Extreme body flex over bumps

[subieworx]

Hey guys. Have an 03 Yukon Denali shorty with 252k miles. Love this thing! I am having an issue though that I wanted to run by you guys to see if it is common and if there is a fix.

When driving down a road or highway (speed doesn't really matter, but it is a bit worse on the highway) if I hit a bump, like an expansion joint, at the same time with both front wheels the bump is felt and the truck traverses it well. However, if I hit a bump that is not perpendicular to the direction of travel and is say slanted 45* or so to where one of the front wheels hits it first and then the other a split second later the entire body structure feels like a wet noodle and there is visible and alarming cowl shake.

Can this be attributed to worn body mount bushings? Or is it just a problem with this chassis and the age? Any frame sitffeners out there?

For mods, I have had three different suspensions on it and I have felt this issue with all of the suspensions. Currently I have it lowered 2" on beltech lowering spindles and springs with Beltech shocks.

 

[retiredsparky]

You could inspect the body mount bushings you mentioned and also any suspension bushings that you have not replaced. Look at both front and back suspensions for excessive wear. It sounds like the control arm bushings have been replaced since you have lowered the vehicle. There are link bushings in the rear, sway bar bushings front and back. How old are the shocks?

Another alternative is to take it to a local suspension/alignment shop not part of a large sales oriented chain store organization.

 

[Rocket Man]

Sounds like swaybar problems to me, I'd check the end links and bushings.

 

[subieworx]

I've had two different sway bar sets on the truck in this time. Stock and Belltech. New endlinks on each.

 

[Rocket Man]

I've had two different sway bar sets on the truck in this time. Stock and Belltech. New endlinks on each.

Are they the correct length? If you're lowered you need shortened endlinks to keep the swaybars parallel to the ground or they don't work well.

 

[subieworx]

This really isn't an engine or drivetrain issue.

 

[Rocket Man]

This really isn't an engine or drivetrain issue.

Nobody suggested it was. It's obviously a suspension or steering problem. I wouldn't be looking at the frame either since our frames are stout. Also, I've never heard of our body mount bushings wearing out . The fact that it has to do with how it acts when it crosses a non-perpendicular bump or depression indicates to me it's a problem with the front suspension or steering or both.

 

[TheAutumnWind]

Nobody suggested it was. It's obviously a suspension or steering problem. I wouldn't be looking at the frame either since our frames are stout. Also, I've never heard of our body mount bushings wearing out . The fact that it has to do with how it acts when it crosses a non-perpendicular bump or depression indicates to me it's a problem with the front suspension or steering or both.

He is saying that because it is in the "engine or drivetrain" section.

 

[Rocket Man]

Doh. I didn't even notice...

 

[TheAutumnWind]

You could inspect the body mount bushings you mentioned and also any suspension bushings that you have not replaced. Look at both front and back suspensions for excessive wear. It sounds like the control arm bushings have been replaced since you have lowered the vehicle. There are link bushings in the rear, sway bar bushings front and back. How old are the shocks?

Another alternative is to take it to a local suspension/alignment shop not part of a large sales oriented chain store organization.

I be looking @ steering links including the box idler/pitman, control arm bushings front and rear, track bar, all of that including body mounts.

If we have eliminated all of those wear items I'd have someone check it over and see if there is frame damage or something that you are missing.

Asking how old are the shocks is a good idea, I have had shocks prematurely fail and chased that problem around with the assumption that "the shocks are pretty new those should be fine" in the past.

Another thought: get the alignment checked out. Is tire wear even?