A hum and a mild shimmy at highway speeds, what could it be?

racertracer · **Posted:** Tue Feb 05, 2013 2:54 am

I am experiencing a hum and a mild shimmy while traveling past the 75 MPH mark.

Any ideas as to what it could be?

arengant · **Posted:** Tue Feb 05, 2013 3:28 am

In your steering wheel?

I'd guess tire balance first. Check with swapping rear to front.

After that you can remove front driveline (if the boot is still intact) and see if it's still there.

After those two steps you might have an intermediate shaft problem.

Way too many posts in the 4x4 section to narrow it down to one cause with out more testing.
:2cents:

racertracer · **Posted:** Tue Feb 05, 2013 3:45 am

arengant wrote:

In your steering wheel?

I'd guess tire balance first. Check with swapping rear to front.

After that you can remove front driveline (if the boot is still intact) and see if it's still there.

After those two steps you might have an intermediate shaft problem.

Way too many posts in the 4x4 section to narrow it down to one cause with out more testing.
:2cents:

Not in my steering wheel.

Had the TC replaced last year by the dealer it gradually increased after that.

I'll check the tires.

Hoosier CRD · **Posted:** Tue Feb 05, 2013 6:21 am

Had a similar experience with my CRD. Turned out to be the tires, at that time they were Firestone Destination LE. I first rotated the right side (Right Front to Right Rear) which yielded no change. Then I rotated the left side and Presto ! It was the Left Front tire. Even though I had no adverse tread wear patterns and could not see any problems like a slipped belt, it still made a difference.

Switched to Cooper Discoverer A/T3 and it is now a much more confidence inspiring vehicle in adverse driving conditions. Hope this helps.

woodtick · **Posted:** Tue Feb 05, 2013 8:31 am

if it is a cyclical vibrationit could be driveshaft out of balance or not running true. if they dropped the driveshaft when servicing transmission they may have caused minor dammaged that has since deteriorated. I would check U joints for play. if thet need replacing consider having the driveshaft rebalanced.

racertracer · **Posted:** Tue Feb 05, 2013 8:46 am

woodtick wrote:

if it is a cyclical vibrationit could be driveshaft out of balance or not running true. if they dropped the driveshaft when servicing transmission they may have caused minor dammaged that has since deteriorated. I would check U joints for play. if thet need replacing consider having the driveshaft rebalanced.

Maybe so.

They replaced a seal around the transfer case where it meets the shaft at the same time that the tC was swapped ..... I don't remember the name of it.

woodtick · **Posted:** Sun Feb 10, 2013 9:16 am

racertracer wrote:

I am experiencing a hum and a mild shimmy while traveling past the 75 MPH mark.

Any ideas as to what it could be?

Racer, have you figured this out? If so, what was it?

racertracer · **Posted:** Sun Feb 10, 2013 9:27 am

Not yet.... but it's leaning towards the drive train because when I disengage the transmission and allow the vehicle to roll. the noise goes away.

woodtick · **Posted:** Sun Feb 10, 2013 9:49 am

is it a cyclical vibration?

racertracer · **Posted:** Sun Feb 10, 2013 10:03 am

Not sure.

It happens between 65 to 75 mph and it is less noticeable above and below that speed.

DOC4444 · **Posted:** Sun Feb 10, 2013 3:16 pm

If it goes away in that 65-75 range when you are in neutral, everything points towards having the driveshaft removed, joints checked and rebalanced.

DOC

racertracer · **Posted:** Sun Feb 10, 2013 3:21 pm

OK... that'll be in the list.

A hum and a mild shimmy at highway speeds, what could it be?

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