FR-S Gear Ratio Comparison
 

FR-S Gear Ratio Comparison
____AT ___MT __# differenc _% difference
1 _3.626 __3.538 __0.088 ____2%
2 _2.188 __2.06 ___0.128 ____6%
3 _1.541 __1.404 __0.137 ____10%
4 _1.213 __1 ______0.213 ____21%
5 _1 ______0.713 __0.287 ____40%
6 _0.767 __0.582 __0.185 ____32%
R _3.437 __3.168 __0.269 ____8%

Did they make the AT ratios higher so it would not be significantly faster than the MT cars?

pretty sure the final drive on the auto is much longer than the MT.

Final drives are the same.

I think it has been mentioned here that all Toyota AT have 4th as 1:1 and all manuals have 5th as 1:1 so the auto will be much longer geared unless they shorten the final drive.

as the manual runs a 4.1:1 final drive then it would be difficult for the auto to be much shorter.

the long gearing of the auto is one of the main reasons (along with the less than sonorous engine) that the BRZ got such a savaging by EVO.

After seeing those ratio's I understood why the AT got better fuel mileage than the MT. It's weird seeing a six speed with only one overdriven gear though. Usually the 1 to 1 hits in fourth, and fifth/sixth are overdriven.

I think you got it backwards... but yeah... it's a bit dissapointing that the gears are so much taller on the autos.

you got your mt and at mixed up.

they made closer gear ratios on mt on purpose for faster acceleraton iirc..

most mts have closer gears than their ats though.

yeah the auto would be much faster than the manual is they had the same ratios, you just cant beat the autos lightning fast shift times

Here's a question: I want to do a 6th gear swap. Would other cars with AZ6 trannys qualify as donors (ie S2K or miata)?? Or is there some minor difference tht would prevent it from happening?

yes, in theory the AZ6 transmissions can exchange parts

the parts are different but the parts should align just the same...

i personally want shorter gear ratios in the auto, but at the same time i dont, i will be going supercharged and the longer ratios would be fine, i dont want to be shifting too much

The problem is no other AZ6s have 6th gears that are any shorter...the S2000 has 0.762 instead of 0.767, that's hardly worth the swap. Dropping the 6th gear about 15% would be a nice compromise between power for hills and higher speeds and fuel economy I think.

If you're hardcore about saving gas, you can pulse and glide it, but it's obviously 10 times easier to just have a longer gear.

Maybe in a future model...

IMO, cars with AT are normally heavier and have more drivetrain loss than MT so with higher ratios, it will compensate the difference but I don`t think the AT can be any quicker than the MT.

The OP reversed the labels.

Quite a few 6-speeds have 5th 1:1, though often times they will have a much taller final drive to make use of it, like the V160 in the Supra, which had a 1:1 5th, but used a 3.13:1 or 3.27:1 final drive.

With the 4.1 final drive and the ratios the way they are in the TL70 (6MT), it will be a very close ratio overall setup.

That's what you really need to be comparing when you're looking at other models, overall ratio. Just looking at the transmission doesn't tell you much, you need to include final drive. Obviously on the Zx6 they're all 4.1 in North America, so there's no need there, I'm just saying.

Jeff

See post 31 for an updated graph!!

What's crazy is that you would need a 3.1 Final drive in the MT to match the same cruise RPM as the AT. IMHO, the 6th gear on the MT needs to be at least 10% taller.

You would lose a lot more in added weight and drive train losses with an auto, than what you would gain in faster shifting. Even if gearing were identical, the manual would still be quicker.

Tell that to the zl1 owners where the auto is faster and the 350z owners too, most of those autos put down better tracktimes and 1/4 mile times than the manual people could post...

That is an absolute statement. Every auto is different thus your statement has no validity.

Especially since it's flat out wrong for multiple cars... :thumbup:

that usualy wrong.

Thanks very much
Can you post up what would happen with the 335 40 17s on an auto compared to a stock MT and AT...

