Why Is Final Drive Ratio Important? Accelerate Faster!

What is a final drive ratio? What does changing it do?
Car Gears - • Car Gears - Explained
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Why Does First Gear Have The Most Torque? • First Gear Torque - Ex...
The final drive ratio is typically the gear ratio for the differential, or the final location where the gearing is altered before being sent to the wheels. Changing the final drive ratio heavily impacts the way the car behaves. If you increase the final drive ratio, each gear will have greater wheel torque, while sacrificing top speed. If you decrease the final drive ratio, each gear will have a higher top speed, however deliver less torque. Raising the final drive ratio also means you'll be at higher RPM in your top gear, raising your engine's speed on the highway. You'll also need to correct the speedometer.
How To Calculate The Top Speed Of A Specific Gear In MPH:
Top Speed = ((RPM*60)/(Final Drive*Current Gear Ratio))*((Wheel Size (in.) +(2*(Tire Ratio/100)*(Tire Width (mm)/25.4)))*Pi)/(5280*12)
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[@Jake-wf2bh]

"And you're gonna hit vtec at some point" That is gold.

[@bernie3075]

I don't get it

[@supps101]

​@bernie3075 you have to understand vtec first

[@evanhasson6032]

I love how casually he mentions VTEC

[@nickpavloff8977]

I want the 1989 gtr vtec

[@al-kharusi]

S2000

[@alexandremelo7656]

@Randy Candelario no vtec is not lame, but people like you are

[@Wazza722]

Why are they lame?

[@bernie3075]

​@alexandremelo7656 what is vtec

[@revans4257]

Also changing final drive to a more aggressive set up can also increase the amount of times you need to shift in order to reach 60mph and may alter acceleration time.

[@TheChasingK]

I believe the proper term is "VTEC Yo!"

[@magistermurray]

Just wanted to say how much I enjoy your videos. I love cars and have always been fascinated with how they work. Your explanations of automotive systems make me appreciate the complexity and beauty of cars that much more. Thanks!

[@christinewesthead3260]

Perfectly explained. Exactly the information I was looking for. Thank you very much.

[@andrewkline]

wow, that old gears video... your marker skills have improved greatly on the whiteboard.

[@sonnytrejo2403]

As always, very well explained and simple understanding! We appreciate ya' Thank you sir

[@emp1985]

Details mentioned that could be included: how to change the gear ratios, and what device/where do you get one to correct the speedometer. If they're mentioned (the first being kind of the tpoci), I'm thinking it's always good to include details. Great vid!

[@laidbackLUKEY]

Fantastic video Jason very informative. I also own an 02 AP1 which I've been considering doing this for a while now as I had seen an original Japanese vtec club style video in which they put a very mildly tuned S2 against a standard AP1 and Ap2,the one which had the shorter final drive was very eager through the gears off the line. I know you was thinking of doing this modification on another previous video of yours I watched so keep us updated

[@TheAmbrose20012002]

Nice explanation that clear and easy to understanding!

[@ChibiChibi310]

very informative! great video! I'm catching up to you buddy.... been working at a mechanic shop! really liked your detailed explanation about why and how the final drive crossover basically can be the meaningless to have it be more aggressive. @4:15 if your're looking at a graph. very informative. keep killing it. love your videos

[@ramiabdelmajid9990]

Clear and detailed explanation. Thank you!

[@aizak7789]

Amazing video as always! Esssentialy its like changing gears in a mountain bike. in 1st gear with the small disk every hard step at each pedal equals front tire lift off, and the more you switch to 2nd and 3rd disk in the pedals, less torque is generated from your own muscles instead of an engine :)

[@rifleman7313]

Great job at explaining everything.

[@PhlBrs]

Thank you so much for thinking of all non-Americans :) Love your channel, keep up the great work! Best wishes from Germany

[@kcwalkman]

Great video Jason, I'm sure glad you haven't stopped saying your signature opening diaogue. it really sets you apart from the other guys. Again thank you.

[@blingbling574]

Consider strengthening your driveline, especially for the drag strip. I snapped an axle at the line, and that was on foot wide drag radials.

