”īishop says that they use a load cell sensor calibrated in tension and compression to activate a relay box, which then sends a signal to the MSD box. The cars run two MSD ignition boxes that are programmed to drop the RPMs about 1,500 RPM when the driver pulls back on the shift lever so they can shift without lifting. They are essentially older NASCAR engines before they switched to EFI. They’ve still got huge tires, huge brakes, big horsepower. “That’s about as high-tech as those cars get. So the company has focused on the Trans-Am gearbox and developed a solution for a no-lift-shift and a throttle-blipper for downshifting. The rules were re-written to favor the European manufacturers, which is where most competitors are for EMCO. The Grand-Am series morphed into United States Sports Cars, and then it merged with the American Le Mans series a few years back. With racing, the rules are constantly in flux. It’s currently running a vintage car right but will be ready for the TA cars next year.” It’s one of the most recent developments. So we have developed an updated version with the clutch in front of the transmission. And it’s offset to the right.”Īccording to Bishop, the first couple of races revealed that customers had to pull the engine to change a clutch. They’re not straight up and down like you find in a four-speed. What’s unique about this gearbox is that the gears lay side-by-side. “That’s the way the cars are designed, and they want to move the weight further back anyway. The EG5S sequential is more compact than the Hewland and uses a setback adapter, so it sits more toward the center of the car. And then it took off and went really well.” “We made it a direct replacement for the Hewland gearbox. We build a sequential gearbox that is limited to five speeds per the rules.”īishop says they came along at the right time because many teams were struggling with their old Hewland H-pattern boxes. They make huge torque and rev up to 8,600 RPM. The cars have 850 horsepower, pushing 900. There aren’t many racing series out there like that anymore. Currently, we’re heavily involved in the Trans-Am series.”īishop notes that the Trans-Am car, sanctioned by SCCA Pro Racing, is one of the few classes where the rules are open, and the components are not “spec” to cap costs. “The IRL transmission was about a four-year program, and then we got into road racing, and we’ve been doing primarily road racing transmissions and transaxles ever since. This transmission is currently in stock, so there is no need to wait months and months.While the IRL program was short-lived due to the series merging with Champcar, the road racing program was just kicking into gear for EMCO. The 6th gear is also taller than in other OS88s as it would not get used anyway on the dragstrip.ġst – 2.890 / 2nd – 1.981 / 3rd – 1.468 / 4th – 1.174 / 5th – 1.00 / 6th – 0.757 The first ratio is taller than standard but not as tall as other OS88s. This version of the gearbox ('option 2 ratios') is suited for street and drag racing use. OS Giken has R3C triple and R4C quad-plate clutches available to suit. The gearbox uses a 26-spline GM input shaft size (same as Holinger) so it needs a clutch with this spline. The dog-engagement of the gears allows extremely fast shifting operation. To do this the gear axis has been increased to 88mm, while most internal parts are forged. OS Giken designed this sequential gearbox to handle 1500hp, while retaining quiet helical-cut gears. It also comes complete with shifter, digital shift indicator and pull-up reverse lock-out sleeve. It bolts up to the Nissan transfer case and has a bellhousing to suit any RB engine. It can also be used in the BNR34 but will require an R33 transfer case and front prop shaft. The OS Giken OS-88 gearbox is a sequential 6-speed gearbox designed to suit the BNR32 and BCNR33 GT-R.
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