Changing CVT Final Drive Gear Ratio Question

[Myx]

Even with the 5.64 final drive? I know stock I'm at 2,000 rpm at 70. Based on what I saw from Engineering Explained I thought highway revs would increase noticeably with such a drastic change in final drive. Well, I guess I'm wrong about the reduced highway mpg's then. My bad.

No, you are right. I just don't know how significant the change would actually be. Will look for an online calculator for this. As for your other post, I'm fully aware of how it'll impact the topend and highway revs and I'm ok with that. Just to what extent, I'm not sure about. Done this same thing on my Subaru SVX (Swapped to 4.44) and my 1989 Subaru XT6 (Swapped to 4.44s). My Subaru XT6 literally revs in the 4k range at about 80mph, which is silly. It's an nervous feeling since it is an older car but I've never had any issues with it.

It is my daily driver though. Thanks for your post. It's informative for those that are not in the know on how this will change/impact their car.

BTW: I do know that my new gear ratio with the 5.64 final drive and my smaller diameter than stock tire combo will make the new effective final drive gear ratio 6.02 (vs 4.811 stock). Now to plug the 6.02 in so see what my new rpm would be at 70mph or so. Kinda curious how this would effect the CVT since it's gear ratios are not locked in place......it's just within a range of ratios.

@gtman I can't leave this alone man because it is all gains without putting any more stress on the engine or the CVT itself.

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[gtman]

It's cool stuff Myx and I'm enjoying the read. I just know for me, the TSP tune and my minor performance mods are about as far as I want to push my daily driver. I'll definitely continue following your acceleration quest vicariously.

Would this help you with some basic calculations?
https://www.crawlpedia.com/rpm_gear_calculator.htm

 

[Hollywoo0220]

@Myx , isn’t increasing the final drive taking your high end away and just providing torque on the low end?

 

[Myx]

@Myx , isn’t increasing the final drive taking your high end away and just providing torque on the low end?

Yes! It's not often I'm travelling at top speed. Actually, it's never. Come to think of it, what is our top speed? And is it gear limited or drag (aero) limited? Either way, I never go over 100mph except on the dragstrip.

 

[gtman]

Yes! It's not often I'm travelling at top speed. Actually, it's never. Come to think of it, what is our top speed? And is it gear limited or drag (aero) limited? Either way, I never go over 100mph except on the dragstrip.

With Ktuner and Hondata, the factory speed limit is removed.

 

[Myx]

Would this help you with some basic calculations?
https://www.crawlpedia.com/rpm_gear_calculator.htm

Not sure how accurate this is with our CVT transmission.
I put in 70mph, wheel diameter of 23.6" (I have smaller tire diameter than stock) and a final drive gear ratio of 4.811. Says I'd be at 4795rpm.
So then I put in 70mph, same wheel diameter and final drive gear ratio of 6.02. Says I'd be at 6000rpm.

So......let's just say I'll be 1205rpms higher than I am at now. And I don't know where it is at now at 70mph. Will have to take a look in the morning when I leave work.

 

[Hollywoo0220]

Not sure how accurate this is with our CVT transmission.
I put in 70mph, wheel diameter of 23.6" (I have smaller tire diameter than stock) and a final drive gear ratio of 4.811. Says I'd be at 4795rpm.
So then I put in 70mph, same wheel diameter and final drive gear ratio of 6.02. Says I'd be at 6000rpm.

So......let's just say I'll be 1205rpms higher than I am at now. And I don't know where it is at now at 70mph. Will have to take a look in the morning when I leave work.

I am interested in knowing how a CVT's Final Gear Ratio can be changed? Since it is a belt being spun on a shaft w/o teeth?

 

[gtman]

Not sure how accurate this is with our CVT transmission.
I put in 70mph, wheel diameter of 23.6" (I have smaller tire diameter than stock) and a final drive gear ratio of 4.811. Says I'd be at 4795rpm.
So then I put in 70mph, same wheel diameter and final drive gear ratio of 6.02. Says I'd be at 6000rpm.

So......let's just say I'll be 1205rpms higher than I am at now. And I don't know where it is at now at 70mph. Will have to take a look in the morning when I leave work.

I think your numbers came out high because you had the transmission ratio set to 1.0 on the calculator..

At 70 mph, it would be lower. Since CVT has variable ratios though, who knows exactly what that number would be.

 

[Myx]

I am interested in knowing how a CVT's Final Gear Ratio can be changed? Since it is a belt being spun on a shaft w/o teeth?

Yeah, I'm curious too. I would've thought that it couldn't but then again....it actually has a final drive gear ratio. If it wasn't a set number and it varied because the ratios are always changing, then I wouldn't bother. So I figured, there has to be something to this since it actually has a final drive number.

I thi k it came out hig because you had the transmission ratio set to 1.0...

At 70 mph, it would be lower. Since CVT has variable ratios though, who knows exactly what that number would be.

All we have to work with are the numbers provided. I like the mystery behind this. If the CRV gear and shaft wasn't discontinued though, I'd ordered it yesterday. Since all the other connecting pieces between the CRV and the Civic appears to have the same number. It'd be simply having these two pieces changed out. I mean, how can that not work....right?

 

[gtman]

I just tried it with the 5.64 final drive with your tire diameter and a transmission ratio of .55 (simulating a 6th gear type overdrive) and it calculated out to around 3000 RPM at 70 MPH. Stock is more like 2000 RPM at 70.

 

[Myx]

I just tried it with the 5.64 final drive with your tire diameter and a transmission ratio of .55 (simulating a 6th gear type overdrive) and it calculated out to around 3000 RPM at 70 MPH. Stock is more like 2000 RPM at 70.

Hell yeah! I can live with that. Thanks bro!
Also, I looked again at the bottom of the page with the discontinued final drive of the CRV. I didn't realize that if you scrolled down the page, it actually tells you what vehicles the part fits, with the Civic 5 door being one of them. This will make cross referencing the parts now much easier. Woot, Woot!

 

[turbo lover]

Ratio for top gear is .405. https://hondanews.com/honda-automobiles/releases/2017-honda-civic-sedan-specifications-features

 

[Myx]

Ratio for top gear is .405. https://hondanews.com/honda-automobiles/releases/2017-honda-civic-sedan-specifications-features

Is this to say that our the CVT is capable of a 253mph top speed if it wasn't held back by horsepower or drag, with a 4.811 Final drive and .405 top gear? Top speed calculator

 

[Myx]

I just tried it with the 5.64 final drive with your tire diameter and a transmission ratio of .55 (simulating a 6th gear type overdrive) and it calculated out to around 3000 RPM at 70 MPH. Stock is more like 2000 RPM at 70.

Without using a calculator..here's my rough math (Ghetto formula) for top gear.
2000rpm = 70mph
4000rpm = 140mph
6000rpm = 210mph
6500rpm = 227.5mph

Is this how this works?

 

[gtman]

Ratio for top gear is .405. https://hondanews.com/honda-automobiles/releases/2017-honda-civic-sedan-specifications-features

There is no definitive top gear, per se. You will only see .405 in certain scenarios under no load. For example, I drive 70 mph on the same highway daily. Even though I'm maintaining a constant 70, as I look down at my tach, it will range from 2000-2500 rpm depending on the area of the highway I'm in. The CVT will change ratios for elevation changes and other factors. That's why you can't be absolute about assuming you'll see that .405 even when travelling at a constant 70 mph. Maybe on a perfectly flat Midwest road but not where I live.

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