The History of the Thor Motorcycle Company
By Greg Walter
The Aurora Machine and Tool Company started as a machine shop in 1886. It
provided forging and machine parts for the then burgeoning bicycle industry.
This was a time when many fortunes were to be made in the bicycle industry. Many
bike manufacturers set up shop. They bought their castings, forgings and parts
like hubs and coaster brakes from Aurora. They would then braze together,
assemble, paint, and market their product. I have yet to see a pre-motorcycle
parts catalogue - however by 1903 (the year of my earliest literature) they had
a large line of parts including 10 different rear hubs, 5 different front hubs,
racing hubs, spokes, nipples, handlebars, special spoke washers to be used with
wooden rims and a large number of patents were listed.
Some time about 1899 Oscar Hedstrom built his first motorcycle. It was a tandem
motorcycle used to pace bicycle races. The front person steered; the back person
ran the motor and made all necessary adjustments to keep it running (hopefully
at the right speed!). No one is sure where that first motor came from. Many have
said it was very similar to the French made De Dion motor. Hedstrom had no
foundry to work from so it is probable that the castings were provided by some
unknown machine shop making their own version of a De Dion or another
possibility was that Hedstrom made the pattern himself and used the foundry at
Warwick Motorcycle in Connecticut. Presumably Hedstrom refined the design over
the original De Dion motor because his machine was notably superior to anything
else available. In 1901 he joined forces with George Hendee and formed the
Indian Moto Cycle Company. During that year three prototype machines were built.
We know from good documentation that in the fall of 1901 one of these prototype
Indians was shipped to the Aurora factory be studied by them. Oscar Hedstrom
went along to render technical assistance. Why Aurora? Apparently they had been
providing Hendee with castings for his Silver King and Silver Queen bicycles.
After several months' work, the Aurora Company produced a new motor of Hendee's
design. These motors differed from the prototype most notably in the use of
three cylinder studs instead of the four (ala De Dion). Also some ribs were
added to strengthen the engine case. Aurora struck a bargain with the fledgling
Indian Company. Aurora would build these engines for Indian but would be free to
sell additional motors to other companies providing that a royalty was paid.
Also it was stipulated that Aurora would not build motorcycles and compete with
Indian. I have yet to see the original contract so the exact wording of the
agreement is still unknown to me.
There were 137 Indians produced in 1902. All of the motors were built by Aurora,
and as Indian had no foundry and limited production capabilities probably most
of the forgings, castings and machined parts. George Hendee was previously in
the bicycle manufacturing business and so it is assumed that Indian brazed
together their own frames, manufactured their own fenders and tanks did their
own painting and assembly. It is known that Indian had patents for the Chain
Adjuster, "Muffler For Internal Combustion Engines", "Valve For Internal
Combustion Engines", Controlling Mechanism For Internal Combustion Engines",
Carburetor, and "Fuel or other reservoir (?)". So presumably Indian used their
own rear hubs, not Aurora's hubs. However, early Indian literature says they
used a New Departure hub. It is unknown if Aurora made or sold any motors in
1902 other than the 137 to Indian. It is possible that that was all they could
produce, as a reference found in the Indian archives mentions how shipments were
often unreliable and sporadic.
In 1903 Aurora founded the Thor Moto Cycle and Bicycle Company. Or at least they
produced a catalogue showing Thor Moto Cycle parts and components. In their
catalogue every part needed to produce a motorcycle was listed for sale. A
picture carefully worded as a "motorcycle assembled from Thor components" was
shown. Interesting that they might have their own tank decal if they were only
selling components for other companies! No frame was offered for sale but all of
the forgings could be purchased to assemble your own. In 1903 trade magazine ads
were seen of companies that would sell you Thor motorcycles built from
components. It is here that we mark the beginning of the Thor Motorcycle
Company. At about this time at least half a dozen other companies sprang up all
producing similar machines built from similar components all looking near
identical to the 1902 Indian and 1903 Thor.
