Why Is Final Drive Ratio Important? Accelerate Faster!

[@Jakedrifts]

"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.

[@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

[@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.

[@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!

[@PhlBrs]

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

[@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.

[@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.

[@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? :)

[@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?

[@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...)

[@itsyaboia-dub1120]

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

[@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!

[@TheChasingK]

I believe the proper term is "VTEC Yo!"

[@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.

[@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).

[@jpardoa94]

Thanks for the Km/h chart!

[@Yathuprem]

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

[@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.

[@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.

[@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 :)

[@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.

[@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...

[@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.

[@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.

[@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

[@bigdeal4147]

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

[@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?

[@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.

[@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".

[@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.

[@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

[@richardstanford8427]

The real win for performance would be to map wheel torque vs. road speed, and find the final drive gearing that gives you the most space under the curve.

[@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.

[@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.

[@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

[@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

[@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

[@endoftheroad10090]

But at the same time, if your main acceleration metric is 0-60mph, a higher ratio final drive might induce an extra shift before 60mph, which depending on the shifting time, might end up being slower than the original FDR. Also, a higher wheel torque assumes you have the traction available to put down that torque. Alsooo, choosing an FDR ratio must take into consideration the fact that specific ratios may induce what's called "heterodyne effect", which destroys your cars NVH.

[@EngineeringExplained]

Agreed, though I don't think the 0-60 metric is the ideal metric to use for acceleration (after all, it's a unit of time, not acceleration). It doesn't tell you what you'll feel. Seconds 1-3 might be very different from seconds 4-6, for example.

[@chriskeiley5343]

well the power band of an engine dictates much of the qualities and characteristics of the acceleration. the powertrain system must be thought of as a unit, everything works together to get the result (work) done. how fast the work is done would be the unit of measure for 1/4 miles race. the amount of work ( load) can be measured in payload or hauling capacity. torque is most effective when hauling, hp is more effective when racing. but we must have both.

[@IaintTrynaGoOutLikeBIGnPAC]

endoftheroad You won't notice the time on the street but that's more for dedicated drag races who that really matters to. 0-60 doesn't matter to manufacturers unless it's their flagship car

[@chriskeiley5343]

I cannot support this theory. my v8 suv with 3.73 gears os super slow off the line, but with 3.55 gears it is almost normal. however the toing capacity is much less.

[@endoftheroad10090]

Considering the average Joe will always say "my car does 0-60 in x seconds" and not "my car has a peak acceleration of 0.85g in first gear", 0-60mph times will always be a requirement for a powertrain configuration and one every manufacturer will consider when picking an FDR ratio

[@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

[@sonnytrejo2403]

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

[@Runnaent]

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

[@TXHeat1776]

Eliminating a gear (or adding a granny gear) can be desirable for trucks that tow or off-road vehicles where 1st gear torque matters.

[@ΑΡΗΣΚΟΡΝΑΡΑΚΗΣ]

you buy a Scania with 730hp and no problem

[@donald_ts]

This is a minimalist idea about modifying stock cars, you can have the same acceleration numbers results by increasing engine power, powerful engines require smaller differential and gearbox ratios. If you have big power and high gear ratios the result is lack of grip and spinning free wheels. Cheers

[@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.

[@boorek0]

can you also explain how acceleration will be affected and by how much? i. e. 0-60 mph and 40-70 in this particular case? I think that's main reason why people changing final drives...

[@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.

[@kayhesse]

in the case of a stock s2k its beneficial to swap a higher final drive just like i did with my integra (btw not needed to adjust speedometer in a fwd gearbox). note: when you change it out for a to short of a final drive or gear ratio you maybe get more wheel torque but when drag racing its harder to get grip in 1st gear and in track racing you have to shift a lot more what Costs time in acceleration/decel balance. its key to Find the balance for your engine power and purpose.

