Manual transmission?

[the thnikkaman]

I am trying to convert an existing kart from a single-gear to a Manual transmission. I didn't want to go out and buy a manual transmission from a motorcycle. I want to make a transmission for my go-kart. From what I have heard, a bicycle derailleur system would just break under the stress. So I put together a diagram of a transmission using electro-magnetic clutches and an extra jackshaft.

The drawing is poor, but you get the idea. The engine has a sprocket on its output shaft which is chained to a sprocket on the jackshaft. The jackshaft has 4 electic clutches (or less depending on how many gears you want). Each clutch is chained to a seperate sprocket on a live axle. When the motor spins, it spins the jackshaft. By engaging each clutch seperatly, you get different gear ratios.

One problem with this setup is it might be hard to find a the right size jackshaft to mount the clutches to. The electronic clutches can be found in some lawnmowers or you can buy them off ebay (http://cgi.ebay.com/John-Deere-160-165-170-175-180-185-ELECTRIC-PTO-CLUTCH_W0QQitemZ300065806369QQihZ020QQcategoryZ822 40QQrdZ1QQcmdZViewItem). I'm not sure that this whole idea could work, so I'm hoping for some constructive criticism.

[robin]

i think that would work nice might be a bit expensiv but ime sur it would work you would have to m ake a switch so you cant turn on 2 at the same time is you culd make a sensor so when the engin rpm gets to a point put it in a higher geer thats a very cool ider

[robertdjung]

that would be really cool. probably expensive, but really cool.

yeah, it would suck to accidentally engage two at a time.. how do those clutches engage? is the jackshaft always engaged to the clutch, and then the outer part of the clutch gets engaged when the switch is thrown?

[mikeandike]

if you could find out how many amps it takes to engagge the clutch im sure i could design a controller...

i havnt checked this site lately due to xmas and other stuff... ill make sure to keep checking again :)

[2or3wheels]

i understand now what your thinking of. but why couldnt you get a bunch of clutches that engage at diggerent rpms making your idea work. the lowest rpm being the steepest gear and so on. that also seems expensive.

[mikeandike]

the problem with that is how do you get the clutches to disengage? once a centrifugal clutch hits a certain rpm the clutch wont disengage until the rpm is back under that rpm

[2or3wheels]

maybe a break on the axle? hmm
maybe a break on the jackshaft? thats the only way i think, but you would also need one on the axle to stop the cart, getting expensive and complicated. it was just a thought.

[mikeandike]

for the controls of the electronic clutches the simplest way of doing it passed right by me... a switch!!! just get a 4 pole switch or a rotary switch from a local electronics store. put the battery positive on the common connection on the switch (or negative, dosnt really matter) then 1 wire to each clutch and the other wire on the clutch back to the negative (or positive) of the battery.

a more complicated way is to configure it with the engine rpm. ill get to that later...

-mike

[my_mini_bike]

i've never tried this idea my self but its been in the back of my mind...
what about the transmission of a ride on mower, 3 speed with reverse. i reocn that would be pretty cool..... (i have a pic but it wont let me up load it because it has too many KB's, any one know how to fix that?)

[the thnikkaman]

When one of my pictures doesn't upload because it is too many KB's, I open it in Power Point, right click on the picture, go to Format Picture, click on the Picture tab, and hit the compress button. Check the box next to Web/Screen and hit OK. After that, right-click the picture and hit Save as Picture and save it wherever. The picture should be significantly smaller. If it still doesn't fit, I don't know what to do. Hope this Helps.:)

[my_mini_bike]

mower transmission....

[PJG1173]

I have often thought of using one so I could have reverse. Pushing a 175lb kart backwards with a 70lb kid gets old after a while, but I have heard that lawn mower transmissions cannot hold up to the stress that a kart would put them through. Something about weak aluminum parts.

