Rear Wheel Bearing Spacers

[Bob_Roller]

There was a thread not long ago, about using a longer spacer/compression ring as BMW calls it on the inner bearing of the rear wheel, to increase the clearance between the swing arm, and a 120 width tire .

I just got everything reassembled and re-installed in the rear wheel, the original inner spacer was damaged from a previous owner, didn't notice it until I got all of the parts really clean for reassembly .

I decided to use the spare spacer that I had ordered, which is the longer spacer, so I wouldn't have to wait a few more weeks for the part .

Here is what I found after putting the wheel back on the bike and torquing it down, with the longer spacer installed, there isn't enough thread of the axle coming through the axle nut, it's recessed about one thread .

A thinner large area washer under the nut would solve this problem .

Standard is to have at least one thread protruding through the nut .

Also there is now a 3-4 mm gap between the rear wheel and the final drive housing, looks like a lot of road dirt and water can get in there now .

I'm going to live with the installation for a while, but I'll install an original length spacer in the not too distant future .

[Mike V]

Bob,

I'm a little confused.  You installed a wider inner wheel bearing spacer?  How did this affect your pre-load and the adjustment of wedding band thickness?  Why would this affect your wheel spacing unless your wheel bearings were grossly pushed outboard?  I'm screwed up somewhere...right?

Or are you talking about the axle spacer and not the inner spacer?

 :-?

[Bob_Roller]

The spacer that extends through the seal, not any of the adjustment spacers in the middle of the stack-up .

[Barry]

That's useful info Bob. The gap to the final drive must look a bit odd. I think I'll bear that in mind when it comes to needing a new tire and not be tempted to go for one that needs the wider spacer.

The rear axle nut is not very thick to start with. Still at around 25-30 ft/lbs you probably have some safety margin as that  thread should normally handle at least 60ft/lbs assuming its 8.8 class or higher.

[nhmaf]

If worst comes to worst, depending on how brave you were you could maybe get another .020" lathed off the left axle shoulder that would give you that extra thread on the right end, and possibly not cause the axle to sit too far in to still extricate with the "puller hole" on the left end.    I'd probably try this with a "spare" exle, myself.

[Bob_Roller]

I think I'll just get a thinner washer, the quickest and easiest way to go .

[Justin B.]

I "cheated" on my stainless rear axle and didn't use a nut but made it flush with the surface of the final and used a cap-screw and custom washer...

[montmil]

The spacer that extends through the seal, not any of the adjustment spacers in the middle of the stack-up .

Often referred to as "top hat".

[DgM]

And the benefit of this is a slightly larger rear tire with a rear wheel out of line with the front?

[Bob_Roller]

BMW says a maximum of 4 mm offset of the front to rear tire is acceptable .

I measured the spacer before installing it, it's 3.97 mm longer .

As far as the wider tire, with the Metzeler's I'm using, the 4.00 width wasn't widely available, the few that were, were old tires, that's the only reason I went with the 120 width, but I never had a problem with clearance of the tire sidewall and swing arm .

[nhmaf]

There are acutally quite a few bikes that don't have the front and rear tires exactly on the same centerline.  And, you might be surprised at how many bikes have a significant weight bias on one side or the other, even if the tires are on the same centerline.