Dana 44 Front Hub Grease Nipple Installation

The internal-spline Dana 44 front hub uses two tapered roller bearings, and a seal at the inboard end of the hub. At the outboard end of the hub is a drive-in cap that can allow water to enter, bringing grit along with it. Adding to the problem is the large volume of air in the hub. If the warm hub is driven into cold water the air contracts quickly, lowering the pressure inside and drawing water in. The way to minimize this effect is to reduce the amount of air in the hub by replacing it with grease.

This drawing is from the 1978 Jeep factory service manual. Other manufacturers used different parts, but on full-time axels the arrangements are similar.

Hubs with lockouts will be different outboard of the outer bearing. Depending on the design, this mod may also grease the lockout components, but it will at least grease the bearings and fill the void between them. However you may need to remove the lockout when greasing the hub; there must be an open path for the grease and the air that it displaces.

For the grease fitting use a Plews 11-101 or similar nipple. It has a ¼?-28 thread and is 0.54? in length overall.

Tools

• The tools you should have for this modification:
• A good drill press (Even better, a vertical milling machine)
• ½? center-cutting end mill
• #3 drill bit
• 1/8? drill bit
• ¼?-28 plug tap
• Also nice ? a ¼?-28 bottom tap

Machining

Set the up hub on the drill press or milling machine table at a 45° angle. Make sure that it absolutely, positively can?t move. Otherwise things will break.

Put the ½? end mill in the chuck and get it aligned exactly at the center of the fillet between the wheel mounting surface and the cylindrical part of the hub, and exactly on the centerline of the hub. You might have to remove the brake rotor first.

Feed the end mill down carefully and slowly. It probably should be at the slowest speed your machine will run. There?s no need to hurry. No cutting oil should be necessary; the material machines very nicely, almost like cast iron.

C heck progress occasionally. When you cut to the bottom of the fillet, stop and take a depth measurement. Then go an eighth of an inch more. That will recess the nipple enough that it can?t get hit as the wheel is mounted.

Take your first measurement here.

Stop when you get here

If you have a center drill or spotting drill, make a starter dimple in the center of the flat. Then drill the #3 hole ¼? deep. If you don?t have a ¼?-28 bottom tap go a little deeper ? 3/16? should be plenty. Finally, chuck up an 1/8? bit and drill all the way through.

Next put the ¼-28 plug tap in the drill chuck and hand-turn the spindle, reversing it every full turn or so, until the tap is well started. Then mount the tap wrench and cut to the bottom. A sharp tap won?t break as long as you don?t put any side thrust on it. If you do, you will need a whole new box of how-to?s.

After tapping to the bottom of the hole with the plug tap, finish the threads with a bottom tap if you have one. Then blow the chips out of the hole, brush the burrs from the inside, and screw the nipple in. It should look like this when you finish, outside,

and inside the hub.

There?s no danger of hitting the nipple with the wheel. With a 4 1/8? center hole wheel, this is what it will look like.

The next trick is to drill a ¼? relief hole in the drive gear so that the grease can fill the volume between it and the outer bearing without building pressure inside. This isn?t as difficult as you might expect. A sharp bit turning slowly with a lot of feed force (160 RPM, .002? feed) will walk right through.

Assembly

Packed the inner bearing in the normal manner. Install it and the seal, and fill the volume between the seal and bearing with more grease. Pack and install the outer bearing according to the manufacturer?s procedure to insure that the preload is correct.

After the lock nut is installed, start putting grease in. You must use a non-locking fitting on the grease gun; the one you use to get to difficult U-Joints. That reduces the pressure that can be developed inside the hub, lessening the risk of inverting the seal and blowing grease out the back.

Eventually you will see fresh grease oozing out between the rollers of the outer bearing.

Next install the spring cup, spring, drive gear (positioning the relief hole down with the nipple up) and the snap ring, and add still more grease until it comes out the hole and oozes around the splines.

Finally fill the volume between the drive gear and hub cap with still more grease and put the hub cap back on.

After getting into water deeper than the hub, pull the cap and look for contamination. There won?t be much if any, but if there is wipe it out and pump fresh grease into the hub until clean grease comes out of the relief hole. That should be all the maintenance the hub needs for a long time.