More compact mounting of CVT

[coachgeo]

1. One complaint of CVT made is that the width/size excerts great force on the end bearing of engine more so that chain drive to remote gear tranny or fixed gear tranny as a normal bike engine.
2. Size/width of CVT protrudes outward more so than other options, even more so than a divorced Harley Gearbox's fat belt drive (Ultima for example)


so how about this. Chain drive from engine UP to a CVT mounted to where its Primary/Drive clutch fills a void under the seat area. This puts the Clutches width under the seat instead of facing outward. The Secondary/Driven clutch mounted as normal on a jackshaft that the rear wheel chain drive sprocket lies.

something like this hacked picture from one of Hieko's bikes

[coachgeo]

Other thoughts from additional research.......

using this format the pulley from flywheel/crank (chain or belt) one could speed up the Drive pulley's RPM's but most importantly? increase Driven Pulley RPM's getting closer to matching the RPM's of the pulley that would be found on an ATV' or snowmobile? Would open a larger group of refurb or used CVT resources.

Also opens another door of adjustability by changing pulley /sprocket sizes

Would this possibly allow also for going with a smaller diameter driven/secondary pulley (space saving?)

Later NOTE: for future reference- This idea is no longer thought to be valid after discovering Polaris CVT's even from an ATV, possibly even from a sled have the ability to be converted to Diesel spec. without much expense.

[Rhynri]

The only downside to that arrangement is if the belt or chain break there is a potential for your crotchal area to ingest some shrapnel. Not likely, I know.

[coachgeo]

ADDITIONAL NOTE- IGNORE this post FOR NOW. New discovery has made this a not valid idea at the moment


Question I have is if one was to say go a ratio above 1:1 of engine pully to Aux. pulley running the drive/primary CVT pulley; What advantages might this gain for example:

1. Does this potentially allow for dicreased diameter pulley's...... such as the driven/secondary pully which is biggest of them all, could this then be smaller... making the set up more compact.
2. Does the drive/primary pully now spinning at higher rpm's allow for faster activation on the go pedal / throttle twist,

What else might be a gain, loss, or wash?

[DieselFly]

Not a bad idea to move the CVT behind the engine*. If you are looking to spin it at a different RPM then you are using the wrong clutch. Remember increasing rpm drops torque so you are better to find a clutch set that will match your RPM range. My current setup engages at 1400rpm and is very controlled. I idle around 1050rpm for cooling (fan cooled)and oil flow
(turbo bleeds pressure at low RPMs). If I crank the throttle engagement is almost instant. If I want to jump off the line I just bring the rpm up till the clutch nibbles then crank it. The Comet 94C can be adjusted to work and can handle the horsepower you are going to use as can the CVTech Series 06. Just remeber in the words of Scottie from Star Trek (with a Scottish accent) "the more complicated the plumbing the easier it is to stop up the drain" So if you don't need to make it more complex don't

Sean

*For future readers the mod swapped in word "engine" replacing misstyped word"Transmission"as noted later in this thread.

[Rhynri]

Just remeber in the words of Scottie from Star Trek (with a Scottish accent) "the more complicated the plumbing the easier it is to stop up the drain" So if you don't need to make it more complex don't

To quote someone else: "Truer words have never been spoken." I firmly agree with Sean's advice in this matter.

[Stuart]

Just remeber in the words of Scottie from Star Trek (with a Scottish accent) "the more complicated the plumbing the easier it is to stop up the drain"
Sean

Scottie was based here in Horsham during the war!

[coachgeo]

CORRECTION: It now appears below post is incorrect information- It appears Polaris ATV and maybe even Sled CVT's can be converted inexpensively to work fine within the parameters of a diesel engine.

here is the issue, 99% of used CVT's available in the US are for petrol machines with much higher RPM's than diesels. The expense it would take to modify the used CVT to fit high torque low rpm engines is significant and potentially more expensive than getting a new one designed specifically for the diesel bike application...

orrrrr.. if my thinking is right you increase the rpm of the two CVT pulley clutches to more closely match the rig it was designed for by using approriate sprocket chain off the engine as described in previous posts. ifffffffff.... it does not rob too much torque away

[DieselFly]

Springs and weights are cheap. A new setup might run you $600 but shop around. A comet Duster 94C is perfect for the horsepower you are looking at and very cheap to tune. Look under Mini Bike andd Go karts at mfgsupply.com

[coachgeo]

interesting setup below. Ideas from it should be usuable in a build similar to what's proposed here

http://www.youtube.com/watch?feature=pl ... Wo4PUofaRg

[coachgeo]

IGNORE This POST- Error now corrrected

In a reread of this thread the part underlined confused me.... either cause Im dense..... or you misstyped. Did you mean behind engine and not behind transmission?

