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 | Regular performance of this procedure is especially important on the front driveshaft. That is because every time you hit a bump in the road, your driveshaft will compress and extend. This is a lot like a sawing motion. On your rear shaft the driveshaft is always turning and circulating the grease around. But on the front shaft, because it is seldom used at high speed, this sawing motion will wipe out the grease film, allowing for metal to metal contact and accelerated wear as compared to the rear shaft. Many people complain to driveline shops of the short life of their front driveshaft even though they "hardly ever use four-wheel drive."
Hardly ever using four-wheel drive is, in fact, a big part of the problem. We suggest that you periodically engage the front hubs or put the transfer case into four-wheel drive mode without the hubs engaged and drive for about 30 minutes at a relatively high speed. By doing this on a regular basis, you should also be able to notice any problems that may be in their infancy on the front shaft. | |
| If you have a double cardan (C.V.) type of driveshaft, grease fittings are usually present, although short of removing the driveshaft, they may be difficult to see and impossible to get to. On a Spicer type of C.V. driveshaft, there will usually be a flush type grease fitting for lubrication of the center pivot point. The problem is, when the C.V. is opened where it would be accessible, this fitting is at the top of the shaft where you can't see it. If you turn the shaft until the fitting is at the bottom, the knuckle closes up and you can't get to it. The only viable solution I know of is to disconnect the driveshaft at the transfer case end, drop it down and grease it then. This should be done at least twice a year.
Of course, most of us use our Jeeps for much more than the occasional trip to the ski lodge. We continually build problems into our vehicle while trying to improve its performance in other areas. Taller tires, differential changes, higher horsepower engines, suspension lifts and transmission swaps will all effect the life of the U joints and driveshaft. With many of these modifications, there is no "factory approved" solution.
Suspension lifts are the single biggest factor in unacceptable driveshaft and U joint life or performance. Most lift kits only address the issue of elevation. The truth is, most suspension lifts adversely effect proper driveline geometry -- especially on short wheelbase vehicles. We need that lift, though, to upgrade our suspension and to get the clearance required to accommodate taller tires.
What can we do? | 
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