Chrysler TorqueFlite 8

TorqueFlite 8, ZF 8HP70 Transmission Specs & Ratios

Ram's 1500 EcoDiesel equipped pickups come standard mated to ZF's 8 speed 8HP70 automatic transmission. The transmission is manufactured by Chrysler in the USA under license from ZF and advertised as the "TorqueFlite 8". Its broad gear spread maximizes torque at low engine speeds, fuel economy with a relatively high final overdrive, and promotes performance at any combination of vehicle speed and load.

At just over 200 lbs, the transmission is relatively lightweight and yet sufficient enough to manage the EcoDiesel's maximum 420 lb-ft of torque. The transmission is designed for engine speeds up to 5,500 rpm, although EcoDiesel applications never realize engine speeds this high. Torque converter lockup is available in all 8 gears, which further promotes fuel economy. The TorqueFlite 8 uses a shift-by-wire electronic shift control system; there are no cables or mechanical linkages and therefore gears are selected electronically. It is advertised that the transmission accomplishes shifts in 200 ms or less, a characteristic that allows for rapid, crisp gear changes.

The transmission's 8 forward speeds are accomplished by 4 planetary gearsets and 5 separate clutch packs. To maximize fuel economy, the a vehicle can cruise at a minimum speed of 43 mph in 8th gear (2nd overdrive). To ensure on-demand performance, the transmission is capable of downshifting from 8th to 2nd gear when conditions require a rapid surge of power for acceleration. The transmission is considered a filled-for-life system; there is no transmission dipstick, fill tube, or required service. A fluid check plug on the side of the transmission is used to inspect fluid level and add as necessary, however Chrysler suggests owners do not need to follow any routine maintenance practices. The transmission's plastic oil pan doubles as an integrated filter assembly.

 

TorqueFlite 8 (8HP70) Ratios

1st

2nd

3rd

4th

5th

6th

7th

8th

R

4.71 : 1

3.14 : 1

2.10 : 1

1.67 : 1

1.29 : 1

1.00 : 1

0.84 : 1

0.67 : 1

3.30 : 1

 

TorqueFlite 8 (8HP70) Specs

Transmission:

Chrysler TorqueFlite 8 (ZF 8HP70)

Type:

8 speed automatic double overdrive transmission

Manufacturer:

Manufactured by FCA under license from ZF Friedrichshafen AG

Production Plant:

Kokomo Transmission Plant, Kokomo, Indiana

Model Years/Applications:

August 2013 - present Ram EcoDiesel

Case Material:

Aluminum

Max Input Torque:

516 lb-ft/700 N-m max engine torque, 561 lb-ft/760 N-m max input torque

Max Input Speed:

5,500 rpm

Max GCWR:

16,000 lbs

Weight:

~ 207 lbs (2wd model w/ fluid)

ATF Type/Spec:

MOPAR ZF 8 & 9 Speed ATF automatic
transmission fluid

Transmission Filter P/N:

WIX 51623 (external filter)

Features:

• Shift-by-wire system; no shift cables, gears are selected electronically.

• Downshifts can occur from 8th to 2nd under appropriate conditions, allowing on-demand power as necessary

• Torque converter lockup available in all 8 forward gears

• Gear shifts transpire in 200 ms or less

• 8HP70 - 8 forward speeds, hydraulic transmission, planetary gearsets, 700 N-m maximum allowable engine torque