Monday, August 19, 2013

How to replace the front bearing and hub assembly on a 1997 GM 2.4L Pontiac Grand Am

     A low howling sound, increasing with vehicle speed, is a sign that a right front wheel bearing is going out. This is a very doable job for the home mechanic if the bearing is replaced as part of  the hub assembly as it is on many GM cars. A video of the job follows the text and pictures.

  Tools: Floor and/or scissors jack to lift the front off the ground.  Jack stands or railroad ties, lug wrench, 30mm deep well socket ½” drive,  3/8” allen socket, T55 socket, a set of chisels, a hammer, torque wrench, breaker bar, 18" pipe wrench, a large flat blade screwdriver.

 Parts and materials: Moog bearing and Hub assembly, $62.39, Advance Auto 8/2013. Wire hanger.

 Savings: $135 average repair shop labor.

 Time: 2-4 actual labor hours for the home mechanic.

                                                                  Disassembly
1) Break lug nuts on the wheel.
2) Jack up the front end. I used two jacks , a floor and scissors jack under these loaf-like projections on two arms angled outward from behind the wheels. Rest the front end on some stands. I used railroad ties.

Front end is jacked up and on railroad ties

3) Remove lug nuts and take off the plastic wheel cover, if equipped. Remove wheel.
4) Put wheel back on and hand tighten a couple of lug nuts.
5) Jack up high enough to set the wheel down on a paver or wood, without removing stands.
6) Break the axle nut loose with a 30mm deep well socket and breaker bar. This is highly torqued nut. I needed a 24” breaker bar and a more than a dozen all-out grunts.
Break out the big one. This axle nut is torqued. 
7) Set the car back down on the stout supports.
8) Remove the wheel.
9) Unbolt two caliper bolts with 3/8” Allen socket. Pry off caliper. May need to use large screwdriver wedged between caliper and rotor.
10) Use a wire to hang the caliper from a strut spring.
Hang the caliper from the spring with a piece of wire
11)  Remove the rotor and set aside.
12) Unbolt the 3 hub and bearing assembly bolts with T55 socket. Must turn the hub to align bolt with large hole in hub so that the long bolts can be removed.
Unbolting the hub/bearing assy with a T55 socket and 1/2" ratchet

13) Now we must break the hub/bearing assembly loose from the steering knuckle. This is the fun part.  I had success after a struggle, with three chisels, pounded in near each mounting hole between the hub assembly and the steering knuckle.  I started with a ½” Craftsman Chisel, then to 5/8 and finished with larger size. As a gap grew to 1/32” I  used an 18” pipe wrench, wide open to turn the hub assembly a few degrees one way and then the other. That was it and it came out of the knuckle.
It's rusted pretty good. I tried a pry bar and hammer but chisels and a pipe wrench finally did it. 

     
                                                                  Installation

1) Clean up the mating surface in the steering knuckle with a wire brush, some coarse sandpaper and finish with a solvent, like lacquer thinner.
2) Mount the new hub and bearing assembly. It comes with an o-ring and a seal and a terrible drawing of where they go. I mounted the o-ring but had trouble with the seal. It appears to go on the inside of the steering knuckle, requiring removal of the knuckle. GM didn't use the seal at the factory and neither did I.  Be careful to line up the big hole in the hub squarely before torquing the bolt. I managed to cross thread one of them in the knuckle and I had to buy a 12 X 1.75 metric tap and fix the threads. Torque to 70 ft lbs.
                   
I'm pointing at where the o-ring goes
3) This is a good time to go over the brakes for wear and at the least clean and put some fresh grease on the caliper pins.  If using the old rotor, put it in the very same position it was it when it came out. It helps to file off a bit of the outer raised ridge of the rotor so the brake pads will fit back over the rotor. Torque the caliper bolts with a 3/8” Allen socket.  If using a torque wrench it’s 38 ft lbs.
4)  Mount the old washer and the new axle nut which comes with the bearing assembly. This is big torque, 192 ft. lbs. My torque wrench only goes to 150 ft lbs. So I gave it one more grunt with a big breaker bar and called it good. Check the wheel by turning it by hand while both wheels are still off the ground. It should turn, but somewhat grudgingly.  Interestingly, they turn in opposite directions while the car is in park.
5) Test drive. Enjoy some smooth rolling down the road.
                                                       Here is a video of this repair:

                                                         
bearing and hub assy
    

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