Countershaft rotation Speed- (chain drive related)

[rick_nowak]

good rule of thumb on sprockets is 16 tooth minimum for reasonable wear and smooth power transfer.  dirt bikes use smaller, mostly because they wear things out rather quickly anyway due to conditions and are not too concerned ultimately with smoothness.  hubs for open class dirt bikes would make good doners though, being light and having usually, alloy rims.  just need to have a cush drive in the hub as none now otherwise in the driveline

[Blake]

http://filebox.vt.edu/users/bstoddar/xz550/sprocket/1.jpg

http://filebox.vt.edu/users/bstoddar/xz550/sprocket/2.jpg

http://filebox.vt.edu/users/bstoddar/xz550/sprocket/3.jpg

http://filebox.vt.edu/users/bstoddar/xz550/sprocket/4.jpg

http://filebox.vt.edu/users/bstoddar/xz550/sprocket/5.jpg

http://filebox.vt.edu/users/bstoddar/xz550/sprocket/6.jpg


drawing of the stock gear drive thing...

[rick_nowak]

so.  remaining issues:  sprocket housing
                               sprocket size
                               machining of bevil gear to receive sprkt
                               welding and heat treating
                               output shaft bearing with shield
                               plug oil return hole
                               chainline determination
                               suitable swingarm
                               suitable hub/wheel assy
is anyone else interested in this?? all the posts are blake and myself lately

[Ron_McCoy]

One thing you haven't mentioned is the need to change the
swing arm pivot location.The stock pivot is lined up with the
u-joint pivot.To decrease variations in chain tension(and thereby increase chain life)and aid handling,the pivot needs to be as close to the countershaft as possible and at the correct height for anti-squat properties.This would not be that difficult to do.Proper alignment could be maintained during fabrication by the use of a fixture utilizing the original swing arm pivot as the reference.An adjustable pivot wouuld not be hard to fabricate to allow dialing in the characteristics you favor in the anti-squat area.Examples are readily available on road race bikes.Of course the pivot would end up occupying the space now taken up by the rear head pipe,so a new exhaust system would be required.I've been working on this chain drive conversion in my head for some time,and have a parts bike to develope it on,but so far I have not had the time to devote to actually doing it.

[rick_nowak]

the pivot could be within an offset drilled big bushing, the bushing able to rotate as a two sided assemblyto raise and lower relative to the sprocket and rear hub assy.  the frame work required would be to accurately place this ring on both sides of frame and box it in effectively to take loads.
the ducati 860 v twin has something like this to allow for chain adjustment primarily, but, as you say, it also has some effect on anti-squat properties
this conversion gets more complicated as it is examined but at least we are identifying the problems.
i can understand why most of our fellow visionaries are reading and rolling their eyes.

[Blake]

haha..yeah...definately seems like were the only ones talking here.. im suprised at that too.. because i remember a while ago..and also every so often, someone will ask about a chain drive conversion.  thats why i put that little poll up to see how many people were interested..  around 50 people looked at it but none said what they thought..  oh well.. if need be ill just have a set (or two) made for myself.  

Something else i was thinking of last night...but ill talk about that in a few..first..the issues:


      sprocket housing: This i dont think will be that hard.  basically if the sprocket doesnt fit, I'll just chop off the shaft drive compartment cover and get like you said, either a dirtbike sprocket cover or something else to that effect, and just make it work..hehe.

      sprocket size:  as for sprocket size..I think that is determined by the rear wheel's sprocket.  we want to try to maintain the 3.something ratio of the shaftdrive or get as close to it as possible.  but i'd say 16 is a good starting point (45 or 46 tooth rear).

      machining of bevil gear to receive sprkt:  BEVEL GEAR..thats what it's called. hehe.. i kept calling it the drive gear.  now i can call it what it really is.  But anyway, last night i sent off an e-mail to a small motorcycle shop that has a machine shop down by Virginia tech (go to school there) that i went to a few times for some bolts (guy was real helpful and we talked about old bikes for a while).  but i tried to describe the gear to him and asked if i could get a rough estimate of how much it would be to machine off the gears.  hopefully ill get something back on that too.


      welding and heat treating:  As for this part..havent thought about it yet.. dont know a thing about heat treating, but also..read what i wrote further..may be a possibility.