[@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

[@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

[@bigpp9054]

A shorter final drive ratio will not necessarily lead to higher wheel torque when you put speed as a constant. E.g. With a stock final drive, a b series honda will hit 100kph at second gear @ 8000 rpm. With a short final drive, at 100kph, the car needs to be put in 3rd gear at 6000 rpm, which produces less wheel torque. The car with the stock final drive will accelerate to 101kph faster than the other. Yes, engine torque is higher at 6k rpm but wheel torque is lower. Top wheel torque rpm matches top hp rpm, with any given gear. You cannot conclude that a shorter final drive ratio would mean better acceleration. One cannot look at final drive ratio separately from its gear ratios. It's a harmony between the 2. Plot a graph of speed against torque using all the gears for each final drive, then you will see which final drive suits the track best (kept at high rpms)

[@DBGMLV]

In most cases, on petrol powered cars, a longer FD is needed. Here is what I mean : 3700 rpm at 70 mph is too much, especially if you have a loud af exhaust. I think manufacturers should take a page from their own book and do what they do on automatics, which is either add more gears, which on a manual is kind of hard, or give cars a longer 5th/6th gear.

[@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?).

[@RootsandTendrils]

You didn't fully explain the ratio of drive shaft rotation vs. axle shaft rotation and how it corresponds to the given numerical figure for Final Drive Ratio.

[@hondacrxrus]

wouldn't changing final ratio from a 4:10 to 4:44 would also reduce the time for gear change. similar like a lightweight flywheel would. I actually did that exact ratio change and I do notice lower top speed as expected and more torque. but it also seems like syncros line up faster on an up shift with less delay in the exact same relation as percentage of ratio change.

[@pachokardana6192]

When you want to cruise at low rpm and you have only 5 gears without overdrive you need longer diff 2.8 - 3.2 otherwise all the engine components are at much higher rpm which leads to fast wearing . So what do you want reliability or acceleration is up to you . I personaly prefer longer diff for my 1.9 litre 140 hp atmosphere engine with 2.8 diff and 3000 rpm at 80 mph it is great.

[@christinewesthead3260]

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

[@chodkowski01]

The computer in my car limits my top speed to 162 mph. With going to a higher gear allows me to still have the 162 mph top speed but it helps my cars acceleration and makes it easier on my clutch also getting my car’s perfect rpm range faster.

[@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.

[@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

[@anguspd]

Changing the F.D in an auto significantly to the point of eliminating a gear, I imagine would be more advantageous than in a manual. For the simple fact you would loose 6th but obtain a gear lower than 1st. I imagine an auto would make better use of this "new" gear as it would be only useful for such a small speed range, ie launching from a start

[@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.

[@pachokardana6192]

whatever you do with your diff ,you have to know something - it's much better when cruising at 2000 rpm rather than 4000 rpm. Plus when cruising at lower RPM every other component in the engine bay will wear much less . So logner diff is the one to get. Shorter diff sucks on highway and on any place except track . Nomather if your car is quicker or not , if you need more power hust swap the engine with bigger.

[@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

[@Shinn_S]

Why do you need adjust the speedometer? I thought the ABS sensor only measure the rev of wheel. Bigger ratio makes car go faster. Faster means higher rev speed for wheel. Higher rev speed for wheel means higher speed on speedometer... I don`t understand...

[@memovillarrealmora1830]

What's your opinion on the Kia/Hyundai DCT-7 coupled to the 4 cyl. 1.6 I Turbo GDI? These are the gear ratios 7-Speed Dual-Clutch Transmission (DCT) - - First - 3.786:1 Second - 2.261:1 Third - 1.957:1 Fourth - 1.023:1 Fifth - 0.778:1 Sixth - 0.837:1 Seventh - 0.681:1 Reverse - 5.074:1 Final gear ratio - 4.786:1 (1/2/4/5) / 3.526:1 (3/6/7/R) Clutch type - Dry type double plate

[@sulimanothman]

U got really good skill in delivering information

[@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!

[@jckgoldness]

Currently running 3.6 trying to get a 4.08 or a rear end from a convertible version of my car

[@TurboSTridders]

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

[@michaelgarrow3239]

My thoughts are -max horsepower in 5th 1/1 should equal the power needed to equal coefficient of friction of the chassis at that speed. Or perhaps max torque?

