Changing CVT Final Drive Gear Ratio Question

Myx

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***UPDATE 7/29/19***
I just found out that a 2018 Honda CRV's differential gears are almost identical to the 2018 Honda Civic EX. The only exception is the Final Drive Gear, which has been discontinued for some reason. The 2018 Honda CRV's Final drive is 5.64. It's even more aggressive than the Honda Fit's Final Drive I previously was looking at.


I've been playing with some thoughts on changing my CVTs final drive ratio. I've had this done this with great effect on two of my Subarus but am not sure how this would be on my Civic. The ONLY purpose in me doing this is to increase lowend acceleration/torque. I'm not concerned with my top speed. So...here it goes...

I own a 2018 Honda Civic EX-T (CVT). Searching around, sites say I have a Final drive gear ratio of 4.811. HERE
I looked at the 2018 Honda Fit EX (CVT). It has a final drive gear ratio of 5.440. HERE
Then I look at the parts list to compare and they don't look a whole lot different. Different part numbers though.

Honda Civic Differential Gear Parts
Honda Fit Differential Gear Parts

Watched this video shortly after posting this~~~>
Why is Final Drive Gear Ratio Important - Acceleration
According to 'Engineering Explained', doing this I can change the amount of torque (hp) I am putting out to the wheels for acceleration by 13% (5.440/4.811).
**Please try to refrain on discussions as to why I am trying to 'gain' more torque on a CVT. Save that for another discussion please. Thanks!**


So...based on the info I posted above, with the parts, etc.....does this seem doable? Doing all my homework now and will be planning on getting the parts together next week to make this happen. I move pretty quickly when I have ideas in my head. Thoughts? Pros/Cons? Just sharing some thoughts and putting it out here before executing and making sure I'm not missing anything. Thanks in advance!


Edit: I'm adding additional videos from here on down for personal reference. Disregard or read if you like. I have a tendency to do this with my posts so I can review them days/weeks/months from now.
Can Gearing Make Your Car Faster? With Proof!


Personal Note:
Currently @ 5.13 Gear ratio with smaller diameter tires (A 6.6% increase in torque from stock....5.13/4.811)
With CRV 5.64 Final drive, I'll be at 6.02 Final Drive.
This will be a 17% increase in torque from where I am at now.
A 25% increase in torque from having stock tires/wheel with 4.811 Final drive gears.
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caspar21

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interested in this, but i would like to go the other direction so we don't have to shift out of second in autocross.
if this works then possibly we can find something for standard civics.
 

gtman

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Can't you do something similar (to a lesser degree) by changing the overall tire/wheel diameter (shorter or taller than stock)?
 
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Myx

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Can't you do something similar (to a lesser degree) by changing the overall tire/wheel diameter (shorter or taller than stock)?
@gtman Yes you can! I've already done that and provided details in another thread. Gear ratio has already been changed by 6%. I'm trying to take it one step further. ;)
Tire Size and Gear Ratio Change
 
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What it really does for the CVT is to increase the ratio of the lowest gearing. The rest of the gearing change can be done by software and that's what driving in S essentially does (of course S can't change the lowest gear ratio). So no brainer. :yes: Looking at MT civicxs, Type R already has higher gearing ratios than, say, Hatch Sport, and so it will cruise at a bit higher rpm on the freeway.

If you want a more aggressive take off and you don't care about lowering your mpg, just go for it. Unfortunately, I doubt anyone will be able to tell you if this is mechanically straightforward or even possible with the Fit parts except someone who tried it before or otherwise is a Honda engineer or very experienced mechanic.

I wouldn't do it myself, but that's just me. I don't do actual competition so quick jerks off the line are not important to me. When I do want to beat someone with my CVT starting off at a green light, I actually let them put their nose out first, and than get them fast. I'm saying "even though I might be slower than you, my car is faster than yours". I believe with the CVT you will see a benefit only in the first second or two, but yes, this should improve the overal 0-60 time a bit.

If you increase the final ratio even more, your civic will be like a Main Battle Tank: you will be able to climb vertical walls, :headbang:but cruise only at 45 mph max.:drive:
 
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Myx

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What it really does for the CVT is to increase the ratio of the lowest gearing. The rest of the gearing change can be done by software and that's what driving in S essentially does (of course S can't change the lowest gear ratio). So no brainer. :yes: Looking at MT civicxs, Type R already has higher gearing ratios than, say, Hatch Sport, and so it will cruise at a bit higher rpm on the freeway.
Exactly! Since I race in 'L' gear at the dragstrip, this is exactly what I'm trying to achieve.




