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Front Wheel Bearing Replacement
 
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Pelican Technical Article:

Front Wheel Bearing Replacement

Steve Vernon

Time:

4 hours4 hrs

Tab:

$40 to $250

Talent:

****

Tools:

Socket set, flathead screwdriver, hammer or press, 5mm Allen, floor jack, jack stands, wheel chocks, safety glasses, torque wrench

Applicable Models:

Mercedes-Benz C250 (2012-14)
Mercedes-Benz C300 (2008-14)
Mercedes-Benz C350 (2008-14)

Parts Required:

Bearing kit

Hot Tip:

Be careful when driving the old race out

Performance Gain:

Restore a tight feeling to the front end of your car.

Complementary Modification:

Replace brake pads and discs

If you are starting to hear a low rumbling sound from your front end or your W204 has over a one hundred thousand miles on it you should inspect your front wheel bearings for replacement. The bearings support the full weight of the car both while stationary and under load. As the mileage increases on the car, heat and lack of lubrication can cause the bearings to wear and possibly fail.

Replacing the bearings isn't a difficult procedure, but it does involve a commitment 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. If you are worried about your skill level you can just buy a new complete wheel hub with the bearings installed.

Before you begin the job place the new races in the freezer, preferably over night if you can. Freezing the races will decrease the other diameter and make installation into the hub easier.

You will need to first remove the brake caliper and rotor or discs. Please see our articles on removing your calipers and disks.

Once the calipers and pads are removed, you'll have access to the wheel-bearing hub. If you are going to be installing new rotors while performing this job leave the old ones on while working. The old rotors will provide a wider base or more stable platform while working on the hubs.

If you purchase a bearing kit it will come complete with everything you need including the grease.
Figure 1

If you purchase a bearing kit it will come complete with everything you need including the grease. Otherwise you will have to source all the parts separately.

With the caliper and disk removed you will be looking at the wheel hub.
Figure 2

With the caliper and disk removed you will be looking at the wheel hub. If you are not looking at this then please go see our articles on brake caliper and rotor removal first.

Remove the dust cap from the front of the wheel hub.
Figure 3

Remove the dust cap from the front of the wheel hub. You will need to gently pry and tap the cap off using a large flathead screwdriver (red arrow). Rotate the hub as you do this to help the cap come off evenly

With the dust cap removed you can see the axle nut that sits at the center (red arrow).
Figure 4

With the dust cap removed you can see the axle nut that sits at the center (red arrow). It's a good idea to wipe off any excess grease on the nut. A note about grease, do not go overboard with the grease. The kit will come with all the grease you need; people seem to think that if a little grease is good a lot of grease must be great. This is not the case. People also think that everything should be greased; this is also not the case. Please follow the greasing instructions to follow.

Use a 5mm Allen key (yellow arrow) to loosen the clamp on the axle nut.
Figure 5

Use a 5mm Allen key (yellow arrow) to loosen the clamp on the axle nut. This clamp holds the axle nut in place on the spindle. Once you loosen the clamp, you should be able to easily unthread the nut from the spindle.

Remove the outer tapered roller bearing (red arrow).
Figure 6

Remove the outer tapered roller bearing (red arrow).

Pull the hub (red arrow) off of the spindle (yellow arrow).
Figure 7

Pull the hub (red arrow) off of the spindle (yellow arrow).

Clean all the grease off the spindle (red arrow), and check it for wear as well.
Figure 8

Clean all the grease off the spindle (red arrow), and check it for wear as well. If the spindle shows any grooves or pitting, you'll want to replace it. Another note about grease, people tend to grease overly up the spindle; you do not need to grease the spindle, as the bearing is designed with an inner race that sits on the spindle. The bearing should turn around the races and not the spindle.

With the wheel hub removed from the car, turn it over to the backside.
Figure 9

With the wheel hub removed from the car, turn it over to the backside. You'll see an oil seal pressed inside (red arrow). You'll first need to remove this seal to remove the inner bearing and race. Use a seal puller to remove the old oil seal from the wheel hub. If you don't have a seal puller you can use a large flathead screwdriver and something to give you leverage. It will take a fair amount of force to pry the old seal from the hub so don't be afraid if the old seal deforms or bends as you pull it out. These are designed as one-time use items. You will more than likely destroy it as it comes out.

Remove the inner tapered bearing (red arrow).
Figure 10

Remove the inner tapered bearing (red arrow). There is enough grease in this hub to do several cars worth of bearing replacements (yellow arrow).

