R90/6 Rear Wheel Bearing issues: Advise?

[banzaibob]

When I got my R90/6 about 7 years ago I replaced the wheel bearings, Steering bearing, swingarm bearings. Due to an electrical problem, the bike is up on my lift getting the shakedown. In going through various things I happened to give the rear wheel a cursory shake an noticed that there appears to be some lateral looseness in the rear wheel. Manual states that the torque on the axle nut should be around 35ft/lbs.. I tightened to specs and there was still wobble. I figured that since it is up on the lift that I should see if a greater torque would tighten it up. 45, 55, finally about 70ft/lbs and it felt like it was good. Not so fast, there is still some play. The wheel turns smoothly as if the increased torque has no effect on it however 70ft/lbs will probably screw something else up once I get it out on the road.

It has been 7 years since I have been in there and my memory of how it is suppose to work is not clear. Should I assume that the bearings are bad? Or is this a problem of not having the proper bearing stack height from normal wear? The bearings are probably available locally but what about the shims?

Basically, since I haven't torn into it yet I don't know what questions I should ask. Anyone got some good advice on this one? By the way, tomorrow I'm going to start to pour over the Snowbum article on bearings.

 

[20774]

If you can get through 'bum's article you'll be doing good! I attended his bearing seminar at the 2004 National.

Do you know if the bearings exhibited this "shake" when you originally serviced them? It could be that they have been like this a long time...which wouldn't be good...the tapered bearings live a long time with a modest amount of preload.

Mike V. had a great article on replacing bearings albeit for Snowflakes but the concept is the same. As I understand it, Mike is working with Snowbum to extend/update the bearing information.

http://forums.bmwmoa.org/showthread.php?46970-Wheel-Bearing-Replacement-Snowflakes

At the minimum, it sounds like the internal wedding spacer is too thick, such that when tightened down, the bearings are not quite seated, thus they move around. The opposite of this is if the internal spacer is too thin, so that when you tighten down, the bearings get really compressed more and more trying to take up the gap there because of the thin spacer.

If you had this latter situation, Duane Ausherman sold think shims that can be easily placed inside the stack to reduce the gap to a reasonable level. Duane's test is called "shake the wheel". Ideally, one would have some wheel movement as the axle nut is tightened. Just prior to full tightness, the wheel movement would be there, but with the last amount of axle tightening, the shake disappears.

If you tighten down and the shake is still there, the internal spacer is too big. The only way to cure that is to remove the stack and go through the steps to develop the right preload on the stack and then reinsert the stack.

Snowflakes and some wheels (like my /7) have aluminum inserts so the bearings can't just be jerked out...heat is needed. Earlier versions (I know my /2 wheels were this way) have steel inserts and can be removed without removing heat, although I'd certainly use heat to aid in expansion and reduce the damage to the internals. Going back in, it helps to cool the stack and heat the hub...should drop right in.

 

[30064]

Bob,

Make sure your axle spacer and top hats are in place, and pinch bolt tightened. Never exceed 35 Ft-lb on your rear or front axle nut. Proper preload should be had in the area of 25 to 35 Ft-lb. Swing arm bearings adjusted? Just make sure the movement you speak of is coming from the wheel bearings and not the swing arm bearings.

If you're still getting wheel movement after these checks I would think about inspecting the bearings and races.

Do you have special tools to do the job? Heat source, proper bearing puller, take-up collar, micrometer to measure wedding band?

-Mike V.

 

[robsryder]

The direct link to Snobum's info on wheel bearings is below -
http://bmwmotorcycletech.info/section4.htm

Duane Ausherman also has good info, including some useful graphics, on wheel bearings. Duane used to sell a shim kit to help adjust the bearing pre-load without needing a large supply of "wedding rings". Duane's webpage is linked on Snowbum's page and is also given below -
http://w6rec.com/duane/bmw/wheel_bearing/

 

[banzaibob]

By "take up collar" I'm not exactly sure what you mean. Is that something that acts as a spacer on the disassembled wheel that allows the "bearing stack" to be in essence, tested off of the bike? All of the other tools I have.

To be completely honest it is difficult for me to remember when the last time I checked the rear wheel looseness was. The play is barely perceptible.....however it IS there. What do you think the chances are of me initially installing the bearing stack wrong and riding around on it like this for years? Is it possible for these old airheads to run for a long time on an improperly adjusted wheel? The reason I ask is because sometimes (rarely) there is a weird resonant frequency at about 85 MPH.

The wheel rolls smoothly and silently. There are no handling issues that one would associated with loose bearings either in the wheel or in the swingarm; no deceleration wobble or headshake.

