Choosing the correct 1999 Jeep Front Hub Bearing

In order to verify which front hub bearing is installed on your 1999 Jeep, it is required that one of the front wheel be removed. Once the wheel is removed, the brake rotor will be exposed and a measurement can be taken. The "HAT" of the rotor will measure 2-1/8 or 2-1/4 inches in height. The 2-1/4 inch rotor is a COMPOSITE rotor and will take the bearing number 513084. The 2-1/8 inch rotor is a CAST rotor and will take the bearing number HA597449 (513158). Use the illustration below as a guide to find the correct rotor/bearing. A measurement of 2.125 (2-1/8 inch) will require bearing 597449 (513158) A measurement of 2.25 (2-1/4 inch) will require bearing 513084 Jeep Front Hub Assembly Replacement Instructions

Jeep Brake Pad Replacement

Jeep Brake Pads Replacement

If the rotors are not warped or gouged, then all you need to do is change your pads. Make sure that the rotors / discs are not too thin or have a large lip where the pad does not run on the outer edge. If in doubt then have it inspected and machined. The minimum thickness pre '89 is 20.7 mm, '90 is 24 mm 4wd and 22 mm 2wd, with '91 on being 22.7 mm 4wd and 22 mm 2wd. Always check the rotor / disc casting in case they have been changed from Jeep original and for minimum thickness. Runout out should be less than 0.1 mm. If you need to change the rotor as well then you can still use these instructions.

After loosening the wheel nuts 1/2 a turn and jacking the axle so the wheels can be removed inspect the rotor / disc to make sure it does not need machining. All that is needed to remove the caliper and or the rotor / disc is the two bolts with the arrowed above. Remove the caliper by pulling from the top. Once free slide off the outer pad. You will need to push the pad inwards so the locating bumps are free from the caliper. Leave the inner pad so you can push the piston back by using a C clamp as shown or G clamp until it is as far back as it can go. Change the disc / rotor at this point if needed.

As you are pushing the pad back keep a check on the reservoir as the fluid will rise and some fluid may need to be removed with a syringe to stop it from spilling over. If any does spill remove it immediately as it will strip the paint. DO NOT rub it with a cloth but pour hot water over the spilled area. The pads are different left to right as well as an inner and outer. Shown above are two inners with the differences arrowed with one a slot (1) and the other just a tag (2). Just compare it to the one you have taken off for the right one.

Push the inner into the piston cup and slide the outer making sure the locating bumps ( arrowed) insert into the holes. Push the sleeves which the bolts pass through back as they have a habit of stopping the caliper from going back on. Also clean the caliper slides and you can even add a very small amount of high temperature grease to them. If there is any glazing of the disc then now is a good time to remove it using emery paper in a circular motion. Place the two slots on the caliper slide at the bottom first and then hinge the top forward.

Pointed out is the two slots in the pads that should be sitting on the bottom caliper slide and the bolts are put back ( 30 Ft-lbs ) when to caliper is pushed forward as far as it will go. Pump the brake pedal up before starting the other side as it will lower the fluid level in the reservoir to make it easier to push back the next piston. No bleeding of the brakes is necessary but if the fluid has not been replaced in over a year it is a good idea to replace it as it draws in moisture from the air and an improvement in braking will be felt after the change. Remember to pump the pedal back up before test driving and allow a time for the pads to set in which will take a few good hard stops, but be sure not to over heat the brakes while doing it. Check also the brake reservoir fluid level.

Jeep Hub Assembly Replacement Instructions

Jeep Hub
Assembly Replacement Instructions

The Jeeps have what is called Unit bearing or Hub Assemblies. The bearings themselves are not serviceable so you must replace the whole hub assembly when they wear out. You can check to see if replacement is needed by jacking up the wheels and grabbing the tire at 12 and 6 o'clock and push with one while pulling with the other hand back and forth feeling for play. There should be none. These are not difficult to change but does require a 36 mm socket and matching impact gun or breaker bar to go with it. Takes less than an hour to do one side if you have the right tools.

Start by removing the wheel and then the two bolts that hold on the caliper. The caliper can then be removed by hinging from the top outward. Place the caliper on top of the lower control arm and then remove the rotor. It may still have some assembly clips holding it on which can be
discarded.

Remove the split (cotter) pin and nut retainer to allow access to the axle nut. I used a 1" drive impact gun with a 36 mm socket but a breaker bar would also have done the job. To stop the hub from rotating while doing this you need to use a pinch bar against some wheel nuts threaded onto a couple of studs or have someone stand on the brake and remove this nut before anything else. The other way is put the wheel back on without the center cap and lower it back on to the ground to stop it from spinning.

Using a 13 mm socket you loosen the three bolts holding the hub in place but only threading them out by about 1/2". Then tap on the heads in turn working you way around to push the hub free. Be careful not to damage the head which can be protected using a socket left on the head or a nylon head hammer. If you are in the salt belt I have been told that putting an old wheel or your spare and using a pry bar you can lever it out by prying between the back of the wheel and the knuckle.

Once the hub is just free of the knuckle tap on the end of the axle to free it from that. There is no need to remove the axle from the housing.

When re-assembling use a little axle grease or anti seize on the splines and the inside of the knuckle. Then just slide the new knuckle in place and if you have a torque wrench handy, torque the hub bolts to 102 Nm ( 75 ft. lbs ) and the axle nut 237 Nm ( 175 ft. lbs ). Easiest way to torque the main nut is to put the wheel back on without the centre cap and lower it back on to the ground to stop it from spinning.