Pulled off a hub cover that needed to be touched up & wondered where all the black build up came from inside.
In all our questioning of the engineering, has anyone mentioned this common sense solution to a concern.

 

Heat hardened grease that ooozed past the cap ?

 

I have never been a fan of greasing twin bearings (wheel, hub, etc) with an external fitting. You have to pump such a huge quantity of grease into the cavity between the bearings before any of it gets into the bearings. You also loose much of your "feel" for how much grease is getting into/past the inner bearing that it's not uncommon to push the inner seal out of position. That big gob of grease sitting between bearings is not doing anything any good.

Dave

 

Point made and really valid if you routinely repack your bearings. Do we know how the grease is introduced. Is it just into the cavity of the outside bearing ?

 

Never actually thought about it that seriously, creeps into the "beer o'clock" time too much.

All my Jags have always had the front hubs dismanted and thoroughly cleaned of all that waxy old grease from the assembly line, within the 1st week of ownership.

New bearings where needed, and repacked with modern day Wheel Bearing Grease.

Old habits die hard, so that grease nipple still gets a few pumps of Wheel Bearing Grease annually.

That grease nipple applies grease to the chamber between the 2 bearing assemblies, and the heat generated from brakes etc, is "thought" to allow that grease to "flow" into the bearings by centrifugal motion (big word for me). No idea if this is fact or fiction, but I have never had a wheel bearing failure on any of my Jags from #1 to the current crop.

 

The "zerk" fitting that is in the front hub, shown in your picture, is where you would plug in a grease gun and start pumping. The plan would be to remove the dust cover so that when the cavity is full and the grease you're pumping in has to start squeezing out through the outer bearing, you can see it. Instructions are written that say you should keep pumping until all the old grease pushes through the outer bearing and you see fresh grease coming out. Job done. All that unused grease between the bearings, and then there's the inner bearing. The inner seal is directly behind the bearing, so where is all the old grease going to go? Out the seal?! If you manage to stop pumping before the seal goes, then you haven't put any new grease into the inner bearing.

It's appealing on paper and seems like an easy "grease job", but taking the hubs off and greasing the bearings properly and then installing a new seal, is by far the best way to do the job. IMHO

Dave

 

Agreed Dave.

Most of mine were 10+ years old when aquired, and had never been repacked since the factory.

Rule of thumb here waaaaay back was when the front brakes were attended to, the wheel bearings clean and repack/replace was part of that procedure.
OK, drum brake days for sure, more involved brake repairs than the modern stuff.

Most of mine had never been "serviced" since the factory fill, and that is why I got into the "catch up" regime a long time ago. VERY time consuming, but ever so satisfying.

Then the fact, greases then are not a patch on the greases today, and that is only of benefit.

Simply filling that chamber and hping for teh best, not going to work out. As you said, that grease seal will pop, and nothing has addressed all teh old gunk until it pops.

Overgreasing was always a problem down here, even with the hand style guns, and the invention of air operated guns, oh dear, what a challenge.

 

I prefer the proper disassemble-clean-repack routine as well. This service is SO often overlooked. I can't tell you how many cars I've serviced over the years that had little or no grease in the bearings.

That said, I think the hub (or the dust cap?) has a tiny bleed hole so, if using the grease gun method, excess grease won't blow out the seal. The grease squirts out of the bleed hole before that much pressure is developed.

I might be wrong and will use my first-cuppa-coffee defense if I am.

Cheers
DD

 

Outstanding feedback ! Lot's of input ! Think we all know the best way using today's products, but seeing two different theories on where the grease goes, between the inner and outer, or just in the outer hub. Am I right ?

 

The grease from the grease nipple definitely goes into the centre cavity in the hub between the inner and outer bearings. The theory is that it will find its way, somehow, from there to the bearings.
Without question, if this bothers the owner, the best thing to do is to remove the hub and regrease by hand. BUT, removing the hub requires unbolting the brake caliper, so becomes a pain. I have owned my car since 1998, and i regrease the hubs every time I have to unbolt the calipers, which is sometimes all too frequently, and sometimes not for years. I have never had a bearing problem. As long as they are well greased up with good quality grease when fitted, then i reckon it does not matter if they are untouched for 30 to 40,000 miles!
I do use the grease nipple now and then when the wheels are off, but I think it only makes me feel better, not the car!
On my XJS Doug, there is an air bleed pinhole in the cap.

 

That little pinhole looked a little small to me for old caked grease to squirt out. The cap comes off with a little tapping and prying and once it's off you can watch for the new grease to push out the old. Then wipe off the old stuff and pop the cap back on. Of course, the disassemble, inspect and repack is always best.

Jeff

 

At the same time I pulled the hubs, replaced bearings, repacked with grease... I also changed the pads and rotors. While the caliper re-mounting is a little clunky, it's a straightforward job that delivers notable improvement and longevity. Also allows you to inspect the spindle for wear.

 

Great feedback from all. Looks like one thing none of us should ever have to worry about is a front wheel bearing failure.Think I will move on to other areas of concern.

 

The stock levels of the beer fridge would be of more concern than any wheel bearing, properly greased, on any pre X308 Jag.

Not sure on the later sealed hub stuff though.

 

Guess I'm just asking how often has anyone had a problem regardless of which way they get lubed ?

 

Never. The only thing that kills the bearing is being FAR too tight, or too loose.

 

Same here.

Our S2 XJ12 Fuel Infected has 654000 +/- kms. Same bearings as when it left Coventry. I repacked them at ownership in 1994, again in ??2005ish, and really saw NO reason to do them at all.

Proper adjustment, now thay would be a LOOOOOONG thread, lots of suggestions etc etc, and way too many beers, but if they are set "proper" they will last forever.

 

What puzzles me reading this is why modern wheel bearings almost never need looking at for 100k miles. I had two of the aluminium XJs and one was well over 100k miles yet never any bearing problems. My Mazda Xedos and then a Rover 75 were the same. Maybe I was just lucky.

 

Same here with the S Types, and the rear on the X Type.

All I can establish is that the "hub assembly" is sealed, and the tolerances are very fine so "fiddling" is not possible. The set up remains the set up.

I dismantled a Ford one at work one day a while back, very impressed with the innards and the spaciing for "pre-load". The grease was really sticky. It was an old unit of about 300K kms, replaced due to kerb contact.

 

Modern wheel bearings are enclosed factory-sealed units, both inner and outer in a housing, all greasing and tolerances etc etc factory set and the housing sealed round them. there are no clearance/adjustment issues as they are just slapped on the stub (if, that is, the entire unit, stub hub and all does not come as a single unit) and the nut done up to 90 ft llbs and that is that. Unless the vehicle gets racing-type cornering and braking loads they will last for ever.
With our earlier technology, unchanged in design since pre-WWII, failures - rare as they are - come about from bad adjustment, water and grit ingress caused by the bad adjustment etc etc.
On the Jaguar rear suspension rear hubs, however, which nobody ever touches, or ever greases, where the bearing clearances are factory-set even if built up at the factory from individual components, and which it is impossible to do anything to without major effort, the bearings DO last for ever!