I ha e an 03 jeep grand cherokee vibration that comes in at 45 then goes away only to come back at 70. I've had the tires rebalanced checked the u joints front hub bearings and the driveshaft has all the weights and is not bent. I need help asap. And thanks in advance for any suggestions

 

It could be one of the tires is starting to get a knot on it or even broken radial belts in one tire. The front tires on four wheel drive vehicles are also prone to shock cupping, a series of scallop type wear patterns in the tires which will usually show up as vibration before they become really apparent to the eye. A worn out steering damper shock can also cause some weird symptoms in the steering as can a bad alignment. When you take the front tires off next time check for stuck caliper sliders and mud buildup inside the wheels, and visually check for a bent wheel when they run on the spin balancer.

 

I've rotated the tires to see if that changes anything but have not had a chance to drive it and see. And do you think the rear ball joint having some slack would cause it.

 

Anything is possible I guess but the rear suspension would be way down on my list of possible causes. 99% of vibration problems have always originated in the front end or front tires in my own experience. These Cherokees are pretty sensitive to T Bar and damper problems and any uneven treadwear or cupping/blistering of the tires is going to shake the front end a lot more than you would think. I know on mine the front end had severe death wobble in it when I bought it and the main culprits turned out to be a bad steering damper and a slightly bent wheel. Moving the wheel to the rear stopped the problem and you could barely feel any shake at all. I went ahead and replaced both the wheel and the damper though to avoid future problems.

 

Also there are I think 4 tie rod ends particularly the one on the axle side of the pitman arm, very hard to detect unless you have someone turn the wheel while you have your hand on it and feel it click. That one was the very last part I changed in the front end and the difference was huge.