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Rear Wheel Bearing Replacement
 
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Pelican Technical Article:

Rear Wheel Bearing Replacement

Steve Vernon

Time:

4 hours4 hrs

Tab:

$40 to $80

Talent:

****

Tools:

Socket set, bearing puller, slide hammer, floor jack, jack stands, wheel chocks, safety glasses, lug wrench, torque wrench, freezer, torch

Applicable Models:

Porsche 944 Turbo (1986-89)

Parts Required:

Bearings

Hot Tip:

Freeze the new bearings before installing

Performance Gain:

All around better and safer performance

Complementary Modification:

Replace brake pads and discs

If you are starting to hear a high pitch wine, like a jet taking off, from the rear end of your 944, or your 944 has over a 100,000 miles on it you should inspect your rear wheel bearings for replacement. The bearing supports the full weight of the car both while stationary and under load. While 944 rear bearings are known to last a long time, as the mileage increases on the car, the bearing will eventually fail. Replacing the rear bearing can be a trying and difficult job depending on the state of the car. You will have to commit to the job, as you will be destroying some old parts in removal and will not be able to use the car until the new ones are installed. Make sure you have everything you need before you start.

Before you begin the job place the new bearing in the freezer, preferably over night if you can. Freezing the bearings will decrease the outer diameter and make installation into the hubs easier.

You will need to first remove the brake caliper, rotor and axles. Please see our articles on these procedures for further assistance.

You will need a bearing puller to remove the wheel flange.
Figure 1

You will need a bearing puller to remove the wheel flange. Most auto parts stores will lend you one or rent you one for a small fee.

Depending on the condition of your car you may be able to pull the hub with a few large pry bars and a couple of good pulls.
Figure 2

Depending on the condition of your car you may be able to pull the hub with a few large pry bars and a couple of good pulls. Make sure the pry bars are seated on the hub flange mount and not on the parking brake apparatus (yellow arrows).

Either way you remove the flange the inner race of the bearing (red arrow) will more than likely come off with the wheel flange leaving the ball bearings in the bearing exposed (yellow arrow).
Figure 3

Either way you remove the flange the inner race of the bearing (red arrow) will more than likely come off with the wheel flange leaving the ball bearings in the bearing exposed (yellow arrow). This is normal and fine, since you are replacing the bearing anyways.

You will need to remove the race (red arrow) from the hub with a bearing puller, air hammer or you can carefully cut it with a Dremel and knock it off.
Figure 4

You will need to remove the race (red arrow) from the hub with a bearing puller, air hammer or you can carefully cut it with a Dremel and knock it off. Use care not to damage the hub while doing this.

With the inner race off check the condition of the flange (red arrow).
Figure 5

With the inner race off check the condition of the flange (red arrow).

There is a very large circlip in the groove inside the hub.
Figure 6

There is a very large circlip in the groove inside the hub. Use the proper large circlip tool as the openings are far apart (red arrow). Do not forget to wear your safety goggles.

Use care and the right tool to remove the circlip.
Figure 7

Use care and the right tool to remove the circlip. It is quite beefy, and you do NOT want to try and pry it out with screwdrivers. The rear hubs are NLA (no longer available) and if you do find a good used one it will cost you a fortune. Use the right tool and save yourself the trouble.

You will need a bearing puller to remove the bearing from the trailing arm (red arrow).
Figure 8

You will need a bearing puller to remove the bearing from the trailing arm (red arrow). Your local auto store will probably have some sort of tool rental or free program that you can use. There are lots of ways out there on the internet (including our forums) on how to make your own puller for a little money from the hardware store; while you are welcome to follow those instructions the fit between the inner hub on the trailing arm and outer ring on the bearing is very small and requires a lot of force on it to pull the bearing out. Porsche trailing arms might as well be made of un-obtainium now so we recommend using a proper bearing puller for the job.

With the bearing removed clean the inside and check for any damage or cracks.
Figure 9

With the bearing removed clean the inside and check for any damage or cracks. The section of the hub that sits in the bearing can get some discoloring but it should be free from nicks, or any heat damage. The hub sits inside the inner races on the bearing. If the bearing fails and the hub starts spinning around, inner race damage can occur. Note: this hub is fine; it is just discolored from the grease from the failed bearing.

Pull the new bearing out from the freezer.
Figure 10

Pull the new bearing out from the freezer. Use some form of heat to heat up the hub on the trailing arm. If you are using a torch, the hub is hot enough when you place a drop of water on the top and it sizzles (yellow arrow). Do NOT over heat the hub. With the hub hot and the bearing cold insert the bearing and push it in as far as you can by hand making sure to get it level and even.

Depending on the condition of the vehicle, the bearing will either slip right in or just to the beginning edge (yellow arrow).
Figure 11

Depending on the condition of the vehicle, the bearing will either slip right in or just to the beginning edge (yellow arrow). The bearing will now need to be tapped or pressed in until flush with the hub. If you are tapping it in with a hammer you must place something over the bearing to protect it and tap it in evenly working gently around the outer ring of the bearing. If you are pushing it in with a bearing tool make sure that the disk you use only applies pressure to the outer ring on the bearing. Pressing the bearing in with the inner ring will destroy the bearing, and you will have to start all over again.

Press the bearing in until it is fully seated and flush with the flange on the hub (red arrow).
Figure 12

Press the bearing in until it is fully seated and flush with the flange on the hub (red arrow).

Use a bearing tool to press the hub into the new bearing.
Figure 13

Use a bearing tool to press the hub into the new bearing. Keep in mind that you must support the bearing on the backside using the inner race of the bearing. If you support the bearing with the outer race only the hub can push out the inner race and destroy the bearing. Installation is the reverse of removal.


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