Front end shake when in 4wd under load

[HARDTRAILZ]

Not when it was properly aligned. It will now that i did the trailside tie rod and needs aligned fully again. I dont have the awd sleeve fyi.

[hilljb]

I think this is almost certainly your CV axles.

Under torque (rotational acceleration), our CV joints will progressively get more shaky as they wear. It gets so bad that they'll shake even without 4wd engaged. A bad alignment significantly affects this. I usually off-road on grippy rock, so I probably experience this more than others as I blow through a set of CV axles roughly every year. They get worse and worse, eventually shaking under torque when I'm not even in 4WD... at which point they're usually spewing grease on my garage floor.

I'm about the replace and flip my UCAs... hopefully that will help, as others have mentioned. In the grand scheme of things though, the CV axles are relatively easy to replace. The Detroit axles seems to last a bit longer than others.

[rScherzer]

I think this is almost certainly your CV axles.

Under torque (rotational acceleration), our CV joints will progressively get more shaky as they wear. It gets so bad that they'll shake even without 4wd engaged. A bad alignment significantly affects this. I usually off-road on grippy rock, so I probably experience this more than others as I blow through a set of CV axles roughly every year. They get worse and worse, eventually shaking under torque when I'm not even in 4WD... at which point they're usually spewing grease on my garage floor.

I'm about the replace and flip my UCAs... hopefully that will help, as others have mentioned. In the grand scheme of things though, the CV axles are relatively easy to replace. The Detroit axles seems to last a bit longer than others.

I had no luck withe the UCA flipped, The alignment it good on mine. I have new front shocks and still shakes. I'm going to toss in a set of Detroit axles shafts to see what that will do. At least I will have a spare set just in case. First thing gotta get my road trip out of the way. Then I can get back under my TB.

[fallen angel]

I'd fully believe worn out axles would be the primary cause. Everything else is tight on mine, alignment is as good as you can get with flipped uca's. I have no grease coming from the cv's and they don't click/pop, but they are stock at 152000 miles, 39000 of those miles being lifted.

[rScherzer]

I'd fully believe worn out axles would be the primary cause. Everything else is tight on mine, alignment is as good as you can get with flipped uca's. I have no grease coming from the cv's and they don't click/pop, but they are stock at 152000 miles, 39000 of those miles being lifted.

Im thinking the same for mine as well. At least I hope. I have after market shaft in mine. Unknown brand as they were in it when I acquired the Trail Blazer at 140K. I don't always drive at WOT in four wheel drive, but when I do I don't care much for that shaking feeling.

[Mirage]

I've been following this thread and others like it and it seems no one has a definitive answer as to what would cause this vibration. Some say CV shafts, some say Disco, some say alignments etc. Here is my $0.02

I've had the same vibration for a while but I can't really say its been since my lift(2.5 Liftmeister) was installed nearly 3 yrs ago. In that time I've changed struts,ball joints (upper and lower). tie-rod ends (inner and outer) both front hubs. Three alignments (at different shops and the specs are the same) and just recently my disconnect (failed bearings due to lack of lube). None of these parts were replaced chasing the vibration but just through normal wear and tear and none have made any impact on the vibration. The only components not replaced are the CV axles. They are original to the truck but not what I would say is high mileage(180,000 klm/112,000 Mi). Due to the lift and the angle the axles rotate at the only logical conclusion is the axles are the source of my vibration. It is not major and doesn't affect 4x4 drive-ability but its noticeable. My passengers have yet to notice or comment so unless I have a need to replace my axles I will probably just live with the vibration.

[maybe2fast]

I have a 2006 Envoy Denali and I have it lifted 3" with 32s. I have been fighting this "only in Auto or 4WD" vibration for awhile. I replaced the uppers (not flipped) and front CV axles...still there

only in Auto or 4wd under acceleration, I get a pretty significant vibration.

[HARDTRAILZ]

Can you share your specs from your alignment after lifting please?

[maybe2fast]

I dont have specs.

I have chanced this shake for along time and dont understand the interaction with auto and 4wd. You can accelerate as hard as you want in 2wd with no ill effects.

[HARDTRAILZ]

It’s the engagement of splined disco.

I bet an alignment will fix it though.

[Trail X]

If you can tell us the relative frequency of the vibrations, it may help us understand the situation. Is the vibration at the same speed of wheel spin? Is it slightly faster (3x), significantly faster (6x)? Slower (1/2x)? Slow vehicle speed or high vehicle speed or both? Each may correlate to a feature of the vehicle. For instance, if 3x, then it would likely point to a tripod joint.

If I had to guess, I'd guess that your tripod joint on your passenger side has significant play (reach in and push up on the tripod housing with a lot of force, if you can move it more than say 1/8", you may need to rebuild your disconnect. Also, grab your CV shafts and try to muscle them around. If you have play in any of them, it may be time to replace a CV assembly. If you only have high speed vibrations then it may indeed be an alignment issue alone, in that you are hitting a resonant frequency of the steering system.

Get under there and start inspecting. Report back.

[maybe2fast]

If you can tell us the relative frequency of the vibrations, it may help us understand the situation. Is the vibration at the same speed of wheel spin? Is it slightly faster (3x), significantly faster (6x)? Slower (1/2x)? Slow vehicle speed or high vehicle speed or both? Each may correlate to a feature of the vehicle. For instance, if 3x, then it would likely point to a tripod joint.

If I had to guess, I'd guess that your tripod joint on your passenger side has significant play (reach in and push up on the tripod housing with a lot of force, if you can move it more than say 1/8", you may need to rebuild your disconnect. Also, grab your CV shafts and try to muscle them around. If you have play in any of them, it may be time to replace a CV assembly. If you only have high speed vibrations then it may indeed be an alignment issue alone, in that you are hitting a resonant frequency of the steering system.

Get under there and start inspecting. Report back.

I will check the "tripod housing"

only in 4wd or Auto under slightly heavier than normal acceleration it feels like I have oval front tires. 2wd its completely normal.

CV shafts were replaced with no change.

[Grimor]

If it helps, I've had pretty bad vibration in 4wd under load on pavement since I swapped to a new AWD disconnect. No amount of alignment has fixed it.

[rScherzer]

If it helps, I've had pretty bad vibration in 4wd under load on pavement since I swapped to a new AWD disconnect. No amount of alignment has fixed it.

I would assume that most of us that have lifted the T.B. are going to experience this to some degree depending on the wear and tear components. I'm lucky enough to have access to a few high-end tools to isolate it. After I found out what was wrong I just learned to live with it.

[HARDTRAILZ]

It would seem to be the decent thing to share this information you derived with your high-end tools.....