Rear wheel play

[ddebonis]

Hello. Some of you may remember I posted about my rear wheel was very loose. If I torqued it down the rear wheel became very hard to rotate. And then the bearing disintegrated while riding. Turns out the Sandia BMW in Albuquerque, NM didn't make sure there was a spacer between the bearings.

Several $$$ later, I have brand new rear axle, bearings, spacer, etc. This was done ~6 months ago (<1000mi ago) and the rear wheel has play in it again. It's torqued down.

Anyone experience issues like this?? Any ideas on what's going on?

Thanks!
Danny  

[montmil]

You may find some wisdom in Snowbum's thesis on rear wheel bearing preload; What it is, why it's important, how to check, etc.

Long article. pack a lunch.

[flybot]

I would take it apart and make sure all the spacers are actualy there. These are old bikes and not all shops are going to have experience working on them. If you cant do it, then find someone who is good and have them look at it. Its not hard, but it does need to be done right.

There is no way it sould be failing again after only 1000 miles. Something isnt right. And I would bet it still doesnt have the correct spacers and/or it wasnt preloaded correctly.

Snowbum has no doubt forgotten more than I will ever know about R65s. He knows a lot! But his how-to's are entirely info overload. There are a few good discussions on this forum about setting up the preload that are much more to the point, and less than 20 pages long. And FYI, preload is one of those discussions like oil. Lots of strong opinions.

[ddebonis]

Thanks! About to sit down and read Snobum's article. At least I'll know more when talking to the shop.

[nhmaf]

There should be the "tophat" brimmed spacers on either side, protruding out past the grease seals on the wheel bearings, plus a long "tube" spacer in between the (2) wheel bearings.   If they don't have them, or the proper ones, then things will not go well.   Plus, the BIG axle nut on the end is supposed to be torqued only so much to achieve the proper amount of preload - it isn't meant to be a test of strength and if torqued to 100+ ft pounds -> it will destroy your bearings.

[Barry]

No substitute here but to learn how to do it right yourself. Even BMW sent them out from the factory with incorrect pre-load. Once it's set up right you shouldn't see any detectable change in play so something is amiss. Possibly if they were set too tight the outer bearing race may have spun in the wheel.

Here's the story of my bearings.

If there is one aspect of airheads that causes more unease than the $2000 O ring it’s got to be wheel bearings. It’s probably fair to say if you haven’t worried about your wheel bearings it’s only because you haven’t thought about the pre-load issue. Having said that, while they are an important safety item the pre-load doesn’t seem to be as critical as some make out and the whole thing can get a bit overdone.
I guess like many of you I rode various bikes for nearly 40 years without giving wheel bearings a 2nd thought except perhaps a quick shake test before the annual MOT. That’s because they were usually sealed ball bearing races with no maintenance possible other than replacement.
Airheads are different if not unique. With the notable exception of the R65LS all airheads up to 85 have taper roller wheel bearings on both wheels which need careful shimming to be safe and long lasting. Unlike the common application of  taper roller wheel bearings on cars which usually run with a very small amount of end float (typically 1 to 5 thou) ours need a small amount of pre-load but not too much otherwise they will run hot.  Measuring end float is easy, measuring pre-load is not.  There are basically two methods: measure the rotational drag of the bearings or feel for the elimination of free play then add a little pre-load.
I don’t know what method the  factory used but they seemed to get it wrong. When checking new bikes for his dealership Duane Ausherman found that without exception bikes came from the factory with too much pre-load. He determined this by carrying out what he calls the shake test.  The idea is to slacken off the axle nut and clamps, then slowly tighten the axle nut while rocking the wheel to feel for bearing play. The judgement criteria  was that if all play disappeared below 15-20 ftlbs the bearing spacer was too short causing excessive bearing preload and if over 25ftlbs the spacer was too long causing insufficient pre-load.   (I’m not sure I agree with that last bit as if all play was gone at 25lbs and I then torqued  to the specified 32ftlbs I’d be happy). Anyway what he found in practice with new bikes was that all play was often disappearing at between 5ftlbs and 10 ftlbs. The inference was that If they were torqued up to the recommended 32ftlbs it would result in too much pre-load and the bearings would then run hot, possibly leading to a bearing outer race spinning in the hub especially on the rear wheel.
My own bike bears out this excessive factory pre-load. It came to me at 28 years old with only 6000 miles, the original tires and even the factory tell tale green paint on the top flat of the axle nuts. So there is a very high probability that the bearings had never been re-shimmed since leaving the factory, in fact I doubt the wheels had ever been off. I did the shake test and found all play on the front wheel disappeared at 15ftlbs which was low but acceptable.  The bearings were still perfect so I cleaned and re-greased them. I then torqued the axle nut until I was sure all play had disappeared and then added a further 2ftlbs.  I was happy with this as the front axle is clamped solidly on both sides. Possibly the bearings would stand half a  thou additional spacing to push the torque figure up a little but in practice there have been no problems and the wheel nut has not moved in 6 years.  
The rear wheel is more critical as the axle is only clamped on one side and the inner bearing buried inside the hub receives no  cooling at all.  The rear wheel is therefore much more susceptible to overheating if pre-load is excessive. It’s much more difficult  to do the shake test on the bike so it’s best to assemble the axle in the rear wheel off the bike. I was dismayed to find that all play disappeared at 5ftlbs and that was being generous. The rotational torque tested with a length of string and a spring balance was also way too high. In fact the drag created by the bearing pre-load was so high it was detectable over and above the normal transmission drag. It was so far out I had to add a 4 thou shim to get the pre-load back in spec. I had noticed that the rear bearing ran warmer than the front but not excessively hot. Of course you can only check the outer bearing and the inner would have run hotter. I was lucky, despite this excessive pre-load the bearings had survived undamaged for 28 years albeit having covered a very low mileage probably at modest speeds. Once re-shimmed the original bearings have been fine for many years now. This tends to suggest that pre-load is not ultra critical but it's still a safety critical item that should be done right.

