racing promotor
Moderator
Sorry should of pointed out I meant the other Mike post #39.
Not that your suggestion might not have worked as well.
Last edited:
Corner Exit Speed
- Thread starter Kartracer123
- Start date
Not that your suggestion might not have worked as well.
alvin l nunley
Site Supporter
Here's something you might be interested in, the difference in gear ratios using the base circle. As the number of teeth increases, the base circles get progressively larger. Not by much, but some. This chart shows the difference in ratios, using the base circles, as the driver gets larger, all with a 4.0 ratio, #35 chain.
Al I write this with respect. You remind me of an engineer I worked with at a fab shop.
He believed if he put it on paper it could be built and welded just as he designed it.
Lesson here is just because you have a chart doesn't mean its always correct.
Sometimes it just comes down to what actually know from experience.
The difference in the tac readings could come from several different things. Toe in or out, air pressure, tire size, camber or castor. Does your chart cover these. I don't think so.
So please quit making this in to rocket science.
He believed if he put it on paper it could be built and welded just as he designed it.
Lesson here is just because you have a chart doesn't mean its always correct.
Sometimes it just comes down to what actually know from experience.
The difference in the tac readings could come from several different things. Toe in or out, air pressure, tire size, camber or castor. Does your chart cover these. I don't think so.
So please quit making this in to rocket science.
paulkish
old fart
I was reading through this thread a little to try to understand how it is currently flowing.
Going back and reading post 39 by msquared followed by Al's post 42, I have to say I think now Al was correct questioning why msqquared would suggest a 6 tooth change.
And >I now think< it was my short coming of understanding and msquared's short coming in writing which lead to Al's correct 6 tooth comment. I now think Al was correctly trying to clarify msquared's post.
Going back and reading post 39 by msquared followed by Al's post 42, I have to say I think now Al was correct questioning why msqquared would suggest a 6 tooth change.
And >I now think< it was my short coming of understanding and msquared's short coming in writing which lead to Al's correct 6 tooth comment. I now think Al was correctly trying to clarify msquared's post.
Pete_Muller
Moderator
Al,
Please stop spreading false information about gear ratios.
For anyone inclined to read one of numerous posts where I have explained how using "pitch circle" has NO relevance to gear ratio, you can just read my post in this somewhat recent message where I covered this:
https://4cycle.com/karting/threads/gear-selection.109995/page-3#post-782544
Please note that I am in no way disputing that changing sprocket sizes (while keeping the same ratio) doesn't make a difference. There are issues such as total drivetrain inertia, and probably things like chain angle, and many others that I don't understand.
But... regardless of that: a gear ratio is a gear ratio. Period.
Pete Muller
Please stop spreading false information about gear ratios.
For anyone inclined to read one of numerous posts where I have explained how using "pitch circle" has NO relevance to gear ratio, you can just read my post in this somewhat recent message where I covered this:
https://4cycle.com/karting/threads/gear-selection.109995/page-3#post-782544
Please note that I am in no way disputing that changing sprocket sizes (while keeping the same ratio) doesn't make a difference. There are issues such as total drivetrain inertia, and probably things like chain angle, and many others that I don't understand.
But... regardless of that: a gear ratio is a gear ratio. Period.
Pete Muller
alvin l nunley
Site Supporter
Calculating ratios using base circles gives you a different number then calculating them using a tooth count. There is a difference. However slight it is. Another thing; that ratio difference changes as the sprockets get bigger versus tooth count.
LMAO
Demanding it is totally wrong, then waivering based on unquantifyable basis.
Speed ratio is speed ratio, whether 9/36 or 20/80. Agreed.
Torque transfer is another animal, totally quantified by basic geometry and simple math.
No longhair bs.
I believe I have even proposed a heads up test in another thread.
Last edited:
Pete_Muller
Moderator
85 shaw,
I'm not disputing or even questioning "other factors". I am simply trying to explain that a gear ration between 2 sprockets is simply that: a ratio between two tooth counts.
Al's "pitch circle" spreadsheet has zero relevance to the ratio between 2 sprockets, period.
PM
I'm not disputing or even questioning "other factors". I am simply trying to explain that a gear ration between 2 sprockets is simply that: a ratio between two tooth counts.
