2012 Lexus LFA clutch

36
Shifting
With regards to the drivetrain, the steering wheel-mounted paddle shift switches
command the automated dry single-plate clutch and rear-mounted ASG (Automated
Sequential Gearbox) transaxle. This fully automated configuration allows the driver to
upshift (+) or downshift (-) while keeping both hands on the steering wheel.
When the driver initiates a gear change using the paddle shift switches, the ASG
computer automatically controls and coordinates clutch engagement, engine speed,
torque transfer and gear select and shift operations.
The engine-mounted dr y single-plate clutch and rear-mounted transaxle are
connected via torque tube to provide the direct feel of a manual gearbox.
The ECU manages gear changes to provide intuitive response to the driver ’s
a c c e l e r a t i o n d e m a n d s . D o i n g s o a l l o w s g e a r c h a n g e s t o b e c a r r i e d o u t
instantaneously, providing a nearly uninterrupted flow of power. The engine speed
is computer controlled on upshifts and downshifts in order to ensure smooth clutch
engagement.
Naturally, shifting can be accomplished manually via the paddle shift switches.
However, shifting can also be performed automatically in AUTO mode. Switching to a
different driving mode using the driving mode selector switch or operating the paddle
shift switches will resume manual operation.
When in a manually shifted driving mode, the shift speeds may be tailored to the
driver’s preferences. Using the shift speed selector, the shift speed can be adjusted in
7 stages to a minimum shift time of approximately 0.15 seconds.

37
Shifting
■
■Dry single-plate clutch
A dry single-plate clutch has been adopted to enable a direct engagement feel. The
clutch in the LFA is a hydraulically
actuated unit controlled by the ECU in order to
ensure quick and precise operation.
A pump within the hydraulic power unit generates the hydraulic pressure needed
to operate the clutch. This pump is powered by an electric motor to ensure a stable
supply of hydraulic pressure. In some cases, one can hear the sound of this electric
motor operating prior to the engine starting. This operation provides the hydraulic
pressure needed to disengage the clutch prior to starting the engine.
Because the LFA employs a dry single-plate clutch, it will not exhibit the slow speed
creep associated with a conventional automatic transmission. The driver must normally
depress the accelerator pedal to accelerate, even in ultra-slow speed situations such
as a traffic jam.
Diaphragm spring
Clutch disc The clutch disc is a compact size [9.45
in. (240 mm) diameter] and features
friction material designed specifically
to comply with the engine’s high-output
characteristics. The clutch cover is
c o n s t r u c t e d f r o m a l u m i n u m f o r a
precisely balanced, low-inertia design
that contributes to outstanding engine
response.

40
■
■Paddle shift switches
I t i s u n d e rs t o o d t h a t d r i ve rs t e n d t o
anticipate downshifts more than upshifts.
To mechanically reflect this phenomenon,
the downshift paddle shift switch (-) has
a comparatively higher force pull than
the upshift paddle switch (+) to foster
a g re a t e r s e n s e o f exc i t e m e n t w h e n
stepping down a gear.

Automatic processes that occur during gear changes
Engine speed control
When the driver commands an upshift, the ECU will automatically lower the engine
speed to facilitate the gear change without requiring the driver to release the
accelerator pedal.
Blipping control
When the driver commands a downshift, the ECU will automatically raise the
engine speed in order match the speed of the transaxle, ensuring smoother clutch
engagement.
Automatic downshift control
The ECU will au tomatically downshif t when the vehicle slows to below a
predetermined speed. This will occur even in a manually shifted driving mode.
Downshift (-) Upshift (+)

41
Shifting
■
■Driving mode-specific shift characteristics
The driving mode selector switch allows the driver to choose the automatically shifted

