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Replacing Wheel Bearings on your Porsche 911 Carrera
 
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Pelican Technical Article:

Replacing Wheel Bearings on your Porsche 911 Carrera

Time:

4 hours4 hrs

Tab:

$120

Talent:

****

Tools:

Wheel bearing puller, breaker bar, or torque wrench

Applicable Models:

Porsche 996 Carrera models (1999-05)
Porsche 996 Turbo, GT2, GT3 (2001-05)
Porsche 997 Carrera models (2005-12)
Porsche 997 Turbo, GT2, GT3 (2007-13)

Parts Required:

Wheel bearing

Hot Tip:

Put the bearing in the freeze prior to installation

Performance Gain:

Smooth driving, no wheel noise

Complementary Modification:

Replace CV joints and boots
Wheel bearing replacement has always been one of those tasks that I have found very difficult to explain in text. So, for this project, I have simply arranged them in order with captions. 
This first photo shows the wheel hub after the car has been raised
Figure 1

This first photo shows the wheel hub after the car has been raised (Pelican Technical Article: Jacking Up Your Porsche 911 Carrera), the caliper removed, and the brake disc removed as well (Pelican Technical Article: Replacing Porsche 911 Carrera Brake Discs). Also, before you raise the car off the ground, remove the center wheel hubcap (see Figure 3 of Pelican Technical Article: Tire and Wheel Sizing on the Porsche 911 Carrera) and loosen the axle nut (blue arrow) with a very long breaker bar while the tire is still on the ground and car is in gear with the parking brake on. The photos for this project are of a front wheel bearing for a four wheel drive 996 Turbo, but the whole assembly is very similar to the 2WD versions.

We're going to be removing the whole wheel bearing carrier here, so we need to disconnect everything that is connected to it.
Figure 2

We're going to be removing the whole wheel bearing carrier here, so we need to disconnect everything that is connected to it. Disconnect the tie rod from the wheel bearing carrier (inset photo--see Pelican Technical Article: Suspension Overhaul of your Porsche 911 Carrera), and also loosen the clamp nut (green arrow) that holds the shock (see Pelican Technical Article: Replacing Porsche 911 Carrera Shocks and Springs). Disconnect the sway bar drop link (Pelican Technical Article: Suspension Overhaul of your Porsche 911 Carrera). Disconnect the wheel speed sensor at its connector.

If you didn't loosen up the axle nut while the car was still on the ground, you can use an impact tool to remove the nut (inset photo).
Figure 3

If you didn't loosen up the axle nut while the car was still on the ground, you can use an impact tool to remove the nut (inset photo). This nut is on very tight, and you might have to work at it with the impact wrench in order to get the nut off.

Use a high-quality ball joint removal tool (yellow arrow) to separate the ball joint from the wheel bearing carrier.
Figure 4

Use a high-quality ball joint removal tool (yellow arrow) to separate the ball joint from the wheel bearing carrier. When the joint is loose, use a pry bar (blue arrow) to push the control arm (green arrow) down while you lift up the carrier. Push the control arm out of the way and then you should be able to slide the carrier off of the shock. If you can't deflect the control arm enough, then loosen the bolt at the other end of the control arm and you should be able to drop it down further. Don't retighten this bolt until the car is back on the ground in its fully weighted position. Remove the wheel speed sensor from the carrier when you have it on your bench.

Here's the axle with the carrier removed.
Figure 5

Here's the axle with the carrier removed. Again, this is from a 4WD 996 Turbo, so there's a drive axle attached to this particular carrier. This design is very similar to the front and rear 2WD Carrera wheel carrier though. The toothed section of the axle generates a signal that is read by the wheel speed sensor that is mounted inside the carrier. If your CV joints need attention or your rubber boot is ripped or damaged, now would be the ideal time to replace it (see Pelican Technical Article: Replacing CV Joints on your Porsche 911 Carrera).

The problem with this car was suspected to lie within the wheel bearing, but we weren't 100 percent sure.
Figure 6

The problem with this car was suspected to lie within the wheel bearing, but we weren't 100 percent sure. With the carrier out and on the bench, a simple spin of the bearing gave the answer--the bearing was toast. It felt like there was sand or something in the bearing and its rotation was rough, not smooth. [NOTE TO LAYOUT - PHOTO IS SUPPOSED TO BE BLURRY, INDICATING THE MOTION OF TURNING]

Positioning the wheel bearing carrier in Callas Rennsport's hydraulic press, we pushed out the inner hub (the part that the brake disc and wheel attaches to).
Figure 7

Positioning the wheel bearing carrier in Callas Rennsport's hydraulic press, we pushed out the inner hub (the part that the brake disc and wheel attaches to). As is common with wheel bearing replacements, the bearing itself fell apart and half of it remained attached to the hub (inset).

