Lowering AT4 rear by 2"

[NonTypicalCPA]

I just picked up my AT4 this morning!  I'm coming from an '18 SLT which I put a 2" RC level in the front and sumo springs in the rear.  So stock, my AT4 front sits similar to my '18 up front with the level.  I like this height as I take off the running boards and can step into the truck comfortably.  I hunt and fish so my truck goes offroad, plus I plow my drive with my truck, but the stock front height is just fine for me.  I'm considering leveling the AT4 by lowering the rear 2".  Has anyone done this yet?  What is needed?  I'm guessing there is a block lift in the back that could be removed, but would I also have to change shocks?  Anything else?

[NonTypicalCPA]

Rough Country has a lowering shackle for the Sierra 1500 but they said it won't work on the AT4.  What's different?

[newdude]

This says not for use on Magneride:  https://www.roughcountry.com/lowering-shackles-rc0504.html?find=2020-gmc-sierra-1500-4wd-740563

 

Doesn't say they don't fit AT4/Trail Boss.  Both those and the regular 4x4 use the same p/n shackle.  

Edited September 23, 2020 by newdude

[mafd2]

I used WULF suspension shackles on my RST. Perfect fit and has 2 holes for 1 or 2" drop and grease zerk fittings. I'm not sure why shackles won't fit the AT4.

[Vigilante375]

There is a 2" block under the leaf springs so that's all that is needed to take off to make it drop 2".  The shocks should be ok but I'm not certain on that.  You might need to replace them with something else for a stock height truck.  Is this a 1500 or 2500?

 

What's the point of buying an AT4 when if you're just going to lower the rear and have it sit the same height as a Z71/X31?  Could have saved a bit of money by not getting it when the Z71/X31 since all you get is a 2" lift.  Yea you get all those camera's a HUD but that's stuff you can get in a higher trim, non AT4.

[Jim E]

Removing the rear levels the truck.  A non AT4/TB is 2 inches lower in the front.

 

Plus, unless I'm missing something, the HUD is only available in the AT4/Denali or High Country.

[Vigilante375]

Im sure. That's why I said higher level trim.

 

My ZL1 has it standard and I've used it a handful of times but since I wear polarized lenses, I can't see it. 

 

Ive used it on the track once and never paid attention to it. Used it on the highway a few times without sunglasses and hardly paid attention to it. 

[NonTypicalCPA]

I’m coming from a loaded, leveled SLT and the AT4 was the truck with the equipment I wanted plus I love the looks of them. I wanted less chrome on this one.  If I remove the rear block do I need to replace the shocks with a non AT4 version? 

[Delson0]

Did anyone end up removing the rear blocks? 

[Grumpy Bear]

On 9/23/2020 at 7:55 PM, NonTypicalCPA said:

I’m coming from a loaded, leveled SLT and the AT4 was the truck with the equipment I wanted plus I love the looks of them. I wanted less chrome on this one.  If I remove the rear block do I need to replace the shocks with a non AT4 version? 

No. Ask yourself why the rear is higher than the front? Answer. So when you are hauling the maximum payload the sticker allows the truck sits......LEVEL! Ergo it is designed that the rear shocks are in mid stroke when the truck is level.  

[Justinv113]

The shocks are longer on the at4. I replaced mine when I removed the block, but only due to the fact that i had king shocks from my old truck that fit perfectly after removing the block. I don't see any way for the stock at4 shocks to hurt anything if left in place, but if the suspension is completely bottomed out, then they may blow out. If they do get damaged, buy new ones that are the correct length for a non at4 pickup. Don't have much to lose. 

[Justinv113]

Side note: If you are concerned about damage from leaving the shocks on, you can simply leave the bump stop extension bolted on to the axle so the bump stop will limit the travel instead of the shock being the limiting factor. 

[AD80]

On 4/9/2021 at 10:13 AM, Justinv113 said:

Side note: If you are concerned about damage from leaving the shocks on, you can simply leave the bump stop extension bolted on to the axle so the bump stop will limit the travel instead of the shock being the limiting factor. 

I know this is an old thread, but did you have any vibrations or have to put a shim like the non at4 has, after you removed the blocks?