|
How to replace universal joints
Step by step instructions
Replacing universal joints is not
an extremely difficult process. Nor is it time consuming or require
expensive tools. If you want to stretch your mechanical abilities
beyond changing sparkplugs, changing universal joints might be the
perfect place to start. If you have average mechanical skills you
should be able to do it. Follow along as RepairNation.com shows
you how how to change a universal joint using common tools and the
tried and true hammer/socket method.
Step 1. Remove driveshaft
Before you begin, make sure the vehicle is in “Neutral” with the
parking brake applied and wheels blocked. With most SUVs and trucks
you can gain access to the driveshaft w/o having to raise and support
the vehicle on jackstands.
The driveshaft should be easily
removed using simple hand tools. Manufacturers use a couple of different
driveshaft mounting schemes but in almost all cases you just unbolt
one or more ends of the driveshaft. Often, the driveshaft requires
prying to remove from it's seat. Just stick a large screwdriver
between the U-joint and pry it loose. Be careful when the driveshaft
“pops” free, it’s heavy! Follow removal instructions in your repair
manual.
Step 2. Mark driveshaft sections
If the universal joint you are changing is connected to a driveshaft
yoke or another mounting piece, mark it and all sections with a
piece of chalk, paint marker, a punch or tape. It's important to
ensure that all sections are reassembled again in their original
location. This is critical because driveshafts are balanced from
the factory and misaligning components can result in driveline vibration.
Step 3. Remove retaining snap
rings
Most universal joints are held in place with snap rings. The snap
rings can either be internal (towards inside edge of driveshaft)
or external (outside edge of driveshaft). The snap rings usually
become covered with dirt and grease and my require some digging
to get at. Inside snap rings can easily be tapped out with a flat
screwdriver and hammer. Outside snap rings can usually be squeezed
together and removed with a pair of pliers.
| **Some manufacturers, most
notably GM, inject a plastic resin into the area around the
universal joint cap rather than use snap rings. The resin does
an excellent job of securing the universal joint - so much so
that it can be extremely difficult to remove the universal joint
by hammering alone. If you encounter an original GM resin-set
universal joint, heat the ends of the U-joint and driveshaft
with a propane torch (MAAP gas suggested) enough to melt the
resin, then tap out the U-joint while the resin is still hot.
Install new U-joint using snap rings. ** |
Step 4. Select the right sockets.
Take a look at your new u-joint and select two sockets from your
tool kit: One socket must
be slightly smaller in diameter than the bearing cap, the other
socket needs to be large enough so that the bearing cap will fit
into it.
Step 5. Tap out U-joint
Set the large socket on the
surface of your bench or cement floor with the open end facing upwards.
Then set the end of the driveshaft on top of the socket so that
the U-joint cap, when hammered downwards, can go down inside the
socket. You may have to hold the driveshaft to keep it on the socket.
Next, take the smaller socket and place it upside down on the top
bearing cap as illustrated in the picture. Hold the sockets and
driveshaft in position and give a few hard blows to the top socket
with the hammer. The idea here is that by hammering on the top socket
you will drive the U-joint down (out of it’s seat) into the larger
socket. It will take several blows and probably considerable force,
but you should see the U-joint slowly move out of it’s position.
Stop hammering when the lower cap is sticking 3/4 of the way out
of the driveshaft yoke. Generally you need to pull the cap the rest
of the way out with a large pair of pliers. It should come out fairly
easily at this point. Then, flip the driveshaft 180 degrees, seat
the U-joint into the cap that is partially pounded through and drive
the cap down the other direction as shown in the picture. You may
need to select a smaller socket for this process.
| **While it's true that hammering
on sockets isn't’t exactly doing them any good, hight quality
sockest should be able to handle the stress. Many prefer to
use an alternative method such as setting the drive shaft between
the jaws of a sturdy vise opened just enough to accept the U-joint
cap and hammer with a 3/4” diameter piece of hardened steel
rather than risk damage to one's precious tools** |
Step 6. Clean drive shaft end
Once all the caps are removed, pull the U-joint out and thoroughly
clean away all dirt, grease and grime from the end of the driveshaft
before installing the new universal joint. Take special care to
clean out the bores where the bearings caps go.
Step 7. Install new U-joint
Remove two of the bearing caps off the new U-joint, wipe the grease
off the shafts to prevent dirt from sticking. Carefully
place the new U-joint into the end of the driveshaft with one of
the U-joint ends sticking through the bearing cap bore. Slip one
bearing cap over the bore and onto the U-joint as shown in the picture.
Gently tap the bearing cap into the bore but hold onto the U-joint.
Apply constant light pressure on the U-joint towards the cap to
prevent any needle bearings inside the cap from being jarred loose
from hammering. Once the cap is flush with the surface of the bore,
use a socket to tap in a little further. You don’t have to hammer
the cap completely in place at this point, just get it close. We’ll
come back and hammer it in completely in a few moments.
Now, turn the driveshaft over, we’ll
install the other cap. Carefully pull the U-joint partially away
from the cap you just installed enough so that you can slip the
new cap over the shaft on the other side and near it’s bore. The
idea here is that by having the U-joint partially inserted in each
of caps at the same time the needle bearings inside the caps cannot
fall out of position. Gently tap on the second bearing cap and drive
it into it’s bore. Again, make sure to hold the U-joint somewhere
1/2 way between both caps so that hammering doesn't’t accidentally
knock the needle bearings out of position. Should a bearing accidentally
fall out of position, the caps won’t go in far enough to get the
snap rings on and you’ll have to remove the U-joint and start over.
If considerable force was used and a needle bearing becomes bent
the U-joint will not be usable and will have to be discarded.
If your driveshaft utilizes a mounting
flange that bolts to the rear axle or transmission, you will have
to install the other U-Joints into the flange in the same manor
as the driveshaft. Using the marks you made earlier, ensure the
flange and driveshaft are aligned in their original position.
Step 8. Install snap rings
Now that the caps are installed, let’s install the retaining snap
rings. Carefully tap the bearing caps to the point where the snap
rings can be installed. Use a screwdriver to tap snap rings in place
if necessary. When finished, check the U-joint for fit by moving
it back/fourth. It should move freely and not be excessively tight.
If it feels tight, one or more of the caps is installed too far
and you’ll have to adjust by working them out slightly. This can
be accomplished by setting the U-joint ends on two 2x4s set edgewise
as illustrated in the picture. Then, lightly tap on the driveshaft
near the bearing cap bore. Check fit again and continue until the
U-Joint moves freely with a minor amount of friction.
Step 9. Reinstall driveshaft
The last step is to reinstall the driveshaft the reverse order as
removal.
|
However, don’t be fooled into thinking you need a fancy press or
other special tools to do this job right. Many racers and accomplished
mechanics prefer to use the tried and true hammer method. The reason
is simple: The U-joint bearing caps fit precisely into a machined
bore at the end of the driveshaft. The slightest cocking of the
U-joint bearing cap during installation can stretch the bore and
potentially ruin a driveshaft. Hydraulic presses and heavy tools
eliminate the “feel” of the cap when it’s going into it’s machined
bore. Performing the job by hand allows you to “feel” the fit and
correct alignment if necessary.