If you want a more aggressive take off and you don't care about lowering your mpg, just go for it. Unfortunately, I doubt anyone will be able to tell you if this is mechanically straightforward or even possible with the Fit parts except someone who tried it before or otherwise is a Honda engineer or very experienced mechanic.
That's why I'm posting up. You never know who's watching/reading in the forums at any given time, any given day. Could luck out with some invaluable information from someone in the know.



I believe with the CVT you will see a benefit only in the first second or two, but yes, this should improve the overal 0-60 time a bit.
Indeed! When trying to get down the track quicker, I divide the track into 3 parts. The start, the middle and the last part. The biggest impact you can have is how the car accelerate from the start (60ft time) in my opinion. This includes grip as well. So even if I can improve my 60ft time by .1 from a change, I'd expect a .2 change at the finish line. I'm only talking about the track but this has real work applications as well (Like accelerating from a stop light to merge, avoiding accident, etc).


So I'm trying to think outside the box on many different things and approaches to accomplishing this on this platform. This is one of them. And to be honest, I'm a little obsessed with @PRL Motorsports 1/4 mile time they achieved on street tires in the 1/4 mile thread. I was the same with @maddmatt02 1/4 mile time (Still is when he runs with his new turbo).
https://www.civicx.com/threads/10th-gen-civic-1-4-mile-times.15758/
I don't have any ethanol in my area so I'm trying to achieve this on pump gas, with the weakest and slowest transmission, with less power adders. I've already calculated the right weather and track conditions to do this. It's all in good fun and I enjoy these things.

Thanks for your insight on this.

Oh BTW: If down the road I decide to go with the 27WON or PRL Motorsports turbo, which loses a significant amount of torque/horsepower below 3500rpm, this will be one of the ways I can compensate for that. And have an even more killer topend as well.......until the final speed is reached.
 
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Myx

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I apologize for this repost. I actually posted this same question back in November 2017. HERE
I accidentally found this post because I was looking for the dimensions of the different parts to compare. This info used to be on Hondapartsnetwork.com but they no longer show this anymore. Fortunately, I actually posted up the dimensions in my previous thread.

I had even calculated the new gear ratio with my smaller wheels and tires as well as the weight saving of the swap in that thread.

2018 EX Hatchback CVT
Differential

Part# 41100-5LJ-003
Dimensions: 20cm X 20cm X 19.5cm
Weight: 8.69lbs
Final Driven Gear
Part# 41233-RJ2-000
Dimension: 21.7cm X 21cm X 4.3cm
Weight: 6.73lbs



2018 Honda Fit Hatchback CVT
Differential
Part# 41100-5T0-901
Dimensions: 16.5cm X 15.2 X 15.2cm
Weight: 6.3lbs
Final Driven Gear
Part# 41233-5T0-900
Dimensions: 21cm X 20cm - 10cm
Weight: 4.2lbs

4.92lbs would be saved in rotational mass with swapping out the differential and final drive gears between the Civic and the Fit.
Also...referencing this 'How Gears Work'
New gear ratio after smaller tire: 5.13:1
Plus differential: 5.76:1
Difference between 4.811 and 5.44 is 0.629,

So the difference in extra torque from my current setup would be 12%. The difference from when I had stock wheels/tires to the new gear with the smaller wheels/tires would be 20%. If I did the math right. **Perfect**

Guess I'm showing my age now. Sorry! :fear:


Personal Notes (Please Disregard)
13.6@104mph ticket using 1/4 Mile Calculator and weight of 2900 is 260hp @ flywheel.

Fit Final Drive Gears...
Change from current gearing of 5.13 to 5.76 is 12%.
12% of 260hp is 31hp.
260hp + 31hp = 291hp.
291hp @ flywheel with 2900 weight is 13.2@108mph in same weather condition as ticket. Same as PRL Motorsports run but without the ethanol...on street tires.

CRV Final Drive Gears...
Change from current gearing of 5.13 to 6.02 is 17%
17% of 260 is 44hp.
260hp + 44hp = 304hp
304hp @ flywheel with 2900 weight is 12.99@110mph


2018 Honda CRV Differential
5.64 Final Drive Ratio
 
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Hollywoo0220

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You still have to contend with the Torque Converter and programming,
So that the TCU registers correctly.
Those 1/4mile calculators are not accounting for CVTs.
Another note:
When you are using “X” Hp in the calculations, what is the torque you are figuring? At approx 290hp @6000 achieve NET Torque just above 250. @5500 you would be 275. Stretch it out higher to 6500 and you would be at 235.
When you pull the trigger on the W1, shoot for 260hp and peeking 225lb ft with the least amount of PSI possible. You will have both - Engine/CVT longevity there.
 
