More compact mounting of CVT

[XLerate]

As I mentioned I don't play with CVT's but just tossing some general ideas here...

Many garden tractors such as my MTD have a vertical CVT that drives to the rear end, possibly a parts source for you guy's experiments? May not have the beef needed, I dunno.

A thought I had, to help that available space problem: a CVT somehow running inline to a shaft drive instead of a chain/belt drive? Dunno on that one either, just food for thought....

[coachgeo]

You are right that they would both need to be flipped togeather was asleep at the switch on that one .

Well that is what I assumed at first.... but now the story Im getting ...... is that too may not be the case. What Im getting now is If the secondary (not flipped) is off set in such a manner so that the two clutch's centers stay aligned thru out the range of sheave movment; to keep belt stays straight, then your good to go with Primary inside out.. yet secondary in typical configuration.

[coachgeo]

As I mentioned I don't play with CVT's but just tossing some general ideas here...

Many garden tractors such as my MTD have a vertical CVT that drives to the rear end, possibly a parts source for you guy's experiments? May not have the beef needed, I dunno.

Maybe a diesel garden tractor so spring and weights are already close to what you need? If they use someone like Comet or CVTech then sure.... cause all the parts to change out weights springs etc to tune to your engine are available. If there chinaclone or some other odd brand... that's not going to be the case.

A thought I had, to help that available space problem: a CVT somehow running inline to a shaft drive instead of a chain/belt drive? Dunno on that one either, just food for thought....

Yes that is definately an option. This is how the Track is done. Would also keep bike more narrow and keep CVT out of harms way as well as more out of the path of dirt etc.

May not be to hard if used either a BMW shaft drive rear. Curtis in TX, has now figured out how to rebuild them even though BMW says they are not rebuildable or only rebuildable by factory. Cant remember exactly the story behind them.... but apparently Curtis is the only one in the country to figure out the parts and tricks to do it. Another option is Honda Goldwing rear.. they show up at fair prices cause when folk build trikes out of a Goldwing.. that ends up an unused piece. Curtis is building my bike in exchange for my giving him my second Tiger so he can build one.

[DieselFly]

As the primary closes the belt centre moves to the fixed side of the primary. At the same time the secondary opens and the belt moves away from the fixed side allowing the belt to remain centred.

You are right that they would both need to be flipped togeather was asleep at the switch on that one .

Well that is what I assumed at first.... but now the story Im getting ...... is that too may not be the case. What Im getting now is If the secondary (not flipped) is off set in such a manner so that the two clutch's centers stay aligned thru out the range of sheave movment; to keep belt stays straight, then your good to go with Primary inside out.. yet secondary in typical configuration.

[XLerate]

As I mentioned I don't play with CVT's but just tossing some general ideas here...

Many garden tractors such as my MTD have a vertical CVT that drives to the rear end, possibly a parts source for you guy's experiments? May not have the beef needed, I dunno.

Maybe a diesel garden tractor so spring and weights are already close to what you need? If they use someone like Comet or CVTech then sure.... cause all the parts to change out weights springs etc to tune to your engine are available. If there chinaclone or some other odd brand... that's not going to be the case.

A thought I had, to help that available space problem: a CVT somehow running inline to a shaft drive instead of a chain/belt drive? Dunno on that one either, just food for thought....

Yes that is definately an option. This is how the Track is done. Would also keep bike more narrow and keep CVT out of harms way as well as more out of the path of dirt etc.

May not be to hard if used either a BMW shaft drive rear. Curtis in TX, has now figured out how to rebuild them even though BMW says they are not rebuildable or only rebuildable by factory. Cant remember exactly the story behind them.... but apparently Curtis is the only one in the country to figure out the parts and tricks to do it. Another option is Honda Goldwing rear.. they show up at fair prices cause when folk build trikes out of a Goldwing.. that ends up an unused piece. Curtis is building my bike in exchange for my giving him my second Tiger so he can build one.

I imagine that as big as MTD is all the CVT parts they use are mfd in-house. They do use Peerless transaxles though, so possibly Peerless does their CVT's too, but I doubt it.

[coachgeo]

....I imagine that as big as MTD is all the CVT parts they use are mfd in-house. They do use Peerless transaxles though, so possibly Peerless does their CVT's too, but I doubt it.

MTD?

Was thinking about shaft drive and it occurred to me... we do not know whose drives are CW and whose are CCW. Guess one could assume by what side of the bike they are mounted.

[coachgeo]

As the primary closes the belt centre moves to the fixed side of the primary. At the same time the secondary opens and the belt moves away from the fixed side allowing the belt to remain centred.

...

Have sat their and done this mentally for hours now.... and I don't see how it would work to only flip the primary though Audiomike swears you can. he's going to try to draw it up.

[DieselFly]

You can't flip one without the other.

As the primary closes the belt centre moves to the fixed side of the primary. At the same time the secondary opens and the belt moves away from the fixed side allowing the belt to remain centred.

...

Have sat their and done this mentally for hours now.... and I don't see how it would work to only flip the primary though Audiomike swears you can. he's going to try to draw it up.

[dieselbikin]

I am not sure that gearing up the primary to increase its RPMs would not work if the final drive was geared down to compensate. If I remember correctly, my CVT tuning manual states the centrifugal force on the fly-weights increase by a factor of 4 in proportion to RPM, so it would not take much to make a difference. Although the torque to the final drive would be decreased, it could be restored to the wheel by lowering the final drive ratio. If done properly the only thing that should change is the operating speed of the primary.

