Sense of fox clutch

[Piet30Topic starterBerichten: 1082]

Hi,
general questions for my understanding to use a fox clutch.

What are the general advantages in using a fox clutch?
Is there an advantage in using a fox clutch modified on a 10,5:1 er mono gear box compared to a standard 100mm vario with 10,5er vario gear box?

[niek1992BijdragerBerichten: 1882]

The general advantages are increase in top-speed. The range of the pouli’s are far greater then that of a 90MM of 100MM clutch. thus creating a ‘longer’ gear.

ArvidW has driven his Citta with a fox-clutch and 1:13.5 gearing around 100km/u if i’m correct. He did this with an modified DRevo, and an shortened Leovince Circuit.

downside to this is that the clutch weighs a lot more, so the needle-bearings inside your mono gear box will wear a lot faster. I was thinking about putting an SKF closed ball-bearing inside the gearbox, where the long axle will come out.
But i don’t have the equipment to weld Alu onto the gearbox. so that’s a no-go for me. scooters use this also. they just have a normal crankshaft bearing mounted in their gearboxes.

Also you’ll need to adjust a few things to have it working. So it’s not usuable ‘out of the box’.

Other than that, it’s a wonderfull transmission. basically you use a better designed clutch, instead of the 20 year old variomatic.

[Piet30Topic starterBerichten: 1082]

Ah,ok.
To use the larger range of the clutch pouly, is a Malossi or Polini variator able to support that?

[niek1992BijdragerBerichten: 1882]

as far as i know yeah, the Malossi (in my case) is able to support the larger range of the pouly’s. At least a lot more than a stock piaggio one.
i don’t think the malossi or polini variator take optimal advantage of the fox-clutch, but if you can drive 100km/u on a citta with 1:13.5 gearing then i’m guessing it’ll be fine!

i’m driving with a stock vario-clutch now, but that’s only because i don’t have a kick-carter, and the fox-clutch doesn’t support starting the motor by running with it.

[Piet30Topic starterBerichten: 1082]

Sounds good

Thanks for that infos.

[ArvidWDonateurBerichten: 6258]

Exactly what niels said only I used stock 1:10.73 “snor” gearing.

The initial drive ratio when driving of from a standstill is very low. I was able to outrun a 43mm DEPS on a sprocatti rotary carter upto 50km/h with my 50cc primerally due to this light gearing.

AW50-4t | 13.13 | Gianelli Citypower | 3.2Nm@6000rpm | 3.0pk@6700rpm
Home made engine dyno

[Piet30Topic starterBerichten: 1082]

haha 😀 bad thing for the sprocatti rotary driver. 😀

Yes, I know your Citta with the 50cc and fox kopeling very well from former nice tours we made together. But didn’t realize that it was a snor gear box.

[ArvidWDonateurBerichten: 6258]

In my opinion “snor” is the only way to go if you want to take full advantage of the advantaged of the fox clutch. As niek already stated on a citta you run out of the gearing around 100kph if you have a high reving engine (approximately 9-10.000rpm for my DR639 engine). On a Ciao it will be more like 125kph which is simply rediculous for a 40kg moped :lol

Owning a fox clutch variomatic is a bit of a love-hate relationship. The performance is really good however at speed it vibrates like hell, bearings last 1500km or so, axles sometimes break, starting without kickstart is a bit of a joke and fabricating the axle can be a bit of a challenge. Furthermore the “torque drive” slots wear out quite quickly.

It may sound like it’s a bit of a problematic system and it sometimes is, however I would build one again if start working on vespa’s again.

AW50-4t | 13.13 | Gianelli Citypower | 3.2Nm@6000rpm | 3.0pk@6700rpm
Home made engine dyno

[Piet30Topic starterBerichten: 1082]

Cool, I like to run my Sprocatti Evo with it, starting will be with a hand drilling machine. So no problem with that.
Will not need to put a screw into the clutch and follow it after engine is running 😀

Also will not reach the 1000 km mark with that engine so fast.

Thanks for you input on that topic.

[Gebruiker]

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