Your lack of common sense is astounding:bonk:

so you want 335/40-17 on the AT and then with MT with both final drives?

Could you please do a graph of the auto with the standard 4.0 rear axle? I would really like to see how much the rpms dip into the "torque hole" area when the auto is upshifted at redline.

It's a consistent 0.713 ratio between gears on the AT I believe, so your rpms will be 0.713*7450 (is that right lol)=5311.

That depends on whether it's a dry clutch or wet clutch, the traditional wet clutch AT is less efficient and tend to be slower overall.

A dry clutch AT is still heavier than a manual gearbox by a good bit. I dunno exactly since I haven't weighed them myself though but it seemed like it was 40-50lbs or so. :iono:

The argument for what's fast and slow really doesn't have an easy answer. The transmission is actually a very small part of what makes a car go around the raceway with many corners. Large portion of the difference in dynamic driving at near limits though is the driver abilities.

Having said this, most traditional AT's even today are much less adaptable to the raceway as it is designed for ease of driving, comfortable shifting, wide range of use and speeds, and efficiency, for any normal car. However, today with advanced manufacturing and design, the sports-AT as we call it, has come a long way from the usual slush box. In the case of the FRS (BRZ/86) the transmission has lockup from 2-6th, it's programmed electronically to produce a very predictable shifts both in engagement of torque and shift timing, and in both up and downward shifts, utilizing the full range of RPM available. So in practical use, aside from the lack of ability of manually shock the drive system, it is very close to the performance and operation of the manual even on the raceway.

There is a big difference at the top 3 gears, between the MT and AT on the FRS... and that is perhaps done to make the AT a wider use roadcar, where efficiency at top speeds, as well as comfort, noise, and all factors combined makes for an all around car. The MT is much more dedicated for sporting roles and has closely packed transmission for having the right gear for every corner of the raceway.

With this being said though, and like I said in the first paragraph, all these data crunching is done on the given assumptions that the driver is of professional level that is proficient on the raceway at the car's very limits. For other less capable drivers, the manual does present the driver with a bit more tasks on the road, and extra precision is needed for rapid shifts, while braking on thresholds, or at the tip toe loads of each contact patch of the tires. For most of the truly modern AT's like this locked torque converter unit 6AT of the FRS, and many electronic clutch type sequential Semi-AT, the drivers rarely do go faster with a full manual, given all other factors are the same. This is why even Formula One cars, WRC Rally cars, etc, are all equipped with paddle shifts and electronic actuators instead of third pedals.

Yes, in theory the AT is much slower in the FRS due to much more spread in the gears. However, for most drivers who are not keen on the raceway condition driving, the smoother shifts of the fully automated box that can think on its own and assist the driver often does make up.

I won't say one being better than another though, as that is owner's prefernce and I prefer the manual too for cars that will be used on raceways often. But the AT does have its strong reasons for the FRS in particular, since it is a better all around gear-ratio for the street, and having all 6 gears, the same number as the MT, the sporting element is not as lost as one may believe like most other cars. It's actually quite intact and Aisin and Team 86 engineers spent a lot of time on this one too.

How did you calculate the RPM drop with the other final drive? Gear spacing shouldn't change with a shorter or taller final drive, just the speed you're going for any given RPM would change.

I made a quick spreadsheet which matches yours with the stock FD, but if I change the FD it doesn't change the RPM drop to the next gear, just the output RPM at the wheel (I didn't calculate speed, just wheel RPM).

The ratio between each gear isn't constant, so the RPM after each shift (at redline) will be different depending on the gear you're starting in.

I think it comes down to meeting targets set by the market

MT: 0-60mph faster than a GTI
AT: 34mpg highway

In this way they can appeal to people that are looking for good fuel economy and people looking for good acceleration.

I think it's really smart.

You're right and I didn't even notice that when I quickly tossed it together. With that being said, I just looked into it and in my haste accidentally carried the 3.727 ratio into my 4.1 FD section for both the 'Start RPM' and 'RPM drop' columns.