AUTO mode or a manually shifted SPORT, NORMAL or WET mode and their
corresponding default shift speed level. The driver may perform gear changes using the
paddle shift switches while driving in a manually shifted driving mode. While the shift speed
is adjustable using the shift speed selector, each driving mode has its own default shift
speed setting. Shift speeds are determined by how quickly the following operations are
carried out: Clutch disengagement, gear select, gear shift and clutch engagement.
Selecting a faster shift speed will shorten the time it takes from the moment the paddle shift
switch is pulled until the shift is totally completed. Faster shift speeds allow for enhanced
response and near-seamless power delivery, but will also result in a greater amount of shift
shock due to the speed at which the aforementioned operations are carried out. Selecting
a slower shift speed will allow the clutch and gear shift/select mechanisms to operate at a
more gentle pace, leading to a smoother application of torque and less shift shock.
Driving modeDriving mode default shift speed
AUTO ■■
2/7 (Non-adjustable)
SPORT ■■■■■□□
5/7
NORMAL ■■■□□□□
3/7
WET ■□□□□□□
1/7
Shift characteristicsLevel 1 n Level 7
Shift speed Slow (approx. 1 sec.) n
Fast (approx. 0.15 sec.)
Shift shock Less n
More

Shift speed selector
When in a manually shif ted driving
mode (SPORT, NORMAL or WET),

the shift speed can be adjusted from
l e v e l 1 t o 7 u s i n g t h e s h i f t s p e e d
selector.
Shift speed is also determined by the
accelerator pedal angle. The more the
accelerator pedal is depressed, the
shorter the shift times will be.
S106-04
Fast
Slow
Fully released Fully
depress
Level 1
Level 2 Level 7
Accelerator
pedal angle
Shift speed

111
Technical information
Clutch and Transaxle
ClutchTypeDry Single-Plate Clutch
Diaphragm Spring
Operation Hydraulic Cylinder
Clutch Cover TypeDiaphragm Spring Turnover
Clutch Disc Diameter 240 mm
Transaxle Type ASG
(Automated Sequential Gearbox)
Transaxle Model RB60M
Front Counter Gear Ratio* 1.259
Transaxle Gear Ratios 1st3.231
2nd 2.188
3rd 1.609
4th 1.233
5th 0.970
6th 0.795
Rev 3.587
Differential Gear Ratio 3.417
Differential Type TORSEN
® LSD
Rear Transaxle Gear Oil Oil Viscosity“LT 75W-85” API GL-5
Rear Transaxle Gear Oil Capacity 5.3 L (5.6 qt., 4.7 Imp. qt.)
*: The front counter gear is lubricated by engine oil.

115
Index
Checking the oil level 69
Clock 67
Clutch 37
Clutch disc 37
Cold starting restrictions 17
Combination meter 57
Connecting an external battery
to start the engine 98
Control characteristics
depending on driving mode 23
Control pad 66
Coolant temperature 60
Coolant temperature gauge 60
Crankshaft 38
Creep phenomenon 37
DDark current (parasitic current) 93
Dead battery 94
Default shift speed setting 41
Departure angle 100
Diaphragm spring 37
Differential 39
Differential oil cooler 39
Digital display 56
Disabling the theft deterrent
system 102
Disabling the tilt sensor 102
Discharged battery 94
Disconnecting the negative (-)
battery terminal 99
Door mirror switches 9
Double wishbone front
suspension 47
Downshift 40
Driving mode 58
Driving mode selection 27
Driving mode selector switch 41
Driving mode selector switch
operation 23
Driving mode-linked variable
throttle response 33
Driving position 20
Driving position adjustment 10
Dry single-plate clutch 37
Dual shaft transmission 39
EECB (Electronically
Controlled Brake) 50
Emergency brake 9
Engine 56
Engine code 16
Engine coolant 60
Engine coolant temperature
gauge 60
Engine coolant temperature
sensor 60
Engine limiters 16
Engine oil pressure 62
Engine oil pressure gauge 62
Engine oil temperature gauge 61
Engine overspeed 70
Engine protection mechanisms 16