CVT CVT Drive Sprockets....

Discussion in 'Transmission / Drivetrain' started by Youngbird, Apr 27, 2009.

  1. Youngbird

    Youngbird Member

    Without implying any indications of disrespect or disappointment with the good folks at Thats Dax....I am wondering who else is selling a drive sprocket like DAX's 10 tooth, 6 sline sprocket. They seem to be tough to come by. Any suggestions?

  2. spad4me

    spad4me Member

    You have to make your own if you want to use bicycle chain, or buy dax's
    I make my own by welding a thin thats dax happytime driven ten tooth sprocket to a well ground down cvt sprocket.

    Or just use scooter size chain and components a scooter rear sprocket a Number 8 chain and the stock scooter cvt drive sprocket.
    If you could buy the dax transmission output sprocket ( he is still sold out )It would fit with only a small amount of trimming.
    If you try the flat universal sprocket try to trim it carefully.
  3. Youngbird

    Youngbird Member

    The flat universal that the one that is really soft? Needs to be heated and quenched to harden? Thats an option....but Id prefer to have the other one....seems to be harder and more applicable to this cause.

    Im considerinf the size 8 components, but I need to be able to get a rear sprocket to fit a S/A 3sp. internal hub. Im waiting to hear from Andy now.

    Its all an adventure from where I sit.*

    Ive got the rear wheel sprocket figured. MonsterScooter had a 54 tooth with the proper diameter hub hole and the S/A 22 tooth has slots in it so I can drill the 54 tooth to bolt up to the S/A. So far Im only finding a 20 drive sprocket for the CVT. Still gotta work on the gear ratio. Maybe a larger rear wheel sprocket.
    Last edited: Apr 28, 2009
  4. Youngbird

    Youngbird Member

    I got my CVT yesterday via FedEx. The lovely Linda @FancyScooters shipped as promised and it traveled the 150 miles from Pennsauken,NJ to Longneck, DE in about 2 days. Im impressed.

    Im also impressed with the size of the unit....its really quite small. Sturdy feeling though. I also verified it to be about a 6.5:1 ratio turning the cluth bell by hand.

    Next step is to see DAX about a Titan and its off to the races.:grin5:*

    *Another issue....If Im right I need a total overall reduction of about 18.5-20:1 to make this all work right. With 6.5:1 in the CVT then it seems I nees about 3:1 between the CVT drive sprocket and the rear wheel sprocket. Can anyone verify this for me before I jump off and buy parts?
    Last edited: Apr 29, 2009
  5. Nuttsy

    Nuttsy Member

    Don't go by the 7:1 or your 6.5:1 ratio in figuring your gearing. That is what the ratio is when the clutch 1st engages and the belt starts to turn. Once the RPM's come up, the ratio starts to go toward the 3:1 or if you're lucky, 2.5:1. That is the number you should use to figure your final, top speed gearing.
    Also, your final ratio will depend on how much RPMs your engine will develop and how the CVT interacts with those RPMs. Then you can get into tuning and such and that's just trial and error.
    My experience was to go with 4.5 to 5:1 final gearing.
    Good luck...enjoy!
  6. Youngbird

    Youngbird Member

    So, if Im reading this right here....I need the 5:1 between the CVT output sprocket and the final(rearwheel) 10 tooth on the CVT and48-54 on the rear wheel, correct?
  7. loquin

    loquin Active Member

    Exactly. With the one I'm designing, I want a freewheel, so I'm adding a jackshaft and a freewheel as the output sprocket on the jackshaft.
    Last edited: Apr 29, 2009
  8. stude13

    stude13 Active Member

    how about with a 24" wheel and an 18 tooth on my belt drive cvt? my motor pulls 11,000+ and i only want 25mph. is that enough info or too much? thanks mitch
    Last edited: Apr 29, 2009
  9. Youngbird

    Youngbird Member

    Wow....what motor do you have that kicks 11,000 rpm?
  10. stude13

    stude13 Active Member

    49cc polini and the reason for the speed, it going on a tipsy trike.
  11. spad4me

    spad4me Member

    You are probably going to be able to do burnouts with that engine.
  12. DetonatorTuning

    DetonatorTuning Active Member

    WOWSERS with that engine on a trike you'll be able to do towing for the school district LOL

    what rpm do you want the 35mph at ?

    18T output in what chain pitch, not that it matters just interested in what chain you'll use to hook that up.


    ps, if you are going striaght to the hub from the approx. 3:1 at the cvt output.....................................

    106T = 17.67:1 = 35@ 8000rpm

    119T = 24.33 = 35@ 9000rpm

    i recommend a jackshaft, even with spacing and secondary alignment issues it'll make things much easier to accomplish. if this is going to be a delta trike you can incorporate a jackshaft right into a rack mount frame over the rear axle.
    Last edited: Apr 30, 2009
  13. loquin

    loquin Active Member

    Do you need (or want) a freewheel between the CVT and the rear hub? It'll let the bike coast with the motor at an idle, but, you won't have engine braking.

    You'll need a total of 31.4 reduction between engine and rear hub. apx. 3.2 reduction is provided by the CVT gearbox, so you would need an additional 9.8 between the 18t CVT sprocket and the rear sprocket. A jackshaft is recommended.

    If you assume a 58t rear sprocket, and, assume an 18T freewheel at the output of the jackshaft, this is 3.22 of the 9.8 you would need. Since you'll need an additional 3:1 reduction, you'll need a 54t sprocket at the input sprocket of the freewheel.

    3.2:1 at CVT output gearbox
    18t at CVT to 54t at Jackshaft (3:1)
    18t freewheel at Jackshaft to 58t at hub (3.22)

    total reduction is 3.2 * 3 * 3.2, or, 30.7

    If you can find smaller primary sprockets (I've seen 14t, #35 chain CVT sprockets and 16T freewheels) you can make the secondary sprockets smaller by the same ratio...
  14. stude13

    stude13 Active Member

    ok, now i think i can get it done. much appreciated.