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Re: oilheads-digest V4 #112

To: Bob Convey

I machined off 6 mm from the wheel's hub and left the spacer off. The
interference happened between the spokes and the brake calliper. I have two
rear rims so I am experimenting with one. Because of the interference I had
to replace the spacer. Even in this situation I moved the rear wheel closer
to the drive unit by 6 mm, relative to it's position when left the factory.
The bike is almost perfect. I still need to remove the shim.
I am not just guessing. I have a couple of engineering degrees and 53 years
spent in engineering design, not on this subject though, but it gives you a
certain way to approach a problem. Moving the wheel towards the drive unit
is based some rough calculations which indicated that the wheel should be
moved by 8 mm.
Regarding the center of the bike, which I consider also the center of the
front wheel, the rear wheel is now 9.5 mm offset into the "minus direction".
There are a lot more to my measurements that I am mentioning here and I am
not finished until my RS will run straight, hands off, without the system
cases, just like my '79 CX500, '84 Shadow500 and the '84 Nighthawke650, all
drive-shaft driven bikes.
I am leaving tomorrow for 3 weeks so I cannot go into too many details.
As far as friction goes, in structural engineering we bolt heavy steel
structures with high-streght bolts without any shims in between members. The
shim provided by BMW is a slippery stainles steel, though having a bit of a
rough surface. If it works for extra friction between aluminium and steel
.... I cannot say, I have no experience with this combination.
I just ordered a used rear calliper to have one to take apart and measure
the thickness of the material, it might be possible to mill off a bit from
it's back. I know cases that this had been done, not on BMWs.
I respect anybody's opinion, I do not want to start a thread, so I may
contact you off-list.
More on my return.
Bob Silas

----- Original Message -----
From: Bob Covey
To: Mick
Cc: oilheads@xxxxxxxxx
Sent: Tuesday, October 02, 2007 1:07 PM
Subject: RE: oilheads-digest V4 #112

>I took the spacer out of mine 60K ago to attempt to address a severe PTTR
>problem. It certainly helped. packing all the heavy stuff in the left I
>haven't experienced any problems that I know of, what am I missing?

There was a court case where someone's rear wheel fell off and he had
removed the spacer.  From what Paul Glaves says, that spacer is actually
a 'friction' device and it increases the clamping force on the rear
wheel to hub.


Hmmm, I certainly don't have your or Paul's experience. I faithfully torque
the the lug nuts, dry and clean. Judging from what it takes to break them
free, they aren't moving at all. I think I'll leave the spacer out until I
some indication that it is a bad idea on MY bike. Others can make their own
decisions. My hand, shoulder and elbow issues mean that I couldn't ride any
distance with the spacer in. I was ready to take the plane home from Bend.
I have to put the spacer in, I'll sell the bike.

Hey, when are you coming to Simi?


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