In typical Harley-Davidson fashion, it turns out that the ’06 Dynas were the testbed for things to come. Due to the aforementioned changes, new, lighter camshafts were also employed. This is a good thing, as the bike’s lifeblood gets into the motor faster while removing power-robbing oil more quickly from the crankcase. Perhaps the greatest improvement comes from a redesigned oil pump, residing in a new cam support plate, that provides 10-percent more oil flow while adding 23-percent scavenging ability. These plain cam bearings were designed to reduce complexity, run more quietly, and increase durability. Instead, the camshafts rotate in well-lubricated aluminum journals. The two case bearings were increased to 1-inch diameter, and the cam plate no longer contained any bearings. Instead of spring-loaded tensioners, the new units use hydraulically activated tensioners that operate in a similar fashion to a lifter (tappet). Roller chains and sprockets that are similar in design to a drive chain and traditional sprocket replaced the Hyvo chains. With the ’06 model year, H-D launched the new Dyna Glides, which featured a completely redesigned camshaft system. This may have been exacerbated with the “inverted” tooth design of the wide Hyvo sprockets. Even how you ride may have an effect-throttle-whackers and aggressive downshifting puts more stress on the valvetrain. Maybe it was a case of variations in the manufacturing of the shoe material, or how the tensioners were installed (we’ve heard that letting the tensioner snap hard against the chain during installation may reduce the integrity of the Vespel material), or maybe the chain itself had deviations, sharp edges, or tight spots that caused premature wear in the tensioners. The problem (if you want to call it that) seemed to be haphazard, as there were bikes with only 5,000 miles with worn tensioners and also bikes with 75,000 miles with barely any wear at all on the tensioner shoes. Both camshafts rested in 0.875-inch-diameter bearings that were pressed into the case, while the other end of the cams spun in bearings attached to the cam support plate.įor the most part this system worked pretty well, though there have been reports of failure of the cam chain tensioners, which led to various cases of engine problems.
Cam chains were kept taut with spring-loaded cam chain tensioners made from Dupont Vespel.
One chain (on the outside of the cam plate) connected the crankshaft to the rear cam via a sprocket, while the front cam was driven off the rear cam, with the secondary cam chain located on the inner surface of the cam plate. This event relegated the venerable single-cam Evo motor to the H-D history books alongside the shovelhead and panhead.īesides the addition of a second cam, the camshafts were now driven off the pinion shaft via sprockets and Hyvo chains (so-called “silent” chains) instead of through gears the way the Evo had been. The following year, a counterbalanced Twin Cam engine found its way into the solid-mount Softail line. Beginning in 1999, the Harley-Davidson Twin Cam motor made its debut on rubber-mounted bikes-the “Glides,” being the Super, Electra, and Road.