Source of vibrations at 40mph on deceleration

[land_shark]

I started feeling vibrations throughout my '05 3.7L when I slowed down as I rolled into Colorado Springs a month ago. I checked my tire pressure and found it had shot up to 55+psi (quite an altitude change from 700' here in Iowa). I had been fighting a crosswind the entire trip out, so I assumed I was experiencing the effects of some pretty severe cupping.

I adjusted the pressure, rotated the tires, and still felt the vibes. The problem was, they weren't happening all the time. It was only after I'd been driving a bit. I checked for play in the wheel bearings as well, and found nothing strange.

Took it to a great local shop (Lovetinsky's in Iowa City) and they found that the Ujoint to the rear differential was shot. 2 of the knuckles were completely dry and had fused. They installed a new joint (which has grease points), and it's good as new.

Thought you all might be interested. hope this helps.

Jason

 

[offrovering]

so did they rebuild your shaft with greaseable joints or did they install something else?

 

[land_shark]

They installed a new, greaseable joint. Not sure if the stock joint was greaseable...

 

[JeepJeepster]

Nope, its not. nothing on a stock liberty is greaseable..

 

[VTNomad]

Altitude

Altitude, even combined with temperature, won't affect tire PSI that much. Last year I was visiting family in Bakersfield, CA and drove up to Sequoia National Park. My family's driveway elevation is 150 feet above sea level, and the roads in Sequoia top out at about 7800 feet. I've also Driven from Denver, CO at approx. 5500 feet up Mt. Evans to an elevation of 14,252 feet (highest paved road in the US). PSI only changed by 4 PSI, didn't even trigger a TPMS alarm.

Running higher pressures in your tires will negate some of the cushion the provide, make vibrations stand out a little more. I keep mine between 30-35 psi when driving on the highway.