With that being said:
http://i108.photobucket.com/albums/n...BRZ_ratios.jpg

Yeah auto and manual are swapped and I believe the final drive ratio is 4.1 in the MT unless it's different for the BRZ?

____MT ___AT __# differenc _% difference
1 _3.626 __3.538 __0.088 ____2%
2 _2.188 __2.06 ___0.128 ____6%
3 _1.541 __1.404 __0.137 ____10%
4 _1.213 __1 ______0.213 ____21%
5 _1 ______0.713 __0.287 ____40%
6 _0.767 __0.582 __0.185 ____32%
R _3.437 __3.168 __0.269 ____8%
F __4.100__4.100?__0.00_____0%


http://www.cusco.co.jp/en/pdf/86%20BRZ%20Gears_A4.pdf

http://www.cars101.com/subaru/brz/brz2016.html

Holy thread necro! Yes he had the MT and Auto swapped, it was mentioned a few posts down after. The final drive is 4.1 for both auto and manual, but the ratio he was giving for R was for reverse not the final I believe.

Yeah sorry I'm digging up stuff while I wait for mine to get built. (Factory order) These are like stop light gears, well with an overdrive which isn't a terrible thing. Minus the OD I think these ratios are taller than the 04 JDM STi driveline I swapped into my 03 WRX.

Sent from my SM-G920P using Tapatalk

They are very tall indeed, but most of them are really close (except 1-2 and 2-3, damn those are apart). 6th gear is very tall on its own and a big drop from 5th, so long that the car cant pull it (maxing top speed aerodynamically rather than gear limited). A final drive swap makes it much better, at least for NA applications. For example, the car can completely pull all the way redline on 6th gear with a 4.88 or bigger FD, while tops out almost at redline with a 4.44 FD (will of course depend on elevation changes and wind direction and velocity).

How about the difference in how it actually feels to drive each, MT and AT? The MT puts a lot more attention on the drivers skill level. Clutching, rev matching, and the rpms at shift are very important factors in the MT experience. While in the AT, suspension, tune, and how much throttle is applied contribute far more to the AT experience. The rpms at shift, when using the AT manual mode, is even more critical than in the MT, since the AT engine has less mechanical advantage than the MT in every gear, less power in other words. The gear spread is wider, and it is harder to shift and keep it above the torque dip in the AT than it is in the MT. The AT really needs two power peaks, one for cruising at low rpms, and one for accelerating at high rpms. I highly recommend a UEL header for AT's to give them two power peaks for the best DD configuration. The tune of the engine is even more critical in the AT than the MT, since the AT has so much less mechanical advantage than the MT, so the AT drivers experience more of how well they're engine is running. I drive an AT, tune it myself, and I can tell the difference between clear sky's and cloudy weather just by how the engine handles running slightly richer or leaner. I've even played with different tunes for different weather, but thought that was a bit much. There has to be a really big difference in a tune for an MT driver to tell any difference with they're "Butt Dyno", but, an AT owner can feel the slightest difference in how they're engine is running, since they feel so much more of the engine running through the taller gears. With an AT, the drivers feels good about a manual shift when the engine pulls without bogging down after the shift. With an MT, the driver feels bad about a shift when it bogs down, because that means they just shifted from 2nd to 5th, instead of from 2nd to 3rd, because shifting without bogging down is just a normal shift with an MT.

@KoolBRZ sumarized really well. Btw, I have a MT with EL headers, full exhaust and tuned. I can HEAR the difference when there's different weather (specially going from not only from wet/dry but hot/cold), but as you say, I cannot feel the difference on the butt dyno. I think I have been lucky enough to drive manual most of my life (since I was 16 in fact) and usually cars with worse trannies so I have luckily never miss shifted, on upshifts nor downshifts (i sux at rev matching tho, thats a story for another day).