XK150 Replacing front hub grease seals
   How to fit

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During a routine check under the car early in 2018, I noticed that grease from the left front hub was visible on the inside of the wheel rim. It was clear that it was time to remove the front hubs and replace the grease seals. It seemed like this task would be fairly routine, but not so ...

On dismantling the left hub, I found the felt seal looked in good shape. After removing the right hub, I found the most of the seal was missing!

front seals left and right

Yet it was the left wheel that had the grease on the inner rim. I know I had not greased the front hubs since I had owned the car. But I could not work out why the left hub was releasing grease. I am still wondering ...

The other stange thing I found when I pulled off the left hub was that the left seal shield was loose - it was not an interference fit in the hub's recess. On the other hand, the right seal shield was static in its hub recess, but it had not been fully inserted and it was a little proud of the hub's innermost face over about half its circumference. Perhaps it was a knife-trimming action on the felt seal over time as the hub rotated, that resulted in the remnant as visible in the photo above.

Here's how I assembled the felt seal and the seal shield ...

(In my case, I was replacing the bearings as well. I had an expert remove the old cups and fit the new bearing cups in the two hubs. I also found that the left stub axle was worn at the inner cone landing area and needed replacement - see stub axle removal tool here.)

First, buy new felt seals and new seal shields.

Ensure the edge of the turned-up shield rim is perfectly smooth and the inner edge of the rim is not sharp, to avoid cutting the stationary felt seal as the hub and shield rotate. Second, make sure the felt seal mating surface of the axle carrier is perfectly smooth and clean, but with a thick film of grease applied.

The felt seal should be not more than 8mm (5/16") thick. If it is thicker, use a blade to rim it to 8mm. Then soak it in thick oil (I used 140 grade) overnight.

The steel seal shield should be an interference fit in the hub recess. In my case, the new shields were a 0.4mm (16 thou) interference fit in the hub recess.

After placing the grease-coated inner bearing cone in the hub, test the shield concentricity by placing it lightly on but not in the hub recess. In my case, the hole in each shield was off-centre by nearly 1mm (40 thou). Not having a lathe, I had to file off metal over about 200 of the circle to provide clearance over the inner bearing cone's roller cage (see photos). Then after ensuring that all edges were free of burrs and not sharp, I tapped the shield into the hub recess, trapping the inner cone loosely in place.

  shield-as-supplied    shield-after-filing

For final assembly, squeeze the oil-soaked felt seal under a flat sheet, to force out excess oil. On reflection, this might be better done by placing the felt seal betweeen two sheets of flat plate, and then squeezing the vertically-oriented sandwich in a vice so the seal is about 4mm thick. Let the sandwich drip for 24 hours.

Liberally coat the faces and the outer and inner surfaces of the seal with high temp grease, and then place the seal in the shield.

At this point, it is worth pointing out that soaking the felt seal in heavy oil makes the seal more manageable. It is near-impossible to make a dry felt seal sit and stay within the shield recess.

At this point, all is ready to ready to mount the hub on the stub axle. The outer cone should be pre-coated with grease. However, no bulk grease should be applied to the hub or the stub axle. The idea is to guide the hub into place without the felt seal coming into contact with any surface other than where the inner cone slides on. If all is well, the seal should have stayed in place inside the shield, and now be pressed up against mating face of the axle carrier.

Insert the outer cone ... etc etc

Warning - after the hub refit is finished. and driving the car for the first time and getting the brake discs hot, watch for greasy oil dripping from the seal area. Eventually, all 'free' oil will dissipate and the dripping will cease. In my case, I wiped the inner disc surface before using the car several times over the course of a week until the drips stopped.

Which leads to the question: Is it best to skip the soak-in-oil step and just liberally coat all faces of the dry felt seal with grease before placing it in the seal shield which has been tapped into the hub recess?

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