The primary and secondary do adjust from different sides, but it appears to be out of necessity rather than because its ideal. For example try to imagine how they could both adjust from the same side without creating a packaging and/or safety issue with the pulleys' safety cover. For the primary to adjust from the opposite side would require the belt to be further from the engine. Likewise the secondary would have the side closest to the cover adjusting in and out. At least that is how I picture it in my noodle.

If the secondary was run on the opposite side it could be closer to the frame since the frame side of the secondary would not be moving in and out.

As far as the chain stretch goes an o-ring 530 chain with a tensioner should handle our dinky engines pretty well. I ride my mildly tweaked 115hp Bandit 1200 like a raped ape and get +10K out its o-ring 530 chain. The biggest mistake I made with chains in my youth was running them too tight. Also, I later learned to rotate to wheel until I found the tightest spot in the chain before adjusting it. Finally, it helps to adjust with the swing arm loaded/compressed since the chain will be tightest when the swing arm is level.

One last thing I about chain life. Larger sprockets wear chains less than smaller ones. I do not recommend a sprocket smaller than 13 teeth. I have had good results with a suggestion I read several years ago. I buy two drive sprockets for one driven. The smaller one wears out faster and once its teeth get pointy and hooked the chain gets eaten up quickly. I change the drive sprocket out about midway through the chain life. Besides, the drive sprocket is the cheapest part of the assembly. Hope this helps.

[coachgeo]

...
The primary and secondary do adjust from different sides, but it appears to be out of necessity rather than because its ideal. .......

I was under assumption both Primary and secondary had to be flipped for things to match properly. Audiomike88 then said.. NOPE... you can flip primary and keep secondary normal just more offset than usual etc etc. He knows more than I; so I assumed he correct.... butttttt now..... I got big doubts.

Here is my drawing version of having primary flipped.... but not secondary. In the bottom drawing you can see that not having both Clutches in normal orientation puts a heavy tweak on the drive belt and it would wear out FAST. Granted only drew the one drawing though. Have not tried it with different offsets.... butttt.... dont think it would work with any offset judging by the pic. (assuming I drew pic correctly).

Thick black line is belt . Rest I hope is explanitory by text in pic.

[dieselbikin]

Always imagined the belt staying centered rather than moving sideways. Thanks for the graphic; it really helped me visualize it.

[DieselFly]

One thing I have seen was when my friend old snowmobiles secondary was frozen. Because it would not open it would flip the belt upside down. So getting any offset in the belt would be a bad thing. Hell it only happened 35 years ago you would think I would remeber right away So lets just say the clutch and belt centres are dynamic not fixed and must move togeather.

[toyotaracer9]

As far as the chain stretch goes an o-ring 530 chain with a tensioner should handle our dinky engines pretty well. I ride my mildly tweaked 115hp Bandit 1200 like a raped ape and get +10K out its o-ring 530 chain. The biggest mistake I made with chains in my youth was running them too tight. Also, I later learned to rotate to wheel until I found the tightest spot in the chain before adjusting it. Finally, it helps to adjust with the swing arm loaded/compressed since the chain will be tightest when the swing arm is level.

One last thing I about chain life. Larger sprockets wear chains less than smaller ones. I do not recommend a sprocket smaller than 13 teeth. I have had good results with a suggestion I read several years ago. I buy two drive sprockets for one driven. The smaller one wears out faster and once its teeth get pointy and hooked the chain gets eaten up quickly. I change the drive sprocket out about midway through the chain life. Besides, the drive sprocket is the cheapest part of the assembly. Hope this helps.

If a chain is used to drive the cvt primary it will be a pretty short chain and be turning alot faster then the final drive chain also the bigger you go with those sprockets the more rotating mass. to overspin the will take even more torque away, so I would say it will kill quite a few hp and trq off of already low numbers.

I also dont see flipping one part of the cvt working.

[coachgeo]

I am not sure that gearing up the primary to increase its RPMs would not work if the final drive was geared down to compensate. If I remember correctly, my CVT tuning manual states the centrifugal force on the fly-weights increase by a factor of 4 in proportion to RPM, so it would not take much to make a difference. Although the torque to the final drive would be decreased, it could be restored to the wheel by lowering the final drive ratio. If done properly the only thing that should change is the operating speed of the primary. ....

Looks like someone tried it (Cdog?) but combined with the unchangable ratio of shaft drive he could got get speeds he wanted. Wonder if the limited rear ratio was less the issue than the HP loss due to any ratio change that may have occured between engine and jackshaft that ran the primary.

Anyone know how to reach Cdog to see if there was a ratio change between engine and primary? Can't tell by pictures

[dieselbikin]

I used to keep in touch with Cdog on the Crazy Jerry site. We even met at my house one time. He did try changing the ratio between the flywheel and the primary, but it didn't help. To increase his overall final drive ratio he would have had to underdrive the primary and then possibly use a lighter spring and/or heavier flyweights. I don't remember if he experimented with different springs/weights after changing the flywheel/primary ratio.

I do remember his final drive being in the neighborhood of 3.3/1. I started out with a similar ratio on my bike and never could get it to perform very well in addition to belt slippage issues. Changing to a 4.6/1 ratio made a dramatic difference.

[coachgeo]

back to main topic of tucking CVT behind engine like one would a Ultima. It was brought up that their is a potential to rotate the drive clutch from the front instead of fliping the butt inside out the as orginally proposed here. Audio mike came up with it and the drawings seam to indicate maybe he's right? One might could keep the CVT facing traditionaly by driving it with a sprocket on it's face. There is a shaft space all the way thru it.