Harley Davidson Knucklehead and Panhead FL FLH History

Harley has been around since 1903.  Over the years Harley Davidson has made many models.  The FL series is the longest running model beginning in 1941. It was originally equipped with a 74 cubic inch   "Knucklehead" OHV engine, (the EL series had a 61 inch version) Fatbob tanks, hand tank shift and foot clutch, rigid frame and springer front end. The nickname Knucklehead came from configuration of the rocker box covers that looked like knuckles.

The FL series had few changes between 1936 through to 1947.  In 1948 a major update happened the being the Panhead motor.  The Panhead included self-adjusting hydraulic lifters and aluminum heads to increase cooling on the motor.  The nickname Panhead again came from the rocker box covers that resembles upside down pans.   There were a few variations to the frames including the front down tubes going from a straight leg to a wishbone configuration.

Hydra-Glide 1949

In 1949, a year after receiving the "Panhead" engine, the FL was given a new front suspension the Hydra Glide featuring hydraulically damped telescopic forks, replacing the inefficient springer front end. 

These forks were standard on all big twin models for 1949, including the E, EL, F, and FL. 

During their debut model year of 1949, Harley referred to their new suspension systems as the "hydraulic front ends". Harley's marketing department promoted the new suspension systems by renaming the big twin models "Hydra Glide" for the 1950 model year. This was Harley-Davidson's first departure from its policy of using alphabetic lettering to identify its models.

This name would change twice in the history of the basic large-framed E and F series models, each time signaling an improvement in the bike's technology. In addition, the Glide ending would be used on other models, based on both and FL and FX formats.

In 1952, the Hydra-Glide's transmission standard hand-shift/foot-clutch was supplemented by the optional foot-shift/hand-clutch. The original format continued to be offered as an option until 1978.

Although Harley Davison was founded in 1903, 1904 was the first production year and the 50th Golden Anniversary was celebrated in 1954.  1954 model Harley-Davidson had special paints and badges on the front fender. In 1954 Harley changed the left hand crank bearings from a roller set up to a Timken bearing set up that was used right up to the twin cam in 1999.

A more highly tuned engine with high-compression heads, higher-lift cams, and polished ports, was offered with the FLH version of 1955.

The Duo Glide

The next major change when Harley developed the swing arm frame in 1958 replacing the bone shattering rigid frame that had moved people around for so many back breaking years.  The swing arm was attached to a set of shocks that dampened the jarring affect from the roads of yesterday and today.  The Hydra Glide was renamed the Duo Glide in 1958.  The same Swingarm shock concept is still used today on Harleys 2015 models.

The Electra Glide

The final change given to the Panhead FL model would occur in 1965, the last year of the "Panhead" motor in a factory Harley Davidson.  In 1965 Harley replaced the oil leaking tin primary covers with an inner and outer aluminum primary cover set that housed the first Harley Davidson electric start motor.  Believe me a welcome change.

I am sure that any of you who have kick started a Harley would agree.  My knee was destroyed many years ago from my stroker backfiring on a kick or worse the gears not meshing and coming down hard on nothing and hyper extending my leg.  F#@k it still hurts thinking about it.

This was the last year of the Panhead, 1966 the Shovelhead made its debut and the story goes on.  At Yales Motorcycle Parts we offer reproductions Harley wishbone, straight leg and Swingarm frames, Springer forks, complete FL Knuckle and Panhead bike kits, reproduction and high performance Panhead and Knucklehead motors, transmissions and pretty well anything else you need to build or restore your FL.

Check out our:

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If you are restoring, repairing, rebuilding, customizing or adding high performance upgrades to your FL Knucklehead or Panhead and need parts check our site Knucklehead Panhead Shovelhead section   @  or send me a MESSAGE

Ride Safe & Ride On

- Yale

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