CVT CVT's and Comet drivelines

[DetonatorTuning]

DT,
CRUD! I just re-read your question and I understand what you're asking. If I'm getting it right... lets say you're cruising along at 25mph. You want to speed up. You twist the throttle to WOT. What happens? Depends on, as CBRobots mentions, many variables.
If the CVT is at its max ratio while you're cruising, then the engine will have to pull the rest. Max is max...period. It's not going to "downshift" to a lower range ratio and then pick back up again. If, however the CVT is "tuned" properly and has some more room to roam, then it will continue to change ratios until it DOES reach its max.
Did that help?
WC

i'm going to be using a completely re-bearinged PB CVT just like yours.

yes, that's the answer i was after.

once the CVT has max'd it's range it isn't going to "downshift" under power, or unless the rpms fall under it's tuned threshold and keep falling.

thanks,
steve

 

[capturedbyrobots]

Just think of the CVT constantly shifting. (constantly variable tranny)

If it's tuned right, you will always be at the same optimal rpm area,
if it drops for whatever reason, you're not tuned in.
On mine, the gearing works for about 0-30, then above that, I'm at 1:1.
If I slow to 20, the gearing will change but rpms will not.
If I start climbing a hill, gearing will change, but optimally, rpms will not.

 

[capturedbyrobots]

i'm pretty well convinced on how this works at full throttle. push the throttle down, it revs out and the CVT pulls the ratio up to the limit. that's all good if you have the gearing purposely set to run wide open all the time.

My Mb is not a CVT drive just yet, just an FYI, only goped CVTs for me right now.

As for full throttle or not, nope...you don't get it.
If I give it even 1/4 throttle, it will still rev up to the set point the CVT is tuned to. Then I will only get to the speed that the 1/4 throttle will bring me to.
WOT has nothing to do with it.
The only time WOT has anything to do with it is after the CVT is at the 1:1.
Then there is no more room to shift, so the motor alone carries it up to top speed.


As well, I personally would NOT replace the clutch bell/variator bushings.
There is a reason, and here it is.

The shaft is a bit too small to fit the inner race of quality SKF bearings well.
It's the crappy chinese machining.
You'll end up having more play in the variator shaft if you try to replace those bearings.
I learned that the hard way. The shaft spun inside the new bearings races.
I epoxied the shaft in to the race, and it worked for a few hundred miles,
then I had to re-epoxy them in.

 

[Nuttsy]

Captured...
You were asking me about my CVT setup. Its still all stock except I sealed the vent hole as mine is mounted upside down. I'm video challanged but I do have some pics of the mounting setup.
As far as the gearing, I'm happy with it at 12-44. Although Florida does not have hills like SF, I have some small ones in my area and some tall bridges to cross in my commute. I haven't been up any of the bridges yet, but on the small hills this thing takes 'em like a dream and even accelerates where the 1-1/8" friction drive would bog and I would have to pedal assist. I've been running it hard the last few days trying to see if it or my bike will fail. Shake down so far is going great...not a hitch yet in about 25 or so miles. Had it up to 30 today and at WOT the engine rpm increased slightly after the CVT hit its limit. So I know I have a good gear ratio. I'm ready and anxious to get this project complete. Although it's gonna kill me to notch the rear fender for the chain. But I knew going in with the rack mount that I would have to do it. I have started a thread about my project in the rack mount forum. Only started it tonight but will be adding to it as time permits; if anyone is interested.

WC

 

[capturedbyrobots]

Ohhhhhhhh, you're 4 stroking it. I never saw that!
Never mind about taking out the rollers then.
You big time torque is right at where the CVT is set at now....
With 30G of rollers it will kick in at 3k-4k rpm, which is perfect for your setup.

If you were running a 2 stoke, that's when you'd have to remove a few rollers
as power would only kick in at 7-8k rpms.

I guess that the stock CVT is perfect for that mini 4 stroke motor actually.
Great job!

 

[capturedbyrobots]

Oh, for your stealth mode,
you should cut out the bottom out of the milk crate,
so it will look like you just have some stuff in the container.
With it upside down, it looks more suspicious.

Fantastic build by the way.

 

[Large Filipino]

So what would be the official name and description of the forum?

"CVT's and Comet drivelines"

Would it go in the garage or clubhouse?

But what if someone out there discovers a whole new automatic tranny for our puppies?


I would simply name that forum "Gears".

 

[DetonatorTuning]

My Mb is not a CVT drive just yet, just an FYI, only goped CVTs for me right now.

As for full throttle or not, nope...you don't get it.
If I give it even 1/4 throttle, it will still rev up to the set point the CVT is tuned to. Then I will only get to the speed that the 1/4 throttle will bring me to.
WOT has nothing to do with it.
The only time WOT has anything to do with it is after the CVT is at the 1:1.
Then there is no more room to shift, so the motor alone carries it up to top speed.


As well, I personally would NOT replace the clutch bell/variator bushings.
There is a reason, and here it is.

The shaft is a bit too small to fit the inner race of quality SKF bearings well.
It's the crappy chinese machining.
You'll end up having more play in the variator shaft if you try to replace those bearings.
I learned that the hard way. The shaft spun inside the new bearings races.
I epoxied the shaft in to the race, and it worked for a few hundred miles,
then I had to re-epoxy them in.

AHA, maybe i finally get it.

no matter how much throttle used the CVT will pull up to high range, then i can use throttle to control speed.

if i'm cruising along at 8600rpm / 35mph @ 1/2 throttle and start up a grade, the CVT will drop range, the rpms will stay the same and i'll proceed, though probably at somewhat lower speed. then when i get to level ground again the CVT will pull back up to high range, all at the same rpm and throttle setting.

is that about correct ?

thanks,
steve

 

[DetonatorTuning]

hey, look at that, 370 views in 44.5 hrs. not to shabby for a limited interest thread.

 

[capturedbyrobots]

Yeap...you've got it.

If rpms drop a bunch in your cruising story when you hit the hill, something is not tuned in. It takes some serious time to tune it in.
If you do not take the time to tune the CVT, it very well might run worse than a
motored single gear system. Nuttsy was lucky he had a 4 stroke
as these CVTs are pretty much set up for them stock.