Helical vs. Spur gears.

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DirtyE
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Helical vs. Spur gears.

Post by DirtyE »

Hey all,

I replaced my Primary Spur gears yesterday with Helical. While the ratio was more suitable for met setup, I also noticed smoother performace all around. Kind of nice. While browsing threads this morning I came across burnt_toast' build thread in the stickys. Hans posts a pic of his freshly updated gearbox that was full of spur gears. On other models in the past ive always replaced stock helical gears with spur gears...you cant find malossi or polini helicals.

So were looking at power transfer losses here. Sliding friction. Im not gonna sweat this right now, but it looks like spurgears do a better job of ttransferring power, and I just went the other way. I guess ill hold onto my stock primaries and look for spur cut secondary gears someday.

EDIT:http://www.green-mechanic.com/2014/05/a ... 7.html?m=1
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Re: Helical vs. Spur gears.

Post by 1man8scoots »

Polini and malossi make helical. They are 16/32 though and you have to use an af05e secondary.
Helical to me feel more solid, but it could be a placebo effect.
I run the 16/32 malossi gears on my kymco zx50 engines as no other gears are readily available. With my kymco it comes out to 6.89:1.
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Re: Helical vs. Spur gears.

Post by DirtyE »

I like the way the full helical gearbox feels, but after reading the post by Hanz(I hope im remembering his name right), I'm wondering what kind of losses im acquiring. Transmission is big as you know. I don't want all my time spent cutting, grinding and measuring stuff to be wasted in transition to the rear wheel.
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Re: Helical vs. Spur gears.

Post by Trafficjamz »

The biggest difference I have noticed between straight cut or helical gears is the noise.

the straight cut gears are a bit noisier than the Helical.
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Re: Helical vs. Spur gears.

Post by 1man8scoots »

Just realized the malossi are straight cut.
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Re: Helical vs. Spur gears.

Post by DirtyE »

The malossi/polni comment was more of a generalization that mostly when you buy gears from them they are spur cut. I'm sure its possible that they make some helical gears, but none that I have used in mina or piaggio motor.

Yes, spur are noisy. I suppose I could dig around on euro forums to see if there are dynographs for this. Its not really that important though, im not gonna fork out the cash to go straight cut primary and secondary anytime soon.
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