k + so I will just fix this one for now. Still considering a 2500 but not sure if I want to stay with Avalanche or go with something newer. Want to pull a 5th wheel which would require a "tow buddy" to make work with the Avalanche.

Still trying to find out about the 3/4 front Knuckles. May just go to a local parts store and check them out. Get a new lower knuckle, get the bigger ball joint installed and upgrade the front. Wonder if 2500 brake systems can be upgraded with brakes from newer trucks.
 
Last edited:
Other than make sure it has oil in it. Mine didn't and I blew it up in short order. Ended up spending $1000 for another one shipped to a rear end shop and them installing it. They didn't even slot the bracket for the shocks like I did. They said the shocks were a little tight to get in there but they got them in.

I have a set of H2 variable rate springs I will be installing shortly along with 5100 Shocks made for 3" lift. The rear end on its own raised the rear of my truck about an inch. The new springs will raise about another 2 inches. Just waiting for my car to get done. I also need to source a lifted compatible brake line for the rear. The one I have now needs to be replaced and it I might as well go with a longer one. I replaced my original brake lines with stainless and on the H2 rear the drivers side works ok. The passenger side is too long and I need to have it shortened or have a custom one made. The locker works well. I just need to figure out a place to but a switch and run the wire to it. Just need a +12 volt and ground to go to it.

Have the 2 piece spacer/adapter on the front that got me to the 8 lug up front but this one probably requires a special lugnut. I bought short ones to fit but they are too wide. Ended up shaving the sides down on a socket to fit the hole.

Do have the original rims I had on my truck up for sale. Have some that were powder coated black and just trying to get them out of my storage now.

Have engine in the engine shop getting redone. The new one, 6.6L previous Lq9. Truck should have a bit more power with a 6.6L newly built engine over the 300k mile 5.3 currently in needing an O ring. Guy I am talking with would like to put an LSA blower on this engine and see if he can get 1000 hp out of it... WIll be looking at transmissions for that.. Probably 4l80e. Checking on 6l90E.. May need its own controller for the 6l80E. We shall see. Hope to have the engine work done in the next year. Still needs some rust repair to get it back to its old self. Rockers are totally gone. But a decent truck to replace this is $35k + so I will just fix this one for now. Still considering a 2500 but not sure if I want to stay with Avalanche or go with something newer. Want to pull a 5th wheel which would require a "tow buddy" to make work with the Avalanche.

Still trying to find out about the 3/4 front Knuckles. May just go to a local parts store and check them out. Get a new lower knuckle, get the bigger ball joint installed and upgrade the front. Wonder if 2500 brake systems can be upgraded with brakes from newer trucks.
Honestly didn't expect a response, thanks. That is an awesome build you're working on, I don't need it that tough but was looking to do the h2 rear, 4l80e, and an lq9 bored out to 6.5 then sleeved back to 6.2.
 
Honestly didn't expect a response, thanks. That is an awesome build you're working on, I don't need it that tough but was looking to do the h2 rear, 4l80e, and an lq9 bored out to 6.5 then sleeved back to 6.2.
Just heard back from the Engine shop today. They are going to paint the black Orange for me and the oil pan and valve covers will be "hammered grey". Should look interesting in the bay of my truck.
 
Just heard back from the Engine shop today. They are going to paint the black Orange for me and the oil pan and valve covers will be "hammered grey". Should look interesting in the bay of my truck.
Well would love to see pics when done
 
How close are you to getting the beast back on the road? Also, let us know when you get an estimate on the rockers. Bumblebee has developed a serious case of body cancer and I too would like to have it correctly repaired vs. buying something new.
 
I am driving the truck now. Just that it has the o-ring knock and 290k miles on it. I pulled my 4600 lbs caprice from one storage unit to another. with the tow dolly was probably 5000 lbs and was hard to tell the car was even back there. The engine is done and they are painting it. I will be talking to the mechanic this next week to figure out a parts list that he will need to get ready to work on the truck. I need to finish transfering stuff from one storage to the other this week so I can pull the truck off the road and get the job done. I have H2 rims that I need to have power coated and new tires put on them. I plan to leave for Texas in January so we will see if I have the truck all done or not by then with the new motor and tires/rims. Putting 33's on it and it looks like may need to do some trimming. Stock size rubs with 2" spacers on them that adapt the 8lug to 6 lug. The 33's are a little taller than stock.

The truck will be off the road about 2 weeks to have the engine swapped, then dyno tuned. Putting E85 compatible injectors in it but will wait until I upgrade the fuel system for the blower later next year before I move to E85.
 
Back
Top