[@VSautomotive]

I've got a 4.27 diff in my E30. It's pretty short, hoping to find a 4.10 LSD.

[@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" ???

[@BrianNC81]

I switched out 3.73 to 4.56 in my diesel truck after moving to 37" tires. It accelerates a lot quicker but I don't care for the high interstate rpm. I should have gone with 4.10.

[@HaworthJimmy]

I’ve used a 4.1 a 4.3 and a 4.7 in my turbo mx5. Real mixed bag of sector times on the Hillclimb. I’ve got 200rwhp and run 205/50/15s with a 5 speed box. The 4.1 has the quickest launch, the 4.3 has 3 out of 6 sector records and the 4.7 took one sector record but by quite some margin (.3 secs) My fastest time is still with the 4.3. I’ve looked at going 3.6 with a 6 speed however thus seems to give the same results as a 5 speed up to 5th gear and I don’t get into 4th on the hill so the extra gears not any advantage. Have you got any thoughts ?

[@josephzaja9210]

I have race with same car weight and all k24 civic gearbox k24 4.7 fd vs k24 gearbox k20 4.7 fd. And k24 longer gears with k20fd smkoes k24 4.7fd.. wtf? We think that shorter gearbox and 4.7 fd will run out longer but no..

[@troysanchez776]

If 8, 9 and 10 speed transmissions become popular, will they do away with some engine complexity and just go for low RPM instant torque? It seems like a second wind from variable intake or variable cam timing is wasted when it just lugs at 80mph in top gear.

[@elliot438bcfcVTEC]

Not worth the mention of added gear changes to reach said speed potentially slowing the acceleration down? Depends a lot on driver skill but you can only change gear so fast with certain transmissions plus the added stress on them if you are trying to change gear at light speed

[@DemeterVT]

But why not a variable final drive ratio system, like what we find on bicycles (but with gearings).

[@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

[@mrgjs4044]

Hang on a sec... The main reason why people change close gear ratios and final drives is for faster acceleration and your gears staying in higher rpm, which means (if you have a turbo or very high lift cams) you will be in the powerband most of the time... Classic example of that is the big turbo setup... You wouldn't want to drop into a different gear and be off boost because of low rpm... Hence the need for close ratio gears and final drive setups... This way you have a better chance of being in the boost or powerband range to give you that acceleration compared to standard gearing :-)

[@BlueRice]

the difference between car enthusiast and an engineer, they know how car works but dont understand what makes a car fun. i remember he picked turbo over supercharger because of how the efficiency it is compare to s/c. then after he drove a s/c he understood the power delivery was linear that of stock engine but more power. thats when he understood what makes a car enjoyable its the same thing why i thought pruis was cool when it first came out. not because how it dive but how it was in conjunction to engine and electric motor.

[@agfdsa123]

5:00 , " one really aggressive gear before all of that" refers to 4.77's 5th gear, the " 4.1" Final Ratio you're pointing or a big Final Ratio # eg 4.77?

[@danparaschivoiu8620]

How about the stress? Gearbox , 4x4?

[@Zavarkinas]

you can switch 4 times gears while lower gears switch 3 times on drag race, whats the differences?

[@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

[@danielmexicanpride]

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

[@mrcowboy69]

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

I thought that speed is determined by the ABS sensors on the wheels, therefore I don't see how a gearing change could affect the speedometer. On the other hand, different wheel size (circumference) should affect the speedo.

BTW I could imagine that a modern car with a GPS has a way to adjust the speed readings. Not that S2000 is one of those cars :-)

[@shi01]

Many older cars use a little gear inside the gearbox which is conected to the output shaft to measure the speed. GPS can't show you your speed in long tunnels.

