Tiptronic
The Porsche Tiptronic Transmission A86/00:
As an alternative to the conventional five-speed manual transmission with mechanical disengaging clutch, a power-shifted five-speed sports transmission, Porsche Tiptronic, is also available.
The principal advantage of this drive system is that it is possible to shift to a lower and higher gear both automatically and manually without a break in the tractive force.
The transmission is produced by the firm ZF in Saarbrucken as type 5 HP 19 FL.
The Porsche type designation for this drive system is A86/00.
The most important data at a glance:
Automatic five-speed sports transmission with integrated hypoid axle drive plus manual and automatic shifting.
Porsche type designation:
A86/O0
Number of gears:
5 forward gears, 1 reverse gear
Total weight of transmission unit:
112.5 kg (without cooling system)
Additional weight for Tiptronic vehicles:
50 kg
Transmission Ratios:
1st gear i = 3.67
2nd gear i = 2.00
3rd gear i = 1.41
4th gear i = 1.00
5th gear i = 0.74
Spur gear:
24/41/30 i = 1.250
Axle drive:
11/37 i = 3.364
Control module with 88-pin plug:
8-bit micro-processor with external 64 KB EPR0M for the program memory
RAM 2 KB to store adaptive values with battery buffer via term. 30
EEPR0M 256 B for fault memory and country-specific codes
Capacities:
Automatic unit:
From empty: approx. 9 liters
ATF Esso LT 71141 ATF change every 100,000 miles
Rear axle drive:
0.8 1 transmission oil Burmah SAF - AG 4/1016
Change every 100,000 miles.
Functioning of Porsche Tiptronic:
Like the Tiptronic of the 911 Carrera, the Boxster's Tiptronic has two selection rows.
In the right-hand row and with the selector lever in position "D", shifting into higher and lower gears is performed automatically.
No "gear lock" is provided which means that only the selector-lever positions P - R - N - D are available.
P = Park
R = Reverse
N = Neutral (idle)
D = Drive (automatic shifting 1st - 2nd - 3rd - 4th - 5th gear)
Driving in selector-lever position "D"
If the selector lever is moved to "D", an extremely intelligent driving program is performed. Shift characteristics adaptation is carried out on the basis of the following information:
Accelerator pedal position - Throttle potentiometer
Vehicle speed - ABS sensors
Longitudinal vehicle acceleration - ABS sensors
Transversal vehicle acceleration - ABS sensors
Engine speed - Speed sensor/flywheel
Apart from the driving style, when the shift map is selected, the intelligent shift program also takes into consideration the road resistance, changes to which are particularly noticeable on upward and downward slopes. When these changes are detected, the shift map providing the optimum gear is selected according to the slope. This results in a reduction in shifting frequency.
Apart from the five shift characteristics ranging from SC 1 = very comfortable and economical to SC 5 = very sporty with high performance, the Porsche Tiptronic also has the following special functions:
- Prevention of thrust upshifting e.g. before curves
If the accelerator pedal is released before a curve, i.e. the throttle is closed quickly, the gear currently being used is retained. If the brake is then actuated, downshifting, appropriate to the current speed, is performed so that the optimum gear is available for the approaching curve.
If the throttle is opened again, shifting occurs according to the shift program.
- Gear retention in corners
The current lateral acceleration is calculated from the current driving speed as well as the difference in engine speed. In corners, the respective gear is retained depending on the shift characteristics and lateral acceleration.
- Active gear shift skip in SC 5
Whenever the vehicle is started, the transmission control module has the shift characteristics SC 1.
Independent from the shift characteristics, if the throttle is opened rapidly, shift program SC 5 can be obtained.
If the throttle is now closed by more than 25%, the previous shift characteristics are resumed.
- Kick-down
To achieve optimum acceleration, e.g. when overtaking, the accelerator pedal must be depressed beyond the full-throttle pressure point (kick-down). The transmission may shift back down to the lowest possible gear, depending on the driving speed. Shifting up to the next gear occurs with higher engine speeds. The kick-down shift speeds remain active until the accelerator has been returned to 70% of its full-throttle position.
- Shift-up with overrun on slippery (icy) road surfaces
In overrun conditions, especially in the low gears and on slippery road surfaces, the engine braking effect may cause slippage or locking of the driven wheels.
This driving condition is detected by the Tiptronic control module which continuously compares the speed of the driven rear wheels with the speed of the front wheels. If the speed of the rear wheels is less than that of the front wheels, the Tiptronic system immediately shifts the transmission into a higher gear so that the dangerous driving condition with locking rear wheels cannot occur.
- Warm-up map
Apart from the 5 shift characteristics, the control module has another warm-up map which becomes active at engine temperatures < 32°.
In the warm-up map, the shift-up points are offset to higher engine speeds, the transmission starts in 1st gear, and the converter lockup clutch is opened.
These measures result in both the engine and catalytic converter rapidly reaching operating temperature.
- Suppression of ignition at gear shift
When gear shifting is performed, the DME control unit briefly suppresses the ignition in order to reduce the engine torque which, in turn, results in smooth shifting.
And this is how the information is processed in the Tiptronic control module
The following measured variables are transmitted and processed several times per second:
Measured variable Type of measurement
Position of throttle valve Resistance value, potentiometer
Actuation speed of throttle valve Time for resistance change at potentiometer
Engine speed Frequency measurement (from DME)
Driving speed Number of pulses from ABS
Vehicle's lateral acceleration Calculation using driving speed and difference between front wheel speeds
Vehicle's acceleration/deceleration Change in pulse time (ABS) within cycle time
Change in road resistance Resistance value, potentiometer for frequency measurement (DME)
Braking, yes/no Pulse for brake lamp switch
Engine temperature Resistance value, NTC