[the thnikkaman]

Yeah, usually mower transmissions don't even have bearings for the axle. The axle rides directly on the transmission housing. Considering the speeds and stresses that a go-kart would put on it, i don't think the mower transmission would work well. Also, mower transmissions are geared mostly for maximum torque for climbing up hills and such, so your kart would go pretty slow(unless you used another secondary gear ratio). If you did get it to work, it would be one sick go kart. There's just something special about driving stick-shift.:)

[mat-20-]

i see all these atvs and off-road buggies with 4speed transmission, but why cant we find/buy these transmissions they use easily? they seem to be used everywhere but ive hunted and i cant find anything

also, would a motorbike transmission be adaptable?

(k, i know these arent cheap solutions but they have been bugging me)

[PJG1173]

Yes a motorbike transmission is adaptable. 100cc Honda dirt bike was the donor for this one.:D

[robertdjung]

For that honda donor -- what's the chain size? Is that something custom, or is it 40 size? If not, how'd you get the sprocket mounted?

[2or3wheels]

Dude u need to post more pics of that kart, looks awoesome!

[PJG1173]

the chain is actually the 420 that was on the donor bike and it fits on the stock yerf dog #41 sprocket (not as snug as the #41 chain). The #41 chain would not fit on the honda sprocket though. I will post a link to pics as soon as I get a new camera. I have just spliced the front of this kart with a 86 model yamaha ATV and redid the shifter linkage. I am currently looking for a free web hosting site that can hold all my pics.

[robertdjung]

put 'em on flickr or photobucket

[robin]

whats it like driving a geard bike i had one with a simlar engin it was 2 up 3 down or sumthing how have u got the geer change hoked up ?

[Kartmofo]

I think it is a good idea for a tranny on a gokart but i think u can only use a motorcycle or fourwheeler tranny. unless u can make it work with a lawn tractor transmission.:)

[robertdjung]

I've seen some trannys that you can use, but they're pricey at around $200-300. Someone posted a while back about scoring a tranny on EBAY... anyone remember that?

[750kart]

My two friends and I are currently in high school and this weekend we just bought a 5 speed Kawasaki 750 for the kart we are planning to build for a class. And I was just curious if anyone have any ideas as to how to hook up the clutch and the footshift so this all can work ? I had the idea of hooking up the clutch cable to a pedal and have the same basic pedal layout as a car then connect a shaft to the footshifter and push down to get it out of neutral then go through the motions of the gears by pulling up or pushing down the shaft. So those are my thought on it and if anybody has any ideas they would really be appreciated we are trying to keep the cost of this thing down thanks

[philip metzner]

hey 750, keep in mind that you have enouph engine to be incredibly dangerous! your frame, mounting, drive line, axles, ect. have to be very robust in design. also remember the engine is air cooled, i assume, and has no fan for cooling. the engine needs to have a good air flow, so dont put it behind the seat. it needs to be on the side of the kart so the driver doesnt block the air.-phil

[750kart]

Yeah the engine has no fan and i was planning on putting it on the side also i have picked out my materials for the frame already and yeah its going to be one heavy duty frame cause well for this prject im the one in the group that has to put the frame together the other two people involved are fixing up the engine and as far as i know the engine should run but like i said in my previous post im worried about the shifting of the engine the frame not so much cause if the cost is too high on the frame i have a relitive that can supply me with a old winged modified frame that just will take some small alterations but thanks agian for your input and if you have any ideas on shifting this contraption that would be great :D

[mat-20-]

hey 750, im doing the same thing but with a 125cc 'pit bike' engine, i was thinking of the similar shifting system, but L shaped, and pivoting from the corner of the L, so you push one end horizontal and the other pushes vertical (shifts gears:D) take heaps of photos of your build, im interested, should be similar to mine

[750kart]

Hey thanks for the bit of info yeah im hoping to get this thing done by at least june cause its a project for a class but right now im trying to find some light weight material for this cause i dont want it to be really heavy which would be the case if i was to you use steel or something i was thinking of some kind of composite but im not all that sure as to how it would turn out i mean i do need this thing to be really durable cause w/ 50 HP from this engine if its not strong enough then i got some flexing gong on and that would not be kul

[mikeandike]

i think with that hp that you would want to go with steel.

[750kart]

We just started welding the frame together today during our auto class and right now we have the center of the frame reenforced so far its looking good but right now im thinking about also taking some really think steel and welding it in to have more support