Return to Transmission Tech Section.

ZF 6 Speed Transmission

ZF S6-650 Transmission Specs & Gear Ratios





ZF 6 Speed Transmission

Ford began offering the ZF 6 Speed in 1998, while GM introduced the option in 2001. The ZF S6-650 is a heavy duty, fully synchronized manual transmission that is liked for its light weight and heavy towing capacity. It should be noted that the GM and Ford versions have suttle differences that make most of the parts non-interchangeable. The ZF 6 Speed features an oil pump and trans fluid cooler, a unique feature that is not common on manual transmissions. While the ZF spec sheet rates the maximum input torque at 520 lb-ft, this is believed to be an underrated, "safe" value, and the actual maximum input torque is inthe 650 lb-ft range (this is based on the fact that the transmission has been used behind many engines producing up to 650 lb-ft, and the name contains a torque designation of "650").


ZF 6 Speed Ratios










5.79 : 1

3.30 : 1

2.10 : 1

1.31 : 1

1.00 : 1

0.72 : 1

5.23 : 1


ZF 6 Speed Transmission Specs


ZF 6 speed ZF S6-650 manual


ZF Friedrichshafen AG

Production Run:

1998 - 2008 (7.3L, 6.0L, & 6.4L Power Stroke)
2001 - 2006 (6.6L Duramax)

Input Torque Rating:

ZF rates the ZF S6-650 at a maximum 520 lb-ft, though the name and applications suggest it is capable of handling 650 lb-ft.

Transmission Weight:

Approx. 235 lbs

Oil Capacity:

6 liters (6.34 quarts)

Additional Specs:

• Fully synchronized.
• Aluminum case.
• 26,000 lb. GCW (Gross Cargo Weight)
• Integrated oil pump that circulates fluid through a transmission cooler, a feature that is not typically seen on manual transmissions.
• PTO cover located on passenger side.