Lets make a new gear..

[jedi-]

I was basically given a complete trans which I will use in my project.
To them it was trash because it was jumping out of 2nd as you can see by the picture of the drive dogs.
Well the culprit isn't actually 2nd that causes all the grief in these bikes , it's actually 5th gear which engages into it that gets rounded worn edges on the dogs of 5th that
causes it to disengage .

I will make a new gear but I will also change the number of teeth of this gear by one tooth just to give it slightly higher gearing without re-making its mating gear.

Pictures to come as I make it :moped2:

 

[one2dmax]

Not sure if it's cheaper for you to make it but there are other alternative gears from Yamaha that would do the trick. Of course to add a tooth you'll want to also make a new mating gear on the other shaft right? So the interface of gears stays the same (since you can't spacer over the shafts).

 

[jedi-]

Not sure if it's cheaper for you to make it but there are other alternative gears from Yamaha that would do the trick. Of course to add a tooth you'll want to also make a new mating gear on the other shaft right? So the interface of gears stays the same (since you can't spacer over the shafts).

No, a new mating gear is not required

 

[steamer97]

I guess I didn't "grok" much when I was in the machine shop. This will be interesting Jedi, thx.

 

[Bill Seward]

If you change the number of teeth on that gear, (obviously keeping the same pitch) you will change the outside diameter of the gear. Seeing that the shafts are not movable, how would you mesh the different sized gear you are making with the gear on the other shaft? Either it will be too big and wont fit, or too small and engage poorly, with a lot of slop between the gears.

Properly hardening this gear in any case, is an absolute must, if you do wind up making the gear(s)..

 

[jedi-]

If you change the number of teeth on that gear, (obviously keeping the same pitch) you will change the outside diameter of the gear. Seeing that the shafts are not movable, how would you mesh the different sized gear you are making with the gear on the other shaft? Either it will be too big and wont fit, or too small and engage poorly, with a lot of slop between the gears.

Properly hardening this gear in any case, is an absolute must, if you do wind up making the gear(s)..

The gear diameter remains the same but with one less tooth.
You will see when it's made that it all fits together.
I have been in the gear industry for forty years and what we specialise in, so trust me it works

 

[steamer97]

Yes Jedi I understand what you are saying, but methinks there will be more lost motion in the gears with accel and decell. Do you agree with my thinking on this? Perhaps not too bothersome? I myself hate slop in the driveline and wouldn't increase it.
But the main problem here that you addressed is the dogs rounding off. How are you addressing that? I remain interested because this has been a major issue for so long and it is currently addressed by "backcuting" the dogs to remedy it. Ideas are something that I enjoy so tell all plz.

 

[[email protected]]

I've seen enough of your artistry to have faith that you know what your doing.

I'm just a lay person and will admit that I don't understand how you can add/subtract a tooth while keeping the original O.D. and pitch.

As always, I'll stay tuned and look forward to seeing the completed project.

Sent from my SM-G930V using Tapatalk

 

[one2dmax]

Are you going to remove one tooth from the drive gear or driven gear? That's the driven gear I believe which is a 26 tooth gear. Reducing it to a 25 will give 6 more mph top speed or a 150 rpm reduction at 70 mph (not much).

 

[jdeitz1979]

The gear diameter remains the same but with one less tooth.

You will see when it's made that it all fits together.

I have been in the gear industry for forty years and what we specialise in, so trust me it works

I machined for 16 years, and have made gears myself. Using a hobbing machine and cnc and we had to hold a critically tight o.d for certain purposes. I’m more then interested in the outcome. Keep us posted


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[jedi-]

Yes Jedi I understand what you are saying, but methinks there will be more lost motion in the gears with accel and decell. Do you agree with my thinking on this? Perhaps not too bothersome? I myself hate slop in the driveline and wouldn't increase it.
But the main problem here that you addressed is the dogs rounding off. How are you addressing that? I remain interested because this has been a major issue for so long and it is currently addressed by "backcuting" the dogs to remedy it. Ideas are something that I enjoy so tell all plz.

