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Old March 10th, 2011, 03:35
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Tim_MN Tim_MN is offline
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Location: Minneapolis, MN
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Re: Front bearings 99 manufac: 5-99 pretty sure but checking

Three different unit hub/bearing assemblies and matching disk brake rotor types were used during the years 1984-2001 on the XJ D30 axles.

Two different steering knuckle types were used during the years 1984-2001 on XJ D30 axles.

If your unit hubs and rotors are not matched by type, there will be interference between the two parts, the tire/wheel assembly will be bound up and not move freely, and the Jeep will not move.

Take note that nearly all XJ, MJ, TJ, and ZJ D-30 axle parts interchange.

Unit Hub/Bearing Assemblies:

1) 1984 through 1989 - Original AMC hubs, use AMC brake rotors, ( Jeep Part Numbers 4723371,

5252725, 53000228, 53000234 ) AMC calipers, AMC steering knuckles, and AMC roller bearing hubs.

The unit hub/bearing are the same part number for both sides of the vehicle.

2) 1990 through 1999.5 - Older Chrysler type unit hubs, use Composite dimension brake rotors,

( Timken Part # 513084, Jeep Part Number 53007449 ) and Chrysler calipers and Chrysler steering knuckles.

The unit hub/bearing are the same part number for both sides of the vehicle.

3) 1999.5 through 2001 - New Chrysler type unit hubs, use Cast dimension brake rotors,

( TIMKEN Part # HA597449 - Jeep Part Number 5016458 ) and Chrysler calipers and Chrysler steering knuckles.

The unit hub/bearing are the same part number for both sides of the vehicle.

Steering Knuckles:

1) 1984 to 1989 - AMC Steering Knuckles. Left and right side steering knuckles have different part numbers and only accept AMC calipers.

2) 1990 to 2001 - Chrysler Steering Knuckles. Left and right side steering knuckles have different part numbers and only accept Chrysler calipers.

Any XJ AMC or XJ Chrysler steering knuckle will fit on any XJ D30. They are all interchangeable but you have to compensate for the lack of the threaded adjuster in the bottom of the pre-1990 knuckle when you swap on the later ones by switching to the later upper ball joint that has the floating pin. There needs to be a mechanism for compensating for the exact precision of the tapered holes which is done with a threaded lower adjuster in the pre-1990 and a floating upper pin post 1990

Brake Calipers:

1) 1984 to 1989 - AMC Brake Calipers. Left and right sides calipers have different part numbers and only fit on AMC steering knuckles.

2) 1990 to 2001 - Chrysler Brake Calipers Left and right sides calipers have different part numbers and only fit on Chrysler steering knuckles.

AMC and Chrysler calipers do not interchange, they must be mounted on the corresponding AMC or Chrysler steering knuckle.

Brake Rotors:

1) 1984 - 1989 - AMC Brake Rotors
2) 1984 - 1999.5 - Composite dimension Brake Rotors
3) 1999.5 - 2001 - Cast dimension Brake Rotors

Additional Info:

- XJ D30 unit/bearing hubs, disk brake rotors, brake calipers, and axle shafts are interchangeable for all years 1990-2001, and for HP vs. LP. You just need to have the rotor type, match the hub type, cast vs. composite. Or, just swap the hubs and rotors as a matched set. The calipers are exactly the same, cast vs. composite or HP vs. LP. The only D30 parts that will not interchange, HP vs. LP, are the ring and pinion gears. Any XJ AMC or XJ Chrysler steering knuckle will fit on any XJ D30. (XJ, MJ, TJ, and ZJ, D30 axles can interchange most parts, so the 1999.5 cast/composite info may apply to all).

- 2000 and 2001 XJ D30's are Low Pinion housings, just like the TJ Wranglers.

- Most (or nearly all) XJ, MJ, TJ, and ZJ D-30 axle parts interchange.

.....................

- Type Identification and Measurement -


** You need to match the disk brake rotor dimensions to the unit bearing/hub type and measurements currently on your XJ. **

Cast iron replacement rotor blanks can be machined to composite rotor measurements. Therefore, you must measure your current rotors, and compare the measurements to the replacement rotors at the parts store before purchasing. Previous owners or a repair shop may have installed different type replacement parts. It is possible to have one old type and one new type unit hub.

If your hubs and rotors are not type matched, cast vs. composite, there will be interference between the two parts, the tire/wheel assembly will be bound up and not move freely, and the Jeep will not move.

Lay your old rotor on your bench and measure from the bench to the top of the rotor. Be aware that your rotors may have been replaced previously and may have a different physical appearance than described below. The physical dimensions will be the same as noted.




Factory original Composite construction rotors had a rounded off corner at the wheel mounting surface and look like two pieces joined together. ( Nearly all factory installed composite construction rotors have been replaced with cast iron replacement rotors that have been machined to composite rotor dimensions. Do not simply look at your rotors and assume you have a certain type, measure them.)

- Cast vs. Composite Dimensions -

Composite dimension rotors had an overall height of 3 3/16". Cast iron replacement rotors can be machined to composite rotor dimensions, which is why you have to measure the parts you have, and the parts you are purchasing. Composite construction rotors had a thin sheet metal like appearance at the holes where the lug nut studs come through and measure about 1/8 "(.125) thick in this area.

Cast dimension rotors are thicker at the lug nut stud holes and measure between 1/4" (.250) to 5/16 (.320) in this area. Cast rotors have an overall height of 3 1/16".

*** Replacement rotors can be machined to Composite or Cast dimensions. Therefore, you cannot rely on appearance alone, you must measure your current rotors and compare the dimensions to the replacement rotors at the auto parts store before purchasing. ***

If your hubs and rotors are not matched by type, there will be interference between the two parts, the tire/wheel assembly will be bound up and not move freely, and the Jeep will not move.


If, after measuring your current rotors, you are still unsure of which type of rotor/bearing you have or if you suspect that a previous owner or a repair shop may have installed replacement parts, compare the Unit Hub Bearings to the pictures below.



.......................

Hub Type Identification -


- 1999.5 to 2001 unit bearing/hub on the RIGHT of the picture below uses the CAST DIMENSIONED ROTOR. The 1999.5 - 2001 unit bearing/hubs have the taller ring around the 36MM shaft retaining nut. It is about 3/4 inch tall and the hub has longer lug nut studs than older hubs. See pictures below.

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- 1990 to 1999.5 unit bearing/hub on the LEFT of the picture below uses the COMPOSITE CONSTRUCTION ROTOR. The 1990 - 1999.5 unit bearing/hubs have the ring around 36MM shaft retaining nut that is approximately 1/2 inch tall. See pictures below.



Cast iron construction replacement rotors can be machined to composite rotor dimensions, which is why you have to measure/compare the parts you have, and the parts you are purchasing.

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If your hubs and rotors are not matched, there will be interference between the two parts and the rims. The rim will be bound up by the interference and will not turn freely, and the Jeep will not move.

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Last edited by Tim_MN; October 30th, 2019 at 17:44.
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