Close Ratio Gearbox

smithyrc30 · Post by **smithyrc30** » Mon Nov 30, 2009 1:02 am

I remember reading in one of the posts that the-elf had had his CR gearbox copied.

I had a look through, but couldn't find it.... Well it was more a skim through actually, I'm a bit lazy....

Can anyone (especially the-elf) remember this?

Who did the work and were the gears any good?

I want one for mine. Missed out on two now on Yahoo Japan, and most of the bits are NLA from kwak, and the ones that are available cost the earth.

Parts guy looked a bit blank when I told him I wanted to buy the gears not the gear cutting machines and the factory as well.

AU$700 for one gear????

Who do they think they are, HRC???

KR-1R · Post by **KR-1R** » Mon Nov 30, 2009 1:48 am

why didnt you win the bottom end auction?

sell you mine $14K

smithyrc30 · Post by **smithyrc30** » Mon Nov 30, 2009 3:51 am

I didn't win because i didn't bid high enough

Own fault, chucked on a bid and went out.....

Got back auction done..... Not won.....

14K????? I only want one, not all of them!!!

KR-1R · Post by **KR-1R** » Mon Nov 30, 2009 4:52 am

bargain, cheapest in OZ

TwoStroke Institute · Post by **TwoStroke Institute** » Mon Nov 30, 2009 6:40 am

A gearbox is at the gearcutter ATM, tall first and shorter top gear is the plan. Along with an alternate primary ratio might be on the cards. For 5 of each individual gears things get pretty cheap.

smithyrc30 · Post by **smithyrc30** » Mon Nov 30, 2009 7:14 am

KR-1R wrote:bargain, cheapest in OZ

I could get Moz's bike for $16500, break it up for the gearbox and sell all the other bits on and it would come out less than 14K....

Besides if the elf has had one or more done I doubt that it will have cost UKP7000..... =D>

I'll wait and see what the elf has to say thanks.....

smithyrc30 · Post by **smithyrc30** » Mon Nov 30, 2009 7:17 am

[quote="TwoStroke Institute"]A gearbox is at the gearcutter ATM, tall first and shorter top gear is the plan. Along with an alternate primary ratio might be on the cards. For 5 of each individual gears things get pretty cheap.[/quote]

Just 1st and top different or all ratios closed up?

Doesn't changing the PDR mean un-riveting the clutch basket from the gear and riveting the new one back on? If you are going to that much trouble, might as well dry clutch it at the same time.

JanBros · Post by **JanBros** » Mon Nov 30, 2009 8:10 am

viewtopic.php?t=853&highlight=gearbox

TwoStroke Institute · Post by **TwoStroke Institute** » Mon Nov 30, 2009 8:52 am

Can change the clutch gear or you change the crank gear or both. There's a bit more to a dry clutch arrangement than that.
The other ratio's are fine just the big gap between first and second and top is an 'overdrive' (0.86) rather than a sixth gear. It won't pull hard on high final drives.

smithyrc30 · Post by **smithyrc30** » Mon Nov 30, 2009 9:07 am

Thanks Jan....

How do you remember or find stuff that quickly? =D>

I have pm'ed the elf. Will see what he says.

If it was UKP500ish in 2007 it will be about UKP700ish now I reckon.

A much better deal than AU$14k, or AU$3.5k for a part complete one.

You can still get the input shaft side but only 5th and 1st on the output shaft according to my local parts man. However 3.5k for a pile of metal is not what I have in mind.

KR-1R · Post by **KR-1R** » Mon Nov 30, 2009 9:31 am

wheres your maths Smithy - that 'R'bottom end went for A$590 = 48,000yen didnt it?

[img]http://kr-1r.com\kr1s\E1361.jpg[/img]

required changes 'S' to 'R' close ratio gearbox
1] SHAFT-TRANSMISSION IN... 15 tooth shaft >>> 14 tooth
2] GEAR,INPUT 5TH,27T ... >>> 25T
3] INPUT 3RD & 4TH, 19T23T ...>>> 22T24T
4] GEAR,INPUT TOP,29T ... >>> 23T
5] GEAR, INPUT 2ND, 22T ... >>> 20T
6] GEAR,OUTPUT 2ND,38T ... >>> 34T
7] GEAR,OUTPUT 5TH,26T ... >>> 28T
8] GEAR,OUTPUT 4TH,25T ... >>> 29T
9] GEAR,OUTPUT 3RD,31T ... >>> 31T Same ???
10] GEAR, OUTPUT 6TH, 25T ... >>> 24T
11] GEAR, OUTPUT LOW, 38T ... >>> 33T
12] 14T >>> 15 output sprocket

Road speed (table) KR-1 vs KR-1R, KR-1R speed in each gear (chart)

a 4th gear comparison - theyre almost identical

smithyrc30 · Post by **smithyrc30** » Mon Nov 30, 2009 10:27 am

TwoStroke Institute wrote:Can change the clutch gear or you change the crank gear or both. There's a bit more to a dry clutch arrangement than that.
The other ratio's are fine just the big gap between first and second and top is an 'overdrive' (0.86) rather than a sixth gear. It won't pull hard on high final drives.

How do you change one gear and keep the centres the same?

You can only go up or down a whole tooth, and if you use the same gear module then the diameter changes (it is a direct multiple of the module). So if you go up one on the crank you will change the diameter by 4%.

This means that you now have the 'wrong' part of the teeth in contact with each other, and possibly a bottoming situation or worse the crank gear now has no running clearance in the clutch gear tooth (or vica versa, it's the same thing) which will destroy the oil film.

At best this will cost you horse power (lots of it) or at worst it will either damage the gear teeth to the point of failure or break up either the crank or the input shaft bearing with equally bad results.

Have you measured the tooth module to confirm that you can go up a tooth or down a tooth without affecting running clearance?

Cheers

smithyrc30 · Post by **smithyrc30** » Mon Nov 30, 2009 11:09 am

KR-1R wrote:wheres your maths Smithy - that 'R'bottom end went for A$590 = 48,000yen didnt it?

[img]http://kr-1r.com\kr1s\E1361.jpg[/img]

1] 15 tooth shaft >>> 14 tooth
2] 22T >>> 20T
3] 38T >>> 34T
4] 19/23T >>> 22/24T
5] 4th 25T >>> 29T
6] 5th 27T >> 25T
7] wheres my crayons
8]
9]
10] I give up for now
11] 12] 14T >>> 15 output sprocket

Yup it did, but I didn't win it so it could have been $50 and it still is not on its way here

The purchase is not the whole story though is it? There is the 'agent' fee, the bank fee, shipping inside Japan, shipping out of Japan, and finally those bloody paypal fees....

The $590 would work out about $900 or there abouts. Still cheaper than $14k though.....

Anyway you only have half the story there, that is just the input shaft, you need the output shaft as well....

Although some of the teeth numbers are the same, the gear is different because its matching one is different, so the gear module has to change to make it connect.

While the KR-1R is a big improvement, the spread is still not the best. Looking at it in ex-smell, the first gear ratio is still to low, and the ratio steps are not what I would expect.

I'm going to have a play with some numbers now....

TwoStroke Institute · Mon Nov 30, 2009 11:27 am

smithy FFS it's called a corrected gear (up to 3 corrections), it's done all the time.No problems with oil film etc etc. If you can't take the word of a gearcutter with over 25years experience,with a rock solid reputation, who can you take the word of.

smithyrc30 · Post by **smithyrc30** » Mon Nov 30, 2009 12:11 pm

So you did change the module then?

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