Lightweight CVT Drive and Driven Pulley Question
 

I'm all about modifiying my new vehicles for added power. I saw a video in another thread about the CVT tranny with the belt so I searched a little and found another one (Posted above). It got me thinking about a lightweight driven and drive pulley. No underdriven but the same diameter as stock. So my questions are....

1) What does a CVT driven and/or drive pulley weigh?

2) Is it possible that someone manufactures lightweight driven/drive CVT pulleys?

I'm thinking the same concept as an Unorthodox racing pulley. I would think this modification would allow more power to go to the wheels by reducing rotating mass (No different than a crank pulley).

What are your thoughts on this? I am always trying to think outside the box. Sorry if this sounds silly. I'll be asking transmissions shops about this as well if I can't find anything on the internet.

BTW: I just sent an inquiry out to Unorthodox Racing. Not that they do or will make such a thing but why not right? They don't specialize in transmissions but this is a pulley nevertheless.

Very interesting question, but I think you are several years too early. IIRC, the most likely point of failure of a CVT is the belt itself. And right now, manufacturers consider a failed transmission as a part to be replaced as a unit, not repaired.

However, we are in the early days of CVT adoption, and perhaps in the future, replacing a belt will be doable, and for a reasonable cost. Imagine if it became not much more hassle than replacing a timing belt? This might drive widespread adoption of CVTs. And as long as you are replacing the belt, well, why not indeed specify the characteristics of the new belt? Nobody worries about changing the timing belt at regularly scheduled intervals. Why not a CVT belt too?

It seems more straightforward, if not necessarily easier to replace a belt than to deal with all the bands and clutches of a conventional autobox. And it's not like they never fail either...

Your post has caused me to reconsider my present negativity about CVTs. Thanks - I guess ;-)

By the way, I seem to recall reading somewhere that CVTs are banned from NASCAR(?), because when they were tried by ________(?), they conferred an insurmountable advantage, because there was no need to deal with weight shifts in cornering brought about by shifting.

I like the idea of thinking outside the box but being a nay sayer this is why I dont think it will happen.


1. CVT is not a performance/race box and are pretty uninspiring to drive. (all the performance GKs in Japan have gone straight to the 6 speed manual)

2. lightening drivetrain components doesnt make a massive difference to performance and when you are lightening drive train parts generally you are making them weaker (unlike water pump pulleys etc which take very little power to turn)

3. replacing these parts would be a large job with engine/transmission out and transmission totally disassembled. With the minimal gains and likely hood of loosing reliability makes the job not very worth while.

So Id be surprised to see any CVT mods popping up for these things.

Points taken Japan Tragic!

To add to what you have already stated, Unorthodox Racing sent a reply already (On a weekend to boot). Here is their statement -->

"The pulleys used in a CVT cannot be changed significantly weight wise as the belt is very abrasive, so they must be made from steel.

Our pulleys are the best way to remove rotational mass. Next would be light weight forged aluminum wheels. Next would be two piece brake rotors with aluminum hats and light weight lug nuts.
:)
AAADEM, LLC"

I'm already familiar with the other lightweight stuff but at least they had some input on the CVT portion of it. It still does not totally sway my thinking on this but it is understood why this approach may not have become mainstream. Manufacturers have made lightweight pistons, connecting rods, driveshafts, etc so you never know. Just keep an open mind about everything.

That's all for now!

Your focus is interesting. But I would submit that it's not just about power, but power to weight ratio. Therefore, there might be something to be gained by lightening the car itself. For example, removing the rear seats. Or all the seats. Well, not the driver's. Is this not what race cars do? Seems a shame to remove the vaunted magic seats, but it's your car.

Others have removed the rear wiper/motor. Or you could make it a habit to never have more than half a tank of gas, or washer fluid . And some race cars used to have the body lightened my placing it in an acid bath to thin the metal. I think it's nuts, but that's just like, my opinion, man.

since when did lowering the rotating mass of the drivetrain not equate to better performance is my question...i mean, isn't that why they make lightened flywheels for manual transmission, so the power from the engine has less weight to turn in order to get the power to the ground more efficiently? as far as OP is concerned, i think this is a very interesting topic and would not mind if someday they were able to achieve what you are talking about with a CVT transmission, but as of right now judging by the response you got back from unorthodox, it looks like no one is willing or able to come up with a way to make that happen unfortunately :(

Honda, Suzuki and Yamaha have been using belt driven CVTs on motor scooters since the mid eighties.. Their have been aftermarket parts and a complete kit called a "Variator" that is lighter and has a wider ratio spread that improves acceleration and fuel mileage.. In the 1990s a guy placed 4th in the Iron Butt Rally on a 250cc Honda Helix with the stock drive train.. He was competing against big touring and sport bikes... The big 600 + cc super scooters are very fast and used for touring all across Europe.. I have a feeling that there will be performance Variator type kits with lighter weight pulleys, spring kits optimizing the ratio spread for modified engines that make power at higher revs and boosted engines with high torque at lower revs... My wife is a hardcore believer in manual transmissions and is upset that the 2015 Subaru Out Back only comes with CVT, as is most others... It makes me think of Harley-Davidson owners that were freaked out by fuel injection, belt drive and ECUs, preferring to stick with carburetors, drive chains and mechanical ignitions...

