[mike16]

u joints, come with needle berings and grease fittings, needle bearings and no fittings, and no bearings and no grease fittings


u joints needle bearings and grease fittings, weakest in terms of strength but that is relevant, in normal use and proper servicing they can easily last the life of the vehicle. in terms of strength they are very stong and rearly fail, usually in off road aplications with extream angles of drive shaft and hi power hi torque.

u joints needle bearings no grease fitting. the holes drilled through the centers of a u joint are drilled there to transfer grease to each set of needle bearings, those hole, when dilled are percieved as weakening the u joint. These u joints dont have grease fittings and those holes are not drilled. They are used in hi torque drag / racing aplications. after a race they are disassembled , inspected and repacked with fresh grease. so servicing them under those conditions , is not problem. the added strength is important but only under very adverse conditions, they must be serviced like normal needle bearing u joints, they just dont have the convient grease fitting.

u joint no bearings nor grease fittings, yep they are out there, rather than a needle bearing they have maybe a bushing, sometimes the bearing surfaces ride directly upon the oposong bearing serface. requires grease between races and carful servicing, extream duty and short lived.

use the best grease approved, grease on a periodic basis and before extream use and after extreame use. worn u joints cause vibrtions that can damage transmission bearings and transfercase bearings(if you have a t221 rockwell transfercase this is important) If you pressure wash tour drive train, grease it up first, wash it then grease it up again.

greasable u joints and mobile 1 grease, ...for ever. if your u joints are failing and you are servicing them properly then ther may be an alignment/ vibration problem somewhere else in the train. if not that then extream angles of the drive shafts. ya gotta fix this otherwise you'll be doing u joints and eventually drive shafts alot and out on the road and triail.