The New And Improved Unofficial R65 Forum V2

Technical Discussion => BMW Technical Q&A, Primarily R65 => Topic started by: wilcom on October 29, 2018, 08:20:00 PM

Title: 120/90-18 rear spacer
Post by: wilcom on October 29, 2018, 08:20:00 PM

I just removed a 120/90 from the rear of my 1984LS and I am going back with a 110/90.

Reading in the archives  leads me to believe that I should have a "top hat" spacer, and that that spacer replaced the standard top hat spacer giving me the extra clearance that I needed t5o clear the swing arm.


I whipped out the Clymers and the rear wheel blowup has nothing that looks like a top hat. When I view the rear wheel I see the Thrust Sleeve with the Oil Seal surrounding it on both sides.


Where should I look for that spacer that should have gone in when the PO went with the 120/90?

Title: Re: 120/90-18 rear spacer
Post by: Tony Smith on October 29, 2018, 09:07:02 PM

On the R65 the "top hat" is on the drive side only, pressure for the non-drive side being provided by the stepmachined into the axle.

Lookign at your wheel it appears to have a perfectly stock "top hat" fitted to the drive side.

Some 120/90s will fit without requiring to be spaced, also the LS wheel is wider than the snowflake and the wider rim means that there is less of a "balloon" in the tyre when fitted and aired up.

Title: Re: 120/90-18 rear spacer
Post by: mrclubike on October 29, 2018, 09:31:15 PM

The top hat spacer or "sleeve" as BMW calls it
Is what the seal rides on
The rim of it is under the seal
You normally remove the seal in order to get it out
I always at least pull the bearings out and inspect them at tire changes and then replace the seal

The standard one is 9.2 mm and the wide one is 11.7 mm

Title: Re: 120/90-18 rear spacer
Post by: wilcom on October 29, 2018, 09:54:51 PM

Quote

Some 120/90s will fit without requiring to be spaced,

Quote

The top hat spacer or "sleeve" as BMW calls it
Is what the seal rides on

Thanks Tony & Mrclubike for the information. If it looks standard to you I'll bolt it back together and give it a go. 

Title: Re: 120/90-18 rear spacer
Post by: georgesgiralt on October 30, 2018, 01:36:49 AM

Bear in mind that the non drive side also have a spacer. This one is (on snowflakes rim) same size as the one on the front wheel.

Title: Re: 120/90-18 rear spacer
Post by: Barry on October 30, 2018, 05:44:05 AM

If the wider spacer had been fitted for a long time you should see a step in the wear pattern of the splines as the wider spacer reduced spline engagement by 1.5mm

Title: Re: 120/90-18 rear spacer
Post by: Bob_Roller on October 31, 2018, 05:45:25 PM

If a longer spacer has been installed on the drive spline side, you will have a larger gap between the final drive case and rim .

Title: Re: 120/90-18 rear spacer
Post by: wilcom on October 31, 2018, 08:24:17 PM

Quote

you will have a larger gap between the final drive case and rim

I'm pretty darn close so it's safe to say there was no long spacer living inside.( shudda cleaned up the rear drive while I was at it :-/)