Al's "pitch circle" spreadsheet has zero relevance to the ratio between 2 sprockets, period.
PM
Pete
The other factors, not including the ones you list, are the reason for why there is a dfference, as seen in on-track performance.
I started the pitch circle theory several years ago, and I stand behind it.
Not a fan of spreadsheets of any kind because you are not able to see where the numbers come from.
(Remember having to show your work in school?)
This is the thread with the proposed experiment.
https://4cycle.com/karting/threads/rotational-torque.110040/page-2#post-783463
All needed information to deny or confirm theory should be there.
The intention for the calculations are to show the differences in the gear sets of the same ratio, and are not intended to be a go-to item for kart racing.
Like most calculations, need to know why you are using them at all.
Ps. Hated showing my work at the time, but have learned the value of doing so since.
The other factors, not including the ones you list, are the reason for why there is a dfference, as seen in on-track performance.
I started the pitch circle theory several years ago, and I stand behind it.
Not a fan of spreadsheets of any kind because you are not able to see where the numbers come from.
(Remember having to show your work in school?)
This is the thread with the proposed experiment.
https://4cycle.com/karting/threads/rotational-torque.110040/page-2#post-783463
All needed information to deny or confirm theory should be there.
The intention for the calculations are to show the differences in the gear sets of the same ratio, and are not intended to be a go-to item for kart racing.
Like most calculations, need to know why you are using them at all.
Ps. Hated showing my work at the time, but have learned the value of doing so since.
Last edited:
Pete_Muller
Moderator
Well, this is obviously a lot more interesting than debating whether 6 turns of a 10t sprocket will produce anything other than exactly one turn of a 60t sprocket !
Have you done your test? Maybe not yet since you say: "proposed". I'll be interested in hearing your results.
Along those lines... as you have probably discovered: no two companies seems to make chain sprockets exactly the same way (especially noticeable on small tooth-count sprockets). If you've ever dug through Machinery Handbook and gone through all the formulas to design a sprocket, you may discover (like I did) that there some "art" to it... it's not an absolute science.
Many years ago (early 90's) I was doing a lot of playing and testing running a direct drive Yamaha on a sprint track. A company in karting approached me about making higher quality (more durable) engine sprockets vs. what was available at the time (mostly from Europe, though I recall there was one from Japan). These were all 10t sprockets for 219 chain. The readily available parts had a fairly short lifespan, as you can probably imagine with a 10t sprocket running 17,000+ rpm.
At the time, my dad owned a company that made gear cutting tools, and I had both a gear hobbing machine and a gear shaper in my own shop. My first step was to just design a sprocket using the basic formulas in Machinery Handbook, and make the sprockets out of 9310 instead of 8620. My dad's company made the shaper cutter for me, and I knocked out a couple dozen or so for testing. The sprockets looked quite different from what was on the market at the time, but worked well. As a matter of fact, if you set the sprocket I made side by side with an Italian one, it was surprising how different they were, yet both got the kart around the track just fine. At the track, I started paying attention to how they ran at different tension (slack in the chain), and how much the chain would vibrate on the top side. They definitely "acted" different watching them run.
As a next step, I designed a sprocket "geometrically" in CAD following pure math on how a chain would wrap around a sprocket (that part is pretty much what the Machinery Handbook shows), but used my ideas for how much clearance the teeth needed on entry/exit (the "art" portion of the design). Had another cutter made, and the results were sprockets that looked a bit different yet again. This design seemed to show less chain vibration than the others I had run. The wear also looked good in this design, though I "suspect" that my own design would have been less tolerant of a well-worn chain since I gave it less "leeway" for increased chain pitch spacing (chain stretch).
The project ended up getting dropped simply because it was too expensive to produce sprockets with the methods I had in my shop at the time, and the material and heat treat were fairly expensive.
The results were something that, at the time, got me to thinking quite a bit about chain and sprockets, since it's somewhat obvious watching a chain that the crankshaft is not rotating a steady rate. (much easier to see what happens through the rev range on a direct-drive kart). I experiment with a couple of different mounting angles of the engine as well (to shift the point of max/min crank speed around a bit relative to the chain angle). There was no clear-cut answers or winners/losers, but it was an interesting time.
