before. I know I used the "new design" bearings. I did NOT pull them
> apart and regrease them like I should have before installation.
> Somehow I missed that so they have been running on the factory packed
> assembly grease. I thought this might shorten the lifetime but I did
Hi,
It's not unlikely this is at the heart of your problem. The factory assembly grease is more of a corrosion inhibitor than a lubricant. So, in essence, you're running a "dry" bearing and have likely damaged it seriously even though it's only got a few miles. The axle nut problem sounds like a second ingredient: if one of the bearings didn't seat properly (bit of foreign material, bearing bound up in hub, etc.) that would add to the problems even if the bearings were properly lubed cuz they're not running "straight" as designed. Be sure to inspect the inside of the hub carefully before having the new bearings pressed in and remove anything that could be problematic.
Working as an auto mechanic for around 15 years (specializing in Asian cars) I have never had to press bearings out on the non-driving wheels. I use a long punch and ball peen hammer to drive the old bearing race out. There has always been a pair of cutouts at the back side of the race to position the punch. I use the old race to GENTLY tap in the new bearing and/or race (most of what I worked with was tapered roller type). When the new race is deep enough, I put the punch on the edge of the new race and tap side to side and top to bottom. When the new race seats at the bottom of its hole, the tapping will suddenly sound and feel very different. This will let you know that you are finished with that bearing.
My experience (limited to the shade tree today--it's been 30 years since I got paid to spin wrenches) is that "sealed" bearings (the ones with some kind of plastic dust seal, like throwout bearings, etc.) are greased properly from the factory as you said. But I don't recall ever buying an "open" bearing that was properly lubed from the factory--some, in fact, had little instruction sheets in the box, warning to wash the packing grease from the bearing and lube it properly before use.
You can get little bearing greasers at the auto parts store that are a miniature version of what we used in the shop. You put the bearing in between two cups and hook a grease gun to a fitting on the top and pump grease in until it oozes out fairly evenly all over the bearing. The bearing ends up pretty well filled with grease. This works well with fairly flat and shallow bearings like you'd have found on the front axle of a rear wheel drive car years ago.
Today, I just pack 'em by hand. Sometimes I'll use a grease gun with a needle for deeper ones, like the rears on my car. It might not be the perfect way, and certainly not the fastest, but (knock on wood) I haven't had a bearing I've packed myself fail yet. I have had wheel bearings fail, but every one of them exhibited signs of running dry (initial lack of grease or it was washed out by water, contaminated with dirt, etc) prior to failure. I don't know if the type of grease matters or not: I've used the black moly-based lithium disc brake grease for years. You just want to be sure if you're re-packing used bearings that all the old grease is washed out so there's no interaction between different types of grease that can lead to bleed out.
On the idea of overgreasing, usually there's plenty of room in the hub between the bearings so any grease squeezed out from hi-spd or heat can find its way in there. Path of least resistance and all. If that area is completely filled, then grease might be forced out the grease seals and make a mess on the hub, but I haven't seen that too often. I prefer to err a little on the too much side and clean the mess rather than risk a failure.
Anyway, I'm sure there are lots of ways to skin this cat, but this is how I do it under my shade tree!
It's a 97 Impreza, there are no NON-DRIVING wheels.......
second, i'd have taken the fact that i couldn't properly torque the nut without binding the wheel as a sign that SOMETHING was wrong on that side, and tore it apart and found out WHAT, instead of just ignoring it, and driving it with the nut "not quite tight".....
Problem is that the car is AWD and the rear is a driving wheel. What I will likely do is have the machine shop press the old one out and then stop so I can inspect the hub carefully. Combined with repacking the bearings after a thorough cleaning should hopefully cure the problem. I will leave the right side alone until it starts to fail.
If I were to buy a press, how much force would be required to do this job? I like doing stuff myself because I know it is done right. I hate having to take a break and jump in another car to have someone do some little part of the job for me.
It shouldn't take a very big press. I've done bearings in driven hubs using null_pointer's method. Lightly oil the surface of the hub and bearing where they come in contact, and things should go all right as long as you don't c*ck the bearing in the hub. I've also made a "press" using such simple materials as heavy threaded stock from the hardware store (1/2" or so) with washers and large sockets squeezed together with nuts on each end. (Double nut one end so you can lock it, then hold that end in a vise if you can. With a large wrench on the nut at the other end, you'd be surprised how much force you can generate.)
I have done this task personally all by myself (with a little support from the woman) You do need a press if you don't want to change you trade name to butcher.
I suspect the new bearings you used are Koyo with rollers (blue box). Now the man from Koyo, he tell me that I must wash-out all the inhibiting grease (non lubricating). He even suggest that I should try and find a ultrasonic bath for best results. I used this plastic coffee bottle with kerosene and shook the bearing like an ultrasonic maniac.
Then the bearing is to be packed with a lubricating grease. (synthetic Mobile is my choice) The gap between the inner and outer race is small for packing grease. For this I used a syringe and needle. The needle is normally used for large farm animals. Beware that the needle does not scratch the inside of the bearing or poke you in the eye. Put as much grease as possible. Excess grease is desired to fill the gap between the bearing and the first seal. The back of both seals must also be filled with grease so that there is no room for dirt and water etc.
The plastic insert that comes with a new bearing should remain in position. The purpose is to keep the inner races together. It will be pushed-out (when using the press) when the hub's shaft is inserted into the inner race. Make sure that the correct race is supported correctly when any pressing is done. Do not allow a shearing action to occur between inner and outer race. (e.g.. do not support the outer and press the inner) Hey, its a race thing!
After all this the bearing will be good.
As for your dilemma of: should you use the bearings you have in there now and just pack them with grease? I suggest no, spend some more money and write them off to experience expenses. (I vote for the next guy who says these expenses should be tax deductible - education expenses) You will probably have to replace the seals as they will be destroyed when removing the bearing.
Since the problem is currently isolated to the driver's side rear, do you think I should redo both sides or do only the driver's side and wait for the passenger side to give out?
I could buy a hydraulic press and do it right myself:
If you're going to the trouble and expense of getting a press, you'll buy yourself some peace of mind to do both sides at the same time. After all, assuming one hasn't already been replaced "out of synch," both sides have the same mileage, so it's probably just a matter of time until the second one fails.
Check out this link and read the wheel bearing replacement stuff. A new way to do it, albeit with special tools, that eliminates the need for a press and reduces the possibility of repeat premature failures.
This makes interesting reading. It has been awhile since I went to the endwrench, last time was for the timing belt change. I decided to take it to the shop. Labor and parts for that was $300.
Guess you need to weigh-up the cost of the special tool verses the ease and time saving it can provide. Using the press is going to be more work and you will have to also provide special sized press collars / mandrills etc. What is interesting is the new bearing that is already greased. Was this not your initial problem/query?
Go ask the dealer what the charge is. The time is specified in the reference below and in the end it may just be worth taking to the 'experts'.
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