ZF 8HP
Automatic Transmission 8HP70
Overview
Manufacturer	ZF Friedrichshafen
Production	2008–present
Body and chassis
Class	8-speed automatic transmission
Related	GM 8L45 GM 8L90
Chronology
Predecessor	ZF 6HP transmission

The ZF 8HP transmission is ZF Friedrichshafen AG's trademark name for its 8-speed automatic transmission models for longitudinal engine applications. The name is short for 8-speed transmission with hydraulic converter and planetary gearsets. Designed and first built by ZF's subsidiary in Saarbrücken, Germany, it debuted in 2008 on the BMW 7 Series (F01) 760Li saloon fitted with the V12 engine. BMW remains a major customer for the transmission.

Another major customer is Stellantis, who both received a license to produce the transmission and set up a joint-venture plant with ZF. Stellantis has built the transmission at its Kokomo Transmission plant since 2013 under their own brand name, the Torqueflite 8.^[1][2] The joint venture plant in Gray Court, South Carolina opened in 2017.^[3]

Design

One of the main aims of the ZF 8HP transmission is to improve vehicle fuel economy with extra speeds. Compared to the six-speed ZF 6HP transmission it uses 12% less fuel, and 14% less than a 5-speed transmission.^[4][5] Due to changes in internal design, the shift times have reduced to 200 milliseconds; additionally, the unit brings the ability to shift in a non-sequential manner – going from gear 8 to gear 2 in extreme situations.^[6] In the 8HP70 version, it has a torque handling limit of 700 N⋅m (520 lbf⋅ft), and weighs 87 kg (192 lb).^[7]

Future development will see two four-wheel drive versions available, with a version destined for Volkswagen Group applications using a Torsen centre differential.^[8] It will be able to encompass a torque range from 300 N⋅m (220 lbf⋅ft) to 1,000 N⋅m (740 lbf⋅ft), and will be available for use in middle-class cars through to large luxury sport utility vehicles.^[8]

2nd generation 8HP products were released starting in 2014. Efficiency improvements over the original design include a wider ratio spread of 7.8:1, reduced drag torque from the shift elements, reduction in required oil pump pressure, and broadened use of the coasting and start-stop systems.^[9] ZF estimated fuel economy improvement over 1st generation 8HP kits to be 3%. Refinements were also made with respect to vibration.

3rd generation 8HP products were released starting in 2018. Major improvements are total spread of 8.6 and a fuel economy improvement of 2.5% compared to the 2nd generation. There are several options in maximum torque available, also the gearbox is available with mild hybrid and plug in hybrid options: With 15 kW and 200 Nm supporting boosting and recuperation in combination with 48 Volt technology up to 90 kW and 250 NM for usage with higher voltage.^[10]

Specifications

Technical data

Gear teeth and ratios			Planetary gearset: teeth				Count	Total	Avg.
Model type	Version First delivery		Sun 1 ${\displaystyle {S_{1}}}$ Ring 1 ${\displaystyle {R_{1}}}$	Sun 2 ${\displaystyle {S_{2}}}$ Ring 2 ${\displaystyle {R_{2}}}$	Sun 3 ${\displaystyle {S_{3}}}$ Ring 3 ${\displaystyle {R_{3}}}$	Sun 4 ${\displaystyle {S_{4}}}$ Ring 4 ${\displaystyle {R_{4}}}$	Brakes Clutches	Ratio span	Gear step
Gear	R	1	2	3	4	5	6	7	8
8HP 70[11]	700 N⋅m (516 lb⋅ft) · 2009		48[12] 96	48[12] 96	69[13] 111	23[13] 85	2 3	7.0435	1.3216
Ratio	–3.2968	4.6957	3.1304	2.1039	1.6667	1.2845	1.0000	0.8392	0.6667
8HP 45[14]	450 N⋅m (332 lb⋅ft) · 2011		48 96	48 96	60 96	28 104	2 3	7.0714	1.3224
Ratio	–3.2952	4.7143	3.1429	2.1064	1.6667	1.2854	1.0000	0.8387	0.6667
8HP 55[14] 8HP 65[14] 8HP 70[14] 8HP 75/I[14] 8HP 90[14]	650 N⋅m (479 lb⋅ft) · 2011 650 N⋅m (479 lb⋅ft) · 2011 700 N⋅m (516 lb⋅ft) · 2011 740 N⋅m (546 lb⋅ft) · 2014 900 N⋅m (664 lb⋅ft) · 2011		48[12][15] 96	48[12][15] 96	69 111	28 104	2 3	7.0714	1.3224
Ratio	–3.3168	4.7143	3.1429	2.1064	1.6667	1.2847	1.0000	0.8392	0.6667
8HP 30[16] 8HP 50[16] 8HP 75/II[16]	300 N⋅m (221 lb⋅ft) · 2014 500 N⋅m (369 lb⋅ft) · 2014 740 N⋅m (546 lb⋅ft) · 2014		48 96	54 96	60 96	24 96	2 3	7.8125	1.3413
Ratio	–3.4560	5.0000	3.2000	2.1429	1.7200	1.3139	1.0000	0.8221	0.6400
8HP 95 [16][17]	900 N⋅m (664 lb⋅ft) · 2014		48 96	54 96	69 111	24 96	2 3	7.8125	1.3413
Ratio	–3.4783	5.0000	3.2000	2.1429	1.7200	1.3131	1.0000	0.8226	0.6400
8HP 51[18] 8HP 76[18]	500 N⋅m (369 lb⋅ft) · 2019 750 N⋅m (553 lb⋅ft) · 2019		48 96	54 96	60 96	24 102	2 3	8.2031	1.3507
Ratio	–3.7120	5.2500	3.3600	2.1724	1.7200	1.3161	1.0000	0.8221	0.6400
8HP TBD	TBD 2020[16][18]		48 96	60 96	60 96	24 102	2 3	8.5313	1.3583
Ratio	–3.5692	5.2500	3.2308	2.1724	1.7692	1.3410	1.0000	0.8062	0.6154
Ratio R & even	${\displaystyle {\tfrac {R_{2}(S_{3}S_{4}-R_{3}R_{4})}{S_{3}S_{4}(S_{2}+R_{2})}}}$		${\displaystyle {\tfrac {R_{2}(S_{4}+R_{4})}{(S_{2}+R_{2})S_{4}}}}$		${\displaystyle 1+{\tfrac {S_{2}R_{1}}{S_{1}(S_{2}+R_{2})}}}$		${\displaystyle {\tfrac {1}{1}}}$		${\displaystyle {\tfrac {R_{2}}{S_{2}+R_{2}}}}$
Ratio odd		${\displaystyle {\tfrac {S_{4}+R_{4}}{S_{4}}}}$	${\displaystyle {\tfrac {(S_{1}+R_{1})(S_{4}+R_{4})}{S_{4}R_{1}+S_{1}(S_{4}+R_{4})}}}$		${\displaystyle {\tfrac {S_{1}R_{2}R_{4}(S_{3}+R_{3})+S_{2}S_{3}(S_{1}+R_{1})(S_{4}+R_{4})}{S_{1}R_{4}(S_{3}(S_{2}+R_{2})+R_{2}R_{3})+S_{2}S_{3}S_{4}(S_{1}+R_{1})}}}$			${\displaystyle {\tfrac {R_{2}(S_{3}+R_{3})}{R_{2}(S_{3}+R_{3})+S_{2}S_{3}}}}$

Variants and Applications

See also

• List of Chrysler transmissions
• List of ZF transmissions

References

External links

• Official website