rominl

iTrader: (4)

no, it's quite harsh. it jerks you totally. on paper it's very fast, but in reality, i can see what scott means it "feels" slow, coz' every shift comes in 2 stages. first choke to shock you, and then another choke to push you. i don't know if that's what lexus wants. but if they want owners to feel the shifting, yes, you absolutely do

motohide

Any shift especially downshift will decelerate a car with positive clutch meet and complete off throttle condition. But in sport driving at limits, that usually happens when you are on the brakes and during the process of aiming for the apex. While most competing cars in this category like the Gallardo LP560 will engage the clutch after a brief blip and harsh engagement that actually is enough for a driver to prepare and correct the line, the LFA in comparison was much milder and no more upsetting than if operated by a manual clutch pedal with an experienced driver. The paddle shifts are to that effect, very smooth as a standard manual car.

Perhaps the harshness you describe is the sheer nature of Scott's driving and high g-forces that result, which is actually very smooth in terms of performance driving but violent in comparison to what most people experience on a usual basis? In the passengers seat, in LFA, these forces certainly does rock your helmet clad head quite hard at each shift and braking points.

Of course, also, in comparison to a more usual electronic AT based paddle shift car like the ISF, where there is still a torque converter to soak up any shocks, the feel may seem harsher in the LFA?

For a standard positive engaging clutch MT based paddle shift, I felt it was one of the most smoothest and predictable shifting cars I have been in. That includes the R8, 996, M3 SMT, Gallardo LP560 and F355/430 all examples of non-AT based paddle MT.

jpvarghese

iTrader: (1)

I've driven Lamborghinis with exactly what you describe. It give you the illusion of being slow, but it is very enjoyable! The momentary pause and silence between shifts adds to the effect. I agree that it is a good way to mimic 'actual' shifting.

07grIS350

motohide, that is a masterpiece of writing. Thankyou for sharing your LFA experience in great details.
I`ll have to show my wife the safe aspect of this car to convince her that it`s not a widow maker.

rominl

iTrader: (4)

i haven't driven other exotics so it's hard for me to quantify to those, hopefully one day. the best i could do is to compare it say with the dct on m3 which we all know is very different. but the feeling was very different too

actually i should be clearer. on the down shift, i think they did a fantastic job on the lfa. like you said, mild, you feel it, but it doesn't disrupt any driving dynamics at all, everything is well under control.

the harsh shift i talked about is actually more when upshifting at redline. that hard choke to your whole body. same with scott, when talking to him and asking him about his comment on the "slow shift", i think he meant when upshift

yes, that's why i keep on saying it "feels" slow. in reality we all know it's very fast. but that sensation and feeling gives you a different perspective. it does feel a lot like hard manual shifting with gearbox. and i believe that's what lexus wants, main reason why they selected single-clutch vs dual-clutch design

TripleL

Great video and write up, thank you both

jpvarghese

iTrader: (1)

This is why is never a good idea to base your 'perception' of speed, whether it comes from shifts or acceleration, on that alone. That is the most biased source of info and cannot be taken seriously in debate. I'm glad you got to experience this first hand. Everything is not always as it 'seems'.

rominl

iTrader: (4)

of course. if one needs that feel, then he would have crashed the lfa, because he/she will not feel the speed at all, the linear power makes it so smooth

07grIS350

I am surprise that the engine sound is not mentioned as a contributor to speed perception. To me, a screaming redlined V10 should be equated to high speed by the brain. I guess I will have to experience it for myself.

flipside909

I'm glad you chimed in....Thank you!

rominl

iTrader: (4)

but it also depends on what gear you are in the car is always screaming, but the thing is you don't really feel the acceleration as much since the power and torque is so linear, until you look at the speedometer

TF109B

It's so gradual it just gets there before you even know it? Of course you will know it, but the car is smooth enough that it sort of isolates you? It seems from what I've heard so far, it's more about the connection with the LFA. It seems like it's a car that doesn't really have you on edge, in a good way, but comforts your driving. I remember reading reviews and owner comments about the 550 and 575 Ferrari's, and how they'd make you seem like a good driver because of their computer systems. Is the LFA different from that in the sense that it's more about the car and not down to the stability and traction control systems?

