Cycle News is a weekly magazine that covers all aspects of motorcycling including Supercross, Motocross and MotoGP as well as new motorcycles
Issue link: https://magazine.cyclenews.com/i/720681
FEATURE TRIUMPH INFOR ROCKET STREAMLINER P100 TRANSMITTING THE POWER "T he transmission is geared for about 420 mph right now. With the high 250 lb-ft of torque that we have in these engines, the strategy is to get it into top fifth gear by about 200 mph, and then pull it on through. The final drive is from an off-shore power- boat; they have these 40- foot speedboats with mul- tiple engines making 1500 bhp each, so our 1000 bhp is chickenfeed by their standards! We use stock Tri- umph Rocket III five-speed street gearboxes, which are strong enough to harness all this extra power without any extra upgrades. The gearshifts are electronically linked together, with the power coming out the drive shaft of the front engine with a single gear rotation which reverses the direction, so that it comes in above the gearbox of the second en- gine's geardrive, then feeds into a transfer case similar to a drag car quick-change rear-end differential. Then final drive and changes in gearing are done by means of a third- and fourth-gear arrangement from a Jericho road race transmission." A standard, but modified gearbox is used to transmit every one of those 1000 horsies. "W e had very limited options what size rear tire to use, because that amount of power requires a large contact patch to get grip on the salt. Denis Manning [owner of two-time LSR holder BUB Seven] contacted Goodyear a while ago about a tire for speed racing, but there wasn't anything they had in production that was suitable. So he paid them to produce a suitable tire, but for some reason he didn't buy all of them, which allowed us to get sup- plies—that's very sporting of him. To make this, Goodyear used the mold for their drag racing Funny Car front tire called a Frontrunner, which is rated up to 300 mph, then developed a cord package rated to 400 to 450 mph, and filled the remaining space around it with rubber. So we have a very old design of cross-ply tire which is however very stiff, so it works. We have a 22-inch front tire and a 28-inch rear, about eight inches wide at the widest part, but a very round profile, and we run them at 150 psi. Like all of the structural metal parts the wheels are made from 7075-T56 aluminum. They're an internal bead design within the externally bolted on bead lockers, so the beads are constrained both from the inside and the outside. A standard bead would come off at 400 mph. And we're aim- ing to go faster than that!" We shall see. CN THE RUBBER SOLUTION Tires are originally designed for a drag racing funny car!