Bouncy ride

matt grz · December 13, 2024

Hey guys. I have a 2024 GMC sierra AT4 3.0 duramax. When I’m traveling at higher speeds the ride is crazy bouncy. It’s like driving a basketball down the road. I thought it was the crappy wrangler tires so I went to the dealer and had them road forced balanced. 3 out of 4 couldn’t be balanced and were replaced under warranty. I paid for the 4th one thinking well at least it’ll solve my problem.

Replacing and balancing the tires did nothing. It’s bounces crazy down the road at higher speeds. It might even be worse with the new tires. I’m at the point of hating driving this thing. Anyone else have a bouncy ride and figured out how to fix it? I have approximately 2500 miles on the truck and it’s been doing it since 0 miles. I figured well maybe things need to break in, but that doesn’t seem like the case. Thank you guys in advance.

Z45 · December 13, 2024

I know someone who bought the same truck back in 2023 and complained of the same bouncy ride. Could not take so he traded in for an 2024 SLT. Its the AT4 suspension, its off-road tuned.

Edited December 13, 2024 by Z45

matt grz · December 13, 2024

Do you think installing like the eibach pro truck stage 1 suspension solve the issue or would that be a waste of money and not do a whole lot on a AT4? I debated trading it in already as well to be honest but I owe way to much on it and just can’t take the hit right now.

I also thought about maybe just throwing a set of bilstein 5100’s just in the rears because it’s cheap and easy, but again I’m not so sure if that’ll do much for my issue.

asilverblazer · December 13, 2024

You have to better describe bouncy.

Does the truck continue up and down motion after hitting a bump, similar to a boat riding up and down waves? No individual impact is noticed.

-OR-

Does the truck hit a bump and experience one harsh hit without continual motion? Every little impact is felt as harsh hits and jars.

Easy things to check:

Tire pressure, no higher than the door sticker.

Easy things to change:

Shock absorbers, there is a bunch of talk about these but you first need to determine what type of suspension motion (spring action) you are trying to adjust.

Edited December 13, 2024 by asilverblazer

matt grz · December 13, 2024

It’s hard to explain and I don’t want to sound TOO dumb, but it’s kind of like a jackhammer type bounce. Not quite a vibration but many rapid small bounces. It’s like someone is rapidly dribbling a basketball very closely to the ground.

matt grz · December 13, 2024

It makes everything jiggle lol.

matt grz · December 13, 2024

21 minutes ago, asilverblazer said:

You have to better describe bouncy.

Does the truck continue up and down motion after hitting a bump, similar to a boat riding up and down waves? No individual impact is noticed.

-OR-

Does the truck hit a bump and experience one harsh hit without continual motion? Every little impact is felt as harsh hits and jars.

Easy things to check:

Tire pressure, no higher than the door sticker.

Easy things to change:

Shock absorbers, there is a bunch of talk about these but you first need to determine what type of suspension motion (spring action) you are trying to adjust.

Sorry forgot to hit the quote button on my above reply. Thank you.

redwngr · December 14, 2024

Tire pressure on the door sticker is the 'cold' pressure.

Pressure sensors will show that the pressure quickly increases as the vehicle is drive.

The tire and vehicle manufacturers knew this when they established the 'cold' pressure.

Are the wheels and tires the standard factory 18" wheels or the optional factory 20" ones? (or maybe something else)

'Jiggles' does sound like a vibration that might occur if something is out of balance.

GM dealers (are supposed to) have a scope that can be installed to measure the frequency of the vibration while the vehicle is driven.

Knowing the frequency should make it easier to identify the vibration source.

matt grz · December 14, 2024

9 minutes ago, redwngr said:

Tire pressure on the door sticker is the 'cold' pressure.

Pressure sensors will show that the pressure quickly increases as the vehicle is drive.

The tire and vehicle manufacturers knew this when they established the 'cold' pressure.

Are the wheels and tires the standard factory 18" wheels or the optional factory 20" ones? (or maybe something else)

'Jiggles' does sound like a vibration that might occur if something is out of balance.

GM dealers (are supposed to) have a scope that can be installed to measure the frequency of the vibration while the vehicle is driven.

