sunny5280

More on my friend 2000 Grand Cherokee Limited...when driving to the mountains over the holiday weekend we noticed a high speed vibration which occurred at 65 MPH. The vibration is such the mirrors would vibrate to the point you could not see out of them and feel it in the seat. It was not the type of vibration one would experience with an out of balance tire (which we knew was not the case as they were balanced a couple of days before).

We spoke to a transmission shop (with great credentials) and they indicated it was likely the drive shaft or worn universal joints. Of course this was based of a description and no actual hands on diagnostics. Given we had just replaced the transfer case seals for both the front and rear axles we decided to take it back to the shop where we had that work performed. We wanted them to double check their work to ensure nothing worked lose or was not properly reassembled. They did so and everything looked good.

The owner took the vehicle for a drive and did notice the high speed vibration which he thought was drive train related as well. He put it back on the lift and had someone accelerate the vehicle to 65. He then checked for vibrations from various components (obviously not the moving drive train parts). His conclusion is the drive shaft and universal joints are fine and the issue was the transfer case. We got a quote to replace and said we'd give it some thought.

We then called the transmission place back to obtain a quote from them. They still believe it's a drive train issue and have recommended we remove the drive shaft and have it tested for balance. A cost of approximately $150.

We're confused as to what we should do. The mechanic who thinks it's the transfer case is a trusted mechanic (he's repaired my vehicles many times and I've never had a complaint with his diagnosis or work). However he specialized in German vehicles (I drive a BMW). He's also not a specialist in drive trains (though I think he's quite capable). On the other hand the transmission place specializes in this type of work and probably has a lot more experience in this area.

So after reading all this my question is: Has anyone had a high speed vibration and what was the cause? Thanks for reading this far if you have.

2Stangs

Sure sounds a lot like a driveshaft out of balance. I can't visualize any transfer case issue that wouldn't have some sort of other symptom that would cause an actual vibration. It could also be if the Jeep is lifted that the pinion angle is now such that, with some worn u-joints, you're now getting this vibration at speed.

Parts alone is about $40 and figure an hour or two of shop time, assuming they are actually going to balance the shaft, so the $150 quote is probably about right. Good luck!

sunny5280

Thanks. We're going to take it in today to have it tested. My mechanic will drop it for $50 and we'll be taking it to his drive shaft specialist to test the balance.

sunny5280

To follow up on this we had my mechanic remove the front drive shaft and we took the vehicle for a drive. Upon reaching 65 MPH we did not observe and vibration. Given this we had the drive shaft taken to a specialist who concluded the drive shaft required a rebuild. However we did not proceed with the work as she ended up buying another Grand Cherokee with 50K fewer miles and in much cleaner condition. So I can't confirm if the drive shaft really was the problem but there's a 99% certainty it was.

Hope this helps someone in the future.