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AntonLargiader
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Charlottesville, VA
Joined: 02/14/2006
Posts: 18

Same bike as my other thread but totally different questions.

I'm overhauling the final drive on our /3. On disassembly I found that there was no pinion depth shim (item 45 in the parts book, shim for setting base distance).

What are the chances that the shimming was ever considered correct without a shim there? On any newer final drive it would be impossible to get the correct tooth contact without a shim, but these are much thinner.

The tooth faces are somewhat spalled but the contact pattern seems to be OK. The backlash was WAY too high, which may account for the tooth erosion. This gearset is a 32:7 for sidecar use; a 35:9 is available new from MT for a very reasonable $500 or so but I'm going to run this one for now.

As for the ring gear shimming, the existing shim (actually more of a bearing; looks like a miniature R247 crank thrust bearing) is 1.8 mm which is the thinnest one listed by Benchmarkworks. Still the backlash is far too much (somewhere around 1mm). How normal is this?

Is my gearset just toasted? Comments welcome.

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Anton Largiader www.largiader.com
Charlottesville, VA

Darryl.Richman
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VBMWMO #6285
Surf City, USA (Santa Cruz, CA)
Joined: 10/27/2006
Posts: 2183
Ring/pinion shimming, R51/3

First of all, let me say that I have no idea, and secondly, I've not openned up the final drive on my R51/3. Wink

I note that the Behelfs-Katalog has a comment on this Paßscheibe: Dicke nach Bedarf, thick as required. It's interesting that they don't give a thickness, or list a range of these shims.

Still, it's a lot easier to envision some dPO* putting it together without it.

*) determined Previous Owner

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