 

[30064]

By "take up collar" I'm not exactly sure what you mean. Is that something that acts as a spacer on the disassembled wheel that allows the "bearing stack" to be in essence, tested off of the bike? All of the other tools I have.

To be completely honest it is difficult for me to remember when the last time I checked the rear wheel looseness was. The play is barely perceptible.....however it IS there. What do you think the chances are of me initially installing the bearing stack wrong and riding around on it like this for years? Is it possible for these old airheads to run for a long time on an improperly adjusted wheel? The reason I ask is because sometimes (rarely) there is a weird resonant frequency at about 85 MPH.

The wheel rolls smoothly and silently. There are no handling issues that one would associated with loose bearings either in the wheel or in the swingarm; no deceleration wobble or headshake.

Bob,

Yes the take-up collar is a spacer used to take up the distance of the swing arm and final drive with the wheel removed to determine preload. My personal opinion is this collar needs to be a precision machined piece with perpendicular ends turned on a lathe. If not, you will be dealing with radial stepping during rotation. Some have used pipes from the hardware store or other items found in the shop. This subject will always bring varying opinions and anecdotes. I'll share my personal opinion based on my actual experience. But let's not get ahead of ourselves just yet ...

If you have the 5-bolt seal cover cap on the left side of your wheel I would remove it. The top-hat, bearing rollers, wedding band and inner spacer should be able to be removed. "If" you have the older style inner spacer with the integrated metal centering rings it may not be able to clear the captured inside diameter of the bearing race unless someone has already reduced the centering rings. You may also have the inner spacer with the plastic rings which should easily be removed. Some inner spacers have two plastic rings, some have one. Not a problem, these rings (or ring) are to roughly center the inner spacer for axle installation.

Remove the bearing cage and wedding band, and inner spacer if possible. Clean the wedding band and bearing cage (rollers) well. Inspect the rollers for discoloration, pitting or brinelling. Inspect the outer race in the wheel carefully also. At this point you can determine if the bearings are damaged and need replacement. I would "assume" the condition of your left bearing and race will be consistent with the captured right side bearing condition. That's just an assumption. Your call.

At this point I want to make something very clear; I don't determine final preload by the "shake test". I determine preload with clean and lightly oiled bearing PAIRS (right and left bearings and races) with the wheel removed. A lengthy process I won't get into here at this time. I use the "shake test" as a final test only at the end of the complete procedure. Others may or may not agree with me. Again ... your call. But if you don't have the proper tools or inclination to fully remove the entire bearing stack you can use this method if you choose.

Your report of a loose condition tells me (and Kurt) the wedding band thickness is too great and needs to be reduced. Obtain a simple caliper, measure and record the initial thickness of the wedding band. On a perfectly flat surface with lightly oiled wet-n-dry fine paper hand mill the wedding band in a figure-8 pattern in 0.05mm increments. Re-measure and record. Reassemble the wheel with clean grease packed bearing and bits and repeat as discussed on Duane's web site.

Unless you determine the bearings are damaged and need replacement - that's a completely different procedure with special tools needed. If you can commandeer a local experienced airhead you may do that as a second pair of eyes.

Bob, I consider this bearing subject a very important safety matter. I've spent a lot of time developing my own procedure with a lot of Guru help. Our airhead wheel bearings are a very robust well engineered system when done correctly and well maintained and have been estimated to last for hundreds of thousands of miles. There's a lot here that will disagree with me and lend their own opinions. Ultimately, you have to decide the safest way to proceed. I'm happy to lend any help I can. Feel free to contact me by PM if you want to discuss by phone.

PS: I need to amend the link posted by Kurt. Since that time I've adjusted my procedure and no longer use the small 0.05mm shims for preload adjustment. I now make preload determination with the wedding band alone.

-Mike V. / San Diego

 

[banzaibob]

CRAP! I think I have a game changer here........

Before I get into this, I remember years ago what happened; The drive splines were pretty worn on the wheel that came with the bike. I bought a used one with good splines, slapped some grease in there and away I went. That is at least 30,000 miles 7-8 years ago. SO BASICALLY......I guess I deserve this trouble.

Removed the wheel. I removed the 5-bolt seal cover cap on the left side. Inner bearing showed indications of very rusty grease. The outer race on the left side simply slipped out......upon further examination, the outer race spins pretty freely in the hub. The spacer tube and spacer sleeve along with spacers and other sleeves do not show any metal transfer or indication of any seizure. I have not gotten the right side bearing out (I assume that you heat everything and push it out the left side?) Inside the hub shows no indication of any galling HOWEVER the left side of the hub where the outer bearing race would be held in with an interference fit (I'm assuming) shows signs of burnishing.