As another point of interest -- (not sure how long you've been in karting) -- back in the mid-70's there was a fairly quick transition to belt drive in enduro racing. Even though a belt (toothed belt) is not quite as efficient at transferring power as a straight-running lubricated chain, we all went faster with belt drives. My "gut feeling" is that the drive system with a belt is just much smoother. Also, since the fibers in the belt don't stretch or compress, they are (by definition) running at or very, very close to the pitch diameter. The teeth on the belt can stretch/compress to fit the teeth in the pulleys (very unlike a chain). Interestingly at the time, someone even brought out a Poly-V belt drive system (no "teeth", rather just a few grooves running around the engine pulley just like the serpentine belt on a modern car). The rear axle pulleys where completely smooth, as I recall. Gear ratio was set by diameters. The whole system worked pretty much like running a flat belt on a smooth pulley when it came to selecting gear ratios, but of course the Poly-V had a bit more "traction" on the engine pulley where it was needed. The system "felt" nice on the track, but it never caught on -- I suspect because it was just so much simpler to select a ratio based on tooth count rather than diameters. Interesting side-note on this: I seem to recall that they made only a few sizes of axle pulleys. The gear ratio was adjusted by running *slightly* different diameter engine pulleys (which were of course super easy to make). I'd probably revisit this idea if I was racing vintage enduros nowadays.
Ah well... enough history and nostalgia.
I'll have to do a bit of digging on some ancient computer backups, and see if I can find my original 10t sprocket designs.
More as I remember it. ;-) .
PM
Have you done your test? Maybe not yet since you say: "proposed". I'll be interested in hearing your results.
Along those lines... as you have probably discovered: no two companies seems to make chain sprockets exactly the same way (especially noticeable on small tooth-count sprockets). If you've ever dug through Machinery Handbook and gone through all the formulas to design a sprocket, you may discover (like I did) that there some "art" to it... it's not an absolute science.
Many years ago (early 90's) I was doing a lot of playing and testing running a direct drive Yamaha on a sprint track. A company in karting approached me about making higher quality (more durable) engine sprockets vs. what was available at the time (mostly from Europe, though I recall there was one from Japan). These were all 10t sprockets for 219 chain. The readily available parts had a fairly short lifespan, as you can probably imagine with a 10t sprocket running 17,000+ rpm.
At the time, my dad owned a company that made gear cutting tools, and I had both a gear hobbing machine and a gear shaper in my own shop. My first step was to just design a sprocket using the basic formulas in Machinery Handbook, and make the sprockets out of 9310 instead of 8620. My dad's company made the shaper cutter for me, and I knocked out a couple dozen or so for testing. The sprockets looked quite different from what was on the market at the time, but worked well. As a matter of fact, if you set the sprocket I made side by side with an Italian one, it was surprising how different they were, yet both got the kart around the track just fine. At the track, I started paying attention to how they ran at different tension (slack in the chain), and how much the chain would vibrate on the top side. They definitely "acted" different watching them run.
As a next step, I designed a sprocket "geometrically" in CAD following pure math on how a chain would wrap around a sprocket (that part is pretty much what the Machinery Handbook shows), but used my ideas for how much clearance the teeth needed on entry/exit (the "art" portion of the design). Had another cutter made, and the results were sprockets that looked a bit different yet again. This design seemed to show less chain vibration than the others I had run. The wear also looked good in this design, though I "suspect" that my own design would have been less tolerant of a well-worn chain since I gave it less "leeway" for increased chain pitch spacing (chain stretch).
The project ended up getting dropped simply because it was too expensive to produce sprockets with the methods I had in my shop at the time, and the material and heat treat were fairly expensive.
The results were something that, at the time, got me to thinking quite a bit about chain and sprockets, since it's somewhat obvious watching a chain that the crankshaft is not rotating a steady rate. (much easier to see what happens through the rev range on a direct-drive kart). I experiment with a couple of different mounting angles of the engine as well (to shift the point of max/min crank speed around a bit relative to the chain angle). There was no clear-cut answers or winners/losers, but it was an interesting time.
