Front End Shake in 4wd

[Ian Mills]

We recently got a bunch of snow where I live (Alaska) so I've been driving around in 4wd more. A few times in the last couple days I've noticed a back and forth oscillation in the steering when accelerating away from a stop in 4. It's kindof like death wobble but it stops as soon as I let off the gas and doesn't occur unless I'm fully stopped and all four wheels slip as I get going.

For context, I'm running 33x11.5 tires with -12mm offset wheels. So they're a bit more aggressive than stock but not giant or super heavy or anything.

 

I also have noticed that the steering is a little sloppy at speed. A small rut or imperfection in the road can cause the truck to want to wander. The alignment is good, I had it done recently.

 

Is this something to be concerned about?

[CamGTP]

A vibration with acceleration and goes away when you let off the throttle is usually a axle issue.

 

Pinpointing which front axle may be a little tough without a lift.

[Ian Mills]

Interesting, I'll look into it. I've had luck in the past putting the drivetrain in neutral, jacking from the frame, and being able to diagnose axles that way.

It's not really a vibration though. It really reminds me of death wobble except that it's obviously not a harmonic resonance issue because it goes away when I let off the gas.

 

EDIT: Also, it doesn't happen every time I accelerate. Only when I've been at a stop and all four tires spin together as I get going. If the tires don't spin as I accelerate, there's no vibration at all. 

Edited November 11, 2020 by Ian Mills

[sefiroxx]

Check alignment and wheel balance

[Ian Mills]

3 minutes ago, sefiroxx said:

Check alignment and wheel balance

The alignment should be good, I just had it done in the last month or so for other reasons. Would a wheel balance issue really pop up only in 4wd at low speed when the wheels are slipping? 

[sefiroxx]

Yes, especially if there is water in the tire. The certain weight at a certain speed will cause a vibration that disappears at spec increases or decreases.

[Ian Mills]

2 minutes ago, sefiroxx said:

Yes, especially if there is water in the tire. The certain weight at a certain speed will cause a vibration that disappears at spec increases or decreases.

But it's not speed dependent. It happens from 0mph until whatever speed I let off the gas and it only happens in 4wd when the front wheels are slipping.

Also, the tires are brand new so I doubt there's water in them.