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You still have to contend with the Torque Converter and programming,
So that the TCU registers correctly.
Those 1/4mile calculators are not accounting for CVTs.
Another note:
When you are using “X” Hp in the calculations, what is the torque you are figuring? At approx 290hp @6000 achieve NET Torque just above 250. @5500 you would be 275. Stretch it out higher to 6500 and you would be at 235.
When you pull the trigger on the W1, shoot for 260hp and peeking 225lb ft with the least amount of PSI possible. You will have both - Engine/CVT longevity there.
When I use 'X' horsepower in the calculations, I'm using the 260 flywheel horsepower that the 1/4 mile calculator comes up with when I punch in 2900lb weight of the car and my best 1/4 mile time. Since I race in 'L' gear, the rpm initially maxes at 6400rpm then tapers down to 6100rpm the majority of the run. So....260hp @ 6100rpm = 224lb/ft of torque. Horsepower Calculator

I know all this stuff isn't precise and I suck at math. Just trying to use what tools are available to me to get an estimate. Many of you here are WAY smarter than I am. :thumbsup: That's why I provide the links and numbers so people can see how I come up with the numbers I do.

This is outside the scope of this thread but when I take off from a dead stop, I count about 1.5-2 seconds before I pump the gas pedal (Myxal Two-Step). This allows the rpm to 'skip' over the midrange torque (3500-4800rpm range) and get to 5500+ rpm as quickly as possible. My timing for this is to shoot for between 3-4 seconds (I time manual trannied Si's when they take off from a dead stop until they reach max rpm in 1st gear. It takes them about 3 seconds from the videos I've watched). When I used to do this in Honda Fit and logged my hp/tq numbers, despite the extra horsepower I made at the top, the midrange torque never registered and the max torque that would show would be close to what I was running at stock. So, I'm applying this concept here from my previous learnings and 1/4 mile runs. It would take me approximately 4 seconds to get the rpm needle to settle at around max Hp. Here's a video example of doing this in my Honda Fit.


Ktuner and Derek's TSP Stage 1 tune already have accounted for the midrange torque so CVTs can operate safely anyways so not to concerned about that. Any future tunes that may be custom (Ex: 27WON/PRL Turbo), I'll always have the midrange torque dialed back and then have it cranked up above 4800rpm to try not to obliterate the CVT. I'm right there with you my friend. ;) I was hoping you chimed in this discussion.

In a nutshell, this gear change should help improve 60ft times as well as getting the engine to max hp as quickly as possible, then it's smooth sailing from there. All really good things for acceleration.
 
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86salmon

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I count about 1.5-2 seconds before I pump the gas pedal (Myxal Two-Step).
Thanks for the video showing the Myxal Two-Step action. I always wondered what it looked like
 
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Myx

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I think I may have found what I was looking for. I posted links to the parts for the 2018 Honda CRV, at the bottom of Post #7. All the differential parts are pretty much the same as my 2018 Honda Civic EX, with the only exception being the final drive gear. And to top it off, the CRV's final drive gear is 5.64 vs my 4.811. This may be what I have been looking for.

However, Hondapartsnetwork says the part is.....discontinued. Final Drive, Gear CRV 41233-5LJ-010
Will need to look more into this.



2018 Honda CRV Differential
Shaft, Final Drive - Honda (23220-5LJ-010) **Discontinued as well**
5.64 Final Drive Ratio
 
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The Accord 1.5T CVT has a 5.36 FD ,those are still available.;)
 
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gtman

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Myx, your quest for the CVT Turbo Civic with the quickest acceleration has been fun to read about.

Is this your daily driver? If it isn't, don't bother reading the rest of this post.;)

Changing your final drive to 5.64 will certainly give you that faster acceleration and lower drag strip times you want, but at what cost everyday?

Do you enjoy the low revving nature of this car on the highway? Well, throw that out the window because cruising at 70 mph will be considerable noisier due to the higher engine revs. You also will be reducing your top speed quite a bit. And of course the Civic is known for great gas mileage. You'll essentially be turning the Civic from a high MPG economy car to more of an average one all while guzzling 93 octane gas. And of course those higher revs will tend to cause more long term wear and tear.

Essentially you'll be turning your car into a CVT drag racer. And that's cool if that's it's only mission. But the flip side are those daily driver negatives I've mentioned.

Food for thought anyway.
 
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turbo lover

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He'll still rev much lower on the highway than the manual transmission - around 2200 rpm at 70 mph vs 2700 rpm for the manual.
 
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gtman

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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.
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