Wheel bearing pre-load - '83 100RT

[Slope'r]

Originally Posted by StephenB

Well, there are the manuals of the world, search functions, forums such as ADVrider and Boxerworks, why don't you research those first and ask then what you don't understand? You do have manual and a right and a left hand, right? ;-)
One Google search for "adjust wheel bearing preload airhead" reveals an articel by Rob Fleischer aka snowbum, one of the Airhead gurus. Does that help? You could have found that yourself, you know?!? Google's your friend.
....SNIP....

Hopefully H. Huester appreciates your posting of snowbums instructions... but Jeesh don't flame him for be frustrated... .

I punched in your google search term "adjust wheel bearing preload airhead" and didn't see snowbums article in the first page of returns.

As someone who is looking for advice during some major wrench'n, I feel his pain when trying to tease out that one description that clicks.

Anyway...
Thanks for the info but go easy when others don't see what you think is obvious.

[StephenB]

No offense or flaming intended, just a bit of black humour mixed with some eye-rolling. As I said, Mr. Google knows everything but I admit you need to be able to prescind and talk "machine", let him know what you want, know the key- or buzzwords.

[H. Huester]

Originally Posted by StephenB

Well, there are the manuals of the world, search functions, forums such as ADVrider and Boxerworks, why don't you research those first and ask then what you don't understand? You do have manual and a right and a left hand, right? ;-)

One Google search for "adjust wheel bearing preload airhead" reveals an articel by Rob Fleischer aka snowbum, one of the Airhead gurus. Does that help? You could have found that yourself, you know?!? Google's your friend.

My apologies, maybe I wasn't clear enough in my original email... you did read it, right? ;)... but I HAVE read through two manuals (that do not really explain the procedure), I HAVE searched through ADVrider and Boxerworks, I HAVE searched Google, AND I talked to the local BMW mechanics... and what I found (during the many hours of searching) was the same thing you found - only a whole lot more of it, and none of the sarcasm. Since I (and apparently some others on the site) found the procedure entirely too complicated (for a bike that everyone raves is so, SO easy to work on), I started this thread so I could get some help from some of the many knowledgeable folks on this forum - I certainly appreciate yours. I'd rather learn to do this on my own than have BMW do it for close to $100 per wheel for me - that part was also in my original email... you did read it, right ;)?

Thank you everyone for your inputs... but it looks like it may be time to let this thread die, and for me to PM some of the responders that appear to have performed this procedure on their own before... (minus the "space-shuttle-launching" level of detail)...

Good riding to everyone!

[Beemerboff]

So - preload torque is aboUt 1 ft - just about the thick end of , err, all play removed.

And dont forget to keep spinning the wheel as you tighten the nut on the end of the spindle - if the bearing tightens up you need a new spacer.

[Reryder]

Originally Posted by H. Huester

Excellent chart... but there is no context there. I saw a chart just like this, but it had numbers up the left side and along the bottom. It is that chart that caused me to ask the original question about the importance of preload. The peak was about 2 million miles, the "disasterous" drop ended at about 1 million miles (if I remember right). Since I don't plan to get 1 million miles - never mind 2 million miles, I did not see the near fanatical obsession with preload.

Having said all that, after all the discussion, opinions, pictures and folklore - I'm still not one step closer to figuring out how the preload is actually performed. CHas anyone accomplished this, and can you pass on how you did it?

Thanks for your help! Heinz

The point the chart makes, regardless of exact mileage/context, is that you can easily run the bearings loose with very little loss of lifespan. But running the bearings tight can very quickly cause a drop off in lifespan. So as long as the wheel spins freely and does not wobble, there is no great point in putting on extra preload.

I checked some of my old Harley manuals for models that use the same tapered wheel bearings as Airheads, and on some older models they specify a bearing end clearance of .002" to .015". That is right, all clearance, no preload. Which of course will have the BMW string and spring gauge brigade shrieking with horror, but Harleys are not known for chewing out wheel bearings as long as the grease is changed with every tire change.

Sometimes I think BMW just think too much and look for complex elegant solutions where brute force and ignorance would actually suffice, in the Harley Davidson manner.

Also, if you rebuild your wheel with new SKF bearings, properly seated by heating the hub before installation, there is about a 90 per cent chance the original spacer will give the correct preload on the new bearings. The tolerances in the manufacture of the bearings is so small there is very very little variation from one bearing to another when new. The variable size spacer is mostly to compensate for variations in the machining of the hub, not the bearings, and the hub does not change after it has been machined, unless a bearing outer race spins and chews it up.

[pommie john]

Originally Posted by H. Huester

Thank you everyone for your inputs... but it looks like it may be time to let this thread die, and for me to PM some of the responders that appear to have performed this procedure on their own before... (minus the "space-shuttle-launching" level of detail)...

Good riding to everyone!

I've done it myself. I used a micrometer to measure the "wedding band" and I made a spacer to fit over the axle so I could do the job without fitting the wheel in the forks. Otherwise, no special tools.

I fitted the new bearings into the hub with the spacer and the wedding band between the inner races and then slid my tubular spacer onto the axle and the wheel nut and washer tightened up onto the spacer. This was all done on a benchtop, not on the bike so I could feel the play better.

There was too much play so the wedding band was too thick. I filed it down carefully using the micrometer to check it was even all round. I reduced it by half thou increments until the play had all gone.
That's it.

You may be better off buying a selection of wedding bands from your local BM shop, it saves some filing and ensures you don't mess up and have a wedge shaped wedding band that will destroy your new bearings quicker than you can blink.

[Wirespokes]

Originally Posted by H. Huester

I'd rather learn to do this on my own than have BMW do it for close to $100 per wheel for me - that part was also in my original email... you did read it, right ;)?

Thank you everyone for your inputs... but it looks like it may be time to let this thread die, and for me to PM some of the responders that appear to have performed this procedure on their own before... (minus the "space-shuttle-launching" level of detail)...

I can understand Stephen's loss of patience. It can be frustrating when the data is all laid out, yet someone says it isn't and asks for something as if it's been with-held. You've read everything on the subject I have - I know of nothing else. This isn't rocket science, but it's also not the easiest thing to describe. It's funny how some of the simplest things can be the most difficult to explain.

Some jobs are best left up to someone knowledgeable and trained, rather than attempting it oneself, and perhaps that's the case here. It might be best connecting up to some airheads in your area and, perhaps during a tech day, have someone go through the procedure with you.

That graph also took me a little while to interpret - it's not laid out normally so can confuse. But the data is all there. As was said already, bearing life is the max with a little preload. As with most things, there's a downside to having no preload, even though that makes it easier setting up the bearings. The downside is possible handling issues such as "THE WOBBLES". I've had them before and don't ever intend to again.