As another point of interest -- (not sure how long you've been in karting) -- back in the mid-70's there was a fairly quick transition to belt drive in enduro racing. Even though a belt (toothed belt) is not quite as efficient at transferring power as a straight-running lubricated chain, we all went faster with belt drives. My "gut feeling" is that the drive system with a belt is just much smoother. Also, since the fibers in the belt don't stretch or compress, they are (by definition) running at or very, very close to the pitch diameter. The teeth on the belt can stretch/compress to fit the teeth in the pulleys (very unlike a chain). Interestingly at the time, someone even brought out a Poly-V belt drive system (no "teeth", rather just a few grooves running around the engine pulley just like the serpentine belt on a modern car). The rear axle pulleys where completely smooth, as I recall. Gear ratio was set by diameters. The whole system worked pretty much like running a flat belt on a smooth pulley when it came to selecting gear ratios, but of course the Poly-V had a bit more "traction" on the engine pulley where it was needed. The system "felt" nice on the track, but it never caught on -- I suspect because it was just so much simpler to select a ratio based on tooth count rather than diameters. Interesting side-note on this: I seem to recall that they made only a few sizes of axle pulleys. The gear ratio was adjusted by running *slightly* different diameter engine pulleys (which were of course super easy to make). I'd probably revisit this idea if I was racing vintage enduros nowadays.
Ah well... enough history and nostalgia.
I'll have to do a bit of digging on some ancient computer backups, and see if I can find my original 10t sprocket designs.
More as I remember it. ;-) .
PM
racing promotor
Moderator
Here we go again another simple question thread totally high jacked off the rails, at least with this one I think the op got his answer before the high jacking.
We see debates why is karting on a down hill trend all the time and reasons why, over complicating things would have to be one of those reasons, I've heard many pit communication between always top 10 finishing drivers, and the tire guy and crew, at races trying to win from
$ 10,000 to $ 50,000 , and hundreds of times trying to win a series race that comes down to 5 points or less, and NEVER ONCE heard
first let me go get my calculator or spread sheet, don't worry about what front driver is on ratio is a ration, don't forget pitch circle theory, do we have enough time to get out our transit, tape measure and go measure the turn radius, JUST SAY " N " !!
We see debates why is karting on a down hill trend all the time and reasons why, over complicating things would have to be one of those reasons, I've heard many pit communication between always top 10 finishing drivers, and the tire guy and crew, at races trying to win from
$ 10,000 to $ 50,000 , and hundreds of times trying to win a series race that comes down to 5 points or less, and NEVER ONCE heard
first let me go get my calculator or spread sheet, don't worry about what front driver is on ratio is a ration, don't forget pitch circle theory, do we have enough time to get out our transit, tape measure and go measure the turn radius, JUST SAY " N " !!
paulkish
old fart
I went back to the past thread indicated and spent a total of less then a minute looking at it.
That is because the first thing I saw was about increasing torque.
Real Quick even for me: The top of my head instantly asked me "Paul ain't there only two ways to increase torque?".
Thought real quick with myself and answered myself with: Only two ways would be to increase input force getting you torque or reduce friction.
Ain't that about it and all of the possibilities?
answer: ????
That is because the first thing I saw was about increasing torque.
Real Quick even for me: The top of my head instantly asked me "Paul ain't there only two ways to increase torque?".
Thought real quick with myself and answered myself with: Only two ways would be to increase input force getting you torque or reduce friction.
Ain't that about it and all of the possibilities?
answer: ????
paulkish
old fart
I got caught up into it also and was only able to get loose using common sense, being that what is proposed can't happen.
The simple common sense answer is if it were true and you considered each gear because they are different as two different machines each operating differently per your calculations, eventually either the pulling chain or feed chain would be stretched and bind the system.
But it doesn't so it ain't so.
Pete_Muller
Moderator
Sorry about that guys.
In the future I'll start a new thread before posting anything tech/math/design/theory related, and will clearly title it with an: "IGNORE this thread" message.
PM
In the future I'll start a new thread before posting anything tech/math/design/theory related, and will clearly title it with an: "IGNORE this thread" message.
PM
flattop1
Dawg 89
With being that close , your going to need to make small adjustments and watch lap times very close . One change at a time , until you find the change that produces a time improvement .
Kartracer123
Member
My son is on a Triton Jr and the other kid was on a Minecon