Lifted Caddy throws me around over bumps, uneven roads,

[iamdub]

Factory bar with the lifts brackets. Fabtech brackets are a lot more beefy and bigger than the RC was but it didn't change this problem. Tried to get a quick pic of the bracket. The angles of everything are good.View attachment 348857

As the others have mentioned, and as you should already know, things are gonna get hairier the taller you go due to the raised center of gravity, etc. But, it sounds like you're describing a lateral "wallowing". At that height, you have to minimize any movement other than straight up or down. This is the purpose of the sway bar and its end links and the panhard bar.

I see the axle side panhard bracket to raise the mounting position there. But is there a frame side bracket to lower that end? You want the panhard to be as parallel with the axle as possible. The more of an angle it's at, the more it can initiate a lateral oscillation when the rear end cycles up sharply, as when hitting a bump/dip. This would be worse if you hit a bump/dip on the driver side.

Also, the factory bar is stamped steel and flexes. This could be helping the situation by absorbing some of the shock rather than transferring it to the frame. But it could also be making it worse from the reduced control.

I'd get a solid panhard, like the Spohn or whatever other(s) there may be. I'd also make brackets to have the bar sit as parallel as possible.


Them extra long sway bar links look kinda spindly and could be flexing, reducing the effectiveness of the sway bar. I'd get some extra beefy links and poly bushings. A firmer aftermarket sway bar would be a nice upgrade, too.

 

[Mordechai]

What you describe is pretty much normal for any lifted vehicle, or any stock vehicle with a high seating position. Geometry: the farther up you go, the more side to side distance your seat travels for each degree of roll.

Stiff anti-roll bars can make this felt even more because the motion in response to uneven surfaces is more rapid.

A stiff suspension on a low vehicle is nice and sporty, but you’re close to the roll axis and you don’t feel much movement.

If you have any experience with larger boats or ships, this is exactly the same phenomenon. Down on the lower deck motions are small. Climb up in the crow’s nest and it’s a wild ride.

Since being thrown side to side hard is apparently your biggest complaint, I’d disconnect one or both swaybars and test drive it. Cautiously. Are there upgraded poly bushings or other harder than normal components in the roll bar bushings or links? Sounds like you need a softer suspension, not a stiffer one like many upgraded struts etc. are designed for.

Yes I have poly bushings all around and poly end links up front. Without them the body roll was miserable.

 

[Mordechai]

You just raised your CG 6 inches....what do you expect?

Take the lift off and pull your big boy pants up....

Wow, mature response.

 

[Mordechai]

As the others have mentioned, and as you should already know, things are gonna get hairier the taller you go do to the raised center of gravity, etc. But, it sounds like you're describing a lateral "wallowing". At that height, you have to minimize any movement other than straight up or down. This is the purpose of the sway bar and its end links and the panhard bar.

I see the axle side panhard bracket to raise the mounting position there. But is there a frame side bracket to lower that end? You want the panhard to be as parallel with the axle as possible. The more of an angle it's at, the more it can initiate a lateral oscillation when the rear end cycles up sharply, as when hitting a bump/dip. This would be worse if you hit a bump/dip on the driver side.

Also, the factory bar is stamped steel and flexes. This could be helping the situation by absorbing some of the shock rather than transferring it to the frame. But it could also be making it worse from the reduced control.

I'd get a solid panhard, like the Spohn or whatever other(s) there may be. I'd also make brackets to have the bar sit as parallel as possible.


Them extra long sway bar links look kinda spindly and could be flexing, reducing the effectiveness of the sway bar. I'd get some extra beefy links and poly bushings. A firmer aftermarket sway bar would be a nice upgrade, too.

There's no lower bracket it just sits in the factory location. I have another set of end links that look a little beefier but are about an inch shorter so wasn't sure if longer meant better lol. But ill definitely check out the Spohn stuff. How hard is it to align the new panhard bar once installed? Also yeah its kind of a wallow but often also will snap me from right to left. Hard to describe.

 

[swathdiver]

There's no lower bracket it just sits in the factory location. I have another set of end links that look a little beefier but are about an inch shorter so wasn't sure if longer meant better lol. But ill definitely check out the Spohn stuff. How hard is it to align the new panhard bar once installed? Also yeah its kind of a wallow but often also will snap me from right to left. Hard to describe.

Also, if this is an AWD, what condition are the mounts for the front differential? One of mine has a lot of play at twelve years old but the Yukon XL is at stock ride height.

You might also get some ideas from this fellow on youtube:

https://www.youtube.com/channel/UCRATb5DOxum-ZqsqFU2J6Qw

And do a search for @Tozan build page on this forum. There's another guy on here who doesn't post so much anymore, he's got one of those light blue 2011 Yukons with a pretty extensive lift and tires, he knows his stuff but his name escapes me at the moment.

 

[avalonandl]

Wow, mature response.

Well, not sure what you wanted. Physics is a pretty much a science. Six inch lift is alot....

 

[iamdub]

There's no lower bracket it just sits in the factory location. I have another set of end links that look a little beefier but are about an inch shorter so wasn't sure if longer meant better lol. But ill definitely check out the Spohn stuff. How hard is it to align the new panhard bar once installed? Also yeah its kind of a wallow but often also will snap me from right to left. Hard to describe.

You mean the other end of the panhard is hooked into the stock mount on the frame? I'm picturing the panhard being at a considerable angle.

As for the end links, you want the two rearward pointing legs of the sway bar to be parallel with the ground. So, however long the links need to be to achieve this is what they should be. However, if you have some links that are beefier, that one inch isn't gonna make any perceivable difference and you'd get more out of reducing the flex than anything.

The adjustable panhard just bolts in. With the stock one removed, the body should self-center over the axle (vehicle resting on the ground at ride height). Adjust the length of the bar so that you can insert the bolts and install it. Simple as that.

We can't guarantee any of these will fix your problem. We're just listing off the things we see that can contribute to instability. Address these things and you should at least see some decent improvement.

 

[swathdiver]

Thinking about this some more, when was the last time the inner and outer tie rods were checked and torqued to specs? They can cause wheel shaking and turning if not tight or within spec.

 

[imi4tth3w]

Do you have any pictures of where the rear track bar mounts to the axle? the bracket that re-locates that mount needs to be 1000% solid. If it can move, it will make the truck very unstable.

I'm planning on having mine welded into place soon as the bolts keep getting loose. I've got a 5" RC (it was originally a 7.5" but i lowered it to 5")

 

[Mordechai]

Also, if this is an AWD, what condition are the mounts for the front differential? One of mine has a lot of play at twelve years old but the Yukon XL is at stock ride height.

You might also get some ideas from this fellow on youtube:

https://www.youtube.com/channel/UCRATb5DOxum-ZqsqFU2J6Qw

And do a search for @Tozan build page on this forum. There's another guy on here who doesn't post so much anymore, he's got one of those light blue 2011 Yukons with a pretty extensive lift and tires, he knows his stuff but his name escapes me at the moment.

The front diff mounts are definitely in need of replacement but I'm not sure how they'd cause this issue. Thanks for the links ill check them out!