Dog-leg gearbox
A Dog-Leg Gearbox is a manual transmission shift pattern distinguished by an up-over-up shift between first and second gear.[1] The layout derives its name from a dog's hind leg, with its sharp angles. Dog leg gearboxes have fallen out of fashion primarily because most manual performance cars now have six-speed gearboxes, which are unsuited to the dog-leg layout.
| Dog leg five-speed layout | Typical five-speed layout |
|---|---|
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Automobiles
Dog leg layout gearboxes are desirable on performance cars because in road racing more frequent shifting occurs from second to third than from first to second gear.
Examples of cars that have used this pattern for performance reasons include the BMW M535, Early 635CSi (non-US) and (non-US) M3 E30, BMW 2002 Tii and Turbo, Fiat Dino 2.4 (ZF Box), Mercedes-Benz 190E 2.3-16 and 2.5-16, Mercedes-Benz 300 CE-24, Mercedes-Benz CW311, Ferrari 308/328/348, Ferrari Testarossa, Porsche 914, early 911, 924 Turbo (all featuring Getrag gearboxes), Cosworth Vega, Porsche 928, Talbot Sunbeam Lotus, Vauxhall Firenza HPF, Lancia Fulvia, Lancia Stratos, Lamborghini Countach, Maserati Biturbo, and De Tomaso Pantera.
Despite the performance benefits, non-performance-oriented cars available with the dog-leg shift pattern were produced. Examples include the Ford Model A, Subaru 360, Datsun 160J Hardtop SSS, 74–77 Datsun 610 SSS, 78–80 Datsun 200sx, 1980 Datsun 210 Wagon (built during the 210/310 crossover), 78–80 Datsun 510, Citroën 2CV, Mercedes 190, Mercedes-Benz 200D, Mercedes-Benz 300CE, Mercedes-Benz 320CE, Mercedes-Benz E320 sedan -94, Mercedes-Benz 300SL (R129), and the 1976–77 Oldsmobile Cutlass or Pontiac LeMans with the 260 V8, the 76–77 Chevrolet Vega or Pontiac Astre, 76–79 Chevrolet Monza or Buick Skyhawk or Oldsmobile Starfire, BMW E21 and the 77–79 Pontiac Sunbird. The early model Renault 4 had a distinctive 'umbrella handle' dog-leg shift, which proved ideal for urban driving, though the shift was later changed to the 'conventional' pattern. In April 2016, it was announced that the Aston Martin V12 Vantage S was to be offered with a 7 speed dog-leg gearbox. In the United States, the dog-leg transmission is only available in a "GTS" model of the Vantage, where only 100 are being produced.
Trucks
Many light trucks have dog-leg five- or six-speed transmissions, because second gear is fine for starting off normally; first is considered a "crawler" or "granny" gear in these trucks and is only ever used for taking off with heavy loads and/or a trailer, or going down very steep grades. In many older trucks, the shifter is marked with "Low" instead of "1", and 2nd gear is marked as 1st instead. A 4-speed truck gearshift might read "R, Low, 1, 2, 3", rather than "R, 1, 2, 3, 4", since the transmission is considered a 3-speed with an auxiliary low gear rather than a normal 4 speed.
The dog leg gearbox is also typical of nine- and ten-speed heavy-truck transmissions. In the case of a ten-speed transmission, the gears are 1–5 in the low range and 6–10 in the high range (the 1 position is not used in the high range of a nine-speed transmission).