Zr2 front suspension

[kylant]

stopped by the dealer yesterday to pick up some other part. 
i looked at the AT4Xs they had on the lot. they are huge. 

hard to believe they are only lifted 1.5" and have a 1" bigger tire on them than my AT4. 

 

are they really only lifted 1.5"?

 

in addition to the parts list, what about torsion keys? are they the same as the other HD trucks?

[GMCnewbie]

36 minutes ago, kylant said:

in addition to the parts list, what about torsion keys? are they the same as the other HD trucks?

My understanding is the AT4 and AT4X share the same keys based on part numbers that I looked up a while ago.  Granted, I have yet to do my conversion even though parts have been in my garage since Nov.  Hoping to take a few days off next month to work on this project.

[kylant]

1 minute ago, GMCnewbie said:

My understanding is the AT4 and AT4X share the same keys based on part numbers that I looked up a while ago.  Granted, I have yet to do my conversion even though parts have been in my garage since Nov.  Hoping to take a few days off next month to work on this project.

thanks

 

also this parts list is based off the ZR2. I assume the AT4x list is the same??
I am looking at all these parts right now, and keep seeing different part numbers listed for the knuckles in addition to the ones listed above?

 

you have all the parts already?

[GMCnewbie]

7 minutes ago, kylant said:

also this parts list is based off the ZR2. I assume the AT4x list is the same??
I am looking at all these parts right now, and keep seeing different part numbers listed for the knuckles in addition to the ones listed above?

 

you have all the parts already?

I do have the parts in my garage (knuckles, control arms, etc).  When I looked them up months ago, the parts for the '24 AT4X had the same part numbers as the ZR2 which makes sense as they're effectively the same trucks underneath the skin layer.  Now you have me wanting to go back thru the part numbers to make sure I didn't grab a wrong part.  lol

[kylant]

4 minutes ago, GMCnewbie said:

I do have the parts in my garage (knuckles, control arms, etc).  When I looked them up months ago, the parts for the '24 AT4X had the same part numbers as the ZR2 which makes sense as they're effectively the same trucks underneath the skin layer.  Now you have me wanting to go back thru the part numbers to make sure I didn't grab a wrong part.  lol

just trying to make sure before I start ordering parts. i have a'25 AT4.

[GMCnewbie]

11 minutes ago, kylant said:

just trying to make sure before I start ordering parts. i have a'25 AT4

I don't believe GM made any changes to the suspension for the '25 models, but you should absolutely verify all part numbers before purchasing anything.  I ordered my parts in Oct when GM was offering 35% off all suspension parts.  Not sure if they similar deals now.  I looked for deals online and found prices to be similar to the 35% from GM, but the online sites charged a ton for shipping.  I want to say i saved like $500 on shipping alone.  Something to keep in mind as you navigate this upgrade.

[KvetL5P]

2 minutes ago, GMCnewbie said:

I don't believe GM made any changes to the suspension for the '25 models, but you should absolutely verify all part numbers before purchasing anything.  I ordered my parts in Oct when GM was offering 35% off all suspension parts.  Not sure if they similar deals now.  I looked for deals online and found prices to be similar to the 35% from GM, but the online sites charged a ton for shipping.  I want to say i saved like $500 on shipping alone.  Something to keep in mind as you navigate this upgrade.

The key to save money on shipping is to limit your order size. Just do multiple orders. My shipping went from 500+ to 140 for 2 orders.

[GMCnewbie]

2 hours ago, KvetL5P said:

The key to save money on shipping is to limit your order size. Just do multiple orders. My shipping went from 500+ to 140 for 2 orders.

That's smart.  Didn't think to try breaking it up into separate orders.  

[OS RR]

4 hours ago, KvetL5P said:

The key to save money on shipping is to limit your order size. Just do multiple orders. My shipping went from 500+ to 140 for 2 orders.

 

Split up how? 2.. 3.. orders? Seperated heavier parts out?

[Epsilon Plus]

On 3/2/2025 at 5:46 AM, kylant said:

stopped by the dealer yesterday to pick up some other part. 
i looked at the AT4Xs they had on the lot. they are huge. 

hard to believe they are only lifted 1.5" and have a 1" bigger tire on them than my AT4. 

 

are they really only lifted 1.5"?

 

in addition to the parts list, what about torsion keys? are they the same as the other HD trucks?

 

You should see it on 37s. It's a monster. Parts list posted on page 10 is complete.

Edited March 4, 2025 by Epsilon Plus

[kylant]

in my parts research all the parts are lining up except the knuckles and lower control arms. i have searched 2 different AT4x VINS and both return 2 different sets of knuckles and lower control arms. 1 set are the part numbers listed here, the other is different. 

all parts are available except the passenger knuckle 85144997

several sites say that part is no longer available. confused as to what to get...

 

here are the parts listed:

driver knuckles: 85124365, 85144996 (listed here, confirmed)

passenger knuckles: 85124366, 85144997 (listed here, confirmed, unavailable any more)

driver LCA: 84735903, 85144990 (listed here, confirmed)
passenger LCA: 84735904, 85144991 (listed here, confirmed)

 

[GMCnewbie]

I can't speak to the new part numbers you found, but I purchased the original part numbers for my truck that you have listed -- 85144996, 95144997, 85144990, and 85144991.

 

I'll look them up again today to see what I can find. 

 

Note: just remembered you have a '25 model.  I'm pretty sure no changes were made to suspension with the new model year, but they could've made slight changes to those two parts specifically.  I recall one of the guys here mentioning there was a change to the knuckles between i think the '22 and '23 years or possibly the '23 and '24 years.  Can't remember which.

Edited March 4, 2025 by GMCnewbie

[GMCnewbie]

1 hour ago, kylant said:

confused as to what to get...

I looked up the new part numbers you found and came away confused as well as one GM parts site claims the parts don't fit the '24 or '25 model year Sierra HDs while other sites claim they do.  I'd suggest calling your local dealer and asking the parts guys to advise which part number are correct for your truck.

[kylant]

4 hours ago, GMCnewbie said:

I looked up the new part numbers you found and came away confused as well as one GM parts site claims the parts don't fit the '24 or '25 model year Sierra HDs while other sites claim they do.  I'd suggest calling your local dealer and asking the parts guys to advise which part number are correct for your truck.

both of the vins i used were 2025s. and i was looking on the actual gm parts website

[Epsilon Plus]

I would not trust a dealer parts rep. The only person I would trust and ask to help with this is @newdude .