[Denny347]

I just replaced the front wheel bearing (hub assembly) on my 330i yesterday. I was going to take pictures but got too involved with it to stop. However, it was a straight forward job that was pretty easy. I bought my replacement hubs from BMAparts.com for $85 a piece. They are F A G just like the ones I pulled off.
List of tools:
17mm socket 3/4 drive
3/4" breaker bar
3/4" torque wrench (installing the wheels once done 89ftlbs)
7mm Allen socket 3/8" drive
6mm Allen socket 3/8" drive
18mm socket shallow 3/8" drive
18mm offset box wrench
10mm socket (3/8" or 1/4")
3/8" extentions
3/8" ratchet
cut up wire hanger
brake pad compressor
Flat screwdriver or cotter pin puller
Rubber mallet

I took about 1.5 hrs on the driver side since I had to stop and buy 2 tools in the middle of it. Took me less than an hour to replace the passenger side. Overall an easy job. Not my first bearing replacement in general but first on a BMW.

-Jack up front end and remove the front wheel. 17mm 3/4" drive for this.

-With a flat screwdriver or cotter pin puller, pop the anti squeal clip off the top of the break pad

-On the rear of the caliper, there are 2 rubber boots covering the bolts that hold the caliper to the carrier, pop the lid off the rubber boot exposing the bolthead underneath.

-Using the 7mm Allen 3/8" drive socket, unscrew the Allen bolts, freeing the caliper from the carrier.

-Once you pull the caliper and pads off, use the cut up hanger to hang the caliper from the spring/strut assembly.

-On the rear of the carrier there are 2-18mm bolts that bolt the carrier to the steering knuckle. Unbolt them and pull the carrier away from the brake disc.

-Use the 6mm 3/8" drive socket to remove the retaining screw on the face of the rotor, holding the rotor to the hub assembly/bearing. Smack the face of the rotor a few times with a rubber mallet and it will pop off easily.

-Use the 10mm socket to remove the 4 bolts holding the protection plate (thin metal shield) to the knuckle. I found that removing this made getting to the hub bolts easier.

-Now look to the back side of the steering knuckle and you will see the 4-18mm bolts holding the hub assembly to it.

-I found that using a offset box wrench helped me break the bolts loose with the longer lever arm it provided. I found out the hard way that all 4 bolts are very easy to get to if you turn the steering wheel as needed. The original bolts are TIGHT when taking them out. They do not loosen up at all due to the locktite on the threads. I have the largest air ratchet Snap-On makes and it would not loosen the bolts...good 'ol elbow grease is the only way. I do not think there is enough room for an impact wrench.

-Once the bolts are removed, take the rubber mallet and give the hub assembly a tap, breaking it free from the steering knuckle. I then took a wire brush and cleaned the mating surface of the steering knuckle. The hub assembly's bolt holes only line up in one direction.

-Assembly is reverse of removal. This time, my air ratchet did help. Getting the new bolts into the new hub assembly was quick and painless.

My original hub assemblies were toast. Spinning them once they were off the car sounded like there were stones inside the assembly. My car has 85k miles on it. The driver rear bearing was replaced at 70k (that was beyond my abilities). I used this time to check the tie rods, etc to looseness. All was nice and tight. I have lots of break pad left or this would have been a great time to change the pads/rotors as well. I did find my factory wheel bolts had lost their black color so I hit them with black engine paint, they look factory fresh. Overall an easy job.

[monkey_wrench]

Nice write-up, thanks!!

[benjlv]

This guide lacks bolt torques for the bolts that hold the bearing assembly to the steering knuckle. I do not know what the torques are for these bolts off hand, but they should be properly torqued since they do hold the wheel onto the car. You dont want this torque to be too low and allow the assembly to work its way loose over time and you dont want it to be too high and risk yielding the bolts. I also believe that since they have loctite from the factory, that they should be replaced. At the very least, the correct type of loctite should be used again after cleaning the bolts.

[Denny347]

Originally Posted by benjlv

This guide lacks bolt torques for the bolts that hold the bearing assembly to the steering knuckle. I do not know what the torques are for these bolts off hand, but they should be properly torqued since they do hold the wheel onto the car. You dont want this torque to be too low and allow the assembly to work its way loose over time and you dont want it to be too high and risk yielding the bolts. I also believe that since they have loctite from the factory, that they should be replaced. At the very least, the correct type of loctite should be used again after cleaning the bolts.

Anyone can grab the torque specs from a Bentley Manual and I used new bolts. However, it's really not hard to do this without torque specs, you will NOT be able to over tighten the bolts that secure the bearing assembly to the steering knuckle unless you use a big ass impact, for which there is no room. Hand tools, tighten until you cannot possibly tighten it anymore.

