Reading Callum's interesting post and suffering the same machine-gun rattle from the belt got me thinking about a way to reduce this.
To get an idea of what’s going on I set up a GoPro and did some test runs, the first was with the belt set at what I would call normal tension and the second with the belt set so tight that you could play tune on it.
What the videos show is the belt is gaining some slack and flapping up and down a remarkable amount even on moderate throttle openings.
Although I have the NVH fitted now I have had a solid bevel box mount previously and could still get the belt to rattle against the aluminium mudguard mount, even with this cut back enough to clear the belt its still flapping about a lot.
There must be some very large forces at play on the belt and some strong resonance from the engine. Maybe the slack is a combination of the Bevel box moving, the swingarm and chassis not having enough strength to stop the taper bearings spreading and maybe the belt stretching a bit, I really don’t know.
I have been trying this roller set up using a Rosta belt tensioner which works in the same way as a trailer rubber Indispension axle system.These are great as they come in different strengths, have a damping effect and the load they apply can be altered by rotating the mount. Its set in the video with not much pressure on the belt and can be easily pulled off the belt by hand but the resistance ramps up the further its deflected by the belt.
The main problem was noise from the roller with the back of the belt being ribbed, I have tried several types going up in diameter and material softness and have ended up with a 80mm diameter 78a skateboard, actually a longboard wheel, with some groves cut in it and is now quiet enough not to notice. Not sure of longevity as have only run 500 miles but with no visible wear, if the wheel can stand doing 70mph going down an alpine road with someone standing on it sliding round the corners i’m hopeful it will be ok, anyway have got 3 spares as you have to buy them in fours.
Just thought I would share this and no doubt you will think I’m mad and its a waste of time🤪
https://www.youtube.com/watch?v=57ykqvhAyLQ
https://www.youtube.com/watch?v=ir3peVEBFoc
https://www.youtube.com/watch?v=ZFbMGPhZVt0
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