Not a bad idea to move the CVT behind the transmission. ...

Sean

[coachgeo]

ADDED NOTE: for sake of discussion below ..... ignore idea presended earlier in this thread of attempting to spin the Primary Clutch faster via a sprocket ratio spread between the Flywheel and the Primary/Drive clutch.

so.... god forbid..... I am getting closer to my build and strongly considering this idea of CVT behind engine in some manner. So beat me up..... tell me why not, I mean a divorced tranny... be it one from a Harley or a Royal Enfield is driven by a chain or belt so why not the cvt?

1:1 ratio will be used from flywheel to Primary clutch.

one negative I came across myself was in reading up on Harley Ultima drives last night. There is a chain system availabe that can replace the huge fat belt drive. There is some negative discussion saying this adds to maintaince due to chain stretch saying chain wont make it 10 thousand miles with out needing it and or sprockets replaced where typical fat (3") belt drive last double that. Yet there seems to be ton of chain driven divorced trannies on indians, royal enfields etc.

The other negative mentioned by friends earlier in this thread is.... adding complexity may not be wise to do since not absolutely neccissary.


so. let the beating begin.

[XLerate]

For the most part I stay out of CVT discussion area simply because it doesn't feed my interests. I had some kind of large minibike thing [brand name was famous, just can't recall] years ago with a CVT and actually it worked quite well, but the poor rig was previously beat to death. I've always been a nut for shifting gears so just sitting back for the ride didn't really appeal to me and I was always waiting for the next 'shift' that never came ha! They work fine though, just like an auto trans so what the hey?

Anyways, I saw that comment about chain stretch and just couldn't let it go by. Sure, chain stretch is a potential issues, sort of. But the main incidence of chain stretch isn't from a chain just sitting there spinning between a couple of sprockets! No, it occurs with a moving swingarm, plus a CHAIN TENSIONER always putting force on the span, and it's quite a long spread too.

For what you're talkin about, Coach, of a short chain to a lay shaft, no tensioner, I believe it's a total non-issue. I doubt chain stretch would occur in 50K miles, let alone 10K, simply because there's no stretch factor except applied torque, which a quality chain is designed for.

Beyond that, 10,000 miles? What, like worry about it every 2-3 years at most? Big deal...and it ain't gonna happen anyway.

BTW: a foggy memory, but I'd swear that bike thing I mentioned did indeed have the CVT tucked up out of the way behind the engine, running on a jackshaft.

[toyotaracer9]

Anyways, I saw that comment about chain stretch and just couldn't let it go by. Sure, chain stretch is a potential issues, sort of. But the main incidence of chain stretch isn't from a chain just sitting there spinning between a couple of sprockets! No, it occurs with a moving swingarm, plus a CHAIN TENSIONER always putting force on the span, and it's quite a long spread too.

For what you're talkin about, Coach, of a short chain to a lay shaft, no tensioner, I believe it's a total non-issue. I doubt chain stretch would occur in 50K miles, let alone 10K, simply because there's no stretch factor except applied torque, which a quality chain is designed for.

Thats not true info, short chains go around the sprockets more often and the pins wear much faster. I still dont understand how moving the drive back is going to make it more compact, seems like you will make is less to me.

[pietenpol2002]

I've reread this thread and I'm still a bit confused. First, Coach I think we need you to clarify Dieselfly's question as to whether you meant "behind the engine, or behind the transmission". I too can't figure out where the transmission entered the picture.

Regarding chain stretch, the tensioner is only taking up the slack on the backside with the accompanying wear being negligible in comparison to what's occurring around the sprockets where each rotation on the pins acts like a tiny little lathe. To that end, my next question would be whether you'd be going with an exposed or enclosed chain drive primary. Adapting an existing primary cover or even fabricating your own would be no small task. To run an exposed chain primary with all the attendant grit and grime would turn down those little pins faster than you could do them on the lathe. And at that point, any discussion regarding tensioner induced wear becomes a moot point.

You asked us to fire away Coach. So, I'm just saying.................

[DieselFly]

If you use a Quad CVT you may not be able to get springs, weights and helix that will work in the RPM range of your diesel. Most quad CVTs are designed for much higher HP and RPM. Spinning it faster to get it to engage will work but then the fun starts as you still have lower HP and the torque will drop. Finding the corrrect parts to tune it may not be possible by nature of its intended design

In a reread of this thread the part underlined confused me.... either cause Im dense..... or you misstyped. Did you mean behind engine and not behind transmission?

