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|The photos at the right are an example of a bad u-joint. The needle bearings had fallen out of the cup and the cross was using the cup as a bearing. Total failure of the cross, u-bolt, or yoke is likely if it is run for long in this condition.|
Fortunately, replacing a u-joint is usually fairly simple. Here is how
it is done.
| To change a universal joint, the driveshaft must be
removed from the vehicle. Soaking the u-joints and u-bolts with penetrating
oil for a few days will make disassembly easier.
Before removing the driveshaft, mark the yoke positions at both ends. When the driveshaft is reinstalled, each end should go back to its original position so that the shaft will be phased properly. If the driveshaft is improperly phased, vibration may damage the u-joints.
Remove the u-bolts (some vehicles use two bolts and a strap instead) at both ends. The bearing cups have usually rusted to the yokes and the driveshaft will not fall on you. With all u-bolts removed, pry the axle end of the driveshaft loose from the yoke and then pull the other end free.
NOTE: Some driveshafts have a double cardan type CV joint at the transfer case end. Mark the position of the flanges and then remove the flange bolts. The flanges will then separate and the driveshaft can be removed.
Manual hubs make it easy to break the front driveshaft bolts loose. Leave the case in 2WD, lock the hubs, and remove the easily reached bolts while the hubs hold the shaft steady. Then reach around, unlock one hub, rotate the driveshaft to access the remaining bolts, lock the hub, and then finish removing the bolts.
| First, a screwdriver is used to loosen the snap rings
by prying the ends out of the groove (right). This step is just to break
some of the rust loose, it will not remove the clip. Tapping on the clip
and bearing cap with a hammer and soft drift punch will also help loosen
the snap ring.
Then, use a pair of pliers to grip the ends and squeeze the snap ring enough to clear the groove (bottom left). Usually a rusted-in snap ring will slide out of the groove with a little persuasion from a screwdriver (bottom right). If you are lucky, the clip pops out (right). Remove the snap rings from both sides of the yoke.
Occasionally the ends of the snap ring will break off and you must cut the snap ring into pieces with a cold chisel and dig them out of the groove with a pick. This is every bit as much fun as it sounds!
| To remove the cross from the yoke, select a large socket
that will support the yoke flange and allow the cup to drop. In this case,
a 1 3/16" socket was perfect. Then drive the cross and cups down with
a hammer and a socket small enough to fit inside the yoke flange. A brass
hammer is easier on the socket, but not required.
When the cross bottoms on the yoke flange, the lower cup can be removed and discarded. Be careful not to damage the yoke by pounding the cross into it.
| With finesse, the cross can usually be wiggled out of
the yoke. If the yoke is too tight to allow this, turn the driveshaft
180 degrees and knock the cap out of the other side. Be careful to keep
the cross straight while removing the second cap or the yoke bore may be
|The yoke is cleaned and the retainer groove is scrubbed with an old toothbrush to remove rust and scale. Check for cracks in the yoke and remove any burrs from the yoke flange.|
| When the yoke flanges are clean, it is time to reassemble
the u-joint. Make sure the u-joint is oriented properly. The small caps
usually go into the yoke and the large caps are u-bolted to the axle or
transfer case yoke.
Lightly grease the yoke bores to aid reassmebly. If it was possible to remove the cross with one cap still attached (as shown above) remove one of the caps that will be installed in the driveshaft yoke. With the other three caps still installed on the cross, finesse the cross into the yoke.
NOTE: Make sure the needle bearings stay in place. Keep the needle bearings and the exposed end of the cross clean, or you will get to do this again!
Inspect the new bearing cap that was removed from
the cross to make sure that the needle bearings are in place. Carefully
align the cap with the exposed end of the cross and press the cap into
the yoke with a large vise or C-Clamp (right). NOTE: For maximum
u-joint strength, you want the zerk fitting to be under compression when
the driveshaft is turning to drive the vehicle forward. In the case of
this driveshaft, this shaft will rotate clockwise as viewed from the end
and the driveshaft yoke will be pushing against the zerk section of the
|Note: For u-joints that will not fit into the yoke unless both bearing caps are removed: First insert the cross without the caps, press one cap into the yoke, insert the snap ring, then turn the shaft and repeat on the other side.|
The completed u-joint is ready and the driveshaft can
be reinstalled. BUT, for an additional $12 you can replace the u-joint
at the other end while the shaft is out of the truck, so go ahead and
replace it too.
Last Update: February 21, 2000