 
      output shaft bearing with shield: 35mm inner, 72mm outter, 15mm depth.  a place i use a lot has some double sealed ones with about 7,000rpm max and like 10,000lb radial load.  Once i get this bearing out (finally got paid, so going to get torx bit this weekend) ill check out the situation behind it, and see if oil splash from behind will be good enough to lube it.

      plug oil return hole: i dont remember if there was an oil return, but definately was an oil feed.  what i think was the case was oile would be forced into there, fill the case up, immersing the shaft gears in oil, and would run back into the case through the bearings..  may be wrong, ill check.  as for plugging the input hole, either weld it up, or maybe tap it and put a bolt in it??

      chainline determination:  This is a very important part because it is needed so that the offset of the adaptor can be determined.  But, to get this, we need to first have the swingarm so that we have something to base the line off of.  just looking at where the shaftdrive comes out of, i dont think the offset will have to be that large in the first place.

      suitable swingarm:  number 2 top priority.  without a swingarm, the project wont work.  true, i can have a swingarm modified, but the goal isnt to spend loads of money on this conversion.  so if something can be found to be an exact fit. great.  if a little smaller at the pivot, we'll use spacers.  its just a matter of finding one with the same pivot legnth.  number one top priority is creating a suitable adaptor.


      suitable hub/wheel assy: as for this, this would go with the swingarm.  why make things harder on ourselves.  if we get the swingarm, im just going to take the same wheel if not forced to get another.




uuummmmm....  oh yeah. so i started drawing the adaptor yesterday (lightning storm made me get off the computer for a while).  For the bevel gear, i made it sort of into an inverted cone (pointy side up), with the center remaining stock.  basically what it would look like if you machined off the gears and flattened off the top (outter portion where gear ID is is slightly higher than center)

but then i started thinking about the top.  i was wondering if it would be possible to make this thing without having to weld...  heres what i was thinking.  you get your blank cylinder.. as wide as the bevel gear(69mm), lets say 50mm high.(way to big actually.but for ease of description)  You machine the bottome, so that it will fit perfectly with the outter slant and flat center of the bevel gear.  much like making a fist, and covering it with your over hand.  itll be centered, and have a lot of good surface contact.

As for the top of it, you would want to have the "spline" for the sprocket to mount to machined out.  maybe 5mm down with the center sticking up.. not too bad. definately wouldnt constitute needing some spline adaptor.. there are maybe 6 teeth, 5mmx5mm..or maybe it does need special tooling. i dont know.

next.  as i mentioned a few posts ago about holding down the sprocket, you get another blank rod, 35mm wide (as big as hole in bevel gear) and 40mm tall (you dont want it as tall as the top part.)  with this rod, on the bottom, you drill a hole 12mm wide and a little more than 9mm high which is the size of the threaded section on the countershaft (that the bolt that held down the gear secured to).  And then you thread it.

ok.. now you would want to drill a bolt hole all the way through from top to bottom and thread for lets say a 8mm bolt.  

Now on the top part, you want to machine out the underside in the middle, for the smaller rod to fit nice and snug in.  And remember, the smaller rod in the center isnt as tall as the sprocket adaptor, so, after you drill out the hole for the small rod, you need to drill the hole for the 8mm bolt too.  the inner rod doesnt go all the way to the top becuase when you tighten the bolt onto the top adaptor, you want to be able to pull down on something. it'll be its own semi-washer in a way.

the theory behind this thinking of this setup, is that you can put on the bevel gear, then screw the inner rod onto the counter shaft, put the top adaptor on, then your sprocket, tighten it all down nice and tight, and its good to go.  see the problem that i ran into was the fact that the end of the countershaft is like a bolt, and doesnt have a hole in the center, so you couldnt just use that to anchor the whole system down.  instead, you have to basiclly convert it froom male to female.


now.. the one thing im still not clear on is..  on the top of the bevel gear is a smooth machined surface, as is the bottom of the adaptor.  the problem?  nothing to keep the top adaptor from spinning wildly.  we need some sort of "put" or anchor.  two things i was thinking of..  either A.  when the bevel gear is machined down,  cut a bunch of grooves in it.  and on the top, cut it so it has the teeth.  and simple mat the two together.    or..

the other idea.  was to keep the surfaces smooth.. and then drill 4 holes(about..just a guess)..  from the side of the top INTO the bevel gear, tap it, and then use nice and strong allen bolts to secure it down.  would that hold the rotational forces? or would they just shear?...  or maybe a third option would be some sort of combination of both..



incase i lost you.. i did a quick (well it took a while..but its poor quality) or my general thinking...

 http://filebox.vt.edu/users/bstoddar/cutaway.gif


any thoughts or suggestions?


