![]() ![]() Tuning: retrofitting sequential transmissions and dog boxes The clutch is hydraulic instead of manual, and a second valve block controls the gear change. ![]() This ensures that a consistent pressure of 40 to 50 bar is maintained for shifting. Sequential transmissions in sports cars usually have their own oil circuit with an electric oil pump. As a sequential transmission has no torque converter, it also saves you fuel. This is irrelevant in motorsport where the transmission only has to deliver top performance once, and can then be replaced. But the gears are under much more stress, which means they wear faster. On a sequential transmission as opposed to a manual one, traction interruption is minimal, which is a big advantage. Cars for road use have helical (bevel) gears and draw-key gears, where a cone/wedge presses balls between the main shaft and the gears in order to change gear. Race cars sometimes even have triple clutches. Semi-automatics change gear incredibly fast on account of the special clutch design (and dual clutch transmissions are faster still). Either way, shift command transmission is exclusively electrical. Race cars usually have a rocker switch on the steering wheel, whereas normal cars have a gear lever. But the types used in Formula 1 and the like are the deluxe version, because the priorities are very different to those for road driving. The reason it’s so loud is because of the straight cut (spur) gears. No doubt you’re familiar with the unmistakeable earsplitting sound a sequential transmission makes – like a wheezing crackle. The technology behind sequential transmissions originates in motorsport. Sequential transmissions in motorsport engineering So a sequential transmission gives you the best of both worlds. When it comes to gears, a fully automatic shifting system is obviously far more convenient because there’s no clutch. One big advantage of a semi-automatic is that there’s no torque converter, which means your fuel consumption is lower. But you do get more of a feel for the car and for driving. Since you can’t skip a gear, your freedom is somewhat limited. For example, at the red light they go straight from fifth to first, which contradicts the usual definition of a sequential transmission. in today’s sports cars, that’s not entirely accurate. That’s why the sequential shifting system is often referred to as semi-automatic. However, the process is largely automated: all you have to do is touch the lever. So you can only ever go up or down one gear. Unlike manual shifting, you change gear in a linear sequence. But the term is also used to mean a transmission that’s a cross between manual and automatic. Fundamentally, it only refers to the actual process of shifting: you have to shift each gear up or down in sequence – you can’t jump from second to fourth for example. Its easy to see why with all this flexibility the 3MO TXB 6 Speed Sequential Transmission is popular with race teams around the world.First of all, the term ‘sequential gearbox’ tends to be used inconsistently. Likewise, gear positions 2 and 3 are rated for 50 hours or 7000km / 4375 miles, with gear positions 4, 5 and 6 being rated for 75 hours or 10500km / 6560 miles. These service life ratings assume the gearbox is being run at the maximum torque loading - clearly if the torque is less than the maximum load, then the service life is extended. With proper shift technique and lubrication dog rings are designed for 60 hours of racing or 8400km / 5250 miles. This super flexible platform is also available in four wheel drive confguration - see HERE. In Drifting applications, this 6 Speed sequential transmission is capable of handling engine torque of 1500 Nm. This TXB is rated for engine torque of 900 Nm / 665 lb ft in Circuit / Road Racing and Rally applications. This highly reliable and precision engineered sequential gearbox delivers ~97% efficiency. When combined with the 3 different drop gear options, there's a setup for almost every situation. With 52 gear ratios to choose from, the dog speed delta betwen gears can be optimsed for lightening quick and almost imperceptible gear shifts keeping the power to the track for the maximum amount of time. ![]() The Drop Gear System allows fine tuning of ratios on race day, and eliminates having to change rear differentials out during the week just to setup for a different track next weeked. This sequential transmisison features a drop gear system with 3 ratio choices which can be changed in 30 minutes without needing to remove the gearbox from the vehicle. The 3MO TXB 6 Speed 900 Nm / 665 lb ft Sequential Gearbox suits race and high performance street vehicles where the engine is logitudenallly mounted in the front or mid positions, and driven through a rear wheel differential. ![]()
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