[@LucasGonzalezA]

Pretty informative. Thanks !

[@robbyclerk8821]

Great vid! You should totally make a vid on the benefits of the FRIC suspension systems that F1 teams use. I think that stuff is super interesting! Thanks!

[@dylanvaughan5392]

Love your videos keep up the good work

[@hojo70]

Excellent explanation, thx

[@swag_turtle4981]

really nice video, i looked at others and this one made all of the other videos make sense. it kinda gave me the last puzzle piece if that makes sense.

[@I_love_drifting]

Thanks this helped a lot I play way too much pixel car racer and didn't understand final drive but now I have perfect torque.

[@ruanrocha3093]

thanks! now i understand what is final drive ratio

[@sulimanothman]

U got really good skill in delivering information

[@itsyaboia-dub1120]

Can you do a similar video in relation to increase/decrease in wheel and tire sizes?

[@mrcowboy69]

awesome video man! very helpful I'm actually debating between 4.77 or 4.57 on my s2k

[@AndrewFRC135]

Thank you for the great explanation! I am doing a rear end swap on my '87 Cougar and I am glad to see that your anaysis and selection criteria agrees with mine. Are you looking at the 4.57 ratio, I presume? 11.5% torque increase seems worhwhile and fuel mileage is not going to suffer much. I myself am going from a 2.73 ratio to a 3.55, which is a staggering 30% increase, and it'll still keep my freeway rpm just under 2k, which is great for a V8. Its fun to breathe a little new life into these older cars, isn't it? :)

[@geraldkrasnow1808]

I have recently gotten into your videos and they are very well done. I like learning about vehicles the way you teach. I would just like to ask if you can make, if you have not already made, a video on why all four tires need to be changed at the same time on a 4x4 when you get a popped tire/low tread. Thank you!

[@Runnaent]

I did not know gear ratios affect speedometer readings, thanks for that info bruv.

[@RHSkmg365]

Awesome, nice job, TY

[@jeffsloane8628]

Great video! Math checks out. Don't forget to mention gear whine. You go too short in the final drive and you will hear the rear end from inside the car.

[@Yathuprem]

Did u change the FDR of ur S2000, if ur planning, pls dont forgot to film it.. Nice video as always.. Thanks

[@7viewerlogic670]

Great info, why don't manufacturers put super tall 6th gears in? If I'm on interstate and have to downshift no big deal, that's what I signed up for by driving manual.

[@EngineeringExplained]

+mike anderson I don't know, I wish they did. Mustangs are the only cars I know of that do this really well. Love Mustang gearing.

[@sadakotube]

Engineering Explained how about other gears. why do manufacturers sometimes seem to spec ratios outside the peak efficiency range?

[@FoDaddy]

The Viper had a very tall 6th gear, 0.50 :1 for 6th, the 4th gen F-Bodies had the same T-56 and also had tall 6th gears.

[@GrandPrix46]

My '95 Z28 M6 has a plenty steep 6th gear, cruising at almost idle doing 70. Obviously a Honda won't be doing that because it has no torque, maybe a better question is, why do they make so many cars that are completely gutless at lower rpm's?

[@sergioferreira5771]

Jeff Smith they do, but those cars dont have top end

[@kodez79]

Good information. What I miss from this video is information about acceleration in ranges that cross gears. Say 50-90 for instance. That would have you take one gear-change with the original ratio and two with the others. Another interesting range would be 0-100, where you would spend less time in the highest ratio with the original gearing.

[@ngrinshift4383]

I learned alot of what you just went through by playing "GRAN turismo" when I was 12 years old. Guess I'm fortunate that way... I should of went to an engineering school because this stuff interests me to no end!!!!! Good Job ! AWESOME !!! Thank you for this contribution. MORE PLEASE ! lol

[@jpardoa94]

Thanks for the Km/h chart!

[@nomodnolife]

This is awesome! For those who know what they are doing lol Thanks for the video! Will help me a lot in the future in my channel

[@forester_overland_nz]

Thank you!