The big thing on my mind; I assume that the left side of the hub that holds the outer bearing race in place has been expanded to the point that either 1) the hub is trash or 2) a repair consisting of a larger outer race has to be used or 3) ???????

 

[30064]

CRAP! I think I have a game changer here........

Before I get into this, I remember years ago what happened; The drive splines were pretty worn on the wheel that came with the bike. I bought a used one with good splines, slapped some grease in there and away I went. That is at least 30,000 miles 7-8 years ago. SO BASICALLY......I guess I deserve this trouble.

Removed the wheel. I removed the 5-bolt seal cover cap on the left side. Inner bearing showed indications of very rusty grease. The outer race on the left side simply slipped out......upon further examination, the outer race spins pretty freely in the hub. The spacer tube and spacer sleeve along with spacers and other sleeves do not show any metal transfer or indication of any seizure. I have not gotten the right side bearing out (I assume that you heat everything and push it out the left side?) Inside the hub shows no indication of any galling HOWEVER the left side of the hub where the our outer bearing race would be held in with an interference fit (I'm assuming) shows signs of burnishing.

The big thing on my mind; I assume that the left side of the hub that holds the outer bearing race in place has been expanded to the point that either 1) the hub is trash or 2) a repair consisting of a larger outer race has to be used or 3) ???????

Bob,

Not sure if you deserve this or not. Sounds like someone has removed/replaced the bearings without heat and damaged the hub interior. That's sure to happen without heat. I guess the question is where to go from here? Hopefully you'll get some helpful information from other members. I've heard of respectable machine shops shimming the wheel hub but I have no personal experience or knowledge of the success rate of this operation while shimming can contribute to other (obvious) problems. Might be best to do a complete bearing stack removal correctly with heat and do a very thorough inspection of things. But if the left side is damaged it may be best to try and obtain a new or used hub in solid condition. My guess is your existing hub is trashed.

Bummer.

I may know of a local source or two here with some extra wheels/hubs - not sure if he is willing to get rid of them or not. I'll keep an eye on your thread, in the mean time I'll send out an SOS for you if you need it. Keep me informed.

-Mike V. / San Diego

 

[banzaibob]

CRAP! Your kind words of wisdom and encouragement not withstanding........I was hoping that you would say that you have an easy fix from $4.99 components from the Home Depot.....crap!

 

[30064]

CRAP! Your kind words of wisdom and encouragement not withstanding........I was hoping that you would say that you have an easy fix from $4.99 components from the Home Depot.....crap!

Sorry, but I don't think Home Depot can help.

Let this thread circulate a bit. You may get some local airheads or forum members that can help, with advice or spare parts. I've sent out a few emails here in San Diego for you, may take a while to get replies. I'll check in from time to time to see how things develop.

Give me a call if you like, I've left my contact information in your PM (personal mail). We'll get you going at some point in time.

Airheads helping Airheads ...

-Mike V.

 

[jad01]

Bob- If you are thinking new hub, you might check with any of the salvage yards in Kurt's Resources and Links thread (see post #2) to see if they have a used one, or are willing to keep an eye out for one for you. I am partial to Mikey at Martindale Motorcycle Works (http://martindalemotorcycleworks.com/index.html or 512-357-2842) and Joshua Buck at Partshaus (562-254-0452).

I've visited Mikey's place in person and bought a number of things from him- he's got a pretty good collection. He might be willing to keep an eye out for you and let you know if he gets one. Pretty solid guy that knows a lot about these airheads.

Might watch the IBMWR marketplace also...

 

[banzaibob]

Ideas: The surface of the area on the inside of the hub does not show galling or metal transfer. The aluminum alloy on the hub appears normal, almost burnished.

Idea #1: I built a diesel motorcycle (no ****) with an open belt driven primary and dry CB750 clutch. Instead of welding the belt pulley to the clutch basket, I used some aircraft grade epoxy to glue the cast iron pulley to the aluminum clutch basket. It works perfectly even after 10's of thousand of miles. After scoring the surface for "bite," using aircraft grade epoxy would hold the outer race in place. I would think that there would be be a lot of force require to keep that race in place.

Idea #2: I can fit a .001 feeler gauge around the outer race and in between the hub. Could you use shim stock to put between the outer race and hub? Like I said, there should not be a lot of force required to keep the outer race stationary.

At this point I would assume that the hub is ruined. Therefore I can be creative with the hub. Stop me if I'm getting too stupid.