What was the difference between a Thor, a Thor clone and an Indian? Well, all
the forgings may have been the same however the frames were all built using
different jigs and possibly different dimensions. It is near impossible for us
to sort this out now because some of the dozen or so 1902 Indians that we know
about have some wrong components. The surviving 1903-05 Thors are even more
dubious. Some clones have been restored to be Thors. Some Thors have Indian
component on them. One "early Thor" uses a skip tooth roller chain (versus
Indian block chain) has a heavier gauge frame tube, uses a Thor rear hub and
both the carb and motor say Thor instead of Indian. Indian would often brag that
they did something secret to their motors that made them superior to Thors but
most experts doubt this. Another difference between the two machines can be
found in the right-sided spark advance. The Indian had a link arrangement coming
out of the handlebar, the Thor had a sort of rack and gear arrangement at the
headstock. Thor also had a kill switch on the engine case that triggered when
the spark was completely retarded - Indian motors did not. It is said that in
1905 half the motorcycles seen at a trade show were Thor clones. Included in the
list are Thor-bred, Reading Standard, Merkle, Apache, Raycycle, Manson and in
years later Sears and Torpedo.
From what we can see Thor did not change their design from 1903-1905. In a 1908
parts book they show a picture of the original 1903 design and call it a
1903-05. They also show a different Model for 1906-07, which uses the same
design with numerous changes. The same model was updated in 1908 and sold as a
model "7". This same design was until early 1909.
Indian literature states that they had their own in house foundry in 1906. In
1908 Thor opened there own dealerships advertised completed machines and
produced their first real sales literature. Thus officially ending any ties. In
addition to the previous model 7 an entire line of new machines with choice of
either battery or magneto ignition were now available. Thor offered chain drive
or belt drive. One new design was a unique appearing twin with automatic intake
valves. The twin had the rear cylinder straight up and the front cylinder angled
forward (as Ducatis were later famous for). By all accounts it ran rather well
which is interesting in the light that both Indian and Harley had difficulties
with automatic intake twins.
Thors changed with the times. In 1911 they offered a free engine clutch for the
first time. They continued belt drive for the last year but only on their single
cylinder models. Apparently the factory felt that the additional horsepower of
the twin produced an unacceptable amount of slippage. Rather than use a more
conventional belt-tensioning device, these belt drive Thors used a complex
device which instead altered the geometry of the frame to tension the belt.
Another addition for 1911 was a change in the intake valve of the twins. A
rather unique pull rod was used to pull the intake valve open. One other unique
design feature was found in 1911 and that was in the magneto timing. Rather than
advance and retard the timing plate on the magneto the ignition timing was
changed by moving the magneto idler gear (a feature that thankfully did not
survive into 1912).
In 1912 an entirely new single and twin were offered both with rocker arms. The
twin was now a more conventional V but unlike Indian's 42 degrees and Harley's
45 degrees Thor chose a 50-degree angle. Also offered was an optional two-speed
transmission. This transmission was aluminum and it mounted to the side of the
rear hub. Apparently of good design the aluminum Thor transmission was sold
until 1914 and was even offered as an option on other motorcycle most notably
the Henderson four. Perhaps the most exciting change for 1912 was that for the
first time Thor was available in White as well as Blue. Apparently Bill Ottaway
had used white as the color for all Thor's racing team. They were very
successful so the factory felt that the public would be interested in buying a
White Thor. I don't know how they figured owners would keep them clean looking
(the owners manual suggests Ivory soap!).
Not much changed in 1913 however in 1914 the twin was offered as a 1000cc and
now a 1,200cc machine. The new bigger twin could also be bought with a Schebler
carb if desired. Up until this point all Thors used their own Thor updraft
carburetor. Like most other manufacturer Thor added footboard in 1914. Thor
still continued its pedal crank rear brake however a pedal and ratcheting device
was added that gave a little additional leverage to a marginal braking system.