To clean up the hub, we used a standard bearing puller to remove the remains of the wheel bearing off of the hub.
Figure 8

To clean up the hub, we used a standard bearing puller to remove the remains of the wheel bearing off of the hub. The inset photo shows the hub all cleaned up with all remnants of the old bearing removed.

When the hub was removed from the wheel bearing carrier, the bearing split into two partsâ€
Figure 9

When the hub was removed from the wheel bearing carrier, the bearing split into two parts--one that was stuck on the hub and the remainder that was stuck inside the carrier. We went back to the press to remove the remains of the bearing. Remove the bearing retainer plate first (inset, lower right). With the bearing completely pressed out of the carrier, it should look like the inset photo in the lower left.

Here's a neat photo showing the physical damage on the worn-out wheel bearing.
Figure 10

Here's a neat photo showing the physical damage on the worn-out wheel bearing. The blue arrow shows pitting of the bearing surface--once this starts in a section of the bearing, it tends to continue and get worse. The bearing should be smooth like the section indicated by the purple arrow. The other half of the bearing is also showing the same deterioration and pitting. Although the seal on the bearing looked intact, this amount of damage leads me to believe there had been some type of contamination issue at play here.

Using the hydraulic press, you can easily install the new bearing.
Figure 11

Using the hydraulic press, you can easily install the new bearing. New bearings should be kept in the freezer right up until they are installed in the car (inset). If they are very cold, it will make pressing them into the wheel carrier much easier. During installation, press on the outer race of the bearing only--don't place any force on the inner race, as this can damage the bearing. When researching this article for the 101 Projects book, we performed the replacement at Callas Rennsport and we came across this question. In the old days, it used to matter which way the bearing was installed (the lighter orange seal used to go to the inside of the bearing). But these days, if you have the older style toothed ring ABS sensor, it doesn't matter, and some of the bearings don't even come with different colored seals on them. We contacted the manufacturer just to confirm that the orientation no longer matters. This is what Tony Callas of Callas Rennsport has been teaching for the past several years in his master mechanic classes.

Now, on the newer cars that have integrated ABS sensor wheels into the bearing, you need to make sure that the sensor side goes next to the sensor itself.
Figure 12

Now, on the newer cars that have integrated ABS sensor wheels into the bearing, you need to make sure that the sensor side goes next to the sensor itself. You need a special $15 magnetic tool to "see" through the seal and figure out that the sensor "wheel" is there. The new active wheel speed sensors work with magnetic sensor wheels, which are integrated in the rubber sealing ring of the wheel bearing. For this, the rubber is enriched with iron dust and then given magnetic fields which are highly sensitive. It is not possible the check the magnetic sensor wheels visually. Before a new wheel bearing is installed, it is therefore absolutely necessary that the wheels be checked. The part could be faulty, and the direction of installation must be determined. But when checking errors in the ABS it may also be necessary in the case of sensor errors to check the magnetic sensor wheels. With the ATE test card for magnetic sensor wheels, these tests can be carried out reliably, easily and inexpensively. The magnetic fields of the sensor wheel are shown visually in the display window of the ATE test card, making it possible to check them. The ATE test card for magnetic sensor wheels comes with an integrated protective case. Benefits: Fast, simple and inexpensive. These test cards are available from Pelican Parts.

Shown here is the wheel bearing carrier from both sides with the new bearing installed and the bearing retainer plate in place.
Figure 13

Shown here is the wheel bearing carrier from both sides with the new bearing installed and the bearing retainer plate in place.

With the new bearing installed in the wheel bearing carrier, it's time now to install the hub back into the inside race of the bearing.
Figure 14

With the new bearing installed in the wheel bearing carrier, it's time now to install the hub back into the inside race of the bearing. This is performed using a wheel bearing installation tool (blue arrow). Using a circular backing plate that is the same size as the inner race (yellow arrow), the tool pushes the hub inward while compressing on the inner race. Crank down the bearing installation tool until the inside surface of the hub rests against the surface of the inner race of the bearing (green arrow). The inset photo in the lower left shows what the backside of the installed bearing/hub assembly should look like when the hub is fully installed. Test the hub on the bearing with a few test spins. Don't be alarmed if it doesn't spin too freely--new bearings are generally pretty stiff at first.

Reinstall the wheel bearing carrier back onto the car securing the ball join, shock tower, sway bar, tie rod, speed sensor connection, brake disc, brake caliper, and anything else you disconnected in the process.
Figure 15

Reinstall the wheel bearing carrier back onto the car securing the ball join, shock tower, sway bar, tie rod, speed sensor connection, brake disc, brake caliper, and anything else you disconnected in the process. Tighten up the axle using a brand new nut.

