ronjenx

I have been wondering why the factory service manual says the front hub unit bearings are non-serviceable. The unit bearings in my old XJ were serviceable, and the JK's look a lot like them. I also wanted to know if my XJ rebuild tools would work on the JK hubs.

I took an old JK hub apart, and this is what I found.

The hub is made by ILJIN, http://www.iljin.com/aboutus.htm
The spindle goes through the center of the bearings, and is swaged over on the inside. This makes a "hat", so the spindle cannot be pressed out until the hat is ground off, which destroys the spindle.
Another feature which makes the hub not serviceable is the bearing inner and outer races are not separate pieces as they were in the past. The spindle has been machined to serve as a race, and the hub housing has been machined to serve as two outer races. It's not a simple matter of pressing out the old bearings, and pressing in new ones. The entire hub and spindle must be replaced.

There was no sign of water intrusion, so the seals appear to be adequate.
There was very little grease in the bearings.
One race had 13 individual dents from 13 of the 18 balls. The spacing matched that of the balls. This indicates not a worn bearing, but a bearing that took a tremendous static shock load. It could have been the swaging process during manufacture, or, from an accident.
On the plus side, the JK ball bearings are bigger than the tapered roller bearings of the XJ hub.

My next step is to perform hardness tests on the races and compare them to the conventional Timken races in the XJ hub.
I will update this post when I do the tests.

GoodysGotaCuda

interesting, thanks for the pics.

mkjeep

X2 rojenx, your posts are very insightful and helpful.

ronjenx

You are correct. The hat keeps the parts from separating. It is called "Self Retaining".
The 2wd JK uses this same hub, with no stub shaft.
Unfortunately, it means there is no preload adjustment in the field. It is set at the factory, when the spindle is swaged on the inner end.
It may also mean there will be variances in preload when the hub is made.
Another negative is the use of ball bearings. They are used because it lowers the cost of manufacturing the hub. Tapered roller bearings would be able to take more abuse, and would last longer.

CerOf

All years of XJs were serviceable or pre-93 or '94?

I ask as the ZJ and WJ (don't know about the WK) were all sealed units. Cost about $120 for the part. (this was back in '01 or '99 when I replaced the hub assembly on my old ZJ.

ronjenx

They all are considered sealed units.
I don't know for sure when and what models started the self retaining, non-rebuildable, hubs. My '88 XJ's hubs were rebuildable. My '88 MJ, too.
Looking at hubs for an '06 TJ, they don't have the swaged spindle end. They appear to be rebuildable.

wildandwillin

Nicely done.

Hellbound13

Does anyone know of a company making good aftermarket hub replacements? Also does anyone know of a write up to change em?

ronjenx

I am hopeful the one made by Timken has tapered roller bearings in it, instead of ball bearings, as in the OEM ILJIN hub.
In my opinion, that would qualify as a better after market replacement.

Here is a link to their site: http://www.timken.com/en-us/products/bearings/productlist/integrated/Pages/generation3.aspx#

Hellbound13

Yeah I guess I will call Timken and find a vendor in NY.