Knowing the frequency should make it easier to identify the vibration source.

It has 20” rims with the duratracs. Adjusting tire psi up and down made no change. I’m leaning towards suspension. I know it’s an off road package but damnnnn so bouncy. It’s almost like the springs and or shocks are overly sensitive. Almost to the point of making me sick. Dealer states no lights no problems can’t reproduce operating as normal. Not wasting my time with those bozos unless a CEL comes on. I’m wondering if the Eibach stage 2 would clear up the bounce.

asilverblazer · December 16, 2024

On 12/13/2024 at 1:47 PM, matt grz said:

It’s hard to explain and I don’t want to sound TOO dumb, but it’s kind of like a jackhammer type bounce. Not quite a vibration but many rapid small bounces. It’s like someone is rapidly dribbling a basketball very closely to the ground.

It sounds to me like you are describing bumps and imperfections that are too small to compress the springs and subsequently too small for the shock absorbers too have any impact as well.

Your basketball dribbling is a very apt description - what is a tire if nothing vastly different from an air filled rubber ball?

Notice the difference in how a basketballs bounce changes based on the amount of air in it?

If you've lowered the air pressure and can't get the dribbling under control that way, the next suggestion would be to try different tires (and wheels with a smaller diameter).

Despite my comments above a softer shock may help some if the dribbling is sufficient to compress the springs.

Lastly it could be a combination of shocks, tires, wheels are needed to get the ride quality you want.

matt grz · December 16, 2024

22 minutes ago, asilverblazer said:

It sounds to me like you are describing bumps and imperfections that are too small to compress the springs and subsequently too small for the shock absorbers too have any impact as well.

Your basketball dribbling is a very apt description - what is a tire if nothing vastly different from an air filled rubber ball?

Notice the difference in how a basketballs bounce changes based on the amount of air in it?

If you've lowered the air pressure and can't get the dribbling under control that way, the next suggestion would be to try different tires (and wheels with a smaller diameter).

Despite my comments above a softer shock may help some if the dribbling is sufficient to compress the springs.

Lastly it could be a combination of shocks, tires, wheels are needed to get the ride quality you want.

Thank you. Air pressure had very little if any noticeable change. It sounds like it’s going to take some playing around on this one. Thank you again for the reply. Have a good day.

matt grz · December 18, 2024

Would it be ok to replace the rear shocks only or do you guys think I need to replace the rears and the fronts? I wanted the bilstein 5160’s but after so much research I’m thinking just going with the 5100’s might be ok. I don’t plan on off roading and if I did it’d be a slow ride down a cool road, nothing crazy or extreme so I’m thinking the oil chamber might not really benefit me at all. Am i thinking about this clearly or are there other benefits to the 5160 that I’m not seeing? My thinking is it’s for heat dissipation when off roading and doesn’t have much to do with additional ride quality right?

Port Tack Farm · December 18, 2024

The comments from @asilverblazer make sense. The imperfections in the road aren't enough to the compress the springs so the vibrations are being transmitted into the truck chassis and ultimately into your seat and your body. It probably has more to do with the stiffer spring rate in the AT4 vs other models and not so much with the shocks. The shocks just slow down or even out compression and rebound from the springs. Rather than trying replace the shocks with the hot name brand, I'd take it to a tire and wheel store that also specializes in suspensions and see what they suggest. Maybe take it to 2-3 places for opinions.

Joe Drives · December 18, 2024

Does the truck continue up and down motion after hitting a bump, similar to a boat riding up and down waves? No individual impact is noticed.

I had ^ this and resolved it with Rancho 9000's set about 7 in the front and 3 in the rear.

I had the dealer install and removed the factory Ranchos at 45,000 miles. It still rides like a truck but only bounces once instead of 3 or 4 times. I have a 2020 Silverado with the Z71 package, Michelin Defender tires installed at about 20,000, original size, from Costco on original 18" rims.

Edited December 18, 2024 by Joe Drives
spelling

xranger90 · December 18, 2024

So, you can't feel that bounce at low speed? A neighbor had a similar experience on his 2023 Sierra at around 40-60mph and it went away after installing the new tires from 4Wheelonline plus the alignment.

Edited December 18, 2024 by xranger90