Close Ratio Gears
- Thread starter acotrel
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I have a complete Quaife 5 speed if he's got deep pockets.
I'm not aware of any kits that change just second and third while leaving first unchanged.
There are a couple of sleeve gear sets that raise everying closer to 4th.
I'm not aware of any kits that change just second and third while leaving first unchanged.
There are a couple of sleeve gear sets that raise everying closer to 4th.
lcrken
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Like pommie john said, I don't think there are any close ratio 4-speed sets that let you keep the original 2.56 first gear ratio. Some of them keep the stock 14/28 first gear pair, but they also change the fourth gear pair (sleeve gear and countershaft gear) from the stock 23/18 to either 23/19 or 22/20, which raises the first gear ratio to 2.18 or 2.2, resp. The closest currently available kit to what you are looking for is probably the RGM close ratio gearbox set with kick start for AMC boxes,
http://www.rgmnorton.co.uk/buy/close-ra ... ox_559.htm
which gives you closer second and third spreads, and a 2.05 first gear ratio.
The Norvil Production Racer 4-speed had a 2.18 first gear ratio, and the 5-star or Barton set had a 2.2 first gear ratio, but they haven't been in production for a long time now, so you'd have to find a good used set. Good luck with that!
I previously posted a table of all the 4-speed combos I know about here
close-ratio-commando-transmission-t22319.html?hilit=gearbox ratios
Ken
http://www.rgmnorton.co.uk/buy/close-ra ... ox_559.htm
which gives you closer second and third spreads, and a 2.05 first gear ratio.
The Norvil Production Racer 4-speed had a 2.18 first gear ratio, and the 5-star or Barton set had a 2.2 first gear ratio, but they haven't been in production for a long time now, so you'd have to find a good used set. Good luck with that!
I previously posted a table of all the 4-speed combos I know about here
close-ratio-commando-transmission-t22319.html?hilit=gearbox ratios
Ken
lcrken
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This is a nice writeup on the available Norton gear sets and combinations, and how to mix and match them. I copied it from somewhere years ago, maybe the NOC site, but I'm not really sure. I've modified it to make it easier to print and scan to a .jpg so I could post it.
Ken
Ken
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Thanks very much for the info, I will pass on the link to this page. I actually have a complete gearbox I could sell the guy for about $1300. However I've always been of the opinion that the gearbox is the heart of any project and I don't know what my next one might be. I think 2nd and 3rd gears out of a manx box would probably be enough for him and cost around $500. He is in his mid-fifties and wants to go faster, however doesn't have much cash to play with.
I was interested in the comment that Dunstall has done this. I paid $700 in about 1985 for the close ratio internals of my 4 speed box, and even then I wasn't smart enough to fit a standard first gear for the clutch starts.
I was interested in the comment that Dunstall has done this. I paid $700 in about 1985 for the close ratio internals of my 4 speed box, and even then I wasn't smart enough to fit a standard first gear for the clutch starts.
Brooking 850
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Plenty of torque will allow you to pull a tall first gear.
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I have used the American close ratio 4 speed box with the first gear which is higher than that of a manx. The last time I raced, I got poor starts in 3 races. In the fourth and last race I bit the bullet and revved the tits off the motor and quickly rode the clutch out. I was in the lead group in turn one, and went under all of them in turn two. I was beside the leader when the fuel line popped off and doused the motor with methanol. I still have not found the money to pay for a ride day so I can test with the 6 speed TTI box. It is extremely frustrating when you are old and have all those silly family issues which use up all the readies.
Actually I was too dumb to simply fit a low first gear to the 4 speed box and I have got plenty of choice in my own shed. A friend of mine who is one of the old A graders, recently told me he has three first gears for his manx to suit different circuits.
Actually I was too dumb to simply fit a low first gear to the 4 speed box and I have got plenty of choice in my own shed. A friend of mine who is one of the old A graders, recently told me he has three first gears for his manx to suit different circuits.
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Take two pairs of good second hand old 28-18t 4th gears.
Take one 28t slleve gear, chop the end off and mill in threee slots as per the std first gear.
This gives you a set of first gears. The 18t gear will need a thin splined shim to position the gear correctly when used as a 1st ...I had a spare knackered one detoothed and sliced up into pot lick thicknesses and a couple came out the required thickness. One could always have the sliced lumps ground to the thickness required to do the job......
Now find yourself a set of 2nds and 3rd with 20-22 teeth . Good seconds are nearly as rare as rocking horse proverbial but new genuine Norton pairs are available if you know where to look..CORRECTLY made ones that is..... who knows what matewrials or hardening some people use these days.........
Now using the other set of 28-18 teeth 4ths you have a cheap set of gears that for racing are perfect as they give a higher bottom gear than std but lower than that given by 4 speed close ratio boxes thus you can get off the line quicker and the rev drop between each gear leaves you well withing the torque range of the motor.
It wastes time changing gear when you ride a torquey twin.............. One friend manufactured a special secuencial gearbox for his err .......side car race bike. He calculated that per lap of Mallory Park it meant that he was 7 feet in front of everyone else using a std box which is a good distance over the competirion....Yes the outfit wins races ........ As to whether anyone has noticed yet ...but how many noticed the Norton rotary race bikes had a special gearbox?? As they were allowed to race clearly no one who was not in the know..... The special gear box case patterns still exist......
Just an ide and a damn sight cheaper than a new 5 speed box from New Zealand of the UK.
Take one 28t slleve gear, chop the end off and mill in threee slots as per the std first gear.
This gives you a set of first gears. The 18t gear will need a thin splined shim to position the gear correctly when used as a 1st ...I had a spare knackered one detoothed and sliced up into pot lick thicknesses and a couple came out the required thickness. One could always have the sliced lumps ground to the thickness required to do the job......
