Modern Vespa

I recently did a belt change & service and installed a 1.0mm fuzzy washer on my Fuoco 500. The Variator faces were quite badly scored so I had to sand them down to flat as best I could using wet & dry paper.

If I took, say, 0.5 mm off each face, how much have I increased the gap between faces? Do I now have the equivalent of maybe 1.5mm of "fuzzy washer effect"?

I have experienced the FW effect of slightly higher revs and a reductiuon in engine breaking, and I am considering taking it out and trying the new belt/flat faces/cleaned up clutch etc. without the FW, and it occurred to me that the sanding may have given me the FW effect, or a proportion of it anyway.

So, mathematically, am I correct? And if so how much have I changed the ratios.

If you took off 0.5mm of stock off of each face of the variator, and if the included angle between the variator halves is 30 degrees, then you would need to add 2mm of "Fuzzy Washer" to get back to the original positions.

This assumes the 0.5mm of stock is taken normal to the conical surface (and is taken off of both surfaces). If the stock is taken parallel to the driving axis, then it is a 1:1 ratio.

This assumes I am correct about the 30 degree included angle; this is very important, so please do not take my word for it.

Don't worry about the angles - 0.5mm off each face is very near to taking away adding 1.0mm of FW.


(The slope is about 1 in 10 - so the angle is about 5°. Roughly - but good enough for 'figgerin'.)

(edited for brain-fart when typing)

nope just the opposite, removing the face of the vari is actually how the fuzzy washer came to be.
Scooter racers were doing this face removal to get a better standing stop jump, this actually increases the distance between the 2 halves thus the belt sits a tad lower. Same as adding a 1 mm spacer (Fuzzy Washer) to increase the distance between the 2 halves.

So taking down the surface and a 1mm fuzzy washer would be similar to adding another 1mm for a total of 2mm. this will give you a super takeoff but will also lower your top end by quite a bit, Also will decrease your fuel mileage some too.

Yup, got it wrong.
Missed the negative sign.




Ahem, well if you ever have to plate on extra material, just let me know....

Thanks guys; thats more or less what I thought. I am missing the engine braking, and the revs seem to have climbed about 1000 from before I went into the tranny. Take-off is epic though
Next time I have an hour or so to spare I'll open it up and take the fuzzy washer out. I'll report when I'm done