Drop shackle vibration?

Snakes709 · July 5, 2021

I have a 2019 sierra at4 that I am removing the lift kit and lowering for multiple reasons, main one being my back injury and sciatic nerve constantly going crazy, which makes it hard to get in and out of the truck. I already removed the rear blocks, currently still have the rancho shocks still installed. I have bilstein 5100 front and back shocks/struts ordered for a base sierra, currently on back order until the end of the month. Talking to the custom department at the dealership about drop shackles to level the truck out once fully lowered, he mentioned ill most likely need shims because of a driveline vibration because im dropping that low. Didnt have time to fully discuss it so im wonder what shims and where do they get installed?

Edited July 5, 2021 by Snakes709

mafd2 · July 5, 2021

If you're just using drop shackles in the rear, you don't need shims. Just spin the existing shim 180° and that gives you the correct angle.

Snakes709 · July 5, 2021

26 minutes ago, mafd2 said:

If you're just using drop shackles in the rear, you don't need shims. Just spin the existing shim 180° and that gives you the correct angle.

I havent messed with leaf springs before. Where are said shims?

lowpro · July 5, 2021

Some good info/photos here:

Snakes709 · July 5, 2021

2 hours ago, lowpro said:

Some good info/photos here:

Sweet, thank you

Delson0 · July 5, 2021

That picture is w/o the rear blocks then?
How much lower are you wanting to go?

mafd2 · July 5, 2021

That thread is for lift blocks and not lowering and shims. Here's a pic of the shim (vice grips shown attached to the lower tie bolt and socket on the top). I have the 2" Wulff shackles on my 19 RST. There's a drop shackle thread on here. I'll find it when I have a chance.

lowpro · July 6, 2021

4 hours ago, mafd2 said:

That thread is for lift blocks and not lowering and shims. Here's a pic of the shim (vice grips shown attached to the lower tie bolt and socket on the top). I have the 2" Wulff shackles on my 19 RST. There's a drop shackle thread on here. I'll find it when I have a chance.

Obviously that thread wasn't talking about lowering but there is good info regarding shims which is what his last question was about...

Here is one on drop shackles specifically:

mafd2 · July 6, 2021

13 minutes ago, lowpro said:

Obviously that thread wasn't talking about lowering but there is good info regarding shims which is what his last question was about...

Here is one on drop shackles specifically:

I understand. Lift blocks do require an opposite pinion angle than lowering. My '19 RST didn't have any blocks and only a shim. I don't think the 4X4 has a factory shim.

Snakes709 · July 6, 2021

7 hours ago, Delson0 said:

That picture is w/o the rear blocks then?
How much lower are you wanting to go?

Yea that picture is without blocks but still with the rancho shocks. 2” drop front and i guess 4” drop in the rear as long as it doesnt cause any issues

dirtfan21 · July 6, 2021

I installed 1.5" rough country drop shackles on my 2020 4x4 RST and had the driveline vibration around 20-30 mph. My truck did not come with shims. I ended up pulling the drop shackles and went back stock for the time being. I now have 2 degree and 4 degree belltech shims sitting on the work bench at home, just haven't had the time to measure driveline angles and do the work.

It appears the u-bolts are one time use as well. Can anyone confirm this so the OP has the correct info?

mafd2 · July 6, 2021

3 minutes ago, dirtfan21 said:

I installed 1.5" rough country drop shackles on my 2020 4x4 RST and had the driveline vibration around 20-30 mph. My truck did not come with shims. I ended up pulling the drop shackles and went back stock for the time being. I now have 2 degree and 4 degree belltech shims sitting on the work bench at home, just haven't had the time to measure driveline angles and do the work.

It appears the u-bolts are one time use as well. Can anyone confirm this so the OP has the correct info?

U bolts one time use?

Snakes709 · July 6, 2021

4 hours ago, dirtfan21 said:

I installed 1.5" rough country drop shackles on my 2020 4x4 RST and had the driveline vibration around 20-30 mph. My truck did not come with shims. I ended up pulling the drop shackles and went back stock for the time being. I now have 2 degree and 4 degree belltech shims sitting on the work bench at home, just haven't had the time to measure driveline angles and do the work.

It appears the u-bolts are one time use as well. Can anyone confirm this so the OP has the correct info?

They are one time use but thats not an issue. There is a local shop that makes u bolts in 15mins for $30 (bolts and washers included). Thats what is installed right now so if I have to get another set made up, not an issue.

dirtfan21 · July 7, 2021

On 7/6/2021 at 10:18 AM, mafd2 said:

U bolts one time use?

Yes, torque to yield or in other words they stretch when torqued. Past generations our our trucks that was the case. Wasn't sure if the T1XX platform was the same.