It should have read behind the engine.

[coachgeo]

I've reread this thread and I'm still a bit confused. First, Coach I think we need you to clarify Dieselfly's question as to whether you meant "behind the engine, or behind the transmission". I too can't figure out where the transmission entered the picture.

There was a misstype by Dieselfly..... there is no transmission in this picture; well except the CVT itself thus the answer is..... behind engine.

... my next question would be whether you'd be going with an exposed or enclosed chain drive primary....

A chain cover was a detail in the plan left out of discussion. Don't see an issue in making one.

You asked us to fire away Coach. So, I'm just saying.................

And thank you.

[coachgeo]

If you use a Quad CVT you may not be able to get springs, weights and helix that will work in the RPM range of your diesel. Most quad CVTs are designed for much higher HP and RPM. Spinning it faster to get it to engage will work but then the fun starts as you still have lower HP and the torque will drop. Finding the corrrect parts to tune it may not be possible by nature of its intended design

Had same assumptions , thus prompted my addition of this ratio change idea to spin the primary clutch faster into this thread. I now know that parts are available to convert a high Rpm clutch to a low rpm clutch so our assumptions were wrong... at least with Polaris Parts. See thread on that topic at viewtopic.php?f=41&t=2450

soo.... with that in mind:
The chain drive from flywheel to Primary/Driven Pulley at this point is planned to be 1:1 .

It should have read behind the engine.

Thought So- Now fixed

[coachgeo]

.... I still dont understand how moving the drive back is going to make it more compact, seems like you will make is less to me.

More compact in WIDTH. Not in length. Typical CVT setup on Diesel Bikes is to mount the Primary/Drive Clutch onto the Flywheel. In discussion with Heiko he said this added width to the bike.... even more so than his setups using a 3" belt drive and ultima.

Thus grew from this the idea to move the Primary/Drive Clutch under the seat into the same space behind the engine where a divorced tranny like an Ultima would sit. This significantly lessons the width of the bike.

. Chain drive from Flywheel to Primary is required to do this.
. to do this I think this will require also flipping the Primary and also the Secondary to match. As in what use to face outboard is now facing inboard. As in the primary and secondary are still located in normal order.... just their butts are now facing outward and their face inward.
. For this to work a Secondary needs the ability to have it's jackshaft go all the way thru the unit so a sprocket can be located in the right place to be in line with rear wheel.
. For Clutches w/engine breaking this "I think" would require flipping the one way bearing on the Primary over for it to work as intended

The clincher... and I have invited someone more expert on here (Audiomike) who might can answer this too..... will the secondary's helix work properly or will it's ramps now be climbing up the wrong direction?

[DieselFly]

You can't turn the secondary around it won't work unless they make a reverse helix. Most units have the spring and helix on the inside but not all. Flipping the primary should be doable. The problem I see with moving the primary is supporting the shaft as it cannot pass through the clutch. So the trick will be getting the bearings far enought apart on your primary shaft to stop twisting of the bearing mounts.

[coachgeo]

Flipping the primary should be doable. The problem I see ...is.. shaft cannot pass through the clutch. So the trick will be getting the bearings far enought apart on your primary shaft to stop twisting of the mounting

Yeppers, aware of this, but thanks for bringing it up.

You can't turn the secondary around it won't work unless they make a reverse helix. Most units have the spring and helix on the inside but not all.

DAMN., was afraid of that. Luckly Polaris; which Im learning toward, has the helix in the form of a cup that is inserted into the secondary. Thus it is possible to get that coppied by a machine shop but with the ramps in opposit direction. BUT... cost...... grrrrrrr.

[DieselFly]

Look down the page on the link it show that this clutch is for a Lambardini. http://www.ebay.ca/sch/i.html?_trksid=p ... &_from=R40
Price is way to high though. You can get the same setup I'm running for about $450 brand new from Gemini Karts in the UK. Someone must sell them at that price or better on this side of the pond seeming they are made here.

[coachgeo]

1. One complaint of CVT made is that the width/size excerts great force on the end bearing of engine more so that chain drive to remote gear tranny or fixed gear tranny as a normal bike engine.

Potentially no longer an issue if one can use a brace as discussed here

2. Size/width of CVT protrudes outward more so than other options, even more so than a divorced Harley Gearbox's fat belt drive (Ultima for example)....

this is where divorce mounting of CVT clutches potential really shines?