Blake

[Blake]

http://www.off-road.com/dirtbike/projects/crf450/gallery/fastway/DSC_0154.jpg.html


heres how close a modern sportbike's swingarm is to the countershaft..thing have to be less than 2 inches away.  however, the vision motor simply wont allow this.  ill have to check how close you can get it, but the physical limitation is the rear of the motor.

also the sprocket cover.  doesnt look like that much of a clearance between the teeth and the actual cover.  dont really need it i guess since the chain is ALWAYS tight on the gear.


just another visual.



Blake

[SY]

Just a thought. Have you tryed to contact John Clemens (the guy with the chain drive Vision Racer in the Vision Gallery").

[Ron_McCoy]

John used a different frame with his bike.You would be very lucky to find a swing arm that you could use with the Vision frame without modifying the frame.Most swing arms have the bearings in the pivot of the arm,not in the frame like the Vision.Also to use the stock pivot,the arm would have to be quite short to keep the wheelbase within reason.I was thinking of making the sprocket adaptor in a similiar fashion to your drawing,but without the taper and using a"dog" to transmit the drive force,basically a fairly wide groove with a matching "tongue".It would be even better to use a dovetail arrangment with the groove being undercut and the tongue being tapered to match.The chainline would be determined by the wheel which must be centered on the bike.

[rick_nowak]

the big nut holding on the bevel(pinion) gear is perfectly adequate to hold on a modified (cut down) bevel gear with a sprocket welded on to it.   the major issue is chainline.  the simplest thing to do is always the best (?) so if it could be determined that a vertical shoulder cut(ground) will allow enough meat for a weld into the teeth of the bevil gear and the outside face (front and backside of sprocket).  some sprockets are located by a couple of keyways and have an otherwise plain round hole.  i have seen these with a dish also(much rarer).  in my mind it's not worth it to try to have a bolt-on sprocket setup-too complex, if a sprocket could be welded to the bevel gear.  do we know what mr yamaha wants for a new bevel gear?  perhaps other visionaries would sell theirs from the parts bikes.(just to shut us up!)

[Silver_Bullet]

I hate to sound like the only naysayer in the bunch.  Seems like an awful lot of trouble for what...saving a few pounds?  Might be better off fabing another shaft/swingarm assembly from aluminum to save the weight.  Nothing to figure out all over again, everything the same dimension.  If you change anything, increase the width so that a wider wheel/tire combination could be  used.  Just my 2 cents(sense).
Mark
P.S.  Deep down, really am envious of your creativity and engineering expertise.

[rick_nowak]

one could just buy a small motoguzzi and be done with it.
i suppose that the point is not just weight, but rotating unsprung weight.  also, i suspect that a fatter rear tire would not have much real effect on basic roadability.  it's not like we have a lot of horsepower to play with, and a bigger tire is heavier in all the wrong places and would likely take a while longer to heat up to operating temps

[Blake]

I'd have to agree..  the point of this is not the weight...every advantage you gain has its disatvantage.. you lose weight..then you have to maintain the chain.. you use a bigger tire..you lose original handling..   the only way i can put it..  i like to tinker..  always have to be modding and chopping..and this...while people have mentioned it before.. have never done it... becides... if our friend Herr. Otto didnt go through the trouble of figuring out the internal combustion engine, we'd never have our famed vision....  im sure people told him "ah..whats the use..thats what we have horses for.."


long story short..  its just something different.. and someone always has to be the first to try something new.. who knows.. after figuring it all out.. it could be simple as cake for others to follow in suit.





Blake

[Ron_McCoy]

I agree with Blake on having something different that you engineered yourself.Other than that,you would lose the shaft drive reaction when you're on or off the throttle,and gain the ability to take advantage of modern radial tire technology.

[sdinino]

haha..yeah...definately seems like were the only ones talking here.. ..

This has been a fascinating thread to lurk on. I don't have anything to offer to the discussion except encouragement, and this seemed like an opportune moment.

While this isn't something I would want to do to my machine, I too applaud your ingenuity. I hope you get it to work!