[Ed Miller]

I put the bike on the center stand, then use a jack stand under the frame cross member (under the swing arm) to keep the rear tire in the air.  Then it's pretty easy to do the shake test, though you have to differentiate between wheel bearing play and swing arm play, if you find any play at all.

[ddebonis]

I took the wheel off and put the axle in and thought I could hear excess noise/resistance at certain points when I rotated it. So I starting taking it a part.

On the left side I was able to pull the top hat piece, then the seal, then the bearing. It looked ok. Then I found a thin, slightly curved 1" shard of metal inside the wheel!!

On the right hand side, I tired to pull the seal. I got the top hat crown piece out first. Then I tried to ply out the seal. It was not seated properly to begin with-- one side was popping out a little, so I tried to help it out in that direction. Nothing. I should say that this seal is metal on it's outward face and the other one was totally covered in rubber. Anyway, I try prying in the opposite direction and it pops back in place and looks like it's seated correctly. And I noticed I've dented the metal part of the seal. (defeated sign....) I try slowly in a couple other directions and dent and dent.

So something is very wrong because of the metal shard.

What's the trick to getting the seal out? Once I do that, I'll see where that shard came from.

I looked at the Clymer again and it says taking the wheel bearings out will damage them. Is that hogwash?

FYI. This is what the shop said when they replaced all these pieces 1000 miles ago:

"Drained rear drive oil-no appreciable amount of metal on magnetic drain plug, but significantly overfilled. tightened axle and confirmed that wheel does become difficult to rotate when torqued, attempted to remove axle, found that wheel bearing inner race was seized to the axle, was able to remove it by removing the mufflers and forcing it off the axle. found that the inner wheel spacer adjustment shim was missing along with the plastic grease shields; one wheel bearing's cage is broken. needs bearings, seals, and shimming to correct spacer. --replaced rear wheel bearings, shimmed to correct prepload, renewed seals and missing inner spacer grease shields."

HALP!  

[Bob_Roller]

Can you get a piece of wood from the side that the bearing came out and tap it with a hammer to get the seal and bearing out ??

[ddebonis]

I can. Should I? I am afraid I am causing damage. Do I need to heat the hub with a torch first?

[Bob_Roller]

No, the only thing you are working against, is the seal .

You don't use that process with the R65, the only thing that holds the bearing in, is the grease seal .

A few taps with the hammer, should push everything out .

[Barry]

To get seals out easily you need the right tool or you need to improvise something that works in the same way. What's needed is something that has a fulcrum in the centre of the bearing and pushes up under the metal edge of the seal without damaging any other part of the seal. There are various seal removal tool designs but they all work on that principle by having a curved end that acts as a fulcrum to push upwards.

What I do is to drop a washer or disc of metal through the seal so it sits on the inner race. You now have something to push against. My improvised tool is a small offset open ended spanner with thin jaws. The curved bottom edge of the jaw sits on the metal disc and the inside tip of the jaw pushes up on the seal. When compared with the screw driver approach it is absolutely effortless to remove a seal this way. It's effortless because you get many times more leverage and so even a tight seal will succumb and it does it without damage.

[Julio A.]

Everytime I remove the seals, it deforms easily. So I seldom reuse them. Sometimes they do take a little more grunt to get out.

I use a long flat screwdriver resting on a block of wood and pry them out in a circular pattern. Although, I have snapped and deformed screwdrivers this way. The last time That happened, rust formed between the steel insert in the wheel and the rubber seal, Bonding it firmly into place. I make it a habit to grease this contact point and it made subsequent removal easier.

[flybot]

There are actual seal puller tools that do the job quite nicely, and usualy you can use the seal over again. Im sure you could walk out of Harbor Freight with something that will work, like this http://www.harborfreight.com/seal-puller-35556.html

Seal removal should be the easy part.

Same shape as mine, but mine is not HF.