[coachgeo]

Look down the page on the link it show that this clutch is for a Lambardini. http://www.ebay.ca/sch/i.html?_trksid=p ... &_from=R40
Price is way to high though. You can get the same setup I'm running for about $450 brand new from Gemini Karts in the UK. Someone must sell them at that price or better on this side of the pond seeming they are made here.

Yes I do believe that is a CVTech Powerbloc ALT sold as for Lambardini to fit I think a Fiat micro car sold in Europe. That CVT is more expensive on our side of the pond. Supply/Demand economics. No manufacture here uses that model on any products. Infact very few manufactures use Comet or CVTech in US.... cause these days ATV and Snowmobile companies manufacture their own....... and that is the Only CVT products in use here in US except custom stuff or Ridely Motorcycles which are rare enough to be considered custom.

Most importantly though for sake of this discussion; swapping to another manufacture still does not address the issue of width of the bike; much less if you lay the bike down and thusly destroy, dent, damage, the primary.

PS- both used Polaris Primary and secondarys can be bought for around 100-150usd each and are not hard to find. According to resources all the parts neccissary to swap to guts for a diesel are available and not to pricey.

Mucho thanx for input thus far.. keep it coming.

[coachgeo]

DING DING DING... do we have a winner from the Peanut Gallery? (AudioMike pipes in via text message on phone). Flip wheel chain drive side from left to right.
Have started a thread on Tigertriple.com on topic of flipping wheel The experts on Tigers hang out there. They'll pipe in there and comment on how possible or impossible this would be.

Problems with helix solved by this?

[coachgeo]

Ding? Course another option that might work is put engine in to where flywheel is on bikes right side and keep OEM chain drive on the left. Jackshaft's put the CVT clutches out of harms way, and more compactly width wise by flipping them inside outward putting them under seat as described earlier, yet keep output on leftside like normal. Seems that would have the CVT arrangement facing in typical fashion thus solving helix issue.... but maybe Im missing something like:

. would that make full time reverse motion bike?? My calculations say it would, but Im hoping one of you correct my calculations proving me wrong
. would it solve helix issue or am I pictureing it wrong?

Might be less fabrication overall if it would work. Then still only doing engine and CVT mount fabrication and not adding to it flipping wheel fabbing and all that involves (moving rear brake master cylinder for one; and remounting rear brake caliper for two, according to TigerTriple (follow link posted earlier)

[XLerate]

Sorry for the confusion on my post. I did a poor job of explaining myself on the chain stretch comment. Where CoachGeo had said:

"1. One complaint of CVT made is that the width/size excerts great force on the end bearing of engine more so that chain drive to remote gear tranny or fixed gear tranny as a normal bike engine."

I was trying to say that compared to the stretch factor of a chain under the tensions of the CVT that an idler chain simply driving a non-tensioned layshaft would be virtually a non-issue. Still not correct to say that all chain stretch is a non-issue but that's not what I was referring to, though it can be read that way. Best if I just stay out of CVT discussions.

[DieselFly]

All four of the bikes I have built have the rear wheel flipped (right side drives were all the rage for a few years). The belt and secondary aren't that wide its the primary that makes the big bump. My custom stainless steel cover is a salad bowl from Walmart. My foot pegs are forward of my drive but if the pegs are behind the primary the belt, secondary and cover will not stick out any more than anyother kind of primary. Once you can set all the parts in the bike and sit on it you can start moving things around. My bike is fun and was not designed for long distance travel. I can ride 60-70 miles then I need to take a break. Also don't rule out doing a frame stretch to make everthing fit this is a very common on diesel conversions.

[coachgeo]

hmmmmmmm..... ok...... back to orginal idea but....... dont flip the secondary inside out. Only the primary. I was assuming that if you flip the primary inside out.... then you MUST also the secondary.

In conversation with two different folk they say this idea of flipping only one could work. You just have to exprement with aligning the secondary to where as each clutch opens* the belt stays in a straight line. They're are pre determined offsets from the factory but in a custom application... such as mix match of primary and secondary manufactures.... you have to finagle with it.


*for those not real familure with CVT's yet... each clutch has only one of two sheaves that moves. (AKA each side of a pulley that the belt/rope sit between is a sheave) Typically the primary moves the face sheave while the secondary moves the opposit; the butt sheave I'll call it.

Face and Butt is my wording in attempt to best describe it. Face sheave on a clutch is the one that lays on the bulky side where all the inner workings are housed. It's butt sheave is where it typicaly gets shafted (poor fella). Just to merky the waters... on a secondary... many can get shafted from either side but their always is the side more bulky where the helix etc. bulges out which Im calling the face.

[DieselFly]

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