The purpose of adding additional gears to a transmission is to allow the engine to operate at lower RPMs when at speed (like on the highway). This not only saves fuel, but also enables a higher top speed in certain applications. The ZF 8 speed transmission known as the 8HP70 transmission, is able to achieve the performance parameters of cars like the Maserati Quattroporte and Jeep grand Cherokee SRT8, while still providing smoothness required for a Rolls Royce Phantom and Aston Martin Rapede. But the ZF 8HP70 transmission can also be found in cars like the Dodge Charger and the F30 BMW 3-Series. Plus, the Chrysler Corporation / FCA even produces them under license in the United States (Chrysler TorqueFlight 8). With the exception of this licensing deal, the ZF 8HP70 transmission was sold as a kit to automakers, who would then apply in their own 8HP70 controller software, torque converter and other components to suit their application. Although this 8-speed automatic transmission is found in a number of different cars and trucks, the way that it performs will vary greatly because of these alterations.
What Transmission Do I Have?
8HP70 Transmission Overview
The ZF 8HP70 transmission uses four planetary gearsets and five multi-plate clutch packs (3 rotating and 2 brake). When the transmission is in operation, only two clutches are open. This significantly reduces spin loss and increases fuel efficiency. The second generation of the 8HP70 transmission (2014 MY) reduces this spin loss even further by integrating springs into the clutch packs so that the friction elements stay completely open.
The ZF 8HP70 torque converter is able to achieve lockup in all 8 gears for maximum performance and efficiency. The 8HP70 transmission can also downshift from 8th directly to 2nd when conditions warrant. If equipped, Manual Shift Mode can execute driver requested gear changes in just 200 milliseconds. This ZF 8-speed automatic may also have shift-by-wire functionality which eliminates the physical connection between the shifter and the transmission.
Optimal pressure control in the ZF8HP70 transmission is achieved by using a chain driven offset variable displacement pump. This also allows for the 8HP70 hydraulic impulse oil storage system, or 8HP70 HIS system for short. If the vehicle application is equipped with a start/stop system, the ZF 8HP70 start/stop system will be able to engage the appropriate clutch pack when the driver lets off of the brake pedal, using stored hydraulic pressure. The reaction time varies from 1.5 seconds to 350 ms, depending on the generation.
ZF 8HP70 Applications
Model |
---|
BMW X5 |
Dodge Charger |
Dodge Durango |
Infiniti QX56 |
ZF 8HP70 Diagnostic Trouble Codes | DTC
Trouble Code | Description |
---|---|
P0705 | Transmission Range Sensor Circuit Malfunction (PRNDL Input) |
P0706 | Transmission Range Sensor Circuit Range/Performance |
P0710 | Transmission Fluid Temperature Sensor Circuit |
P0711 | Transmission Fluid Temperature Sensor Circuit Range/Performance |
P0712 | Transmission Fluid Temperature Sensor Circuit Low Input |
P0713 | Transmission Fluid Temperature Sensor Circuit High Input |
P0714 | Transmission Fluid Temperature Sensor Circuit Intermittent P0715 |
P0717 | Input/Turbine Speed Sensor Circuit No Signal |
P0729 | Gear 6 Incorrect Ratio |
P0730 | Incorrect Gear Ratio |
P0731 | Gear 1 Incorrect Ratio |
P0732 | Gear 2 Incorrect Ratio |
P0733 | Gear 3 Incorrect Ratio |
P0734 | Gear 4 Incorrect Ratio |
P0735 | Gear 5 Incorrect Ratio |
P0750 | Shift Solenoid 'A' |
P0755 | Shift Solenoid 'B' |
ZF 8HP70 Transmission Recalls
– Recall ID – NHTSA: 16V24000 – ZF 8 Speed Automatic Transmission
— Summary
In April 2016, Fiat Chrysler / FCA recalled 811,290 Chrysler Group vehicles equipped with the ZF 8-speed transmission and monostable gear selector. These vehicles include:
2014-2015 Jeep Grand Cherokee
2012-2014 Chrysler 300
2012-2014 Dodge Charger
— Consequence
Due to the nature of the shifters design, it always returns to the center position, which may confuse some drivers. According to the recall, there may not be adequate warning to the driver when they open their door and the transmission is not in the Park position. In such a scenario, the vehicle may still be in gear or placed in Neutral. If this should happen, the vehicle could roll away unexpectedly, causing serious injury or damage. The death of Star Trek actor Anton Yelchin is speculated to have been caused by this shifter’s design.
— Remedy
Dealers were instructed to update the vehicle software to alter the shifter’s behavior. For more information, owners may contact Chrysler customer service at 1-800-853-1403 (refer to the Chrysler recall S27) or the National Highway Traffic Safety Administration at 1-888-327-4236
Recall 14V-161 / P13 – Failed Park engagement
2014 Ram 1500 5.7L Hemi and 8-speed automatic transmission
– Summary
According to the recall, some 125 copies of the 2014 Ram 1500 equipped to with the 8HP transmission may have had improperly machined Park rod guide plate mounting surfaces inside of the transmission case, which could cause the fasteners to loosen, preventing the Park prawl from fully engaging.
– Consequence
If the above condition occurs, the transmission may slip out of the park position and unexpectedly roll away, causing serious injury or property damage.
– Remedy
The transmission will have to be replaced. Concerned owners can contact Chrysler customer service at 1-800-853-1403. You can also contact the National Highway Traffic Safety Administration at 1-888-327-4236
8HP70 Transmission Specs
General – 8-speed automatic
Application – RWD/AWD/4WD
Max Engine Torque – 516 lb-ft
Variations – with/without engine stop/start HIS system and 4WD/AWD
Production Began – 2008
Weight – 207 lbs +/-
Fluid Type – ZF Lifeguard 8
8HP70 Transmission Gear Ratios
**actual gear ratios may vary depending on application
***Gen 1 (gear ratio spread 7.0:1) / Gen 2 (gear ratio spread 7.8:1)
What Transmission Do I Have?
First – 4.71/5.00
Second – 3.14/3.20
Third – 2.10/2.14
Fourth – 1.66/1.72
Fifth – 1.28/1.31
Sixth – 1.00/1.00
Seventh – 0.83/0.82
Eighth – 0.66/0.64
Reverse – 3.30/3.45