We have a 2008 Aspen with 35000 miles on it and get an intermittent vibration at highway speeds. Once it starts it is constant at all speeds and then will just go away. You first will feel it in the footfeed and then the whole vehicle will have a vibration like an out of balance wheel. Sometimes it will last for several miles, sometimes just for a few and then it will just go away. It has done it at the beginning of trips and this weekend after driving 150 miles it started lasted about 5 miles and just quit. Is it possible that the AWD is trying to lock in and the dry pavements causes this?

 

Could be a suspension problem. I've also heard of vibration with a fouled plug under load.

Does it only happen when cyl deactivation occurs?

 

I had sort of ruled both of those out because of the fact it stays with you at any speed. Once it starts even if you really get into it (I should have mentioned it has the hemi engine) is stays with you until it just quits.

 

Sticky caliper piston? Lightly tap the brakes the next time and see if it goes away (or gets worse).

Engine mounts?

I'm leaning towards shocks, because the stock shocks SUCK on this vehicle. Most are dead by 40k.

Does it go away if you put the vehicle into neutral? Trying to eliminate major issues...

 

I'm having sort of the same issue with my 08 Limited Hemi too. At 62-65 mph a slight vibration is felt in the footwell and seats - no steering wheel shake. 3X on the Hunter road force balancing machine at a very reputable shop (recently got new tires, but the vibration was there before that I attributed to the old out of balance tires) and each time the new tires come back dead on. Had new shocks put on all around (Monroe Reflex) and no improvement. Any suspension components I can easily check (with tips on how to to it and what to look for) by jacking it up? - ball joints, tie rods, driveshaft, etc.

Thanks. Maybe between the 2 of us we can figure it out.

 

I had the same issue. I went to the dealer and they did a road force balance. It did not solve the I went to another dealer and the service adviser said that whoever does the road force better know what they are doing. They did the road force balance and the vibration went away. Just my $02.

One more thing, before I did the road force balance, I also read about driveshaft issues.

 

As my previous post, I felt a vibration at 62-65 mph in the drivers floorboard. I swapped the driver's side front and rear tires and the floorboard vibration was now felt slightly in the seat at the same speeds. This suggested to me that the drivers front tire (now on the rear) was not balanced properly as per fledda's suggestion. Had the questionable tire road forced balanced again (same shop, different tech) and now all is smooth. Finally found someone who knew what they were doing with the road force balance.

 

In all fairness, the 20s on the Aspen are a real PIA to balance. The last time I got new tires, the tech shook his head in defeat when he saw the wheels.

 

If the tech "shook his head in defeat" I would be moving on to a reputable tire installer. Talk with folks at car shows who they use. Foreign car enthusiasts (higher end cars) tend to be rather picky who they let touch their cars.

 

They better get used to them. 20s are the new 18s. 20s come OE on a lot of cars and trucks. I know the OE 18s are cr@p tires anyway (SRAs). Mine were all out of round when new. Luckily, GY let me swap them out (gave me full price for them) for a set of new Silent Armors. They are great -- except for MPG. My next set will be LRR.