In 1915 the white color scheme was gone. Everyone else was offering electric
lights as an option so Thor mounted an electric headlight and a Splitdorf mag
dyno and they had an electric model too. 1915 was a banner year for Indian,
Harley, and Excelsior. They each offered a three-speed transmission of
conventional design. The best Thor could do was a new designed cast iron two
speed that mounted aside the rear hub. While maybe this unit was rugged in
design its huge size and weight left much to be desired.
Having carried one from one end of a swap meet field to the other I can attest
that it was just too heavy.
Along with the usual singles and twins offered in 1915 was a Short Coupled
racer. It was actually a short-coupled version of a 1914 street bike. Given the
tremendous competition on the board tracks in 1915 it is doubtful that anyone
could have thought this bike to be competitive. More likely a marketing decision
on a way to sell some of last years left over inventory.
1916 was for all intents and purposes the last real design change. Thor offered
a three-speed transmission and clutch of conventional design. After 1916 there
were no changes made to the motor design. Actually some evidence suggests that
all motors sold after 1916 were built in 1916. In 1917 a front stand was
offered. In 1918 the fender valence was changed, as was the luggage rack. A lug
was added to the front down tube of the frame to mount a sidecar. Conjecture is
that this was done to appeal to the military market. I have seen no
documentation of any number of Thors sold to the US military. However given the
number of olive drab parts turn up as well as the proportion of 1918 and later
machines that exist in Europe it is probable that some country must have bought
purchased a large number of machines.
Thor continued on to produce a line of motorcycle under the parent company of
Aurora Independent Machine and Tool. At the same time Aurora continued to market
forgings to other companies and to sell Pneumatic and power tools under a
different division. There is scarcely a brand of american motorcycle that wasn't
in some way "touched" by Aurora. Reading Standard, Flying Merkle, Raycyle,
Indian, Sears have all been mentioned. Cyclone (? - well the fork and frame
forgings at least were), Henderson (? - well the 1913-14 models sold a Thor two
speed hub as an option), Harley (? - the 1911-14 single speed hubs were of Thor
design and manufacture). Another tie in to Harley was in the arena of racing.
Thor had a racing division from about 1908 to 1912 and they had a fair amount of
success. It was run by William Ottaway. Bill left in 1912 and formed the
incredibly successful Harley Davidson racing team, which bought Harley from
relative obscurity in 1911 to arguably the American champions in 1916.
By 1918 the Thor Motorcycle Company was fading into obscurity. We know they
brought a new model single out in 1918 mostly from left over parts. Enough
changes were made that we know that the company was still producing bikes.
In 1919 Thor brought out a new sales catalogue however except for the cover and
a change in name the motorcycle was identical. The parent company transferred
motorcycle production to the Aurora Pneumatic Tool Company of Chicago Illinois.
Which was simply just a different division of the same company. In 1920 the
board of directors announced a halt to motorcycle production.
In 1965 an employee of Thor who was a semi-retired janitor sent a letter to the
AMCA stating that he hard worked for Thor until 1916 when they stopped
motorcycle production and sold everything to a salvage company. Based on this
account many books erroneously state that Thor ended production in 1916. Well it
is easy to prove that production continued until 1918 because of the changes
advertised in their sales brochure. Many of those parts exist today as proof. I
don't know of a complete machine that claims to be later than 1917 and even that
one has the wrong motor. I have seen three motors in 1918-20 frames with serial
numbers inside the case showing they were built in 1916! Maybe the last motors
were built in 1916 who can say? Maybe the last machines were assembled in 1918
and sales were such that they continued to have inventory until 1920? It is hard
to know. Thor did continue to produce power tools under the name Thor well into
the 50s. A separate division of the Aurora Company known as Hubley Manufacturing
produced a line of home appliances such as clothes washers, irons and
dishwashers using the Thor brand name. At one time they produced a combination
clothes washer - dishwasher which may help explain why they are no longer in
business!
