Rear wheel spacer?

[nmbeemer]

I just took the the rear wheel off my RT to change the tire and I noticed there wasn't any sort of spacer between the wheel and the FD. Isn't there supposed to be one? And if so, how bad is it not to have one?

[duckbubbles]

Realoem shows a 2mm spacer. Maybe somebody left it out?

 

Frank

[Bob Palin]

Are you certain it's not stuck in place? It can get a bit rusty in there. As far as I know all R11xxRTs have the spacer though I'm not 100% on that.

[nmbeemer]

I'm sure.

 

I'm thinking that I heard someone say something about some people taking the spacer out to correct the bike's tendency to pull to the right? Has anyone heard of someone intentionally removing their spacer?

[DavidEBSmith]

There was some discussion on the IBMWR list a while back about the spacer as applied to K-bikes. The gist of it was that the spacer is there to increase the friction between the wheel and the hub. Supposedly, without the spacer in place, the wheel can move slightly on the hub under hard acceleration, eventually loosening the wheel bolts and leading to catastrophic events. The specific finish of the spacer purportedly provides increased friction and reduces the slippage. As one of the posters pointed out, if BMW simply wanted to offset the wheel by 2 mm, at some point (like the introduction of the Oilhead) they could have added the 2 mm to the thickness of the wheel, which suggests some other purpose behind the spacer.

 

Now, I have no personal knowledge of any of this. Don't rag on me if you don't believe it. The information supposedly came from depositions of BMW engineers in a lawsuit. The two people who passed along the information, Paul Glaves and Don Eilenberger, are reliable sources and certainly in a position to know what they're talking about.

 

So, is it bad not to have the spacer? A whole lot of people have removed them to try to cure PTTR, and there isn't a rash of rear wheels falling off. On the other hand, if you're the one it happens to, that's very bad. My inclination would be to replace the spacer. But do you need to stop riding the bike until you do? If the failure mode is that the wheel bolts loosen, checking them regularly until you replace the spacer should minimize the risk, if there is any.

[Edgar]

I removed the rear wheel spacer some time ago and presto the PTTR ended right then. I’ve been through a couple of rear tires since and have not seen any issues. The wheel bolts have always maintained their correct torque (`75 flbs), with most of the miles 2 up. But, as Eebie points out, there is always risk when you don’t follow the manufacturers instruction.

[nmbeemer]

I think I'll ride without the spacer for the meantime but plan on replacing it when I get a chance. Any ideas on where I can pick up the spacer? Is there somewhere that sells the spacer plus the crush washers for changing fluids in the FD, trans, and oil?

[Ken H.]

If you are looking for a place to buy BMW parts on-line (vs. your local dealer) Chicago BMW, MAX's BMW, BMW of Santa Cruz, and others all sell parts on-line.

 

For part numbers MAX's, realoem.com, and others have on-line parts fiche.

 

The part number for the spacer is 36317653286.