ZANE. Ramblings from a lunatic....

G

ghwallice

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Location
Ipswich
OK, I?m bored. Missus has gone bed, I?ve had too many beers, and I?ve got Floyd cranked on the stereo (missus has earplugs?.)
I?m putting together 2 of Zane 750S engines. 1 of for road bike that I bought new, the other from bits and pieces from Eurobrit Melbourne for a track bike. (They wrecked Zanes and I bought out their Zane stock some years ago. In retrospect a stupid thing to do, however?.)
I?ve rebuilt 3 of my cranks so far, and I?m happy. They have come together really well.
I?m short the crank gear to drive the clutch housing gear, so can?t progress with the 750 track bike.
But if I use a 650 crankshaft gear and 650 clutch housing gear in the 750S, which will fit, I can progress?
I?ve been trying to get head around this?.
Crank gear /clutch basket gear for 750 is 37/89, giving a ratio of 2.4054:1
Crank gear /clutch basket gear for 650 is 37/76 giving a ratio of 2.054:1
So if I fit the track bike with the 650 shit, and adjust with final drive sprocket ratios, will this give what feels like a closer ratio gearbox???
I?ve never raced a bike, only really played with them. Isn?t what a close ratio box is wanted?
 
Simple answer is no.

Go to bed, sleep and then in the morning cook up a storm of bacon yummm and eggs any style you want,, then google close ratio gear box and all will be revealed.

As for me well I'll have a few more refreshing ales to make up for not being able to drink for a few days.. I'll then wake in the morning have my bacon and eggs and then take my Unfaired English Jota out for a run as it will be the coldest day in over 2 years...

But I do like the way you are thinking over Floyd and beers  :D ..psst instead of another brick in the wall,.... another beer down the gullet sounds like a better deal this time of night.

Oh hell another beer sounds like a good deal so hear ya go we can read together... over another cold one..

http://www.5speeds.com/ratios.html
 
I'd have to say i'm a little surprised looking at those primary ratios. The 750 runs the clutch slower than the 650.
Basically, the closer to engine speed you run the clutch, the higher the torque capacity it will have.
I've not compared 650/750 clutches so don't know any differences - but for a race engine, I'd always go for the lightest clutch possible which would mean using the 650 primary ratio...
 
Brett said:
Simple answer is no.
Click to expand...
No too what? Floyd, more beer, change in drive will result in close ratio box, or close ratio box not better for track bikes, or just no, give it up...OOOh, no to missus wearing earplug. Sorry, now ive got it..

Reducing primary ratio from 2.5 to 2 to 1 spins clutch faster. Greg T's point noted about torque increase. Reduce final drive ratio (sprocket mix) to compensate for top end speed.

This will result in a taller first gear, but 6th will be the same (with matched final drive ratio), therefore, impact will emulate a close( closer) ratio gearbox.

Isn't part of the idea of a close ration box on the track to allow better use of torque and power curves, but also allows the loading of the box to reduced as more gear changes are happening???

Or am I just full of shit????

Regards, Greg

 
Answer stays no...

Changing the primary ratio and then the final drive to compensate, does nothing to the box ratios, they stay as they were.  Only advantage/disadvantage is the differing clutch and box loading, depending on which way you go.

A close ratio box will have the individual ratios closer to one another, usually meaning having to cope with a very high first gear, but with spacing between the remaining ratios a lot closer.  Means it can be easier to choose a gear for a given rpm for a certain corner exit, very desirable.

piet
 
And a pain in the arse for a road bike. My dirtbike has a 6-speed close ratio box, and it comes close to spoiling it for my use. I would have loved an overdrive 6ths gear for transport stages, instead, it would rev its tits off and uping the final gearing gave it a way to high 1st gear. There great for racing but horribly limited for street use.
 
Greg, if it were that easy, nobody would ever have built close ratio gearboxes  :D

A faster spinning clutch (and gearbox) means lower torque loads on those components, but as with most things mechanical, there's rarely a benefit without a cost. Faster spinning things have greater flywheel effect so engine won't pick up revs as quickly.
 
Dellortoman said:
Greg, if it were that easy, nobody would ever have built close ratio gearboxes  :D

A faster spinning clutch (and gearbox) means lower torque loads on those components, but as with most things mechanical, there's rarely a benefit without a cost. Faster spinning things have greater flywheel effect so engine won't pick up revs as quickly.
Click to expand...

How much effect the clutch and box has on the speed of engine pickup largely depends on the mass of those bits compared to the mass of the crank and it's attatched parts. Usually the crank is the larger mass - with big bits of it spinning at large radii compared to the box...
I've done close ratio conversions - 20 sets so far for Aermacchis. Very worthwhile as the 4 - 5 gap in that box as std is sufficient to hamstring top speed badly. A gap such that the engine stays in the power band when 5th is engaged has been shown to be worth around 15mph top whack on NZ tracks.
 
sfcpiet said:
Answer stays no...

Changing the primary ratio and then the final drive to compensate, does nothing to the box ratios,


Piet, that was the bit in my head that I was missing! think I've got the picture complete in my head complete now. Thankyou, Greg
Click to expand...
 
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