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2009 gmc envoy_slt
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153 Posts
Discussion Starter #1
Hi All
I don't know if this is related or not but a week ago I backed out of the garage in Full Time 4X4 and felt a clunk. (Icy driveway when driving into garage and wheels slipped so I engaged 4X4 and forgot to disengage). I switched to 2wd and all was fine as I drove away. Then about 2 hours later, I felt a vibration when between 40&50 mph like I was driving on rumble strips. I took it to a shop and the mechanic test drove & suggested brakes. I took the brakes apart and cleaned them up - all seemed fine and no change - new brakes about 40K ago lots of pad left and rotors look OK. Tires are now about 4 months ago so I don's suspect the balancing is out and all weights seem to still be there. Now when accelerating slightly between 30 & 40 mph I get a real bad rumble strip type vibration. If I let off the gas, the rumble goes away - give it a little gas and the rumble comes back. Feels like it is coming from the right front but it also seems like it could be a vib from the center of the vehicle so I suspect a drive train component. Steering wheel is fine during all this. Coasting downhill has no vibration either and applying the brakes doesn't change anything.
I'm taking it to a local mechanic next week to have a look on a hoist because I'm stumped. To me it could be: bearings, Front CV joints, Drive shaft U joints - hopefully not front diff or anything more serious - how do you diagnose where it is coming from? Any ideas? Safe to drive?
 

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2004 gmc envoy_slt
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2,239 Posts
U-joints would be high on the list. Also, when was the transfer case fluid changed? It is required to be changed every 50K miles.

An inspection of the drive train should reveal the source.
 

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2009 gmc envoy_slt
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153 Posts
Discussion Starter #3
I change the drive train fluids every 30K miles so it shouldn't be from a lack of maintenance. Appointment is on Wednesday - I think it is a U joint somewhere too. Hopefully an inexpensive fix.
 

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2009 gmc envoy_slt
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153 Posts
Discussion Starter #4
The local shop says it is the rear U joint that is loose and causing the vibration. They say the other U joints appear to be in good shape. $300. I'm glad I didn't try the DIY route as I would have replaced the front passenger side axle.
Problem solved - hopefully and the bank isn't broken.
 

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2002 chevy trailblazer_lt_ext
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8 Posts
could be a tire out of balance

Hi All
I don't know if this is related or not but a week ago I backed out of the garage in Full Time 4X4 and felt a clunk. (Icy driveway when driving into garage and wheels slipped so I engaged 4X4 and forgot to disengage). I switched to 2wd and all was fine as I drove away. Then about 2 hours later, I felt a vibration when between 40&50 mph like I was driving on rumble strips. I took it to a shop and the mechanic test drove & suggested brakes. I took the brakes apart and cleaned them up - all seemed fine and no change - new brakes about 40K ago lots of pad left and rotors look OK. Tires are now about 4 months ago so I don's suspect the balancing is out and all weights seem to still be there. Now when accelerating slightly between 30 & 40 mph I get a real bad rumble strip type vibration. If I let off the gas, the rumble goes away - give it a little gas and the rumble comes back. Feels like it is coming from the right front but it also seems like it could be a vib from the center of the vehicle so I suspect a drive train component. Steering wheel is fine during all this. Coasting downhill has no vibration either and applying the brakes doesn't change anything.
I'm taking it to a local mechanic next week to have a look on a hoist because I'm stumped. To me it could be: bearings, Front CV joints, Drive shaft U joints - hopefully not front diff or anything more serious - how do you diagnose where it is coming from? Any ideas? Safe to drive?
vibration at that speed could be a tire out of balance
 

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2009 gmc envoy_slt
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153 Posts
Discussion Starter #6
Apparently the vibration as I experienced is very characteristic of a bad U-Joint - not a tire out of balance or brakes/rotors. It would vibrate when accelerating and went away when coasting. I did go under the vehicle and tried to wiggle the U-joints prior to replacement (when it was bad) but there wasn't any movement so I didn't think it was a bad J-joint. I was wrong. I also remember some squealing a few months ago when backing up with the brakes on and though it was perhaps work pads - but when I had a look, they were good. Also the squeal is symptomatic of a bad U-Joint as well. Symptoms were there - I just didn't recognize them. Hopefully this helps others.
 
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