[@Rickyboy707]

I've tried to explain this subject to some of my knucklehead friends who think that the taller (numerically) the gear, the faster you'll go in a quarter mile. Yes, to a certain extent, but the elapsed times, and more so, MPH, will eventually drop off. I know this because I experienced it in my own racing career. This video explains very well what happens, so I'll be sending this link to some friends. But, alas, they probably still won't get it.

[@thomaspc0]

Nice video, as always. One thing though, the 4.77 gears are a LOWER gear than the 4.1. You stated it the other way around (at 4:48 & 4:55 time).

[@JPRTonundFilmstudio]

I would tune the car the other way, increasing the top speed to finally get a lower rpm when driving on the highway (especially with older cars...)

[@danielmexicanpride]

I just bought 4.77 fd for my s2000 and I find this video! Subbed!

[@TheIrishPhantom]

Going from 3.21 to 3.92 in my truck tomorrow. Also dropping a positraction in. With 8 Gears I'm not too worried about top speed suffering.

[@angeljoy5234]

Thanks! Now I can fine tune my drag car in pixel car racer

[@rizazhafiry6435]

Ancel Curativo Bout to make that sub 6 drag car

[@TheOnlyHMR]

Thanks now I can tune my car on forza horizon 3 hhaha

[@nickpavloff8977]

TheOnlyHMR I used em for grand Trismo lol

[@BlueRice]

go with 4.77 final drive ratio. you can take off like a rocket.

[@DefWun]

There's also added stress on components. Axles come to mind.

[@boosted2.4_sky]

Johnny Doe I was thinking the same thing... If you Increase torque you'd better increase axles.. and supporting components. ..👀👍™

[@0xXKARLOSXx0]

not really, your tyres will break traction before your axles start deforming

[@boosted2.4_sky]

not if you have good tires. Axles and drive shafts break alot. ...

[@mihpop9733]

Karlos understands it and depending on the car's age and condition it should be able to handle it unless you go over the top

[@AdussFadass]

No need to worry about a stock S2000 breaking any axels though. They are only rated at 162lb-ft of torque. lol

[@nicolaandria522]

Thank you for the explanations (and the other video with the tests on the Honda), luckily for me all the downsides are meaningless since I am going to modify a track car

[@yyyoyyyo202]

Going for a shorter gear is good if you can bump your redline up some like 500rpm if you can make or hold power up that high. That way you don't have to shift earlier/you can hold the gear the same amount of time while keeping the benefit of multiplied torque down low and in the mid range.

[@lionzoo71]

Thanks for releasing this on the same day I (likely, pending tear down,) blew up my final drive.

[@jonasarche]

hey great video as always! I just have one small question, in a front wheel drive car is the same exact thing? as the final drive is in the gearbox not spaced out by a driveshaft. keep going!

[@io504]

I've got a close ratio box in my Suzuki and it's fantastic, though I wish 5th were a bit longer - doing 4k rpm while cruising is a bit irritating

[@clonious]

I learned much of this while tuning cars trial and error style in Forza racing games, but I didn't know that until I watched this...

[@Militaristics]

years ago when i was street racing with a 79 monty with a 355 and 3 speed auto I learned a lot of this the hard way. my car was traction limited by the real wheel size i could fit and my transmission ratios were set in stone because I couldn't afford to change the ratios or add a OD. I did run a much looser converter 3500 rpm. after doing some testing and basic math I figured out a 4.56:1 ratio would be the best ratio for 1/4 mile, because it would let me run through the traps in 3rd near my TQ peak, I also learned the 4.56: would over power the traction limits of my rear tires with the suspension setup i had at the time. it took a bit of tweaking with the geometry of the 4 bars to get the pinion angle corrected and the reaction of the setup to plant the tires instead of wheel hopping and wasting energy twisting things. this was around 30 years ago. thanks for the videos that shed some new light on things

[@darrenmorris869]

Militaristics Wow! 4.56 for 1/4 drag race!? How tall were your tires? 32+s? In the 90's I used to bracket race my old 1977 Trans Am with 4 speed in the 1/8 mile. It had a 3.73 final and 28 inch tall tires (275/60r15). It had a warmed over 400 Pontaic with Edelbrock heads. Cruising 70 mph down the highway the engine was running just over 3k. Didn't even need to down shift to pass. I can't imagine what 4.56 gears would do in that thing.