Wow, this is great. Some history behind these things. Thank you for your post. Also, I was just sending Unorthodox Racing an email inquiry just as a starter. They are by no means an end to it all.

As Note-ified stated, lightening rotating mass is just that. There has to be gains from it and lightening it should not necessarily mean it has to be weaker. Stock parts are made at cost. Finding something lighter and harder should be doable. Again, I know nothing about this stuff but these type of thoughts just float through my head so I have to get it out there. I know this isn't new because there are people (Like you folks) that are WAY smarter than I.

My simplified approach would be to get a hold of a drive/drive pulley somehow, weigh it and send it to a machine shop to see if they can construct a lighter part without compromising its strength. Just a thought!

I wish I had this enthusiasm with CVTs, you guys have driven one right?

for a daily trundler/bumper to bumper traffic car Ill live with it, but honestly its the only regret I have with my GK, should have forced a manual on the misses.

not sure about everyone else in this thread, but personally i can say that i have some experience with them now seeing as my Note is a CVT model and although i had heard so much negatives about CVT's over the years i decided to try one out for myself by buying the Note that i now have and was actually surprised by how different the CVT in the Note operated compared to an 2007 altima that i had for a rental for a week. compared to the CVT in the altima the one in the Note is alot more eager to respond to the actions of your foot on the gas pedal than the slow as molasses reaction that i experienced when driving the altima with a CVT. im talking when you put the pedal down you get instant acceleration where as in the altima you had to wait a couple of seconds for it to find the right spot in the CVT to accelerate, so yes at least in my experience CVT's can be good or bad just depending on how they are set up. There is one thing that the Note's CVT has over the CVT in the altima though, and that's the fact that it has an auxiliary gearbox so in a sense it is a hybrid transmission crossed between a traditional geared automatic and a CVT where it has 2 actual gears, one for accelerating from a stop up to a certain speed where the CVT belt takes over, and one higher gear for low RPM freeway cruising. im still curious to find out what route Honda took with their CVT to see the differences in design between the Note's CVT and the Fit's CVT.

Some info on Variators and Roller Weights.

I just didn't want to lose that page or info (I'm at work).

pretty much nailed it.
Ill tell you right now for the cost of labor just to remove the transmission and install such "aftermarket" parts into a cvt and not guarentee any performance gains is going to be in the thousands. Your better off finding power from Intake, Header, Exhaust.
One big factor you guys arent considering is that when the transmission is altered, the PCM needs to be able to compensate for it. CHeck engine lights like a mofo...
Annndddd... good luck having hondata EVER having a reflash or tuning soloution for this car. No body wants to play with honda Direct injection.

Never say never lol

Lol, nobody said it but you... silly goose... :rolleyes:

Interesting question but not worth the time to research. The 'discs' have not only to be light but have superior wear characteristics and outside of a manufacturing with millions in their budget its not for the local shops.
Besides, with the emphasis on mpg you're chances of success are slim to none.
Instead, I suggect you check out what it would take to convert the CVT to DSG, Honda to VW.
If Sochiro were still runnig Honda at least the Si would have exactly that DSG. And leading the pack. Again.

you mean the gearbox the hybrid Fit here gets that has had mass recalls and been headaches (just like the VW) ? I honestly like the idea of it but not at the expense of reliability.

i'm not aware of the Fit Hybrid having a dual clutch automatic. All the info I've seen is the hybrid has a CVT due to its better efficiency just as my Prissy (prius C) does.
I'm also not aquainted with any reliability problems with VW and Porsche DSG's; just what problems are showing up in Japan's VW, Porsche, and others DSG's? The ones I've driven here or ridden in on track are flawless and much quicker than standard manuals. If Honda has equipped the Fit hybrid with a dual clutch auto how about some info.
thanks

Hybrid fit only comes with the new DCT (DSG if speaking VW) and its had issues, as has the VW. I think the gearbox in VWs are what is giving them the reputation for some of the most unreliable cars on the road (I guess they have a heap of engine issues too LOL)

Head to Head test of GP Hybrid DCT Vs GK RS with manual the RS was much faster even with the Hybrid technically having slightly more power from its electric motors. The testers said even though its more direct it still has all the same draw backs of an automatic. When its built for economy it cant match a manual.

What info do you want on the new fit transmission? it may be mainly in japanese but its all out there.

HONDA 3rd FIT(JAZZ) Hybrid

I have contacted Team Industries to see what they have to say on the possibility of increasing the performance out the Honda Fit CVT.

Yes, I'm not one to leave well enough (or the impossible) alone. Can't hurt right?

Feel free to visit their website to see why I'm inquiring on what they can do.