Rear wheel bearings

[georgesgiralt]

Hi Lads,
I've found a quite new rear wheel to replace mine which has a worn out brake. And I can't find someone in town able to turn the brake properly. (i guess I've exceeded the limit, though).
So the wheel is new. But the bearings have seen water and are toast.
I'm surprised that the BMW fiche does not show adjusting rings for the pre load. How is it set on these rear wheels ?
TIA and have a nice Sunday.

[montmil]

After reading through this information, take a break and determine what you'll need to do with your new rear wheel -sans bearings.

http://bmwmotorcycletech.info/section4.htm

[georgesgiralt]

Ouch !
Snowbum ! I'll clean my goggles, take a couple aspirin and start reading...

[Mike V]

Georges,

As painful as it may be - I would recommend reading through Snowbum's article.

I'll start off by saying a lot of people don't agree with me at times regarding wheel bearings and preload, I'm a bit over the top anal and nerdy. I've invested a lot of time with this procedure, both the rolling inch-ounce pull and "feel" procedures.  There's not an easy or short answer to your question. But done properly your bearings will last longer than you will if maintained and adjusted. The design is robust and over-engineered.

You'll need at least a couple special tools ... a bearing race puller and take-up collar. I never recommend tapping out outer races with a drift or narrow punch. Cycle Works offers both these recommended special tools to name just one supplier.

I'll just say at this time it's important you have a general understanding of the wheel bearing function on our bikes and how preload is determined with our bearing stacks in regards to the tapered roller bearings.

The outer bearing races are fixed in position by way of the wheel hub. The target for preload is to apply the appropriate pressure of the tapered rollers against the fixed outer races under torque by way of the axle nut. In other words; finding the correct position of the rollers inside the bearing stack as they contact the outer races ... this is determined by the width of the wedding band. Keep in mind the wedding band is in contact with the inner spacer, which is a constant width. Adjustment is made with the width or thickness of the wedding band.

If the wedding band is too thick - the preload will be too "light" or "loose".  If the wedding band is too narrow - the preload will be too "heavy" or "tight".  The rollers are brought inward towards the outer races by way of the axle nut until they are mated or limited by way of the inner spacer and wedding band.

Never exceed 35 Ft-lb of torque on your axle nut.

*Note: wheel picture is from my R100/7, not my R65.

[Tony Smith]

I have found that if you replace the bearings with the same brand, you usually get away without having to fiddle with the "wedding ring" adjusters - also you do have a certain degree of tension adjustment available in the form of the axle nut.

Doing the job properly means that your wheel bearings could do several trips to the Moon and back before wearing out. Accepting slightly higher tension than ideal means that they will probably only do a couple of hundred thousand miles.

I try not to lose sleep worrying about if my bearing tensions are "just right' - I do however look at them and re-pack every major service and if they show distress, swap them out.

[georgesgiralt]

Thanks guys, I already own the Cycleworks puller (I used it to remove the bearings on the swing arm prior to the powder coating).
I know the rationale with tapered roller bearings as my studies where those of an engineer (even if I did not use that knowledge to earn a living). I just wanted to know if there was something special about these bearing on the R65.
Tomorrow morning I'll buy a couple of bearings and prepare my air gun !
Thanks lads !

[montmil]

Yes. Two schools of thought each has it's place in our big church. Thank you, Tony.  

Both Mike V's  and Tony's techniques can be considered correct as each method has its pluses and minuses.

While I yearn for the patience, knowledge and skills of the Valenti School of Precision, I confess I utilize the same thought process as DownUnder Tony. That is, if I'm utilizing the same brand of bearings and changing nothing else -which I have done, I'll try not to fix something that ain't broke...yet.

That whole wedding band +/- measurement is just counterintuitive to my pea brain.

[Mike V]

Respectfully, Georges states he has a different wheel and will be installing new bearings, unless I've misunderstood something.

Chances are slim his different wheel and new bearings will offer the same preload with his original wedding band and bearing stack components. Not impossible, but doubtful.

I would recommend measuring your wedding band thickness with a quality caliper, recording it, installing the new races and lightly oiled bearings, install the bearing stack with a take-up collar, torque the axle nut to ±25 to 30 Ft-lbs and check the rolling resistance by feel. If the bearings feel loose, start hand milling the wedding band in 0.05mm increments and retrying the feel.  If the bearings feel tight you will need to purchase a thicker or wider wedding band. You're after a slight amount of drag with a smooth spinning axle, and no lash or play in either a radial or axial plane.

I would also recommend inspecting your top hat spacers for wear grooves from the seal wipers.  If so replace them.  And I highly recommend new seals, annually or at every bearing service.

There you have two different options or schools of thought as Monte mentions on how to proceed. While the range of acceptable preload is fairly wide, it's an application I like to get right for safety and piece of mind. I depend on my wheels to hold me up and support my tires, power train, frame geometry and suspension's function.

Keep us in the loop ... happy to help if called upon.

[Bob_Roller]

Mike V, how does the pipes on the axle to press on the hat spacers, inner bearing race working for you ??

Make it easier to set the rear wheel bearings ??

[Mike V]

Bob,

The take-up collar is essential for obtaining and measuring the preload with the wheel off the bike.  It basically takes up the space of the rear drive, top-hats and frame arm in order to apply torque on the stack.

 The top-hats are not used when using the take-up collar.

I modified my spacers offered by Dan Neiner at Cycle Works. This is a very long story I will try to make very short,  to share my experience regarding the importance of the take-up collar.  I hear a lot of the guys just using a 3/4" pipe from the local hardware store.  I disagree with doing it that way (personal opinion).  The reason is, if the take-up collar is not centered on the inner shoulder of the rollers and the take-up collar ends are not perfectly perpendicular to the axle, you will get stepping-out in the rotational movement.  You know; when turning the axle it will reflect in a go-stop-go-stop type action.  Makes it impossible to replicate the assembled situation, or measure the preload with a pull scale.  The scale will bounce all over the place.

So I had my collars turned on a lathe and PVC inserts made so the inner diameter of the collar closely matched the diameter of the axle.  In my spare time I want to search a metal shop for the correct inner and outer diameter of round stock so I can trash the idea of the inner PVC inserts. Snowbum mentions the correct inner and outer size on his web page.

You guys can use a pipe section from the hardware if you like, it will work but I was doing a lot of testing and discovered the most important thing about the collar is the precision of the ends to give me a constant consistent rolling action while measuring the radial rotational torque. I know, anal and unnecessary a lot of you guys will say. Maybe, but for my testing it was very necessary.  After you have the correct collars the whole process is very simple and fast and accurate.

Did I answer your question?

[mrclubike]

 If he has the Wedding ring that come with the new wheel he has a good chance the new bearing will preload within spec And  if not hopefully they will be on the loose side and he can just sand a little off the spacer and be good to go.
If you want actual shims you could check with a industrial supply company and you could get very thin shims and use a narrower  wedding ring with the shims.
Here in the USA a company called McMaster Carr has this kind of stuff.  
Max Motors shows new spacers ranging from 6.300mm to 7.700 mm

[mrclubike]

While we are on the subject
What are the Timken numbers for the bearings.
I would like to know before hand how available they are

[Bob_Roller]

40x17x14

[mrclubike]

40x17x14

Sorry Bob that is only the size
The cup and cone should have a Timken part # on them

[Mike V]

What are the Timken numbers for the bearings.

The bearing number is 30203.  Very common and most likely found at your local auto parts store.