Now find yourself a set of 2nds and 3rd with 20-22 teeth . Good seconds are nearly as rare as rocking horse proverbial but new genuine Norton pairs are available if you know where to look..CORRECTLY made ones that is..... who knows what matewrials or hardening some people use these days.........
Now using the other set of 28-18 teeth 4ths you have a cheap set of gears that for racing are perfect as they give a higher bottom gear than std but lower than that given by 4 speed close ratio boxes thus you can get off the line quicker and the rev drop between each gear leaves you well withing the torque range of the motor.
It wastes time changing gear when you ride a torquey twin.............. One friend manufactured a special secuencial gearbox for his err .......side car race bike. He calculated that per lap of Mallory Park it meant that he was 7 feet in front of everyone else using a std box which is a good distance over the competirion....Yes the outfit wins races ........ As to whether anyone has noticed yet ...but how many noticed the Norton rotary race bikes had a special gearbox?? As they were allowed to race clearly no one who was not in the know..... The special gear box case patterns still exist......
Just an ide and a damn sight cheaper than a new 5 speed box from New Zealand of the UK.
Kvinnhering
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J. M. Leadbeater said:
Can you please explain this further? Can you transform gearbox from rotary into a Commando??
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'It wastes time changing gear when you ride a torquey twin.............. '
What is quicker than standing on the gear change lever of a close ratio box as the revs approach 7000 RPM ? I don't even back off the throttle. I just keep that heavy crank spinning the whole time, as you approach 7000 RPM the load on the gears comes off slightly anyway. Somebody once told me that if you have a torquey motor, you don't need a close ratio gearbox. I don't believe he had ever used a close ratio box. The difference in acceleration between using the standard commando box, and the close ratio American 4 speed box is amazing, however first gear during a clutch start is a bugger. If you let a commando with the heavy crank bog down then wait while it winds up using the standard gearbox, you will wait forever.
What is quicker than standing on the gear change lever of a close ratio box as the revs approach 7000 RPM ? I don't even back off the throttle. I just keep that heavy crank spinning the whole time, as you approach 7000 RPM the load on the gears comes off slightly anyway. Somebody once told me that if you have a torquey motor, you don't need a close ratio gearbox. I don't believe he had ever used a close ratio box. The difference in acceleration between using the standard commando box, and the close ratio American 4 speed box is amazing, however first gear during a clutch start is a bugger. If you let a commando with the heavy crank bog down then wait while it winds up using the standard gearbox, you will wait forever.
Kvinnhering
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Bernhard said:
Perhaps you would like to share this information with me as I cannot remember what number of teeth, and the 3 gears you had to change as I did not record it :?:[/
Bernhard.
I'm curious how it goes with your improved (stronger) first gear? Have you tested any gears?
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I sent the link for this page to my friend and I understand he is in touch with RGM. I believe 2nd and 3rd gears from a manx box fit straight in without modification, first is then probably a bit low to use at a slow corner on most race circuits. It is the same problem you have when you build a racer out of a T250 Suzuki - first gear is much lower than 2nd.
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Kvinnherring :
'Like pommie john said, I don't think there are any close ratio 4-speed sets that let you keep the original 2.56 first gear ratio. Some of them keep the stock 14/28 first gear pair, but they also change the fourth gear pair (sleeve gear and countershaft gear) from the stock 23/18 to either 23/19 or 22/20, which raises the first gear ratio to 2.18 or 2.2, resp. The closest currently available kit to what you are looking for is probably the RGM close ratio gearbox set with kick start for AMC boxes,
http://www.rgmnorton.co.uk/buy/close-ra ... ox_559.htm
which gives you closer second and third spreads, and a 2.05 first gear ratio.
The Norvil Production Racer 4-speed had a 2.18 first gear ratio, and the 5-star or Barton set had a 2.2 first gear ratio, but they haven't been in production for a long time now, so you'd have to find a good used set. Good luck with that!
I previously posted a table of all the 4-speed combos I know about here
close-ratio-commando-transmission-t22319.html?hilit=gearbox ratios '
'Like pommie john said, I don't think there are any close ratio 4-speed sets that let you keep the original 2.56 first gear ratio. Some of them keep the stock 14/28 first gear pair, but they also change the fourth gear pair (sleeve gear and countershaft gear) from the stock 23/18 to either 23/19 or 22/20, which raises the first gear ratio to 2.18 or 2.2, resp. The closest currently available kit to what you are looking for is probably the RGM close ratio gearbox set with kick start for AMC boxes,
http://www.rgmnorton.co.uk/buy/close-ra ... ox_559.htm
which gives you closer second and third spreads, and a 2.05 first gear ratio.
The Norvil Production Racer 4-speed had a 2.18 first gear ratio, and the 5-star or Barton set had a 2.2 first gear ratio, but they haven't been in production for a long time now, so you'd have to find a good used set. Good luck with that!
I previously posted a table of all the 4-speed combos I know about here
close-ratio-commando-transmission-t22319.html?hilit=gearbox ratios '
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Kvinnhering said:
I believe the rotary racers ran 6- speed FZR1000 internals, but they didn't use AMC gearbox cases either - a very different animal.
I heard they still had issues with bent mainshafts, but I never found out whether it was due to crashing or 'normal' wear & tear
Fast Eddie
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B+Bogus said:
Yes, later ones had Yamaha boxes as I understand it. Early bikes, at least racers, had Triumph boxes.
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The rotary Interpol2, Classic and Commander gearboxes were predominantly Triumph T140 guts modified to have the input and output on opposite sides. (a crossover box) The F1 rotaries have 5 speed FZ Yamaha internals though a popular mod is to fit 6 speed FZR1000 gear sets
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