05RollaXRS

Correct.

Perception of speed comes from "peaks and valleys" in the torque curve. Such is the case in the turbo cars where turbo lag causes the car to not respond and suddenly surge ahead creating a false sense of rate of change of acceleration.

LFA's dynos show, it has absolutely no peaks and no valleys in the torque. Just a straight line going from 3000 rpm to 9500 rpm with over 95% available from 3000 rpm to 9500 rpm.

I know it well because my car has the "infamous Celica GTS VVTL-i lift". At 6000 rpm, when the car switches cam, the car jerks and throws you back in the seat when the torque curve suddenly surges about 25 - 30 ft-lbs of wheel torque within 200 - 300 rpm. The effect is like a big surge in power and then it stays in lift till 8400 rpm.

Also, you mentioned the transmission system, you have to remember the LFA engine (like the Porsche Carrera GT) and unlike any other supercar today has no internal inertia. If you want some of the Justin Bell videos, you can see on part throttle how the needle is shaking because the engine is so sensitive to throttle inputs.

The flywheel is an inertia storing mechanism that allows smooth starts and smooth shifts since the weight of the flywheel gradually speeds and slows down due to the weight rather than suddenly in the case of a light flywheel.

Inertia in a heavy flywheel keeps the revs from falling when the engine and transmission system connect especially for cars that are intended to tow a lot of heavy weight. Obviously, in racing it is quite the opposite where the car needs to respond as quickly as possible at the cost of progressive feel of the engagement.

With a car having no internal inertia, it gives incredibly sensitive throttle response at the cost of drivability and smoothness.

The downside is, it will almost be impossible to get a smooth shift especially at 9500 rpm when it is spinning so fast and then suddenly loses speed when it gets disengaged or getting off the line smoothly since the engagement due to lack of inertia will tend to bog the car down, if it does not have sufficient revs off the line. I hope it makes sense.

p.s. I drive a car with only a 7 lbs Fidanza flywheel so I have first hand experience of driving a car with very little internal inertia.

While I lift off the throttle shifting at 8400 rpm making it a bit more gradually into the next gear, Lexus LFA (as you kept the throttle WOT and never lift off the throttle) slams it into the next gear (flat shift). I could imagine how brutal it must be with such a light flywheel suddenly engaging the transmission with the powertrain that is essentially spinning at full speed.

motohide

LOL! In the USA, anything with four wheels and paint on the skin that costs $400,000 is a widow maker. That is unless you are of middle eastern descent and have ordered 6 of them at once for each of your spouse, or if your wife's name is Danika.

motohide

That's what the LFA does so well however, its is very gentle in relation to previous forms of paddle non-AT based manuals I have driven. The ECU and Transmission control computers are so well programmed that at each shift, there are very fine-tuned calculations for timing of ignition and fuel and flywheel revolutions and driveline speeds are very well matched before things engage positively, and also it does this by slight light pressure engagement and heavy duty synchronizer within the very durable gearbox.

If anything is a testament, the older of the LFA touring the USA, the dark gray one, has seen tens of thousands of track abuse at these events with hundreds of test and sample drivers as well as Scott Pruitt doing hard laps for the last 10 months. I was surprised to see that it was still on the same clutch plate installed at initial production!!

The downshifts are very well timed without much delay, and more importantly very intuitive and consistent, which helps to assure confidence when on track, and all contact patches are loaded on a fine balance on fairly peaky set of street tires like Potenza 01. The engagement speeds and touch are programmed differently for each condition and especially during downshifts on turn-in, things just work smoother than any paddle shift car I have driven.