[@Militaristics]

i remember running 26 or 28 in tall tires on that car with a powerband of 4500-7500 so that's why i ran the 4.56's crusing rpm wasn't a big factor as I did not drive the car for any distance and couldn't afford a gear vendors OD unit.

[@cs7777]

thks for your effort to show conversion in kph!

[@EngineeringExplained]

Sure thing, finally starting to listen to people about this haha.

[@tripointkid]

A big disadvantage you didn't mention is the effect to throttle response, say mid turn feathering the throttle. The 4.77 is very very jerky in these conditions and can often unsettle the rear end. Taller gearing smooths out the jerkiness at the expense of less torque. I think this is very important to mention.

[@willc5512]

Like a 2.41 or 2.28 gear in the old GM cars? Or is there a cut off where u loose ALL performance potential?

[@moabsh]

Thank you

[@jgjgjgj1]

Random question, since you are amazing at explaining mathematical calculations could you do a video explaining what is more efficient when heating a house in the winter, if keeping your furnace set to one constant temperature is more efficient than lowering it during the day and raising it back up at night. I'm sure the formula involves rate of heat dissipation and the rate in which the furnace can pump out heat Vs the energy it uses doing so, now I wonder if the heat dissipating is a constant variable or if house is warmer it dissipates faster, thanks if you get around to looking into this, great channel btw always watch your videos

[@CartoonAnakMalaysia]

thanks

[@belaybekele2625]

WoW Very Nice Engineering E..

[@anhiirr]

various reasons, fuel efficiency, power efficiency, top speed......but you may also benefit from a down tuned gear ratio. Depending on the track or demand of power application

[@anujitganguly2029]

Very nicely explained for a person like me who does not have any engineering background. So can we vary the FD ratio on the fly ?? like switching between the "Eco mode" to "sports mode" ???

[@MarkLockHolmes]

sick vid

[@Genthar]

Commonly done with offroad vehciles when you up tire/wheel size. Need to regain some of that lost power so you regear to compensate.

[@agift4u240]

Awesome!

[@skillstacking]

Great stuff. Is there a chart online that we can go to that shows what happens to the top speed if we change the gear? For example, if I have a 2011 wrx and I want to change the gear, is there a chart on line I can go to to see my options and what will be the differences?

[@chillipompom5263]

mitsubishi lancer , outlander sport and outlander final drive ratios are all above 6 ,stock.but because of cvt and a very low final gear ratio they cruise so very well on highway.

[@bigdeal4147]

i learn more in this video than a semester in physics class

[@John-uj9zy]

I was looking for 3.90 or better in a truck for towing. Got one with a tow package @ 4.30. I would have been happy with 4.10, but Im not going to be picky since I didn't have to get my hands dirty. It kills MPG but sure is handy backing up a trailer or off-road.

[@prayerpowersr854]

I just watched your car gears video from 2011, I must say, you have become a lot more confident and mature since then, and also glad you've ditched that 'High School Musical Zac Effron' hairdo

[@dknollRX7]

I changed the front and rear sprocket on my ZX10R because it would hit 105mph in first gear! I went down a tooth up front and up 3 teeth out back. Now it accelerates even better, but hits about 85 mph in first gear, making it a little more "practical".

[@ianmcvicker2509]

Hey. Could you possibly do a video comparing straight cut gears vs helical cut gears? Thank you.

[@sieghail86]

You need better rear axle/subframe bushings and reinforcement to compensate the increased torque transmitted by the differential. And engine wears faster due to higher rev.

[@dhananjaypatil1111]

could you possibly make a video on the amount of air flowing into the engine for various loads and cc's

[@comaradelee]

good video

[@sadakotube]

great info. next question: how do manufacturers decide the gear ratio, why does it sometimes ignore peak torque?

