2018 Denali acts weird in rain?

Hello everyone, have a question for my parents about their 2018 Yukon Denali.

This Yukon has stock rear suspension, and the deleted Magneride kit up front, with a small level to raise the nose up a bit.

When driving in rain on wet pavement, the whole thing will suddenly start whipping side to side at random points sometimes. Not just the rear, but the entire thing.

Of course you would think tires, so they had a new set of Michelin tires put on. Finally got some rain today, and didn't take long to find out that wasn't the fix.

Seems like this would have something to do with suspension, since the tires didn't change anything, but I am not sure what it would be.

I wouldn't think a simple level kit would cause it, especially since it has been properly aligned again. Is there something up with the Magneride delete suspension kit that could be doing this? Or is there something completely different we should be looking at?

Anyone ran into this before?

@PG01 Pete?

Any messages coming up on the DIC while this is going on? How about Traction Control and Stabilitrak lights?

It only does this in the rain? Never while driving in any dry weather conditions?

What magnetic ride delete kit is installed up front?
What leveling kit is installed up front?

How many miles are on the SUV?
Are the sway bar bushings good?
Are the control arm bushings is good shape?
When was the last time it was aligned? An alignment and suspension inspection will tell you if there are worn out parts.

I would look into these items first.

88lance said:

Hello everyone, have a question for my parents about their 2018 Yukon Denali.

This Yukon has stock rear suspension, and the deleted Magneride kit up front, with a small level to raise the nose up a bit.

When driving in rain on wet pavement, the whole thing will suddenly start whipping side to side at random points sometimes. Not just the rear, but the entire thing.

Of course you would think tires, so they had a new set of Michelin tires put on. Finally got some rain today, and didn't take long to find out that wasn't the fix.

Seems like this would have something to do with suspension, since the tires didn't change anything, but I am not sure what it would be.

I wouldn't think a simple level kit would cause it, especially since it has been properly aligned again. Is there something up with the Magneride delete suspension kit that could be doing this? Or is there something completely different we should be looking at?

Anyone ran into this before?

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I would take it to a different alignment shop and have it checked (again) there isn't anything else that would cause that but steering/alignment
the only else I could even fathom is if maybe one side of the leveling kit is higher than the other like if it has a different size on the left and a shorter or taller one on right.
but even then that would just make it sit funky.
I would say the alignment is off a smidge

Can we get a better description than whipping side to side? The way I read that sounds like the vehicle is suddenly losing control but that doesn't match with the rest of what you typed. There's nothing on the vehicle that could act on the suspension in a sudden manner no matter what the magride or lack thereof was doing but the steering could. If it is the conditions or location causing it you would have to see something obvious on the road that caused something like that unless it was steering or grip related. If you are flooring it in the rain and traction control kicks on then you can definitely get some weird behavior but I would suggest that's an issue of user error and it not having supercar level of traction aids to overcome it.

So is the car rocking side to side or swaying or swerving or what? I really can't tell.

gtrslngrchris said:

Can we get a better description than whipping side to side? The way I read that sounds like the vehicle is suddenly losing control but that doesn't match with the rest of what you typed. There's nothing on the vehicle that could act on the suspension in a sudden manner no matter what the magride or lack thereof was doing but the steering could. If it is the conditions or location causing it you would have to see something obvious on the road that caused something like that unless it was steering or grip related. If you are flooring it in the rain and traction control kicks on then you can definitely get some weird behavior but I would suggest that's an issue of user error and it not having supercar level of traction aids to overcome it.

So is the car rocking side to side or swaying or swerving or what? I really can't tell.

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whipping side to side sounds like death wobble to me, anything else would result in pretty much crashing/loss of control period

Hello everyone, sorry for the late response. It only does it if it is raining and pretty wet, which is what made me think tires at first.
The Yukon has 102,000 miles.

The leveling kit is a 2" kit, and the struts are Arnott.

They mentioned that it doesn't have to be puddles, but it does have to have a lot of water on the road for it to do it.

The body doesn't seem to roll, it just goes side to side in front and back. No traction control lights or any other warnings. They said that they have to let off the gas and reduce speed to make it quit, and then once it quits, it's good to bring back up to speed again.

They mentioned that it is almost the same feeling of hitting a puddle, how it pulls the vehicle to the side, but it is doing it back and forth quickly, and will do it randomly, not just if there is a puddle that was hit.

So it seems to have something to do with handling in heavy rain, which makes it confusing that the tires didn't fix it.

I'm not sure when the last alignment was, or about swaybar and control arm bushings, so the alignment shop may be what needs to happen next.

I was thinking it wouldn't be as likely, at that mileage, but it's definitely worth a check. It makes sense that it sounds like something to do with suspension linkage not being tight.

They asked if it is possible that the lane assistance could be flipping out, but I kind doubt it would react that dramatically

88lance said:

sounds just like death wobble, when they take it in for the alignment have them tell the advisor it appears to have death wobble at speed, when wet out. they should be able to inspect for any worn parts and/or adjust it correctly.

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that occurs when the alignment is not quite right, it will drive normal up to a certain speed then begin to wobble back-n-forth, sometimes you can accelerate out of it but normally just letting off the gas and slowing down brings you back in control. a wet surface likely triggers it in there case

88lance said:

They mentioned that it doesn't have to be puddles, but it does have to have a lot of water on the road for it to do it.

The body doesn't seem to roll, it just goes side to side in front and back.

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This sounds to me like hydroplaneing with bad shocks. The rear shocks could be causing front to back motion. Have those shocks checked out.