U-Joint Lubrication

Contributed By: Michael Baxter

Just a reminder that it's time to get out your trusty grease gun and grease-up the U-joints. Having never submerged my U-Joints in water (there's not a whole bunch of deep water crossings around here) and making sure they get greased every year are the sole reason why I still have all my factory joints. Properly set-up quality (Spicer) U-Joints should last you...or say 165,000 miles at least (that's the mileage on the Wag.).

As a review on the proper way to grease them: Use Extreme Pressure (EP) grease that isn't too thick. Don't use lithium based grease unless you've changed the joints and used it initially. Not supposed to mix greases and Jeep used EP grease at the factory although, I've found that any grease is better than no grease.

A good grease gun is required and you'll need a "needle" adapter for the end of the hose in addition to the standard zirk adapter. The needle adapter will attach to the end of the hose and they look like an oversized needle. You should be able to find one at a automotive tools or a good size auto parts store.

You can use the needle adapter to grease all the fittings if you don't want to crawl out and swap them when you run out of standard zirk fittings. But, a manual grease gun with a needle adapter requires either ingenuity or three hands to operate. One hand to hold the needle tight in the hole, one to hold the grease gun and one to pump the handle. However, I have done it with a manual gun and only two hands in the past and if I can figure-out how; you can too.

Luckily, I now have a air driven grease gun as well as a good manual one and I use the air gun for the hard to reach fittings (read the Double Cardan joint).

I start at the back and work my way up front. You can start anywhere you want. My garage floor is flat and I can roll the Jeeps along to expose the zirks/cups but, you may have to jack yours up so you can turn the drive train. Jack both ends if it's Full-Time FWD.

Take a rag or two along when you dive under there. If you can gain access (you can't always), clean each zirk/cup fitting off with the rag before you grease the fitting.

On the rear drive line, you'll have three fittings to grease (unless you have a LWB truck with an intermediate shaft...in that case more fittings). One zirk each screwed into one of the saddles on the cross of each U-Joint. Just pump the grease gun until you hear a "pop" noise or you see grease just starting to emerge from the cups. The "pop" is the air being displaced by grease.

The third zirk on the rear shaft is on the slip joint. Connect the grease gun, and then pump while watching in the saddle of the "U" at the very end of the tube. Essentially looking through the U-Joint at the beginning of the driveline. When you see grease start to come out of the vent/overflow hole at end of the tube stop pumping. Then stick your finger up in there and plug up the hole (oops...three hands with a manual gun again) and continue pumping until you see grease start to emerge around the splines at the slip joint.

Do the very front U-Joint and the front drive shaft's slip joint the same way.

Now the Double Cardan: This is the fun part. First, if you don't know what a Double Cardan cross is just crawl under there and find the single driveline joint that looks totally different from the rest. It's a constant velocity joint and it is essentially two U-Joints in one.

Don't skimp on this joint! Especially if you have a Borg-Warner Q-T. If you ever loose that joint at highway speeds, it'll take your transmissions case with it. You'll find yourself at the junk yard asking for a new case. The junk yard owner will know why your there and charge accordingly. He's seen a lot more like you in the past.

The Double Cardan has three grease fittings. At least one of them will probably be the cup style. The cup style fittings are "cup" shaped and the have the steel check ball right at the bottom of the cup. On my Cherokee, all three are the cup style. I've seen others in the past that had regular zirks on the crosses and the only cup was the one in the middle.

These three fittings can be hard to find (especially on the BW Q-T FSJs). It's tight around the joint. They get covered with grease and dirt and it always takes me a little searching to find them. A good light is a necessity.

Grease the fitting on the crosses just like the other U-Joints. Until you hear a "pop" or start to see grease coming out of the cups at the end of the crosses. I should've better defined "grease coming out of the cups" before. I'm taking about the cups at the end of the crosses in the U-Joints that contain the needle bearings and not the cup shaped zirk fittings.

The rear most cross in the Double Cardan is the hardest fitting to find, clean and grease. On my '79s (BW Q-Ts), I can usually get it using the needle while it is at a 45-60 degree angle from straight down. But the zirk/cup pointing straight down is not out of the question though. You may be able to get at it through one of the holes in the cross member (which are intended for this very purpose).

Right in the center between the crosses, there are two holes 180 degrees apart. At the bottom of one of those holes will be a cup type fitting. You will (unless you are an Ape) have to position the fitting so it points straight down and then push the needle & hose through one of the holes in the cross member. You'll also need to get your head in just the right location to be able to see the fitting while your greasing (I believe you'll be looking through another hole in the cross member). You have to be able to see the cup to be able to tell if you have the needle seated properly. If it's not seated just so, you'll pump a bunch of grease into the middle of the joint and it's hard to clean it out of there. Pump until you see grease emerging elsewhere in the joint (not around the cup). You are all done.

The real reason I did wrote this is because i want someone to console with. I hate doing this chore every year. I get a little better every year at doing it and it pays off in the long run. So, hurry-up and do it so you don't all have to live vicariously through me and my miserable experiences.

BTW, I learned the proper greasing technique from an old guy at my favorite tranny shop a few years back. Mainly the part about plugging the hole with your finger so you can force grease up to the spline.

-- Michael Baxter
From Reno, NV USA on 21-Apr-1997 at 13:00:54 PDT