[@EngineeringExplained]

This may help you out! kzbin.info/www/bejne/sIulopVmj6-Grbc

[@Loyal_Honda_Fan]

any advice to make my cl7 accord faster? ( k20z2 155hp) ima get a magnaflow at first.. Edit: great video!

[@07wrxtr1]

Good explanation, also, if you're going to change the final drive, you can also upgrade to a better non crappy stock lsd (most stock lsd's are kind of pathetic in most cases, they may as well be called an open diff in all honesty) like a quaife in the process (not cheap, but considered the best for street use). Kind of a no brainer upgrade rather than throwing thousands at the engine unless you want to go forced induction and risk reliability. This is my next mod after the lighter weight 2 piece rotors/pads/fluid and exhaust is changed. Now if we only had shops in Oregon that had people that actually know how to properly install parts (staff that's worked there for greater than 6 months..), now THAT should be your next video! Best shops in the NW and why (besides Cobb in Tigard because not everyone wants a ME TOO subaru right?).

[@trued2010]

A short video on over/under drives would be a nice follow up to this.

[@EngineeringExplained]

I believe the definition essentially comes down to having a gear ratio under 1 for overdrive.

[@zwild1160]

Application is everything when choosing a final drive ratio. How will the vehicle be used. Towing, race, everyday driver, or somewhere in between. The engines power curve is a big factor along with the transmission in deciding. If it doesn't work together as a unit it's not going to perform well at all. You can easily over gear and find you have run out of engine. I've seen plenty of guys do this.

[@congenio]

Correction: The speedo will NOT become incorrect by changing final drive ratio. Speed is usually calculated by measuring revolutions at the wheels (via an odometer that is also used for ABS and ESP) and taking the known wheel circumference into account. This is not at all influenced by gearing. The only way that gearing could have an effect on the speedometer reading was if the speed was calculated from RPM multiplied by the gearing currently in effect.

[@kristianhermann5971]

Not necessarily - some cars use a sensor to measure rotations of the differential gear for speed (usually called a vehicle speed sensor as opposed to a wheel speed sensor) - in this case changing final drive (i.e. number of teeth on the ring gear) does effect the speedo unless a new speed sensor gear is installed to compensate

[@bergi85]

I would check that second gear on the 4.10 again. I autocross my stock 2003 AP1 and my 2nd gear bounces at 63ish.... no where close to 68mph. And the info on S2ki confirms.

[@DENicholsAutoBravado]

In computer gaming. I got a lot more performance out of cars by increasing the final drive ratio. Then, for the last manual gear I could use, I'd make it taller than how the car was stock. Why? Because I needed a higher top speed. It was extremely effective. Occasionally, when a track wouldn't work out if I did my normal adjustments, I'd go for a taller 2nd to last manual gear to meet in the middle. There was 1 track where even the last gear needed to be shorter and if it was like the scenario in this video, I even made the 6th gear shorter than the 5th gear. If you know exactly what you want a car purposed for, you can dial in gear ratios, if you don't, or if you just want a car that's more fun, but you don't want the highway to break the bank? Well..tough choices unless you can also change the "over drive" gear. Apologies, I was a bit vague on the final gear number, and I wasn't referring to the final gear ratio when I said last manual gear. I don't remember anymore how many gears I had to chose from.

[@davidyanagi2680]

KZbin unsubscribed me from your channel... :'(. now I have tons of videos to watch to catch up! :)

[@ray-2647]

I did a version of this on my RSX transmission, where I changed the final drive from a 4.3 to a 4.7, and I switched my 6 gear for a tsx 6th gear, also put an lsd in from an si.

[@joeyhammer1998]

Did the 4.7 make any noticeable changes in acceleration?

[@ray-2647]

SD70ace_railfan it’s not a big difference, it feels more rev happy though. The 4.3 is better if you plan to do turbo though.

[@LurkerDanny]

Could you please make a video explaining how increase ( or decrease ) in wheel and tire size effects gearing? For example my car ( 1994 Toyota Mr2 ) came with 205/50/15Front tires and 215/50/15 Rear tires. I currently run a 225/45/17 Front and 265/35/18 Rear. Thanks!

