a few wheel bearing questions - PeachParts Mercedes-Benz Forum

RG5384 · #1 06-10-2002, 12:22 PM

I am well on my way to having new ball joints

but in the process, i think i may have ruined a wheel bearing

, it fell out of the rotor onto a fairly dirty garage floor with bits of leaves etc on it, i seemed to have wiped it all off, but i'm still leary. If i soak the bearing in a bearing cleaner and then re-grease it(repack it) should it be OK? What is the standard procedure for re-packing bearings? i've got to get this thing done this week so it can be on the road by next, that way i'm never out of a car

thanks,
Ryan

#2 06-10-2002, 01:13 PM

one thing all the old timers used to warn me about before I became an old codger myself, was that after very carefully cleaning a bearing in shop solvent, you should never blow it dry with a pressure air hose, because the air blast can spin the dry rollers so fast that they get scored from contact with the inner race. I've never seen it happen, but then, I've never used an air hose on bearings . . . .

If you don't have one of those repacking gadgets (two metal cones to clamp, one on each side of the bearing, with a zerk fitting in the center of one) then you just get a big wad of grease in the (carefully cleaned) palm of your hand and squish the bearing around in it until you're sure that the whole row of rollers all around is full of grease, with no serious air pockets left.

In my experience, the hardest part is not dropping it again before you've finished.

DieselHead · #3 06-10-2002, 03:17 PM

I think you probably should be ok too, but if you're going to order something from FastLane (or whatever parts place you use) soon anyway, you might as well order new bearings. I remember them not being too expensive.

Alex

speedy300Dturbo · #4 06-10-2002, 05:21 PM

Make sure no sand or grit gets in the bearing. Degrease that thing and clean it out as best you can, and repack it with some high quality grease. Should be fine... I did the same thing recently.

tcane · #5 06-11-2002, 01:19 AM

I've cleaned and re-packed with grease many 1,000's of bearings of all kinds including a fair number of wheel bearings. Very good comments/suggestions by the other members about cleaning in solvent, not drying by spinning the bearing with compressed air (drying with compressed air is OK so long as the bearing is not allowed to spin - and compressed air should remove any remaining crud/grit), and re-packing by putting a glob of grease in your palm and filling the bearing with grease ( a bit of a mess that can be lessened by wearing surgical/vinyl examination gloves).

I would add that you want to use a wheel bearing grease with a melt temperature in excess of 450 degrees F (high melt temp prevents liquifying causing the grease to flow out of the bearing and subsequent loss of lubrication and some greases with melt temps below 450 but good enough to use will have some liquification that will cause a mess on your wheels/tires/other front end parts close to the wheel).

And, look to see if the grease has a specific gravity of greater than 1.0 so that water will not displace the grease causing the loss of lubrication and bearing damage. Instead of giving a specific gravity spec., the grease may say it is not displaced by water.

Do you have the info on how to adjust the front wheel bearings after installing them?

Good Luck!
Tom

RG5384 · #6 06-11-2002, 01:22 AM

uhhh, adjust the bearings??? you dont just put them back in? i think i need to be versed on this topic now......... thanks!?
?Ryan?

tcane · #7 06-11-2002, 03:06 AM

The official M-B repair manual calls for using a dial gauge to set the end play of the wheel hub (part the wheel/tire are bolted to using the lug bolts). Most don't own a dial gauge so in the Haynes manual you'll find this procedure that I've used and modified a bit:

*pack both inner and outer bearings with high temp grease;
*install bearings using a new grease seal for inner bearing;
*install washer and lock nut;
*tighten lock nut while turning the hub until the hub is very hard to turn (Haynes says till hub won't turn, I found this was too tight because I own and used a dial gauge to check);
*back lock nut off (loosen) 1/3 turn (make sure it is 1/3 turn), loose is better than too tight (tight means the bearings will get too hot and fail - wheel comes off usually at the worst time; but, too loose causes the front end to have alignment problems and tire wear);
*strike the kingpin (shaft the bearing and hub mount to) a sharp blow with a hammer to release the tension on the bearing (I use a punch placed in the hole in the center of the kingpin and hit the punch instead of the kingpin);
*tighten the Allen head bolt in the lock nut;
*replace the dust cap.

If you do not own the Haynes manual - I suggest you buy a copy, lots of good info.

Good Luck!
Tom

RG5384 · #8 06-11-2002, 10:31 AM

okay, thanks. What you said makes alot of sense, i never thought about that before, so i'm very glad you said something! The grease i bought is the durablend sythetic, it says it's good from -25 to 400, so that should be close enough right? thanks again
Ryan

tcane · #9 06-11-2002, 01:44 PM

I just received in the mail an official M-B maintenance manual (991 pages) covering all diesel and gas models up to year 1980 from the 220D to the 450 and including the 600 long with 6 doors. The procedure for adjusting the wheel bearings is as I outlined above and the Haynes manual uses (including what I found that to tighten the lock nut until the hub is hard to turn then back-off 1/3 turn, unlike the Haynes that says to tighten the locknut until the bearings/hub won't turn - then my new manual says to check end play using a dial gauge).

