Top speed on a torque converter?

[bob58o]

I understand , on paper it does not make sense

That's the kind of data I was hoping for. Both setups should give 5.4 :1 when fully shifted. The results don't really surprise me, but until I understand WHY, this is still going to bug me.

The only thing that is different, that I can think of is how high the belt rides between the driver sheaves. If the sheaves cannot close all the way, the belt must ride lower. But it doesn't seem like the belt is slipping when all the way at the top - because the engine didn't rev. If it was slipping the engine would still rev higher, but the MPHs wouldn't come along.

And if the driver doesn't close all the way, the driven probably doesn't open all the way - so the belt probably doesn't ride as low in the driven.

I don't get it. Is more power being lost to heat (without the shim)?

 

[karl]

I don't get it. Is more power being lost to heat?

Im just a dumb blue collar mechanic, but I did notice with the shim, the belt wears a lot less. I still have the factory belt on my monster moto 212cc ( multiple bikes), I drive it 6+ miles at a time without worry, higher rpm.

 

[Preduhtor_122]

So today the torque converter blew on me. Where the weights and garter springs are. I recovered all the parts but my guess is that the bolt going into the crankshaft came lose. When I saw o noticed the bolt only goes in about 3 or 4 threads. That’s all That grabs on. I thought about putting blue lock tight and re tightening it. Any thoughts??

 

[Brianator]

Yes! Get a longer grade 8 bolt (fine thread - 24tpi) and then install it with blue threadlocker, torque it down and that should be last time you have to deal with that! Lol

 

[Preduhtor_122]

Will do. That bolt shouldn’t be going anywhere after that. Also the belt was kinda engaging at idle. Not enough to move the bike but the sheave does start to grab at the belt and start almost engaging. Does this mess the belt or torque converter up or is it normal. Again. The bike doesn’t move with a rider on or with it just leaning on the kickstand but you can kinda see it jumping a bit. Should I change to white springs Thag engage around 3000 rpms or leave as is

 

[Brianator]

That's fairly normal I'd leave it but see if I could drop the idle down just a hair, if anything that should at least give you extra piece of mind if nothing else.

 

[stroc1]

I have a tule trooper with a stock 4 HP Briggs with a high low gearbox everything else STOCK 15 MPH in low 46 in high

 

[bob58o]

I like turtles.

 

[Denny]

Is that your school picture?

 

[bob58o]

Is that your school picture?

 

[Denny]

So then that was like grade 5?

 

[BrownStainRacing]

So then that was like grade 5?

@bob58o , was the smartest 15 yr old in his class.

He read Dr. Seuss, "Green eggs and ham" faster then any of the other 3rd graders in his class.

 

[Rat]

This thread looks a lot like a rinse and repeat of my drama.
While my 208 is built, it's a mild tune it is a scary torquer.
Simply put, your top speed will boil down to just how damn fast you can make the crank spin under full load while maintaining enough torque to keep the sheeves shifted (this may lead to spring adjustments and/or swapping). I used a 208 snow thrower engine because A) almost everyone uses a predator, and B) The 212 is a Sissy when it comes to torque, built or especially not built.

This thread caugt my attention because of similarities to my set up...

2.50-18 tires (23.89) rolling diameter
208cc with a mild Revpro 6500rpm cam
Koso PWK copy [24mm]
Unrestricted ignition coil
Governor delete
27/25 hardened stainless valves
18cc head (recently verified)
22# springs and split keepers
5.5 hardened stainless rods
HD Champion 1:1 rockers
Comet 30 copy full stock w/ driven spring in default

It will yank the front wheel off the ground without hesitation if I flick the throttle, will pull hard and fast up to 30/35mph before the acceleration slows.
After an initial acceleration up to 5k-5800 rpm the TC drags the rpm back down into 3800-4k range.
The top speed (in the mountains without a lot of room to really let it open up) has been 40mph in a relatively short distance with another 1/4 worth of sheeve to shift... which is most likely more related to belt stretch than just not having the room to run it all the way out.

 

[bob58o]

I didn’t read all of this but it was the most relevant CVT tuning for buggies paper I could find. Some sort of small buggy Baja race thing.


Conclusion

This paper shows that there are many parameters which do not significantly affect
CVT performance along with others which can be varied individually to achieve a very
significant change in CVT performance. Thus, teams should move away from the
ineffective approach of manual trial-and-error and instead shift towards faster and more
effective numerical approaches such as the MATLAB model used in this paper. The
conclusions below are based on individual tuning objectives that were identified at the
start of the study i.e., changing engagement speed and changing shift RPM

1. For a change in shift RPM, the focus on tuning should be majorly oriented on
secondary’s Helix ramp angles, primary pulley spring’s linear rate and on the
overall flyweight system

2. For a change in Engagement RPM, the focus on tuning should be majorly
oriented on the Primary Pulley because only flyweight masses, flyweight ramp
angles and the primary spring’s linear rate influence engagement speed.

3. If drastic changes are required: for instance, if the CVT is severely
underperforming or not able to shift out to the high ratio fully, the focus should
be on changing flyweight ramp angles and flyweight masses.

4. If relatively minor adjustments are required: tuning should be focused on
secondary springs as these provide smaller changes in CVT performance.

https://www.researchgate.net/publication/365339303_Analysing_Impact_of_Different_CVT_Tuning_Parameters_on_Baja_Vehicle_Performance_Through_MATLAB

 

[Denny]

You guys are aware this thread has been dead for almost 4 years right?

 

[Rat]

You guys are aware this thread has been dead for almost 4 years right?

Lmao nah... I don't have the attention span for that dedication after midnight

 

[ezcome-ezgo]

Never to late to GAB on a subject.

 

[bob58o]

Everything, of course, is fundamentally Yang and Yin. The life of a thread is inseparable from its death like the flickering of a candle.