Lost motion? No, slop? No. The only backlash between the two gears is the backlash I apply to the gear when I cut it.
The dogs will have increased angle to address the possibility of wanting to disengage which is done with milling and spark erosion.
Pictures will follow when I do it

 

[jedi-]

Are you going to remove one tooth from the drive gear or driven gear? That's the driven gear I believe which is a 26 tooth gear. Reducing it to a 25 will give 6 more mph top speed or a 150 rpm reduction at 70 mph (not much).

Yes 26 drops to 25 , not a big difference at all really but I had to make a new gear anyway so why not get creative whilst I'm at it

 

[jedi-]

A few pictures, the gear blank after I machined it.
Hobbing the gear teeth and a picture of it in mesh with the mating gear.

I need to rough the dog teeth on the mill and I'll finish them on the spark eroder.
I will probably wire cut the 6 tooth internal spline next though.

 

[one2dmax]

Looking good so far anyway!

 

[Bill Seward]

I just might be mental blocked here, but I honestly don't see how this will work. Example, greatly simplified: 1inch pitch 10 tooth gear would be 10 inches in circumference. It would be 3.183 inches in diameter.. An 11 tooth gear of the same pitch would be 11 inches in circumference. This gear would be 3.501 inches in diameter. If you go smaller, a 9 tooth would be 2.864 inches. I know the trans gear is a much finer pitch, but a gear with more or less teeth would absolutely be bigger or smaller. The extra tooth, even with the smaller pitch and smaller percentage of increase would, in my opinion just not fit.

I suppose a solution would be to manufacture the gear, knowing it's a bit larger in diameter. Then turn down the outside to the original diameter, to maintain the proper fit of the gears on the shafts. You'd lose a tiny bit of mating surface, but I'd bet that won't be a problem. Seems like you're pretty darn good at making these parts.

 

[jedi-]

I just might be mental blocked here, but I honestly don't see how this will work. Example, greatly simplified: 1inch pitch 10 tooth gear would be 10 inches in circumference. It would be 3.183 inches in diameter.. An 11 tooth gear of the same pitch would be 11 inches in circumference. This gear would be 3.501 inches in diameter. If you go smaller, a 9 tooth would be 2.864 inches. I know the trans gear is a much finer pitch, but a gear with more or less teeth would absolutely be bigger or smaller. The extra tooth, even with the smaller pitch and smaller percentage of increase would, in my opinion just not fit.

I suppose a solution would be to manufacture the gear, knowing it's a bit larger in diameter. Then turn down the outside to the original diameter, to maintain the proper fit of the gears on the shafts. You'd lose a tiny bit of mating surface, but I'd bet that won't be a problem. Seems like you're pretty darn good at making these parts.

No, what you don't understand is gears does not have to conform to a standard diameter. The 25t gear is called modified oversize. Gears can be modified oversize and undersize.
Even the stock vmax 5th gears already have modification to them, they are not standard diameter for their module ( pitch)

 

[Trondyne]

Very interesting... It sounds like a whole new set of ratios could be done fairly easily... (for you)

With a small change on each gear above 1st it should be possible to have the desired last gear ratio without much loss in performance getting there...

 

[Bill Seward]

Not being too conversant in the manufacture of gears, I'll go with your explanation. I'm gonna look that term up - never too late in life to learn something.. Thanks for the explanation.

 

[davesax36]

No, what you don't understand is gears does not have to conform to a standard diameter. The 25t gear is called modified oversize. Gears can be modified oversize and undersize.
Even the stock vmax 5th gears already have modification to them, they are not standard diameter for their module ( pitch)

So the teeth on the new gear have valleys closer to the center point? That makes it modified oversize, and modified undersize would be if the valleys were farther from the center point? I'm also trying to figure this out by looking, and have never made a gear or even had a successful threading operation on the lathe (YET).

This stuff is very cool

 

[one2dmax]

There are a number of ratio gears that can work on the Vmax with different spreads but some require an entire geartrain swap vs just a gear and some recut work on the dogs (like our overdrive 5th gear). Here's a screenshot from my trans worksheet that shows what's out there and a few pre-calculated inputs. For the big bore engines the 98-up RS (see the blue version) would be an ideal ratio set to stretch out those gears a bit. Our overdrive is done with the stock 1-4 gears (from the yellow area) with the 5th gear from the RS tour deluxe (red area).

***Note, there are a few Gen 2 calculations in there. I do have the full form I made if anyone wants it to play with.

Sean