BMW F97 - Page 25

F97/F98�Complete�Vehicle
4.�Powertrain
21
With�the�M8HP76�M�Sport�Steptronic�transmission,�which�is�based�on�the�BMW�AG�8HPTU2�gearbox,
customers�benefit�from�significantly�improved�gear�shift�responsiveness�and�even�further�optimized
control�of�the�converter�lock-up�clutch.
This�has�been�made�possible�by�the�further�development�of�converter�technology�to�effectively�damp
rotational�irregularities�in�the�drivetrain�with�a�turbine�torsional�vibration�damper.�As�a�result,�the
operating�ranges�in�which�the�converter�lock-up�clutch�has�to�be�controlled�are�reduced�even�further
because�the�converter�lock-up�clutch�is�fully�engaged�in�the�vast�majority�of�driving�situations.�This
provides�for�an�even�more�direct�connection�of�the�M8HP76�transmission�to�the�complete�drivetrain,
resulting�in�an�even�sportier�driving�experience�and�reduced�fuel�consumption.
The�power�transmission�capacity�of�the�torque�converter�has�been�adapted�to�the�S58B30T0�engine.
In�the�F97/F98�the�“Idle�coasting”�function�known�from�the�BMW�AG�vehicles�is�not�implemented.
However,�the�M8HP76�supports,�as�known�from�the�BMW�AG�vehicles,�the�“ConnectedShift”
function.
Transmission�ratios�–�F97/F98
F97/F98
Transmission�designation M8HP76�(ZF)
Transmission�ratio�spread 7.8
Maximum�engine�speed�[rpm] 7200
Torque�[Nm] 650
Ratio�[:1]�1st�gear 5.000
Ratio�[:1]�2nd�gear 3.200
Ratio�[:1]�3rd�gear 2.143
Ratio�[:1]�4th�gear 1.720
Ratio�[:1]�5th�gear 1.313
Ratio�[:1]�6th�gear 1.000
Ratio�[:1]�7th�gear 0.823
Ratio�[:1]�8th�gear 0.640
Ratio�[:1]�reverse�gear 3.478
4.2.2.�Transmission�oil�cooling
The�plastic�transmission�sump�has�been�replaced�by�an�aluminum�version�with�larger�cooling�fins�and
the�opening�point�of�the�transmission�oil�thermostat�lowered,�thereby�improving�the�cooling�of�the
M8HP76�transmission.
A�transmission�oil�cooler�with�a�thermostat�is�used�to�cool�the�M8HP76�on�the�F97/F98.�This
additional�transmission�oil�cooler,�which�is�designed�as�a�plate�heat�exchanger,�operates�according�to
the�oil-to-air�heat�exchanger�principle�and�is�installed�vertically�in�front�of�the�radiator�assembly.