Unit Bearing Compatability ?

I have a couple extra unit bearings that were handed down to me to use as trail spares.

I have a '98, I read somewhere that there was a year change on these where the "hub" protrusion is around 3/4" whereas the earlier version is around 1/2"

Is this only to accommodate a thicker brake disc or is the spline axle spline length longer on the later type ?

The spares I have are the 3/4" type, can they be used on my '98 if I have the 1/2" type or are they of no use to me ?

Thanks in advance for the info.

http://naxja.org/forum/showthread.php?t=1058413

in the faq's

With matching rotors, either style of UB will work. Basically you will need to pull a wheel, caliper and rotor and measure the lip of your UB. If same, they good to go. Otherwise plan on carrying a matching set of rotors as well.

You will find out real quick if you have a unit bearing that is the wrong size. I just did work on a 99 and had the wrong unit bearing and when I bolted it all in with the tire on the ground the disc of the brake was grinding into the knuckle and the jeep wouldn't even roll when I gave it throttle.

Johnnie Walker said:

With matching rotors, either style of UB will work. Basically you will need to pull a wheel, caliper and rotor and measure the lip of your UB. If same, they good to go. Otherwise plan on carrying a matching set of rotors as well.

Click to expand...

this.
I've run early rotors and bearings on a late model axle with the late model calipers.

rotors and bearings must match.
calipers and knuckles must match.