Vibration at 70mph

[NickCG01]

Hello all,

Got an issue I can’t seem to pinpoint. I have my 03 Tahoe, all the u-joints were replaced and everything is balanced but I am experiencing a vibration under my seat at 70mph. Has 152,000 miles on it.
Possibly transfer case going bad? Any ideas?

Thanks,
Nick

 

[CJ Rodarme]

Is the alignment good? Is it a 4wd? Original hubs?

 

[Woodblocker55]

Tires can do some crazy stuff rotate and reevaluate where the shaking is. If it changes it might be a tire.
I had a viberation on car only at 45 and I thought it was a tranny issue shifting etc . Only took about trying everything come to find out it was a tire that bulged right at seem where it was bonded together Michelin ...changed tires was perfect . Don't let cheaper fixes be over looked is my new model.lol

Sent from my LGL84VL using Tapatalk

 

[Erickk120]

Hello all,

Got an issue I can’t seem to pinpoint. I have my 03 Tahoe, all the u-joints were replaced and everything is balanced but I am experiencing a vibration under my seat at 70mph. Has 152,000 miles on it.
Possibly transfer case going bad? Any ideas?

Thanks,
Nick

Wait, so did you 40mph go away and now you have it at 70mph? Or are you dealing with multiple? Balancing tires is the easiest, after that you can try to chase it else where if it didn't go away after that.
Vibrations could be caused by anything rotating at the right frequency.

Drive shafts/Hubs/CV's/tranny/Tcase/Diffs/Bentwheels/Out of round tire/fallen weights/ I would say most of the time it ends up being tires followed by the ds that has been worked on. What kind of a vibration is it also, is it booming, or just pure vibration? Driveshafts usually have the booming effect, hard to miss as its a unique noise accompanied by vibration around the seat area, I'm also in the same boat with an E150 that I haven't had the time to check out, it vibrates around 65mph and it is smooth at around 75+ mph.

One last question, by having everything balanced did you mean tires and drive shaft, or just tires? As I've mentioned before too. Make sure the ds is in the correct phased orientation, I know I've said this several times but mine vibrated at the same speeds you describe and it boomed while deceling 70-80 range give or take.

 

[Jim Clifford]

Had the same problem ... it was the CV joints

 

[Big Mama]

Had this at 75 mph it was the uneven tire wear from bad alignment.

 

[MartyMcFLy]

Hello all,

Got an issue I can’t seem to pinpoint. I have my 03 Tahoe, all the u-joints were replaced and everything is balanced but I am experiencing a vibration under my seat at 70mph. Has 152,000 miles on it.
Possibly transfer case going bad? Any ideas?

Thanks,
Nick

Are there any check engine lights? Check the fluid in the transfer case (top it off until it is right beneath the plug). Do the same with the rear diff.

 

[InterceptorF]

I'm having a similar issue with my 2003 tahoe LT. I replaced the transfer case in 2017 with a rebuild and last year the wife blew the transmission which I replaced with a rebuild from AAMCO which has been working great but last week the button went to "4-auto" and would not switch. I loosened the bolts on the encoder and got it to switch to 2 wheel but it went back to 4 auto after some time. Also after some time the "Check 4X4" lit on the info screen. What I am also noticing is at 70 + mph the Tahoe starts vibrating slightly and it feels like the t-case output shaft or the rear drive shaft where it connects has a slight wobble. I haven't looked any closer yet but if I let off the gas the sound its making changes. Things I am suspecting... low fluid, loose mounting bolts to trans, bad encoder motor (making the computer try to do the 'auto 4x4' stuff), failing bearing in the T-case, drive shaft out of balance or possibly the front u-joint on the rear drive shaft but I'm pretty sure I have already replaced that u-joint last winter. Any other ideas are welcome. I am hoping the T-case is just low on fluid at this point and will be looking closer in the next few days but will keep updating this post on what I find.

 

[S33k3r]

I'm having a similar issue with my 2003 tahoe LT. I replaced the transfer case in 2017 with a rebuild and last year the wife blew the transmission which I replaced with a rebuild from AAMCO which has been working great but last week the button went to "4-auto" and would not switch. I loosened the bolts on the encoder and got it to switch to 2 wheel but it went back to 4 auto after some time. Also after some time the "Check 4X4" lit on the info screen. What I am also noticing is at 70 + mph the Tahoe starts vibrating slightly and it feels like the t-case output shaft or the rear drive shaft where it connects has a slight wobble. I haven't looked any closer yet but if I let off the gas the sound its making changes. Things I am suspecting... low fluid, loose mounting bolts to trans, bad encoder motor (making the computer try to do the 'auto 4x4' stuff), failing bearing in the T-case, drive shaft out of balance or possibly the front u-joint on the rear drive shaft but I'm pretty sure I have already replaced that u-joint last winter. Any other ideas are welcome. I am hoping the T-case is just low on fluid at this point and will be looking closer in the next few days but will keep updating this post on what I find.

The last post on this thread is from 2019... You might want to start a new post. Otherwise, please do share what you found.

 

[InterceptorF]

So I put the 2003 Tahoe up on jack stands and noticed that with the '4-auto' button lit that the front driver tire and the back tires would rotate (but not the front passenger tire?). I tapped on the t-case encoder with a hammer and got it to shift to '2wd'. I heard the front differential motor unlock the front tires but it then went right back to '4-auto' on the button. At this point I suspect the t-case encoder motor so I removed it from the t-case and played with the dash buttons. The system intermittently would go into '2WD' and I could hear the front diff motor working but the encoder motor did not do anything. By the end of the trouble shooting the led's on the switch buttons were not lit at all. I suspect a bad connection inside the t-case encoder motor assembly and have ordered a new one. I believe the vibration and sound that was coming from the T-case area was due to going 70+ with the front tires engaged and the t-case was vibrating due to the computer trying to 'automatically' run the t-case with the t-case not responding to commands. Saturday the new encoder motor will arrive and I will install and (hopefully) any signal the computer is depending on from the t-case motor will be good again and it will shift normally out of 4-auto.