4 Wheel Drive/SUVs/Vibration

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Expert: - 10/15/2004


Question
Dear Sir,
I have a 1998 5.9 Grand Cherokee, I have already had the Hybrid shaft and frontend diff rebuilt (just for history sakes) I get a nasty vibration which seams to come from the rear end at about 50 mph and at other speeds as well, iot tends to happen when  I'm on the throttle but as soon as I let off it goes away, I have also just had the rear shaft U-Joint replaced the thing is the replacemnet U-joint isn't the correct one,( it's for a dodge 2500 )it fits but there is some "play" in the bushings.   when I called the Jeep dealer the say the u-joint is specific for that year Jeep, and nobody seems to have the part number or have the correct one except for the dealer.  So I guess my question would be with just a little play in the drive line would that make the whole car vibrate like that or could it be comming from some where else, like the transfer case for instance, but I would think that if it was comming from the transfer case I would feel that under my feet or in the shifter.  
any help would be great.
Thanks
TJ Goosley

Answer
TJ,

The u-joint must be the right one, and has to be tight.  Any play at all, will give you a vibration.  This can, also ruin bearings in the transfer case, and rear end.  I would contact some different shops, and see if you can find the right u-joint.  If not, then call another dealer.  If you can't find one that can give you the part number, then I would suggest that you contact the Jeep corporation itself.

Carl

4 Wheel Drive/SUVs

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Carl Brandt

Expertise

Will discuss suspensions, lifts, lockers along with tire suggestions. Trail ratings and possible requirements needed for specific type of trails. Safety equipment and what you should carry with you. Certified off-road instructor. I am not a mechanic, and 4-Wheeling is a hobby, so if I can't answer a technical question it is due to my mechanical knowledge being related to vehicles that I have owned, or have worked on. I do not have manuals on all vehicles.

Experience

40 plus years of 4 wheeling in a variety of vehicles. At the present time, my major off-road rig is a 94 Jeep Wrangler with a spring over and a 1 1/2" suspension lift. This gives me a total lift of 7" or so. I have lockers front and rear. I have removed the track bars, and sway bar for maximum articulation. I am running a stock 2.5 ltr 4 cylinder with a Jacobs ignition along with a cold air high flow filter. It has 4.56:1 gears with a Dodge NV4500 transmission along with a 3.8:1 Atlas II transfer case. This gives me a final ratio of 105:1 in low gear/low range. Other vehicles I own, are a 96 Ford F-250 with a 6" lift, posi rear end, 36" Hummer tires, 5 speed with a fuel injected 460 ci engine, an 87 Samurai with an 8" lift, Ford 9" rear end with a spool, Chevy Dana 44 front end with an electric locker, 5.88 gears, 16% reduction in high range and a 6.5:1 low range with 35" Baja Claws, and a stock 2003 Grand Cherokee Overland. Trails I have run are the Rubicon (10 times), Dusey Ershim, Fordyce Creek trail, McGrew trail, several trails in Moab, Utah along with local monthly runs.

Organizations
Lost Coast 4x4's Cal 4-Wheel Corva UFWDA Blue Ribbon Coalition

Education/Credentials
Certified off-road instructor - Certificates in engineering/electronics

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