BudgetXJ
05-23-2009, 05:31 PM
I noticed a couple days ago that my front axle u-joints are pooched so I've been looking into what options I have as far as upgrades. It is fairly commonly known that the newer XJ's came with bigger u-joints so I am going to get those but for ease of installation I wanted to get the unit bearings with the axles and install them as a unit (that and mine are puking grease all over the insides and I'm hoping the newer ones will be in better shape). Here's what I found:
Mid 1999 was the change over. 1990 to 2001 parts will interchange provided your hubs and rotors match, read on.
Three different hub/bearing units were used over the years on XJ's. The hub/bearing units are the same part number for both sides of the vehicle. The model years for hub/bearing assemblies were:
1) 1984 through 1989 (early style rotors)
2) 1990 through mid-1999 (composite rotors)
3) late-1999 through 2001 (cast rotors).
** You need to match brake rotors to the unit bearing/hubs on your XJ D30 axle. **
Lay the rotor on your bench and measure from the bench to the top of the rotor.
Composite rotors will have an overall height of 3 3/16". Composite rotors will have a thin sheet metal like appearance at the lug nut holes where the studs come through and measure about 1/8 "(.125) thick in this area. Composite rotors have a rounded off corner at the wheel mounting surface and look like two pieces joined together.
Cast rotors will have an overall height of 3 1/16". Cast rotors are thicker at the lug nut holes and measure between 1/4" (.250) to 5/16 (.320) in this area. Cast rotors have a square corner at the wheel mounting surface and look like they are one solid piece of metal.
Parts store replacement rotors may have a different appearance but should measure about the same.
On late 1999 - 2001 unit bearing/hubs the ring around the 36MM shaft retaining nut is almost 3/4 inch tall and the hub has longer lug nut studs than older hubs ( see picture). These hubs use cast rotors.
On early 1990 - 1999 unit bearing/hubs the ring around 36MM shaft retaining nut is about 1/2 inch tall (see picture). These hubs use composite rotors.
Two steering knuckle designs were used: 1984 to 1989 and 1990 to 2001. Left and right side knuckles have different part numbers.
Two types of brake caliper styles were used: 1984 to 1989 and 1990 to 2001. Left and right sides are different part numbers.
Mid 1999 was the change over. 1990 to 2001 parts will interchange provided your hubs and rotors match, read on.
Three different hub/bearing units were used over the years on XJ's. The hub/bearing units are the same part number for both sides of the vehicle. The model years for hub/bearing assemblies were:
1) 1984 through 1989 (early style rotors)
2) 1990 through mid-1999 (composite rotors)
3) late-1999 through 2001 (cast rotors).
** You need to match brake rotors to the unit bearing/hubs on your XJ D30 axle. **
Lay the rotor on your bench and measure from the bench to the top of the rotor.
Composite rotors will have an overall height of 3 3/16". Composite rotors will have a thin sheet metal like appearance at the lug nut holes where the studs come through and measure about 1/8 "(.125) thick in this area. Composite rotors have a rounded off corner at the wheel mounting surface and look like two pieces joined together.
Cast rotors will have an overall height of 3 1/16". Cast rotors are thicker at the lug nut holes and measure between 1/4" (.250) to 5/16 (.320) in this area. Cast rotors have a square corner at the wheel mounting surface and look like they are one solid piece of metal.
Parts store replacement rotors may have a different appearance but should measure about the same.
On late 1999 - 2001 unit bearing/hubs the ring around the 36MM shaft retaining nut is almost 3/4 inch tall and the hub has longer lug nut studs than older hubs ( see picture). These hubs use cast rotors.
On early 1990 - 1999 unit bearing/hubs the ring around 36MM shaft retaining nut is about 1/2 inch tall (see picture). These hubs use composite rotors.
Two steering knuckle designs were used: 1984 to 1989 and 1990 to 2001. Left and right side knuckles have different part numbers.
Two types of brake caliper styles were used: 1984 to 1989 and 1990 to 2001. Left and right sides are different part numbers.