[Rick G]

Your a better man than I ,Charlie Brown, if you can detect any throttle reaction from the shaft, maybe on a Beemer or Guzzi ,. As to why racers want chain drive , yes its lighter ,but mostly so they can regear  ro differant tracks.  Kenny Roberts  built a chain drive vision and an aluminum frame  racer many years ago , there was a picture of it in the news letter a couple of years ago. As to getting any information out ot  John Clemens, Lots of Luck, you might get 2 words (if your lucky)

[QBS]

You guys are wonderful.  Years ago, when the 750 Honda was new, I toyed with the idea of converting it to shaft drive.  Ended up riding an R60/5 BMW for ten years instead, although I'm sure the Honda would have been more fun.  Blake, you have a super imagination and will make an excellent engineer.  Think NASA and don't neglect to add this very long thread to your resume.

Regarding the swing arm:  Another complicating factor in trying to use an off the shelf componet here will the swing arm location and attachement of the mono shock.  I'm sure that whatever swing arm is finally chosen will probably work pretty well without major modification regarding attachement to the frame and closeness to the output shaft.  However, I doubt we will so fortunate as to find an arm that will allow the stock shock to be used(even if that was desirable) without modifing the arm to locate the lower shock mount.  This modification would in all likelyhood involve welding.  Not a really big deal, but still outside the "plug and play" specification for this project.

I just reallized another significant benefit from actually doing this project.  Namely, the ability the use another (newer/better)shock besides the stock one.  Maybe, one from a recently crashed sport bike.  Even a low miles OEM unit would have to be an improvement over our 20 year old worn technology.  If you go with new from an aftermarket mfger. bring $$.

[rip_brotz420]

I  believe the yamaha factory made a 920 RH RJ that is chain drive and carry the same bearings on there counter shaft  that allow that possability they are chain drive

[Hugh Jass]

I was looking in the gallery and noticed that the guy with the dragster vision converted his to chain drive.  Maybe he would have something to say on his experience with it.

His site is:
http://www.thefang.co.uk/gallery.htm

[Blake]

oh wow... that definately helps.


I just sent an e-mail out to the guy and asked if he could possibly help me out with some details (swingarm, how he mounted a sprocket to the countershaft.)


I've put the chaindrive conversion temporarily on hold for the time..  as i just bought myself a welder (was getting tired of trying to find someone to let me borrow one..and renting one for more than 3 days..well..would cose as much as buying a new one)..  but anyway, i bought the welder and im currently making some good progress on an exhaust (total cost: i'd say less than 50 bucks USD for parts..  ALL parts came from local home depot...and best part.. the pipe im using..is electrical conduit pipe.  seriously.  i looked at it and then at some exhaust pipe.. except for the fact that the conduit is galvanized and slightly thicker.. i dont see any reason not to use it.  heck..  a 10 foot long piece of conduit (1.5") only cost me 7 bucks, when that long of exhaust pipe around here would run me 20-30... so yeah... took me a while to remember how to weld again (its a wire-feed, using flux core)..had my mistakes of it not holding (not enough power), burning right through the pipe (way too much power)..but after practicing some on a few scraps i had lying around, its slowly coming back to me.  mainly..to take it nice a slow at the right amp setting.  its starting to come out nice now.  


but yesterday i finally took the plunge and welded a pipe to one of the exhaust connectors and bolted it up the the rear cylinder..  and it fits pretty well..  hopefully by friday i can have the collectors finished..which is the hardest part.. after that..its just cut and paste for the bigger pipes for each cylinder.  When the parents get back from their week in detroit (family wedding) i'll definately be sure to take some pictures for all of you and post them up here.




heh..  Maybe i should just start a new post called "Another one of blake's crazy ideas.." and whenever i get a new idea just post it..hehe..   anyone want to know of the new idea for the day? (i have WAY too much free time at work)..

take a look here:  http://www.markvanderkwaak.com/dbbp/cadbikes/cadbike09/cadbike9.html

a Eaton Blower on the vision... now THAT would rock...hehe...hmmm...makes you wonder if that flywheel REALLY needs to be soaked in oil...or can it be used as a power takeoff for other "accessories"...(diferent alternator(maybe a harley generator-cheap and readily available, blower?..hehehe)...  yeah yeah...by the time i get done with this thing you wont even notice its a vision anymore.




Blake