Primary Housing Big Twins 1965→

Primary housing 1200 and 1340 with electric starter

In 1965, Harley-Davidson launched the next primary housing development stage for the Big Twins. As a result of ever louder customer demand, the electric starter was introduced with the last "Electra Glide" Panhead model. As the electric starter on the 1200 Big Twins engages in the clutch like a car, the primary housing is revised - along with many other things: made of cast aluminum, with a good seal between inner and outer case, and with a cast-on "nose" that houses the release mechanism and the starter reduction.

On the versions up to 1984, the primary drive chain still has drip lubrication, from 1985 onwards it runs wet, i.e. in an oil bath.

Is the primary leaking? Tips to remedy the situation

In the past, you often heard "A Harley doesn't drip, it marks its territory." This is actually nonsense. Even a Harley should not drip more oil than necessary. First of all, you should check whether the oil is actually leaking from the primary housing or from the gearbox. If the primary is the source, there are two possible causes: the seals themselves or the sealing joints. There are seals between the inner primary housing and the engine and, in the first 5-speed gearboxes, between the gearbox and the primary housing, as well as between the inner and outer primary covers, below the clutch and behind the inspection cover. If the oil leaks between the two primary covers or between the inner cover and the crankcase, the inner primary case should also be checked for distortion. Especially on FLH, FX, Softail or Dyna models with the long primary cover, the inner primary can warp due to careless tightening of the connection to the engine and transmission. This will of course prevent it from being tight.

Cannonball expressly recommends, that the engine bolts and transmission studs on the reproductions of the inner primary cases from 1965-1969, which they offer, should only be tightened once the primary is precisely aligned with the engine and transmission.