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Dala
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Reduction gear ratio swap?

Mon Mar 23, 2020 7:31 am

Hi,
I recently found this excellent video taking a deep-dive into the Nissan Leaf reduction gear housing
https://www.youtube.com/watch?v=UxJTEXxveUg

Summary, seems like there are two versions of the gearing
7.94:1 for 2011-2013 ZE0 (White interior)
8.30:1 for 2013-2017 AZE0 (Black interior)

This would explain why the first gen seems a bit peppier than the second generation.

Do we know if these can be swapped between versions? Both ways would be interesting, the ZE0 version is better for quick acceleration, and the AZE0 is better for energy economy, so it would depend on your usecase what you desire. Anyone tried this?

EDIT: Further research on this has proved the opposite. The ratios should be turned the other way, 1:7.94 accelerates slightly slower than the 1:8.30 version!
Last edited by Dala on Tue Mar 24, 2020 10:39 am, edited 3 times in total.

LeftieBiker
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Re: Reduction gear ratio swap?

Mon Mar 23, 2020 1:26 pm

The change in acceleration is from a change in the magnets in the motor and in programming. This happened for 2013, while the first gearset was still in use.
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estomax
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Re: Reduction gear ratio swap?

Mon Mar 23, 2020 1:56 pm

you have the gear ratios backwards maybe? a lower gear ratio will result in slower acceleration, a higher gear ratio will result in faster acceleration because it multiplies the torque more. This means the 2013 and up Leafs should accelerate better (very slightly) than the first gens, but have a lower top speed.

interesting that it is different, i didn't know that myself. i suppose the change came along with going from a separated motor levels in 11-12 and integrated vertical stack of stuff in 2013 and up.
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powersurge
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Re: Reduction gear ratio swap?

Tue Mar 24, 2020 3:54 am

estomax wrote:
Mon Mar 23, 2020 1:56 pm
you have the gear ratios backwards maybe? a lower gear ratio will result in slower acceleration, a higher gear ratio will result in faster acceleration because it multiplies the torque more. This means the 2013 and up Leafs should accelerate better (very slightly) than the first gens, but have a lower top speed.

interesting that it is different, i didn't know that myself. i suppose the change came along with going from a separated motor levels in 11-12 and integrated vertical stack of stuff in 2013 and up.
No, the original poster was correct. The low number transmission will be peppier.. Just like the front crank on a bicycle. The larger chain ring will improve top speed, and the middle chain ring will improve acceleration.

This is interesting that there are several versions of the transmission... However, the original poster cannot be thinking of changing his transmission just to get a different one? That would be foolish. Really foolish.

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Dala
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Re: Reduction gear ratio swap?

Tue Mar 24, 2020 6:19 am

That's where my logical thinking brought me too. So the 7.94:1 is better for acceleration. Topspeed is irrelevant, since it is software limited to 150km/h, so it would be very interesting to time some 0-100 testing with the two different ratios.

Why do you think it be foolish? You can get the gears or the whole case for quite cheap.

estomax
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Re: Reduction gear ratio swap?

Tue Mar 24, 2020 8:47 am

top speed is limited by motor max speed to some extent also, which i am not sure how close we are to hitting, but you're right, software limits it primarily.

i think you guys are looking at the transmission backwards, the small gear is the input shaft, and the large gear is the output shaft. The more turns the input gear does, for each rotation of the output gear, the faster (easier) you will accelerate (just like on a bicycle as referenced above), thus 8.3:1 being faster at accelerating than 7.9:1. Unless the leaf transmission is completely backwards from a normal car gearset, then i have been confused the whole time as the ratio should be 1:8.3.

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Oilpan4
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Re: Reduction gear ratio swap?

Tue Mar 24, 2020 8:53 am

My 2011 could use some extra towing grunt.
But it's only about a 4.54% difference.
For a pickup truck a slight change in axle ratio can be the difference between base and off road or towing package.
But the difference between standard and off road or towing gear ratios is more like a 10% change.

On gasoline powered street cars they always want the numerically higher ratio for better acceleration.

If all first Gen leaf cars peak at 210 ft•lb of torque then early cars make 1,667 ft•lb to the wheel and later cars make a tire smoking 1,743 imperial units of torque.
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nlspace
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Re: Reduction gear ratio swap?

Tue Mar 24, 2020 9:38 am

Looks like it should be good for about 1g acceleration--anybody ever use a g-analyst or similar tool to measure it?

estomax
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Re: Reduction gear ratio swap?

Tue Mar 24, 2020 10:08 am

nlspace wrote: Looks like it should be good for about 1g acceleration--anybody ever use a g-analyst or similar tool to measure it?
that's a neat thought, my estimates based on a 1500kg car with 8.3:1 gearbox and 24.9 inch diameter tire indicate that 1g of acceleration requires 413 lb-ft at the motor. If the motor can put out 210 lb-ft, then max acceleration is right around 1/2g. This is assuming no losses from friction and gearbox (perfect world). The number will drop a bit as we add in motor and wheel inertias as well as friction losses.

oilpan, i agree that only a 4.5% difference will make it very hard to measure acceleration difference in a real world comparison.

in pure math, the difference seems to be around 2% faster acceleration between the two gearboxes.
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75k, 83% SoH 2/20

Oilpan4
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Re: Reduction gear ratio swap?

Tue Mar 24, 2020 11:33 am

4.5% more torque with the early more aggressive motor/inverter ramp up rate might be fun.

Now if only we could find someone who sells modded VCUs.
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