hub/axle questions

It's to my understanding that the XJ D-30's up to 1993 have wheel bearings that require 'servicing'...meaning taking the bearings and repacking them etc.

From 1994+ the D-30's on all jeeps have the unit hub bearings.

My question(s) is can I use the outer knuckles from a late model XJ,YJ,TJ and then use the unit hub bearings...and if so will any brake or steering mods be necessary??

I have an '86 MJ and want to put in a '96+ HP D-30 for the non-disco and to have the unit hubs...but they aren't easy to track down so if I can modify my current axle instead...???

Also...as I said I want to go non-disco as all the jeeps I;ve had have been as such. BUT...how is the vacuum disco axle? I know it's "one more thing to go wrong" but if maintained right etc...how do they hold up?

I think your information is incorrect. As far as I know all 4WD XJ's use unit bearing hubs. My 87 certainly did. The serviceable ones must be for 2WD. There was a change in the hub unit itself, along with the brake mounting - I'm not quite sure of the year, but 93 sounds about right - and the early and late ones will not interchange, but that's a matter of dimensions, not basic design.

Matthew Currie said:

I think your information is incorrect. As far as I know all 4WD XJ's use unit bearing hubs. My 87 certainly did. The serviceable ones must be for 2WD. There was a change in the hub unit itself, along with the brake mounting - I'm not quite sure of the year, but 93 sounds about right - and the early and late ones will not interchange, but that's a matter of dimensions, not basic design.

Click to expand...

I believe that is correct, I think all 4WD XJ's have the unit hub bearing. Again with varyations in different year Cherokees. I have a 91 Laredo, and just relaced the unit hub bearings.

Go to a u pick it, or junk yard at look for a set. I'm sure you can find a set with low miles pretty cheap. I got mine from a vehicle with 40,000 miles for $40 (set). Have also seen them on Ebay for certain year XJ's for about $80 each.

If you need any pointers with getting them off let me know. I have lived and learned on this subject.

This is good to know. I've never torn into one older than a 1996 so I'm still learning...haven;t even pulled mine apart as of yet.

Makes sense on the unit for the 4x4 vs the serviceables on the 2wd..

THANKS,
Jason

I think that the changes were made in 1990 not 1993, that is the year the brakes and knuckles changed. And my 1990 and 94 axle looks to be identical

I believe this applies only to the 2WD models.

ALL XJs, 2wd and 4wd use unit hub style bearings. There was a part number change in when they started using composite style rotors.

The disconnect d30s are typically ok for light wheeling...anything over a 31 inch tire and you will start breaking ujoints.
all years previous to '97 except ABS used 5-260x u-joints in the axleshafts. ABS equipped and 97+ use the 5-297x (aka 5-760x) ujoints which are twice as strong as the 260x

The outter knuckles will interchange in any year, so long as you keep the rotors and calipers with the corresponding knuckles. all XJ steering components from all years are interchangable. You can also upgrade to 94-98 V8 ZJ drag link and cross tie rod. This will increase the diameters to a full 1" and the cross tie rod is solid instead of hollow.

I put a 'super 30' LP D30 from a 94 Grand cherokee in my 87 xj...excellent brakes, and 297 u joints. However, I had to shorten my front driveshaft 1" due to the LP snout being one inch longer than the HP