Paulwhite Posted March 10, 2010 Share Posted March 10, 2010 hi all im coming up with ideas so i can build a bike, and was thinking of something like a belt driven torque converter attached to the output shaft of the engine with a sprocket on the other end of the torque converter similar to what u get for go karts has anyone heard of this being done before? thought if i can get one with a 2 to 1 ratio, then with the centrifugal force of the drive shaft spinning it will turn to a 1` to 2 ratio, i should theoretically get twice as much mph? it would b slow on pull off with standard sprocket sizes but should almost double top end speed shouldnt it? Link to comment Share on other sites More sharing options...
Paulwhite Posted March 10, 2010 Author Share Posted March 10, 2010 just had a thought if its on the drive shaft id have to set it to work in 4th to 5th gear as the drive shaft spins faster the higher the gear, so from 1st to 3rd it will be half the normal speed but twice the pulling power??! also might see about setting the front pulley to half way then it will be 1 to 1 ratio till it reaches a certain rpm then itl go to 1 to 2 ratio and increase the overall speed well theoretically anyway. any comments? or ideas on improvements? Link to comment Share on other sites More sharing options...
Moderator Cynic Posted March 10, 2010 Moderator Share Posted March 10, 2010 hi all im coming up with ideas so i can build a bike, and was thinking of something like a belt driven torque converter attached to the output shaft of the engine with a sprocket on the other end of the torque converter similar to what u get for go karts has anyone heard of this being done before? thought if i can get one with a 2 to 1 ratio, then with the centrifugal force of the drive shaft spinning it will turn to a 1` to 2 ratio, i should theoretically get twice as much mph? it would b slow on pull off with standard sprocket sizes but should almost double top end speed shouldnt it? Can't say i have, can't see the point, torque converters are heavy and suck up gobs of power just to work. Alright on something like my Rangie, at nearly 5litres the engine can happily deal with the losses. Cant see a bike engine dealing with it. The drive on the karts is centrifugal as i understand, friction pads thrown out by the rotation transmit drive. Lot different to a torque converter. Link to comment Share on other sites More sharing options...
Paulwhite Posted March 10, 2010 Author Share Posted March 10, 2010 yeah i typed belt torque converter into google and found this My link its 2 v shape pulleys with a belt and it starts with the one at the engine. the belt runs close to the shaft then as the speed increases the pulley's walls get closer together increasing the belts circumference, the other pulley works in the opposite way starts with a big circumference then gradually gets smaller till the belt is running on the shaft . all this changes the gear ratio from say a 2 to 1 ratio then as rpm increase it gradually turns to a 1 to 2 ratio now if i attach it to a 19bhp motor and lock the 1st pulley half way it gives me a 1 to 1 ratio then i could set it to reach a certain rpm before the 1st pulleys circumference begins to increase say for example 4th gear then when it kicks in il theoretically get a 1 to 2 ratio which would double the sprocket speed giving me more mph .....i think . sorry for waffling on a bit its a bad habit of mine. so yeah what do u think? Link to comment Share on other sites More sharing options...
Moderator Cynic Posted March 11, 2010 Moderator Share Posted March 11, 2010 yeah i typed belt torque converter into google and found this My link its 2 v shape pulleys with a belt and it starts with the one at the engine. the belt runs close to the shaft then as the speed increases the pulley's walls get closer together increasing the belts circumference, the other pulley works in the opposite way starts with a big circumference then gradually gets smaller till the belt is running on the shaft . all this changes the gear ratio from say a 2 to 1 ratio then as rpm increase it gradually turns to a 1 to 2 ratio now if i attach it to a 19bhp motor and lock the 1st pulley half way it gives me a 1 to 1 ratio then i could set it to reach a certain rpm before the 1st pulleys circumference begins to increase say for example 4th gear then when it kicks in il theoretically get a 1 to 2 ratio which would double the sprocket speed giving me more mph .....i think . sorry for waffling on a bit its a bad habit of mine. so yeah what do u think? Sorry to be negative here, but you want to increace the gearing on your motor in 4th gear by a factor of 2, most would sruggle to pull a quarter of that. Link to comment Share on other sites More sharing options...
Paulwhite Posted March 11, 2010 Author Share Posted March 11, 2010 Sorry to be negative here, but you want to increase the gearing on your motor in 4th gear by a factor of 2, most would struggle to pull a quarter of that. well it is all theory based but in reality il probably only get about 10 or 20 mph extra if im going down hill with a strong wind the engine im thinking of strapping it to is a 140cc 19bhp pit bike engine going to 14000rpm they only have 4 gears so should have plenty of pull but in theory because its a torque converter it should work, plus im not looking for extreme acceleration just more top end speed the idea of making it work in 4th is if it kicks in at 2nd then it will be fully on in 3rd and 4th and then as u said the engine would really struggle i think the trick would be to make it engage at a certain rpm on a certain gear to gain maximum effect. say 3rd gear is best for getting the most out of ur engine i.e acceleration, torque ect. and say i set it to work about a quarter of the way in to the power band say its 6000rpm then in theory with 3 quarters to go in the power band it should pull the bike with no problem, plus as i said before if i set it to a 1 to 1 ratio to start then the gearing wont be affected till the torque converter engages plus there is the gear ratio of the sprockets to consider could set them for acceleration then that will give me the best of both worlds, good acceleration till the converter kicks in then its just more speed Link to comment Share on other sites More sharing options...
Paulwhite Posted March 12, 2010 Author Share Posted March 12, 2010 just thought where will i b able to get a case for it?! id have to find somewhere that do metal castings either that or build a aluminum furnace in the back yard and have a crack myself. Link to comment Share on other sites More sharing options...
Recommended Posts