W210 - Front wheel bearings - PeachParts Mercedes-Benz Forum

raMBow · #1 11-30-2007, 10:48 PM

Thinking about changing or repacking these.

Are special tools needed?

Is this a simple project?

What type of grease to use?

Procedure?

Thanks

TMAllison · #2 11-30-2007, 11:27 PM

Complicated procedure and tool set designed by engineer per WIS; dial gauges, etc. Or use allen wrench along with common sense as you've always done it the past as with any other car.

Take cap off and you'll understand.

Repack with bearing grease, tighten, smack with hammer to release tension and spin rotor to dbl check.

raMBow · #3 11-30-2007, 11:32 PM

What grease would you advise?

TMAllison · #4 11-30-2007, 11:45 PM

I used a standard high temp/pressure wheel bearing grease to repack mine.

MB prob has their own private label brand sold by the gram.

sokoloff · #5 12-01-2007, 09:31 AM

Mercedes, at least for my older cars, has a very convenient 150gram tube that their wheel bearing grease comes in. I say nice, because the wheel bearings only call for a specific amount of grease, typically about 65 grams for each side. With this tube of grease, it's pretty easy to get just the right amount of grease for the application. Without it, it's pretty easy to over pack the bearings which can cause problems.

Racekar · #6 12-01-2007, 10:18 AM

It's impossible to overpack bearings, the excess grease just squirts out the other side of the cage. Infact thats how you know they are packed properly and fully.

I am partial to synthetic grease, years ago I had a 280Z racekar that would eat front wheel bearings and spindles on a regular basis. After I tried synthetic the problem went away.

JimSmith · #7 12-01-2007, 12:38 PM

Quote:

Originally Posted by Racekar

It's impossible to overpack bearings, the excess grease just squirts out the other side of the cage. Infact thats how you know they are packed properly and fully.

I am partial to synthetic grease, years ago I had a 280Z racekar that would eat front wheel bearings and spindles on a regular basis. After I tried synthetic the problem went away.

In reality it is not only possible to overpack bearings, but a frequent occurrence and leads to low life due to over heating. The grease works in a ball bearing by reaching a certain temperature and then releasing the oil it has in suspension. The oil forms a hydrodynamic film between the ball and the race, and is subjected to very high, very localized pressures. The film thickness for a given application is ideally thicker than the defects in the surface finish of the balls and races, and any of the grease thickening agents or other additives. The oil also acts to remove heat from the bearing rolling elements and contact areas of the races. As the oil cools the bearing the temperatures drop into a range of acceptable (in a balanced design) temperatures where the grease pack can resupply the oil being lost to evaporation and mechanical destruction on a molecular level, for a regular, repeatable time period.

Overfilling the bearing causes the balls to have to churn the extra grease as they spin, and it adds drag to the cage. This all makes additional heat and makes the normal flow oil less effective as it runs out of the working area and it evaporates sooner, leaving little more than the thickeners and additives, which are not lubricants in most cases. It is well documented that too much grease leads to premature failures from over heating.

Newer greases with better oils and thickeners are probably more tolerant of this condition, but they are not immune either. The tolerance comes from higher temperature grade oils and thickeners, all of which are usually more expensive, and that leads to using less rather than more grease in a bearing repacking more often than not. More is not better when it comes to packing bearings. The right amount is best, and that amount is determined by the bearing size, the bearing housing shape and the loads. Jim

Racekar · #8 12-01-2007, 01:39 PM

It is not a closed space, the extra grease works it's way out of the space the first time the wheel is turned and gets the grease hot. Front wheel bearings are tapered roller bearings, there is no possible way that you can over pack them by hand. Most ruined bearings are caused by over tightening, not over packing with grease.

aklim · #9 12-01-2007, 01:46 PM

The 150 gram tube works fine unless you have multiple cars that you are working on. Otherwise, it just sits on the shelf waiting to get squished at an inconvenient spot. Ask me how I know. I use lots of dielectric grease so I have a big tube. Things I use rarely, I get as small a tube as possible.

JimSmith · #10 12-01-2007, 02:15 PM

Quote:

Originally Posted by Racekar

It is not a closed space, the extra grease works it's way out of the space the first time the wheel is turned and gets the grease hot. Front wheel bearings are tapered roller bearings, there is no possible way that you can over pack them by hand. Most ruined bearings are caused by over tightening, not over packing with grease.

If you mean packing the space between the rollers/races only, you are correct. If you are speaking of the cavity they sit inside of, it is sealed. If you fill the entire cavity at reassembly the grease will not have room to leave the space. The area is sealed to keep dirt and water out, and the grease in. So, the cavity is not without limit. If your method of greasing is to fill the bearing outside the cavity, install it, rotate the hub, and only add grease in the cavity outside the working area, a 100% fill of the bearing itself might be ok.

I would also concur that over tightening is a frequent error. As is loss of cleanliness. But overfilling a bearing cavity when regreasing is also common. It is the primary reason why bearing greasing evolutions on industrial machinery calls for filling a specific grease cup with the desired grease, and using the grease cup to dispense the specified volume of grease. Jim

280EZRider · #11 12-01-2007, 07:19 PM

One very important point that has not been mentioned here: after packing the bearings, be sure to pack grease in each dust cap up to the flared edge. This is the only thing required by MBZ that is different from any other car.

Matt L · #12 12-01-2007, 07:37 PM

The other thing that hasn't been mentioned is to not mix greases with incompatible soap bases.

If you don't completely clean out the old grease, be sure that you add the same type.

raMBow · #13 12-01-2007, 11:41 PM

Thanks for the responses.

Are any special tools needed? Don't know why I am afraid of this job, just did the lower control arm bushings and sway bar links two weeks ago, so this should be "simple", just have never done it before and don't want to mess anything up.

280EZRider · #14 12-02-2007, 02:42 AM

No special tools required, and you're right; it's a simple job. Be sure to hang your brake calipers with an old coat hanger or similar. Don't just let them hang by the brake lines.

sokoloff · #15 12-02-2007, 12:55 PM

Quote:

Originally Posted by 280EZRider

One very important point that has not been mentioned here: after packing the bearings, be sure to pack grease in each dust cap up to the flared edge. This is the only thing required by MBZ that is different from any other car.

Need to check the manual to be certain. I haven't seen the procedure on the 210 chassis, but it's likely similar to the others that I've seen. Mercedes specifies a certain amount of wheel bearing grease for the bearing itself and for the grease cap. Usually it's something like 15g and 50g. Maybe filling it up to the flared edge is the right amount, but I've never seen it stated that way in any Mercedes manual.