[benjlv]

Originally Posted by Denny347

Hand tools, tighten until you cannot possibly tighten it anymore.

This varies drastically from person to person, length of the tool, and experience of the person as well. Sure yes, you may have got the torque within a band of what is acceptable, or perhaps you yielded the bolt and now you don't know. Theres a reason that OEMs employ torque wrenches on the assembly line.

Think about it. do you tighten your wheel bolts as much as possible? nope, you are using a torque wrench there to make sure you don't under or over torque the bolts. The bolts on the wheel are a similar size and pitch as these hub bolts...and they also hold the wheel onto the car. I don't know why you'd take any less care here. Not to mention that the next guy who works on this part will be happy that the last guy didn't tighten them to super gorilla tightness. I'm not saying that you should go take your car apart, i am just including this information for any DIY that comes along and wants to tackle this job with these instructions.

[Efthreeoh]

I just performed this DIY on my right front wheel bearing. A few helpful comments:

The bolt install torque is 110 NM or 81 Ft/lbs. (from the BMW TIS and Bentley).

Expect high level of difficulty removing the old bolts; you will almost start to think they were cross-threaded upon installation. The bolts are loaded with red Loctite, which over time and with heat, really locks in the bolts to the bearing hub. I have an air impact wrench with 1,000 lbs of reverse torque and it was having difficulty removing the old bolts.

It is advisable to turn the steering to swing the hub to a position that allows the best straight-on access to the boltheads (18MM). The most difficult bolt to get to is the upper, rear-most bolt as it is partially blocked by the bottom of the strut body. With the hub turned so the rear of it is facing out (e.g. turned left for the right hub and turned right for the left hub) you can get a 3/8-drive 18MM socket and extension bar in there without the need of a universal. Non-impact tools will fit even better, as impact-rated sockets and extension bars are a bit thicker than non-impact tools. Remove the front two bolts first, then remover the upper rear-most bolt (the hardest one to get to) then remove the last lower rear-most bolt (the easiest one to get to).

The bearing should fall right off the hub carrier (at least mine did, but I did use impact tools that introduced vibration into the assembly). If the bearing is stuck to the hub carrier, there is a slot in the bottom (6 o'clock position) that you can use to pry it off the hub carrier. Be careful removing the hub bearing! the speed sensor is in the cavity behind the hub bearing, moving the hub bearing around too much could damage the speed sensor.

Installing the new hub bearing is easy. The new, Loctite impregnated bolts thread into the new hub bearing very easily (the opposite of removing the old ones).

All in all, very easy DIY. Just make sure the car is firmly supported on 4 jackstands. The OP's write-up was very helpful in assisting with this DIY. Thanks.

[BashShah]

Denny347, why did you replace your bearings?

What were your symptoms?

Thanks again for a great write up.
DN

[Efthreeoh]

Originally Posted by benjlv

This varies drastically from person to person, length of the tool, and experience of the person as well. Sure yes, you may have got the torque within a band of what is acceptable, or perhaps you yielded the bolt and now you don't know. Theres a reason that OEMs employ torque wrenches on the assembly line.

Think about it. do you tighten your wheel bolts as much as possible? nope, you are using a torque wrench there to make sure you don't under or over torque the bolts. The bolts on the wheel are a similar size and pitch as these hub bolts...and they also hold the wheel onto the car. I don't know why you'd take any less care here. Not to mention that the next guy who works on this part will be happy that the last guy didn't tighten them to super gorilla tightness. I'm not saying that you should go take your car apart, i am just including this information for any DIY that comes along and wants to tackle this job with these instructions.

It's an M12 bolt and hardened steel, there is no way you can over torque the bolts with hand tools (or any air tools that'd fit in the space between the hub and the frame) that would anywhere near reach the bolt's yield strength.

[Denny347]

Originally Posted by DarkNemesis

Denny347, why did you replace your bearings?

What were your symptoms?

Thanks again for a great write up.
DN

Rumble noise coming from the front end.

[Denny347]

Originally Posted by Efthreeoh

It's an M12 bolt and hardened steel, there is no way you can over torque the bolts with hand tools (or any air tools that'd fit in the space between the hub and the frame) that would anywhere near reach the bolt's yield strength.

Thank you

[chupa_cabra]

Just wanted thank you for this write up. I finished replacing mine this past weekend and was quite happy with the results (no more vibration). I also took some pictures while I was working on it. Feel free to use or not use as reference in your DIY.

https://www.flickr.com/photos/881197...7646199514022/

[Denny347]

Originally Posted by chupa_cabra

Just wanted thank you for this write up. I finished replacing mine this past weekend and was quite happy with the results (no more vibration). I also took some pictures while I was working on it. Feel free to use or not use as reference in your DIY.

https://www.flickr.com/photos/881197...7646199514022/

That's awesome!!! Glad it helped.