NC35 (RVF400) cush drive conversion
Running the TZ350 close ratio gearbox in the RD350 engine without a cush drive made us a bit nervous. As the NC30/35 swinging arm hub doesn't incorporate any kind of cush drive, a solution was needed. The goal was to be able to use standard sprockets so that sprocket replacement and gearing changes would be straight forward using off-the-shelf parts. We looked into using a Triumph and VFR800 style cush drive, but didn't like the bulk of it. Plus, it wasn't going to be a straight bolt-on conversion either. So, after a bit of thinking, we decided to produce a new part, a "spider" that would hold six cush drive rubbers and bolt onto a revised standard NC30/35 sprocket carrier.
The cush drive rubbers are Honda RS125 parts. While the RS125 uses only three cush drive rubbers, we decided to use a full completement of six for longevity reasons. Plus, the standard sprockets have six mounting holes. The spider is small enough in diameter to accomodate down to a 38 thooth sprocket. Here is what the complete cush drive conversion looks like.
And here are the piece parts:
- The cush drive spider
- The modified NC30/35 sprocket carrier
- The sprocket with the cap head bolts to locate the cush drive rubbers
- The six nuts bolting the assembly together
And finally, this is what it looks like assembled on the bike. Hopefully, this will be adequate protection of the gearbox internals.