![]() Given the relatively unknown performance of the cars, NASCAR will likely specify a number of drop gears that teams should carry to each race, to enable fine-tuning similar to its previous use of primary and alternate ring and pinion setups. Xtrac will supply three main gearbox configurations, A, B and C, covering high- to low-speed tracks. Notably, at the uniquely demanding Martinsville short track, the gearbox will only be used in a 4-speed configuration to save costs for teams using the extreme ratio. Xtrac established that a combination of 13 input drop gears and three ring and pinions would cover the required range. The new transmission uses an input drop gear arrangement to tune the overall ratio (in the existing setup, top gear is a direct drive from the clutch to the rear axle) and to provide the required increments to enable NASCAR to fine-tune from event to event. “We did some analyses of what cluster ratios all the teams are using, and from that tried to get within a small percentage of those with a selection of fixed cluster ratios.” Currently, the overall gearing in top gear is mandated by NASCAR for each track, defined using the ring and pinion ratio for example, a superspeedway such as Daytona will see a 3.45:1 ratio, while a short track such as Martinsville will use a 6.20:1. ![]() “We’ve got a lot of experience supplying the existing ratios for the different tracks,” outlines Barton. With cost control in mind, NASCAR wanted a limited set of ratios to help reduce teams’ inventory and thus costs. One of Xtrac’s first tasks was to ascertain the gearing spread needed to accommodate the varied tracks Cup cars visit. The use of a transaxle layout was driven by the series organizer, as relocating the gearbox from the front of the car would reduce the volume of the transmission tunnel, in turn enabling the driver to be placed nearer the center of the car – desirable from a safety perspective.īeyond this stipulation, Barton says that the specification was wide open, even so far as not specifying the number of gears required. Paul Barton, assistant vice president of Xtrac’s North Carolina operations, explains, “We started looking at what the best packaging for a hybrid motor would be in terms of where to put it, starting with something along the lines of the Australian Supercars transmission with the addition of a P2 hybrid arrangement, where the hybrid motor would be introduced at the input of the gearbox, but off-axis.”įollowing this initial work, NASCAR issued a request for proposal in June 2019, for a transaxle unit with hybrid integration potential. Xtrac began early concept work on a potential Next Gen NASCAR transmission in mid-2018, at the request of a manufacturer wanting to assess options for adding a hybrid system to the cars. Though better known for its sportscar and single seater transmissions, the company has a long association with NASCAR, having produced a 4-speed H-pattern gearbox and range of ring and pinions, with the latter providing a step change in durability and efficiency when introduced over a decade ago.
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