FR-S Gear Ratio Comparison

[Allch Chcar]

Originally Posted by SpeedR

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?

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.

[DSR2409]

Originally Posted by carbonBLUE

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

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.

[carbonBLUE]

Originally Posted by DSR2409

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...

[OrbitalEllipses]

Originally Posted by DSR2409

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.

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

[Dave-ROR]

Originally Posted by OrbitalEllipses

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...

[SpeedR]

Originally Posted by DSR2409

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.

that usualy wrong.

[SpeedR]

Originally Posted by 3MI Racing

I'd worked up gearing a while ago but never bothered with the auto because...well that doesn't need explanation.

Here's a quick screen print with the redline set back to 7400. You'll see RPM drop for each gear as well.

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...

[WolfpackS2k]

Originally Posted by carbonBLUE

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...

Your lack of common sense is astounding

[3MI Racing]

Originally Posted by SpeedR

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...

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

[Sport-Tech]

Originally Posted by 3MI Racing

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.

[serialk11r]

Originally Posted by Scion FR-S

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.

[Allch Chcar]

Originally Posted by DSR2409

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.

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.

[Moto-P]

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.

[wparsons]

Originally Posted by 3MI Racing

I'd worked up gearing a while ago but never bothered with the auto because...well that doesn't need explanation.

Here's a quick screen print with the redline set back to 7400. You'll see RPM drop for each gear as well.

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).