 

[20774]

To run with the scoring idea, I think the term I've heard is knurling. I've also heard people consider an appropriate Loctite that can wick into the small gap...a version of green as I recall. One thing you have to be careful of is being sure that when all is said and done, the bearing center is still in the exact center, otherwise you're going to have alignment and rotation issues.

 

[barron_williams]

What did you do with the original wheel that had the bad splines? If you still have it, maybe that is a solution for you.

Barron

 

[donbmw]

Whie doing my wheel bearings I found the left hand outer race was loose in the hub. It would come out by hand with just little wiggling. I used loclite 242 to seal it in place. After setting the preload I found that the wiggle I had when behind 18 wheelers and pulling a trailer was gone. I like you had changed wheel bearings a few years ago. Did not notice this unti a few years later. At first I thought the problem the streamlining the trucks had started use.

 

[banzaibob]

Here is what I think I'm going to do:

First, I absolutely understand that this fix is not optimal. In fact, it may be a waste of time. The point is; for all intents and purposes, the hub is ruined. Used wheels appear to come in at about $250 minimum. New ones I don't even want to think about right now. In order for me to stay married and have a lot of cool bikes I have to weigh the economics of NOT being married because I spent too much money on cool bikes. This fix represents an honest challenge. If it fails? I've wasted a days labor. Also, it has already failed and the rear wheel did not lock up and kill me; chances of that happening appear remote at best.

I bought all new bearings, $45. The clearance around the cup appears to be about .002". Once I get the bearing stack correct I am going to cut from a .001" feeler gauge 3 small pieces, probably 10mm square. After heating the hub, I am going to drop the bearing cup in and try to press in those little shim pieces at 120 degree intervals between the cup and the hub. I am then going to use the green Locktite (called "sleeve retainer" by Permatex). Let 'er cure and ride off into the sunset.

Am I a dead man, or the stuff of legends? (somewhere in between? )

 

[SCBuckeye]

A couple of things I would do to try that can't hurt your old hub.

When you put in your new bearing race ("cup") use a dremel with a grind stone on it . Grind a slight (very slight) groove into outer surface of bearing - the part that actually touches the alum. hub. - do one groove around the surface, and do several crossways (parallel with axle). Then, do a similar slight groove inside the hub - in the same area as where bearing seats. Then, use either the Loctite Bearing retainer as some have described OR use Devcon. Devcon is the best and is excellent for such uses. It, when hardened, will be just as strong as your hub, and maybe even stronger. Make sure everything is totally clean and free of oil or grease so that the Devcon (or Loctite) can bond with both the race and the hub. The grooves actually allow the bonding agent to "grab" on both the wheel hub and the bearing.

We did such practice quite a bit when repairing manufacturing machines. Would be as good as new.


Sorry, but .001 out of alignment will not make that much of any difference. I doubt that when manufactured new, that the tolerances were that tight on this type of machining. Cylinder rods, yes. Wheel hubs, no.

When bearings are inserted, I (me personally) would take the wheel and have it put on a lathe spinning on the actual wheel axle (I did this with my R100/7) and do a very light machining of the surface where the tire mates to the wheel. This would "true" up any sort of out of spinning alignment. Doubt that there will be any, but this would do it for sure! Good machine shop would do it for pretty cheap if they have a large enough lathe.

If you took most wheels and could put a dial indicator on the inside surface of the wheel - where the tire mounts, I would bet a paycheck that there is misalignment. Not much, but some.

 

[banzaibob]

The repair is sitting with locktite green curing. It is curing on the hub with the entire bearing stack in place and axle tightened one notch over hand tight. The big monster time vampire was getting the bearing stack correct. Short version is; if the outer sleeve is loose when tightened to 35ft/lbs the stack needs to be shortened. If it is too tight to move between the two cups, add a shim of appropriate size. In the end I was basically "lapping it in."

One final question; anybody got a problem with me staking this hub around the bearing cup with a punch?

 

[banzaibob]

Got everything put back together at around 1:00pm. Took a 250 mile ride up one side of the Missouri river and down the other. I would stop about every 25-50 miles to shake the rear wheel. Roads were mostly rough 2 lane county and state routes. Speeds were usually 80mph with one high speed run of 110mph (the next thread I start will be asking how to get better gas mileage). No problems.

 

[SCBuckeye]

Got everything put back together at around 1:00pm. Took a 250 mile ride up one side of the Missouri river and down the other. I would stop about every 25-50 miles to shake the rear wheel. Roads were mostly rough 2 lane county and state routes. Speeds were usually 80mph with one high speed run of 110mph (the next thread I start will be asking how to get better gas mileage). No problems.

I would bet a paycheck that you will never have a problem with what you did - as long as you shimmed up properly to get the correct "preload" on the bearings.