2005 Yukon feels loose on the freeway

[Peeledpeas]

I've looked at everything I can think of and nothing appears worn out or loose with the suspension. But when driving on the freeway the whole vehicle feels unstable, like, swaying a bit in the rear end. The only real defect I can see is that the air compressor is not working for the auto ride suspension. The expensive rear shocks are in good shape and were replaced a few years ago. Could the compressor not working actually make the car unstable at freeway speeds? I've checked it all, wheel bearings, tire pressure, ball joints, tie rods, track bar, trailing arms....etc.

 

[Fless]

Two things I'd look at: do the jounce stops on the front end contact the lower control arms at ride height? They should since they are a fulcrum point in the suspension.

Any recent work done on the front end? Is the center link correctly oriented? https://www.tahoeyukonforum.com/threads/make-the-tahoe-new-again.131838/post-1645765

 

[rockola1971]

Check tires for a busted belt. I caught a nail in my Tahoe's rear passenger tire and it went through the belt. The belt exploded within the tire then steel wires started poking out the sidewall.

 

[Peeledpeas]

Tires are all good. Nearly new Coopers.

 

[Peeledpeas]

No recent work. A while ago I did and idler arm, tie rod and bearing/hubs and then got an alignment right after.

 

[Pressureangle]

I've looked at everything I can think of and nothing appears worn out or loose with the suspension. But when driving on the freeway the whole vehicle feels unstable, like, swaying a bit in the rear end. The only real defect I can see is that the air compressor is not working for the auto ride suspension. The expensive rear shocks are in good shape and were replaced a few years ago. Could the compressor not working actually make the car unstable at freeway speeds? I've checked it all, wheel bearings, tire pressure, ball joints, tie rods, track bar, trailing arms....etc.

Your airbags are deflated? Yes, this can cause wandering because the lowered rear end changes the caster of the steering. Also, check your steering shaft for play in the slider between the column and box.

 

[Peeledpeas]

Your airbags are deflated? Yes, this can cause wandering because the lowered rear end changes the caster of the steering. Also, check your steering shaft for play in the slider between the column and box.

It doesn't rely solely on air bags though. The shocks have air bags and it has normal springs.

 

[bill1013]

How are the swaybar bushings looking? My 1999 Tahoes bushings were just about gone which caused all kinds of problems. It felt like I was driving a big boat in rough seas at times. Replaced all the rubber bushings and stability returned. Just saying.

 

[Pressureangle]

You didn't say how many miles on it, so absent anything obvious I'll toss out some possibilities.
My '04 2500 is sensitive to tire pressure. The door says 80psi rear, 50 psi front but with the pressure that low in front it feels mushy. Your 1500 may like higher pressure than door specs. Easy enough to go to sidewall max and find out.
Idler arms are difficult to judge whether they're worn enough to contribute but they wear quickly relative to other parts if they're not greased regularly.
Rear spring bushings get loose, particularly in concert with loose u-bolts (unlikely but possible) I assume the 1500 has leaf springs? If coils, then you have control arm bushings to study. I don't know the steering shaft on the gmt800, but on the gmt400 the shaft itself wears and introduces a driftiness that is annoying and difficult to find. If you're high mileage, check the rag joint and shaft play. <shrug> that's all I got.