Vibrate/Shimmy or giggles w on bumpy road.

Williehays01 · July 28, 2021

I have a 2021 GMC 1500 SIERRA SLT X31 WITH 4600 MI. When driving my truck on smooth surface the truck drives great, but as soon as you hit a bump or rough road the truck vibrates in the rear from side to side depend on the bump. Are there anyone experiencing the same thing in their new truck.

Phantom 4D · July 28, 2021

The back end is lighter. The off road shocks make the ride stiffer. So hitting a bump, at speed will cause the truck to "skitter". My 2019 SLT X31 does the same thing.

Wiggums · July 28, 2021

In my RST Z71, I've lost traction because of the violent judders in the back which sent my truck into a tailspin and I nearly hit a pedestrian. I don't drive it much anymore, it was going to be a truck for the ranch but now it sits there nine months a year. I will never drive it again.

Amcguy1970 · July 28, 2021

1 hour ago, Wiggums said:

In my RST Z71, I've lost traction because of the violent judders in the back which sent my truck into a tailspin and I nearly hit a pedestrian. I don't drive it much anymore, it was going to be a truck for the ranch but now it sits there nine months a year. I will never drive it again.

Hey I remember your posts, they were hilarious. Try slowing down and driving with caution. There should be no situation where you driving with any sort of normalcy should put pedestrians in danger and you spin a new truck with stability control.

OP, it is a truck with a live rear axle and bumps will throw it out of line if hit right at a descent speed, it is pretty normal with all brands. I have never driven a truck where there wasn't an occasion where the rear steps out a hair in the right situation but I am also driving mostly at a reasonable speed and paying attention to the road. Washboard roads this happens often at higher speeds with a slant or a slight curve. Different shocks can and do help as the stockers were made to handle a wide range of test environments. Either way, this video shows in an extreme (notice none of these trucks step out to spin out and almost hit a pedestrian) how live axles and leaf springs made to carry weight act in regards to bumps... I think trucks these days have gotten a little worse as they have much stiffer frames/body's and the suspension is designed to carry more weight to the suspension is stiffer in most regards. About the only way to really negate this is an IRS.

Tyler

c0ld29 · July 29, 2021

On 7/27/2021 at 8:54 PM, Williehays01 said:

I have a 2021 GMC 1500 SIERRA SLT X31 WITH 4600 MI. When driving my truck on smooth surface the truck drives great, but as soon as you hit a bump or rough road the truck vibrates in the rear from side to side depend on the bump. Are there anyone experiencing the same thing in their new truck.

21 hours ago, Wiggums said:

In my RST Z71, I've lost traction because of the violent judders in the back which sent my truck into a tailspin and I nearly hit a pedestrian. I don't drive it much anymore, it was going to be a truck for the ranch but now it sits there nine months a year. I will never drive it again.

Everyone who changes out their shocks to the billstein 5100s says it helps tremendously with this issue. One person changed out the rears only (quicker and easier) and said it helped with the rear end. I have a standard bed and driving on roads in Louisiana causes this to happen a lot. I definitely plan to throw some 5100s on this year.

Wiggums · July 31, 2021

On 7/28/2021 at 9:57 AM, Amcguy1970 said:

Hey I remember your posts, they were hilarious. Try slowing down and driving with caution. There should be no situation where you driving with any sort of normalcy should put pedestrians in danger and you spin a new truck with stability control.

Wasn't hitting gas or the brakes, and if you were paying attention, you'd notice others with the same RST with Z71 have reported this. I was the first to mention it because I was one of the first few with the same configuration. Had to deal with stupid people with different trucks chiming in on my driving habits. Hilarious? No, it was a dangerous situation and that should not have happened. This goes to show you I am not the only one.

I'm still putting you on ignore for thinking it's "hilarious" - you're not worth my time.

Edited July 31, 2021 by Wiggums

Wiggums · July 31, 2021

On 7/29/2021 at 5:48 AM, c0ld29 said:

Everyone who changes out their shocks to the billstein 5100s says it helps tremendously with this issue. One person changed out the rears only (quicker and easier) and said it helped with the rear end. I have a standard bed and driving on roads in Louisiana causes this to happen a lot. I definitely plan to throw some 5100s on this year.

I simply stopped driving it on the dirt roads (it first happened on a dry road with dirt caked on it from the rains) and I only use it on highway drives. I am aware of the Bilstein 5100, but it seems to be backlogged so I'm going to wait on this. I want to get all fours on that.

Acpantera · August 18, 2021

I only have a couple of hundred miles on my new RST rally package(big black 22 inchers). Now I'm a car guy and all the people around me are floored that I bought a truck, but most forget my first vehicle was a new 1980 black Chevy LUV 4x4 with white wheels, white roll bar and black tonneau, really styling in those days....lol. Anyways, I know it's a truck and the rear springs are real truck springs. I have just ordered Bilsein 5100 rear shocks and if that doesn't calm the rear end I'm going to take one leaf out of the spring pack(each side of course}, confident that will give me the car like ride I desire and if I need extra load capacity, air bags are an ez install that I have done before on my Astro"s back in the days of towing 4 snowmobiles and our family of 6.

Acpantera · August 27, 2021

So I put the 5100's on the rear and that was a big improvement, I'm pretty sure I'm going to put a set on the front.

I didn't study the fronts too hard but I'm wondering why most people are mentioning getting a front end alignment when changing the shocks out.

Do you have to pull the upper control arm off?? I know it's a coil over set up, but it's not a Macpherson strut.

AirForceAngler · August 27, 2021

24 minutes ago, Acpantera said:

So I put the 5100's on the rear and that was a big improvement, I'm pretty sure I'm going to put a set on the front.

I didn't study the fronts too hard but I'm wondering why most people are mentioning getting a front end alignment when changing the shocks out.

Do you have to pull the upper control arm off?? I know it's a coil over set up, but it's not a Macpherson strut.

Which version of the 5100s did you install? Do you have a part number and where did you get them from? Thanks!

JimCost2014 · August 27, 2021

On 8/18/2021 at 9:51 AM, Acpantera said:

1980 black Chevy LUV 4x4 with white wheels, white roll bar and black tonneau, really styling in those days...

Off topic, really like those little trucks! Think they were an Isuzu with Chevy badging.