[@namoroman666]

What is the most efficient internal engine on the planet? Difference between cylinder size and their efficiencies? If I can say, you are the Neil Degrasse Tyson of the car world :) Thank you for your passion in your work! Very inspiring!

[@travezripley]

I absolutely love your explanations and love your channel. How can I obtain a tshirt?

[@hapaworm]

axle ratio play an important role in commercial vehicle as well. Both fuel consumption and weight carrying capacity are vital. Assuming a vehicle carrying a fix amount of weight and cruising at a constant speed, reducing the axle ratio will contribute in fuel saving however it will greatly impact the wheel torque due to decrease in engine rpm (from engine torque curve). At what axle ratio the vehicle will not produce enough wheel torque allowing the vehicle to travel at the same speed and load? thx

[@SheepDogReady]

I have a 2012 Jeep Wrangler with an Edlebrock Supercharger, 4 inch lift and 35 inch tires. Do you think it would benefit me to change the gears from 3.73 to 4.88?

[@JongTheDIYCarGuy]

Hi, from 4.1 down to 3.3 final drive will it affect shifting of an automatic transmission? Will the shifting get ugly?

[@FoDaddy]

About the lower top speed thing. If you're driving in a vacuum then the top speed will be limited. But in the real world where there's air resistance. Changing the final drive won't necessarily reduce top speed. It's dependent on how much power the car's engine makes. For example a stock new edge Mustang GT with the manual has a theoretical top speed of about 219 MPH (24.9 inch tall tires, 3.27 axle ratio, and a 0.62 5th gear ratio). But obviously it won't have nearly enough power to reach that speed because the dread hand of aerodynamic drag will limit keep things to about 140 MPH. So if you were to change out the rear end gears to something like 3.73, the theoretical top speed will drop to around 191 MPH, but again because the engine doesn't produce enough power to reach that speed, the actual top speed will still be around 140 MPH. It might be a bit higher because the engine will be turning more RPM for any given speed and will be making more power when it hits top speed vs. having the stock rear end gearing.

[@TurboSTridders]

I would love to see how this applied to AWD. How is that the front and rear has different ratio and power.

[@Josh-to7it]

Hey, Jason, could you possibly explain how final drive ratios work in vehicles with transfer cases and/or AWD?

[@Josh-to7it]

Arthur Friday yeah, cause I know with 4WD you have to have the same gears otherwise your drivetrain will lock up, I just have trouble understanding how the system integrates between the rear and the front, and why they need to be the same, or different with different sized wheels.

[@imadecoy.]

Not such a huge deal with AWD because of the center differential (allows the front and rear to turn at different speeds). The reason you need equivalent ratios with 4WD is because it doesn't allow the front and rear to turn at different speeds. Can you see why that might be a rather large problem?

[@forrest225]

On 4wd the transmission inputs power to the transfer case. When the case is in 4 hi or 4 low it mechanically locks the front and rear outputs to the same speed. If the front wheels were smaller, in 4wd they wouldn't spin fast enough if the axles had the same ratio.

[@PhaQ2]

I had an old mid 70's Chevelle that had 2.73 gearing. It was a complete pig off the line. (145 bhp/250 lb.-ft) With bigger 15 inch tires and enough road, I could do 155 mph/250 kph. I miss that old boat.

[@fbdowntown21]

So I'm considering this option for my frs. But in the long term how would this effect the engine being at a higher rpm on the highway? Would it put more stress on the engine shortening the life of it?

[@julianoliva2850]

I recently bought a 2011 chevy Colorado with a 10 bolt 8.5" I dont know the gears ratio but I want to know for what are they designed ... cause I wanna make some upgrades to drifting and some 1/8 mile races...

[@mrzzatvlogger6526]

I'm just be in here. Sorry for asking, what i'm understand here is, if the final ratio is lower, then the top speed will increase? It's that true?

[@Divisionsixty]

I LOVE YOU man