Clean the inside of the hub and check the condition of the races.
Figure 11

Clean the inside of the hub and check the condition of the races. They should both be clean and smooth with no signs of scoring, heat damage or grooves. If you are replacing the bearings you should change the races out as well. You can remove the outer race (yellow arrow) with a press and the inner race with a punch (red arrow).

You can remove the outer race with a socket and hammer.
Figure 12

You can remove the outer race with a socket and hammer. You will want to apply an even force to all sides of the race when removing, but I prefer to use a press. If you have a press it is best to use it, as this will keep even pressure side to side when removing or install the races. Find the right sized socket (in our case a 30mm) and press the old race out. When installing the new race take it out of the freezer and press it back into place making sure the tapered side is facing correctly.

For the larger race on the opposite side, you'll have to use a smaller socket or large punch and hit the edge of the race at an angle.
Figure 13

For the larger race on the opposite side, you'll have to use a smaller socket or large punch and hit the edge of the race at an angle. It helps to hit the race around the diameter of the edge to drive it out evenly (red arrow). You will not be a able to get a large enough socket inside the hub to apply even pressure during removal so take your time and constantly rotate the hub to remove the race as evenly as possible. Patience is a virtue here. You need to make sure you do not damage or scratch the inside bore of the wheel hub.

Take the new inner bearing race and place it in the bore on the rear of the hub.
Figure 14

Take the new inner bearing race and place it in the bore on the rear of the hub. M-B makes an expensive tool to seat the race but you should be able to find a socket large enough to use to press the race in. I found an old ball socket that fit perfectly. You'll want to position the tapered section to accept the bearing (red arrow). Now press the bearing race into the hub until it seats against the bottom flange of the hub. If you're having to do this with a hammer take your time and make sure that the race goes in straight. It's very easy to cock the race in the bore.

Another word about grease, the packet of grease that comes with the kit is all the grease you need to install the two bearings.
Figure 15

Another word about grease, the packet of grease that comes with the kit is all the grease you need to install the two bearings. Grease is only needed on the races and bearings. If you are going to use a bearing packer you will need more grease than this to load up the packer but you do not need to apply a greater volume of grease than is in this package.

Before installing the bearings into the wheel hub, it's necessary to pack them with grease.
Figure 16

Before installing the bearings into the wheel hub, it's necessary to pack them with grease. The idea here is to fill all the open spaces of the needle bearings. There are a couple different ways of doing this. You can buy a wheel-bearing packer, which uses pressure to push the grease in from the open ends. If you are doing it by hand push grease in through the openings on the ends (red arrow) until grease comes out the other end. Then rotate the bearing back and forth.

I highly recommend getting a bearing packer (yellow arrow).
Figure 17

I highly recommend getting a bearing packer (yellow arrow). Pelican Parts sells a few different ones; they are cheap, very effective at packing the bearings with grease and make what might be one of the messiest jobs in all of motorsports clean and easy.

Be sure to also put a coat of grease on the face of the bearing race (red arrow).
Figure 18

Be sure to also put a coat of grease on the face of the bearing race (red arrow). Once the bearing is packed, drop it in place on the hub. It's not a bad idea to hold the inner part of the needle bearing and then turn the hub to distribute more grease through the bearing. Clean any grease that may be on the inner races of the bearings (red arrow). You want the bearings to spin in the races, not the races to spin on the spindles.

Clean up any grease that may have gotten on the outer surface of the hub where the oil seal fits, and center the seal in the bore.
Figure 19

Clean up any grease that may have gotten on the outer surface of the hub where the oil seal fits, and center the seal in the bore. Carefully tap the oil seal into place taking care that the seal does not get cocked in the bore on the wheel hub (red arrow). Keep tapping the seal until it bottoms out in the bore.

Now fit the wheel hub back over the spindle and push it back until the seal pops over the flange on the back of the spindle.
Figure 20

Now fit the wheel hub back over the spindle and push it back until the seal pops over the flange on the back of the spindle. Install the freshly packed outer bearing keeping in mind that the tapered section of the bearing fits into the race facing inward (red arrow). You'll now need to adjust the wheel bearing. While all bearings should be set with a dial gauge and holder the truth of the matter is most DIY mechanics do not own or know how to properly use this equipment. If you do, please adjust you're bearing accordingly. If you are contemplating doing this without it all I can write is that adjusting bearings is really a matter of feel and experience. You should tighten the clamping nut until you feel all of the play between the bearings gone; the hub should still turn but should not spin freely in your hands. The last step is to use a hammer to lightly tap the cap back into place.


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