Harley-Davidson will launch an all-new Big Twin powertrain for 2007

July 14, 2006

Milwaukee, WI - Harley-Davidson will launch an all-new Big Twin powertrain for 2007, as the Twin Cam 96/96B engine and 6-speed Cruise Drive transmission debut together on all Touring, Softail and Dyna models. The new engine, which will only be available with Electronic Sequential Port Fuel Injection (ESPFI), offers a nine percent increase in displacement and up to a 17 percent increase in torque (varies by model) over the Twin Cam 88/88B engines it replaces, and features a number of design enhancements making it more powerful, reliable and smoother.
“The Twin Cam 96 has been the biggest new-engine program in the history of Harley-Davidson,” said Skip Metz, Program Manager-Big Twin Powertrain. “There are more than 700 new part numbers associated with Twin Cam 96. The only areas that didn’t change are the cylinders, rocker arms, rocker boxes, and items in the top part of the engine. Crankshafts, connecting rods, crank cases, transmission cases, and all the transmission parts are new. We think this next-generation Twin Cam will set the standard for the industry.”

The Twin Cam 96 displaces 1584cc (96 cid), compared to 1450cc (88 cid) for the Twin Cam 88 engine it replaces. The added displacement was achieved by increasing stroke from 4.00 inches to 4.38 inches. The Twin Cam 96 cylinder bore is 3.75 inches, the same as that of the Twin Cam 88. The Twin Cam 96B is designed to be rigid-mounted in Harley-Davidson Softail models, and is equipped with internal counter-balance shafts to provide a smooth and powerful ride.

The Twin Cam 96 produces up to 93 ft. lbs. of peak torque at 3500 rpm, compared to the Twin Cam 88 at up to 82 ft. lbs. at 3500 rpm.

The 6-speed Cruise Drive transmission, which was introduced on the Dyna family in 2006, features gear ratios optimized to match the torque curve of the new Twin Cam 96/96B engines. The addition of a higher-ratio sixth gear reduces top-gear rpm by 11 percent, compared to the previous 5-speed Big Twin transmission. At 75 mph, engine speed is reduced by 368 rpm, from 3227 rpm to 2859 rpm. Second through fourth gears have helical-cut teeth for quieter operation, and load carrying capacity has been increased significantly.

Twin Cam 96 Highlights
Traditional V-Twin Styling: The Twin Cam 96/96B remains the styling centerpiece of each Harley-Davidson Big Twin model, and it retains the look, sound and feel that has always been part of the Big Twin character. The Twin Cam 96 preserves the styling characteristics of the Twin Cam 88 and the heritage of its predecessors.

New Crankcase Design: The starter is now bolted directly to the inner primary housing, eliminating the starter jackshaft for improved starter performance. An integral oil filter adapter eliminates gaskets and hardware. Internal oil passages between the engine and transmission on the Twin Cam 96 eliminate external oil lines and fittings.

Reduced Reciprocating Mass: Lighter pistons and lighter, shorter connecting rods increase performance and reduce vibration. Despite an increase in displacement, the Twin Cam 96 and the counter-balanced 96B are noticeably smoother than the Twin Cam 88 at most engine speeds.

Improved Camshaft Design: The new cams are lighter and use improved materials for enhanced durability. New hydrostatic, plain cam bearings replace the previous roller bearings and offer increased durability, reduced complexity and quieter operation. New multi-piece assembled camshafts replace the previous forged, single-piece cams. A new, hydraulic automatic cam chain tensioner replaces the previous spring-loaded mechanical tensioner.

Improved Oil Pump: A new oil pump assembly provides 10 percent more flow and 23 percent more scavenging capacity than the previous design. The Twin Cam 96 also has an integrated oil cooler adapter.

Improved EFI: New 25-degree fuel injector nozzles offer better fuel atomization and spray targeting than the previous 8-degree injectors, and help reduce exhaust emissions and improve driveability. A new O2 feedback sensor in the exhaust helps fine-tune EFI performance and reduce exhaust emissions.

New Primary Chain Tensioner: A new automatic primary chain tensioner eliminates the manual service adjustment of the primary chain. The inner and outer primary drive covers are redesigned to improve the appearance of the painted, polished or chromed surface.

New Exhaust Tuning: Muffler tuning has been changed to both improve exhaust flow for increased performance, and to improve the sound quality of the exhaust. Low frequencies have been enhanced to give the Twin Cam 96 a new, commanding exhaust tone that preserves the legendary Harley-Davidson sound.

Bolt-On 103 Big Bore Kit: An increase in displacement to 103 cid can be achieved by adding a bolt-on Big Bore Kit with 3.875-inch bore cylinders and matching pistons from Harley-Davidson Genuine Motor Accessories. It is no longer necessary to add a stroker kit to get to 103 cid.

6-Speed Cruise Drive Transmission Highlights New Gear Ratios: New gear ratios have been selected to match the torque curve characteristics of the Twin Cam 96 engine. Roll-on acceleration performance is improved in all gears. Top gear cruising ratios are reduced significantly with the addition of the sixth gear and passing capability is improved.

Smoother Shifting: Shift effort is significantly reduced because steel “dog rings” that slide to cause gear changes replace moving gears. Because the dog rings have less mass than gears, shifting is quicker and smoother, and the throw of the shift lever is reduced.

New Transmission Case: Larger internal bearings, larger gears and a stiffer transmission housing all combine to improve over-all durability, and torque-carrying capacity is increased by 28 percent. The transmission for Dyna and Touring models has internal oil passages that eliminate external oil lines and fittings and the opportunity for leaks. The Softail transmission retains external oil lines.

New Gears: Helical-cut gear teeth, initially developed for the VRSC family, present a larger contact area than the previous straight-cut gears, so they are stronger and also quieter. A new cassette gear cluster is easy to remove for improved serviceability.

Reduced Clutch Lever Effort: Reduced clutch spring rates, a revised ball-and-ramp design, and a new, more-efficient clutch cable combine to reduce clutch lever effort by up to seven percent (varies by model).

Service Intervals: The new Twin Cam 96 engine primary chaincase drain interval is 10,000 miles, while the 6-speed Cruise Drive transmission drain interval is 20,000 miles.