unit hub dilema

I have a 1990 XJ. This is the 7th XJ I have owned and I do most of my own work (95+% of it). I have also had 2 MJ's and 2 TJ's.

Unit hubs should not be this big of a mystery for me.

BUT...

according to somewhere on these forums...the '84-89 hubs are the same. According to NAPA part numbers this is true (I only went back to '86 on NAPA). And according to these forums the '90-mid '99 are the same. Also true according to NAPA.

HOWEVER also according to this website the hubs up to 1990 have a recessed bearing and a knuckle mating surface to wheel mounting surface distance of ~1.85". Then the later model hubs have a flush bearing and the same mating surface measurement of ~2.15" A difference of a tad over 1/4".
NAPA shows pcitures of the hub up to '89 with recessed bearings...and flush bearings 1990+.

This is conflicting information as one bit of info says the hubs are the same to '89...then the other says they are the same to '90.

I have even more conflictiing info...the hub on my 1990 has a recessed bearing but a mating surface measurement that is about 1/4" more than a hub we pulled off an '86 today. It was also different from the one at the parts counter as THAT one has a flush bearing.

Anyone have any ideas other than this one bearing (no I have not pulled off the other side yet) is so goofy? This isn't my first rodeo by any means but it is the first time I have run into this big of an issue.

I intend to get the BOM of the axle tomorrow to see if that may shed some light but all outward appearance tell me this is the original axle...and probably the original hub (took almost 3 hours to get it loose).

that is weird. it seems there is a lot of conflicting info for 1990 XJ's parts all over the interwebz. when i replaced my unit bearings, i ordered timkens from amazon, fit no problem and were a good price.

The first generation hubs/knuckles have calipers that bolt onto a bracket or something different like that. 1990-2001 knuckles use the same style of caliper mounts.

It may be possible that somebody swapped the outer knuckle ?

Two steering knuckle designs were used: 1984 to 1989 and 1990 to 2001.

Two types of brake caliper styles were used: 1984 to 1989 and 1990 to 2001.

.

Read this info -> http://www.naxja.org/forum/showpost.php?p=244574496&postcount=2

Tim_MN said:

The first generation hubs/knuckles have calipers that bolt onto a bracket or something different like that. 1990-2001 knuckles use the same style of caliper mounts.

It may be possible that somebody swapped the outer knuckle ?

Two steering knuckle designs were used: 1984 to 1989 and 1990 to 2001.

Two types of brake caliper styles were used: 1984 to 1989 and 1990 to 2001.

.

Read this info -> http://www.naxja.org/forum/showpost.php?p=244574496&postcount=2

Click to expand...

Yep, the 84-89(and some 90's) have the 2 piece knuckle and will use the older style uni-bearing that from what I understand is rebuildable. As long as you use the proper hub with the proper knuckle then all should be fine.

I pulled the other one off and it is as it 'should be' with the flush bearing and the larger measurement from surface to surface.

Apparently the bad one I removed is 'special' having both the recessed bearing AND the large measurement.

I hope to have it done and off the driveway later today. Then it's a few more things to put her on the road. This is my CHEAP dd project. Only paid $150 for the whole jeep and plan to keep it under a grand and use as a secondary dd or foul weather rig when I am too lazy to put the top on my CJ5.

And that's the Joy of Jeep. For about twenty years, they were either built by AMC (~1965-1988) or to AMC specifications (1989-1990.)

AMC = American Motors Corporation. AMC &= "All Makes Compatible." Running into parts goofiness like this - particularly on "transition years" - is awfully common. Fortunately, I enjoyed coming at problems sideways, so I enjoyed working on AMC vehicles while they were still around (some years and models of their passenger cars could get very interesting!)