I wasn't suggesting that GPS would be actually used to measure speed, for that it is way to unprecise in many situations (slow, changing speed, tunnels - like you mentioned etc.). I was merely saying that under certain conditions can the GPS be used to adjust the speedometer value (ie. by comparing the measured speed of the vehicle to the GPS speed on a motorway). For example to account for tread wear. BTW: Is this gearing inside the gearbox used still in new cars or is it something from the past? Because I don't think the car makers would use another device (= costs) if they can measure speed otherwise (ABS sensors). But I can't be wrong, of course.

[@BarbecuedPossum]

Thing is, you also have to account for the time in having to change gear more and in turbocharged cars the turbo having to spool to full boost again. I don't really see the point in changing final drive unless doing specific runs or with a sequential or dct box

[@ΑΡΗΣΚΟΡΝΑΡΑΚΗΣ]

you ever heard about antilag?

[@BarbecuedPossum]

Arthur Friday Yeah that's what I meant :) like for the 1/4 or mile

[@BarbecuedPossum]

ΑΡΗΣ ΚΟΡΝΑΡΑΚΗΣ Yes because every road car has anti lag......

[@ΑΡΗΣΚΟΡΝΑΡΑΚΗΣ]

BarbecuedPossum it's doesn't need to spit flames...

[@BarbecuedPossum]

ΑΡΗΣ ΚΟΡΝΑΡΑΚΗΣ since when did I say it did?

[@x3D]

Engineering Explained you shouldn't need to change your speedometer reading because modern (ish) cars use the ABS rings to determine speed? Or does your S2K just use a gearbox sensor?

[@CyclicPilot]

My pick would be FD of 4.57 so you reach 60 in 2nd, or just 4.1 with 'shorter' gear ratios before 6th so you get decent wheel torque in lower gears and better fuel economy in 6th (more choice, that's why you have gears right? :p)

[@WhyteLis21]

i see this more for racing especially short circuit tracks n drag. why would u do this in your daily when it gets worst mpg? still great to talk about though.

[@davidjames1684]

I disagree with your statement that going "too" aggressive on the final drive is pointless cuz then you are just "throwing away" the top gear and inserting a new lowest gear. There are many good things happening with an aggressive final drive that I didn't even hear you mention. One being that the speed range of each gear with the more aggressive final drive is shorter, meaning the driver can "zing" thru each gear quicker. Also as I mentioned in one of your other similar videos, if possible, the best idea would be install a very aggressive final drive for maximum fun, but also somehow swap out the top gear so that it is same as stock (overall), so you can still cruise at highway speeds at low RPMs. This is not a cost effective solution but would be the "best" overall. You might also want to mention if someone wants just a mild overall reduction, it is cheaper to go 1 size smaller on the tires than to swap out the final drive (ring and pinion gear), especially if you need new tires anyway. It might only be 5% (or less) change but it would effectively be "for free" (if you needed new tires anyway). Another option is to do a mild change on the ring and pinion but also drop 1 size in tire diameter so the combination of the 2 give you a significant torque increase in all gears.

[@dylanvaughan5392]

Love your videos keep up the good work

[@godzuki2099]

Rearwheel drive, VTEC... Is this car yellow by any chance?

[@ballista7367]

+Engineering Explained can you make a video on what a car weighing 3000 lb with 1000 hp and 100 lb tq, and another with 1000 lb tq and 100hp. Although I know that these figures may not be realistic(At least with their pairing figures) but I think it could show just how important each can be and just what each does.

[@EngineeringExplained]

Very similar video here: kzbin.info/www/bejne/eamuYattdqpmqZo

[@flyfaen1]

Doesn't most cars use the ABS wheels speed sensors for the speedometer? At least every car I've worked on made in 1990 and later uses the ABS-speed sensors, thus you can use whatever final ratio you want and the speedo will remain true, set aside a purpose-made error of showing 5% more than you actually got, and ofcause effects of actual wheel rolling OD.

[@M4Nathan007]

Why don't car manufacturers have a 6th (or 7th, 8th, etc) gear that is purely there for fuel economy with an extremely high top speed, that basically lets the car run at 1500rpm at 70mph without changing the final drive of the other gears? I know it wouldn't be smooth shifting from the previous gear, but wouldn't that have a huge benefit to MPGs?