With the car back on the ground, use a really big torque wrench to tighten up the axle nut.
Figure 16

With the car back on the ground, use a really big torque wrench to tighten up the axle nut. If you don't have a really big torque wrench, you can use a long breaker bar and your bodyweight to apply the torque. The torque value for this nut is 340 ft-lbs, so if you divide 340 by your weight (for example 200 pounds), you will need to stand on your breaker bar with your full weight, 1.7 feet (1 foot 8 inches) away from the center of the wheel. Do this with the breaker bar perfectly parallel with the floor.

It's important to note that you do not always need to remove the wheel bearing carrier from the car in order to remove the wheel bearings.
Figure 17

It's important to note that you do not always need to remove the wheel bearing carrier from the car in order to remove the wheel bearings. In the case of the 4WD Turbo, it was necessary because the axle was inserted in the inside of the carrier, and it was not possible to remove it without removing the carrier. In some cases, you can replace the wheel bearing with the carrier still installed in the car and avoid using the hydraulic press altogether. In this photo (and Photos 18 and 19 as well), you can see part one of a bench demonstration of the process of pulling out the wheel hub using the tool. Put a backing plate on the inner race and use the tool to pull the hub out of the bearing (the bearing will break apart at this point).

Here's part two of the process of pulling the bearing using the tool.
Figure 18

Here's part two of the process of pulling the bearing using the tool. With a backing place the diameter of the outer race on the back side, the tool can simply pull the rest of the bearing out of the bore using the long center screw.

Part three of the process involves using the tool to press in the new bearing.
Figure 19

Part three of the process involves using the tool to press in the new bearing. Using a really big backing plate that compresses against the back of the aluminum wheel bearing carrier, the front part of the tool compresses the wheel bearing into place. Finally, the installation of the hub into the carrier is performed in the exact same manner as shown in Photo 13.

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Comments and Suggestions:
Mario Comments: Is this DIY also for the 2000 c4 ?
November 13, 2016
  Followup from the Pelican Staff: Applicable Models:



Porsche 996 Carrera models (1999-05)
Porsche 996 Turbo, GT2, GT3 (2001-05)
Porsche 997 Carrera models (2005-12)
Porsche 997 Turbo, GT2, GT3 (2007-13) - Nick at Pelican Parts
 
Cog_Zoom Comments: A couple of questions I hope someone can help answer:
1 My 996 is a race car built off of a stock 1999 C2. Is it better/possible to go with the motorsport bearing indicated for the Cup, R, etc., or should I stick with the "normal" bearing?

2 Is the removal/installation of the rear wheel bearing any different? Are additional special tools required other than indicated here?

Thanks
May 17, 2016
  Followup from the Pelican Staff: I would go with the race bearing, if you are racing the vehicle.

The procedure is similar. You may have to unbolt a cover when pressing the bearing in and out of the spindle.- Nick at Pelican Parts
 
L Comments: The new bearings are already sealed and greased internally, correct? I purchased a set of FAG bearings for replacement, and just want to make sure I don't need to grease them prior to installation.

Thanks,
L
January 25, 2016
  Followup from the Pelican Staff: Sealed bearings come greased for life. What vehicle? - Nick at Pelican Parts  
king Comments: do you guys have a time-sert kit for 2002 996 front driver side wheel carrier hub had thread stripped in the hole where caliper bolt goes into. Thanks
April 15, 2015
  Followup from the Pelican Staff: I just did a quick look through the catalog and did not see any thread repair kits but you might want to give our parts specialists a call 888-280-7799. Tell them you need a thread repair kit for an M12 x 1.5 bolt hole. If we do not have it MCMASTER-CARR is a good resource for those items. - Casey at Pelican Parts  
martywilde Comments: Is this a special tool or a generic bearing puller?

==Marty
January 29, 2015
  Followup from the Pelican Staff: These are generic hub and bearing removal tools used with a hydraulic press. - Casey at Pelican Parts  
FFaust Comments: Thanks Nick, and thanks Pelican Parts, this DIY was very helpful.
February 8, 2014
  Followup from the Pelican Staff: Thanks for the feedback. Glad we could help.
- Nick at Pelican Parts
 
FFaust Comments: I have heard I think that you can only replace the bearing once or twice before having to replace the upright/bearing carrier: Is this true?

Thanks
Francois
996 GT3
January 19, 2014
  Followup from the Pelican Staff: I think I have read this somewhere. Some mechanics prefer to do it this way and some prefer to reuse the carriers. All depending on the condition I assume. - Nick at Pelican Parts  

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