Your ques. about the synthetic grease with a 400 degree melt temp - I am not familiar with this grease, but as I wrote greases with lower melt temps will work but many will have a bit of liquid at room temp or at higher temps that will seep out and coat the wheel, tire, and other parts with oil. Remember, your have disc brakes and they reach higher operating temps than the old drum brakes and require greases with higher melt points (I did a lot of experimenting with greases when I was a tech advisor to American Honda) and I found that 450 F. and specific gravity greater than 1.0 was what I wanted. This was more than a few years ago, and the only greases that met my needs/requirements were BG SLC wheel bearing grease part no. 607 (available from BG distributors, BG products are used by some M-B dealerships, other car dealers and independent repair shops as well - not found in any auto parts store; can be bought usually from the BG dealer or a car dealership, look up an old post in the Tech forum for info to find BG products or an internet search or call around - BG makes some very good products, they test them here in TX at Texas A&M in College Station) and Lubriplate 1200 wheel bearing grease which is easier to find. I am sure there are now other greases that will work fine, provided they have a melt point of 450 F. or higher and a SG greater than 1.0 (or says water will not displace).

Your synthetic grease may work OK, but it may seep some liquid. The only way to know is try to put a little on an impenetrable surface surface (like a plastic sandwich baggy, a plate, a piece of metal, etc.) and put it out in the hot sun to see if liquid seeps out - if it does then you're wheel, tires, etc. will get coated and is a mess needing more frequent cleaning because it is a dust/dirt/grime magnet. Let us know what happens.

I do know from extensive use that BG SLC grease will go 50,000 miles before needing to repack the wheel bearings and water will not displace it. Maintenance spec calls for repacking at about 25,000 miles and/or 2 years and more often in dusty or wet conditions (rainy areas or going through low water at stream crossings and/or rain run-off). Since I've found a grease that works, I'm sticking with it.

Good Luck!
Tom

Kyle Blackmore · #10 06-12-2002, 12:10 AM

I was suprised to learn(from the service CD)that MB specifies a certain amount of grease (60grams/+/- 2 oz).Being the anal guy I am I borrowed the kitchen scale and weighed out the right amount only to find out it is exactly enough to repack the inner and outer bearings and fill the space between them(which is the way I've always done it).Too much grease will cause it to seep out the seal or cap.Good luck Ryan.

tcane · #11 06-12-2002, 01:00 AM

Actually, the reason why you pack grease in the hub area between the bearings and in the dust cap is to build/form a dam/wall to prevent the grease from flowing out of the wheel bearings when the grease gets hot and turns to a liquid. This problem occurs with greases having low melt temps that were the standard wheel bearing greases used when the manuals were written and many greases sold today have the same characteristics.

Using BG SLC wheel bearing grease I only packed the bearings and no more on my '77 300D for the last 12-13 years and 300,000 miles. There is no grease in the dust cap or in the space between the bearings - also, a lot less mess when handling the wheel bearings and related parts, plus less wasted grease. I also used the same technique for wheel bearings used on vehicles when I worked at the dealership level, in fleet applications for cars and trucks having up to 40,000 pound gross vehicle weight, and other applications. The interval for repacking the bearings was 50,000 miles and I only had the bearing itself packed with grease - not the dust cap or space between the bearings. No wheel bearing failure ever occured using BG grease and this packing method because the grease failed (failures happened because of other reasons like not adjusting the wheel bearings correctly or defective bearings). Lubriplate 1200 worked similar to the BG grease, but I preferred the BG grease because it has a formulaton that causes the grease to cling together and prevents the grease from leaving the wheel bearing. When I remove the bearings grease is not slung all over the place like most other greases, but in the bearing where it belongs.

That said, the choice of a wheel bearing grease is up to each individual. Since most people seldom think of their wheel bearings much less greasing them, my suggestions are meant to educate and enlighten so others can reduce needed maintenance of a vital/critical area and attain a higher level of safety. Poor wheel bearing maintenance can result in having a wheel/tire coming off your vehicle - which I've seen many times.

Good Luck!
Tom

#12 08-24-2002, 01:07 PM

Have been reading over the archives on wheel bearing packing and came about Tom's very informative posts concerning the subject. Am quite interested in the posting of using BG products and the recommendation to use the BG SLC wheel bearing grease. Did a search on BG products and saw that SLC is listed, but also another product, Special Wheel Bearing grease. Which would be a better product to use?

Thanks,
Gympie

#13 08-26-2002, 11:22 AM

I would suggest not hitting the kingpin as stated in the Haynes manuel... I've done that and now the top of the king pin is compressed and the threads are squeezed together making it very hard to get the lock nut back on.. "not to mention it leaves metal flakes everywhere"
this method is just to set the bearing up for vibration which I dont see why thats needed thighten up all the way and back it off so it spins as normal works for me

oldsouth · #14 08-26-2002, 11:46 AM

I have been using Mobil 1 systhetic grease with good results. Dropping point 550 degrees and Water Washout, ASTM D 1264, 79°C (175°F), wt % 6. Pretty good stuff.

leathermang · #15 08-26-2002, 10:53 PM

J Shepardson, I guess they failed to mention what old mechanics already know... anytime you want to hit something which has threads you put the nut on first ... AND.... you use a piece of hardwood...like oak ... between it and the hammer.... or you can use a lead hammer with the nut on the threads.... but few people own those anymore.... they came with cars which had actual knock off hubs like the 140 jag and the mgc's....