Home / History / EasyRider’s account of the history of the panhead (4 pages)

EasyRider’s account of the history of the panhead (4 pages)

Easy-Rider-Panhead-HIstory-Page-1The Overhead Valve (OHV) Panhead model was produced from 1948 to 1965. It’s development and refinement set standards in design that are still influencing motorcycle styles today. The new OHV, introduced in 1948 was borne of the economic boom following WWII. It’s predecessor, the OHV Knucklehead was Harley-Davidson‘s first production OHV twin engine model. Immediately popular with riders, it pioneered new ground with it’s introduction in 1938. It suffered continual teething problems with oil leaks, soiling both engine and rider.The industries of World War II reversed the Depression and reinvigorated the economic landscape in this country. Women went to work while their men were away fighting on foreign battlefields. Harley’s war model WLA did much to introduce and popularize a whole new generation to the fun and excitement of motorcycling. Faced with surging demnad for motorcycles after the war, Harley-Davidson was challenged to develop better products and keep up with the demand. Raw materail shortages made matters worse for manufacturing firms trying to supply post war demands for goods and services. Today’s demand outstripping the supply of new Harley Big Twins is deja vu to Milwaukee. Advertising literature apologized profusely into the 1950s and explained they were doing everything possible to meet demand and maintain high standards.

YEAR AFTER YEAR THE LEGEND GREW

1948-LAST YEAR FOR SPRINGER FORKS AND FIRST YEAR FOR THE PANHEAD ENGINE

1948 was a milestone year for the Motor Company. The new OHV Panhead engine’s design change would alter the machine’s persona for decades. Material used for the head was changed from cast iron to aluminum. Overhead valve design required a continuous oil supply to lubricate it. The OHV Knucklehead had ongoing problems with oil leaks from it’s heads. A complex assembly of tin cover4s and aluminum rocker boxes that vibration and improper assembly could loosen would allow oil to leak onto the exhaust pipes and down the cylinders. A simple but effective cover was devised to seal the entire top of the 1948’s new head.

The cover looked like an inverted cooking pan, thus the term was born: Panhead. A thin steel reinforcing ring set was introduced later in the year to strngthen the surface contact area of the pan covers to the heads. New 14mm spark plugs replaced the old 18mm ones. Historically painted black since the 1920s, the top end now had silver-coated cylinders and aluminum heads topped with brightly chrome-plated rocker covers. While the new engine stood out, the rest of the Panhead’s basic design was relatively unchanged from the 1947 model. The OHV engine was offered in 61in and 74in displacements. An entirely new face design graced the edge lighted speedometer with an easy to see red speed indicator needle. The UL 74in side valve (FLathead) model was discontinued at the end of the year.

1949-FIRST YEAR FOR THE HYDRA-GLIDE FRONT FORK

Accompanying the new Panhead engine, new forks, frame, and fenders were of contemporary design. This was the first year of the Hydra-Glide front fork assembly on the OHV model. Hydraulic forks first tried on a short lived experimental XA war model were reintroduced on the 49 Panhead. The timeless style, utility, and popularity of the new fork was proven by it’s continual use on Big Twins for the next 48 years.

The front brake assembly was totally redesigned and larger in diameter than the springer brake. A new, larger sealed ray headlight was offered on OHV models and two chromed parking lamps were attached to the upper fork tube covers. The frame was modified with dog-legged front down tubes instead of traditional straight legs used on the Knucklehead. The frame redesign accommodated the slightly taller Pan engine in it’s cradle. The valanced springer rigid fenders used since 1934 were abandoned in favor of a pair of smooth sided mudguards with a rocketship look. New polished stainless steel covers were used on the heads. A black painted horn was moved to the upper fork downtubes under the steering head. An unusual stainless stell cover shaped in the form of the fishtail muffler was attached over the muffler in 1949 only. The five piece fork trim covers, primary chain inspection cover, and clutch derby cover were all polished stainless steel. Three new horizontal chevrons enhanced each side of the tombstone taillamp.

1950-FIRST YEAR OF THE “TRAIL-A-WAY” HYDRA-GLIDE ADJUSTABLE FORKS

“Smooth as flying” is how the Hydra-Glide forks were described in period sales literature. The fork lower legs were polished on the touring Big Twins from this time forward. There was a 10% boost in horsepower with a design change and an increase in size of the intake ports. The carburator was updated with an improved Linkert M-74B. Gas lines were rubbermounted. An adjustable trail feature was introduced on the Hydra-Glide forks to improve handling on sidecar and package truck applications. A handlebar riser link introduced in late ’49 was first illustrated in advertising on the 1950 OHV model.

1951-ENGINE CAM IMPROVED, EXHAUST PIPES CHROME-PLATED

A new chrome-plated brass script gas tank name plate with underline replaced the late 1940s fireball emblem. Chrome piston rings were installed for a tighter compression seal …..continued on page 2

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