Zr2 front suspension

[newdude]

7 hours ago, kylant said:

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)

 

 

 

85144997 is not "unavailable anymore", its currently on backorder.  ETA is end of March for stock.  

 

If you are trying to get one ordered, make sure you have a VIN for an AT4X HD or a ZR2 HD as a VIN is required to put an assistance case on it.  Don't give them your VIN, GM's system will reject it.  

 

 

You also state you show two different knuckles.  If you are seeing 85124366 and 85124365, those are for regular HD, NOT for ZR2/AT4X HD.  

Edited March 4, 2025 by newdude

[kylant]

2 minutes ago, newdude said:

 

 

85144997 is not "unavailable anymore", its currently on backorder.  ETA is end of March for stock.  

 

If you are trying to get one ordered, make sure you have a VIN for an AT4X HD or a ZR2 HD as a VIN is required to put an assistance case on it.  Don't give them your VIN, GM's system will reject it.  

 

ok, thanks. so it is still an active part number. 

i guess i will order all the known good part numbers

[kylant]

16 minutes ago, newdude said:

 

 

85144997 is not "unavailable anymore", its currently on backorder.  ETA is end of March for stock.  

 

If you are trying to get one ordered, make sure you have a VIN for an AT4X HD or a ZR2 HD as a VIN is required to put an assistance case on it.  Don't give them your VIN, GM's system will reject it.  

 

 

You also state you show two different knuckles.  If you are seeing 85124366 and 85124365, those are for regular HD, NOT for ZR2/AT4X HD.  

great, thank you. i was wondering why there was 2 sets listed for the at4x. obviously a mis-list

 

can you confirm the LCAs too?

[redwngr]

On 3/2/2025 at 7:46 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?

 

GM shows 2025 AT4X standard bed is 2.86" taller than 2025 AT4 standard bed.

 

2500 AT4 standard bed is same as other crew std 4wd 2500s.

2500 crew std bed 4wd is 79.82

 

 

For 1500s' AT4's are shortbed.

Crew 4wd short is 75.51", lifted crew short is 78.35, and AT4X is 78.65 

 

 

I find it interesting that a standard height 2500 is taller than a lifted 1500

 

[Epsilon Plus]

The parts list I posted on page 10 is the complete swap, front, rear, & skid plates. Look them up at parts.gmparts.com if you need to. Scroll down and check the fitment tab and look for chassis code ZRX

[OS RR]

On 3/3/2025 at 7:31 PM, Epsilon Plus said:

 

You should see it on 37s. It's a monster.

 

Need some walk around pictures.

[Epsilon Plus]

Towering over a lifted JK Rubicon on 35s. If I stand next to my bed, the top rail of the bed is at my Adams apple. I'm 6'2".

 

Stock ZR2 height with 37*12.5x18

[TS423]

For those that have swapped knuckles, what torque spec did you use on the caliper bracket bolts? Im seeing anywhere from 100 ft lbs to 221 ft lbs. I didnt see it listed with the other torque specs that @Epsilon Plus listed..thank you btw. 

[Epsilon Plus]

221lb/ft (300nm) with thread locker for front and rear according to GM service documents.

[kylant]

22 hours ago, Epsilon Plus said:

Towering over a lifted JK Rubicon on 35s. If I stand next to my bed, the top rail of the bed is at my Adams apple. I'm 6'2".

 

Stock ZR2 height with 37*12.5x18

can you post pics of the cv axle and tie rod angles? thanks

[GATORB8]

45 minutes ago, kylant said:

can you post pics of the cv axle and tie rod angles? thanks

Stock ZR2

[Epsilon Plus]

[kylant]

thanks guys. 

those LCAs look slightly different, maybe it's just the camera angles.

 

are the endlinks different on the x/2?

[GMCnewbie]

Finally gonna do the suspension swap on my '24 AT4.  Parts have been sitting in my garage since mid-Nov.  Weather should be nice next weekend.  New wheels/tires are on order and should be here in the next week or so.  I also went ahead and bought the Cognito Comfort Ride torsion bars and leaf springs.  Not sure what to expect from all of this, but I'm excited to dig into this project.  I decided to do the Cognito parts simply because I don't plan to haul super heavy loads anytime soon.  A 22% loss in capacity shouldn't affect my usage much at all.  That and the fact that I got a really good deal on my truck last year from the dealer that even after ordering all these parts and wheels, my out-the-door price on the truck and parts included is still less than MSRP.  That's how I'm gonna justify it in my head at least.  lol

 

I'll post pics next week when it's all wrapped up.  

 

On a side note, I apparently ordered a pair of the rear suspension spacers that for the Zr2 only according to the GM parts diagrams.  I clearly wasn't paying attention when I placed my order.  Let me know if anyone needs/wants them.  I think I paid around $100 for the pair.  Not sure what GM is charging for them these days.

[Epsilon Plus]

Are you doing the full front/rear swap? Technically, you'll have a ZR2 after and will need them. What spacers are these that you refer to?