classic motorcycle forum
Motorcycle Discussions => American Bikes => Topic started by: friday on August 24, 2023, 10:44:43 PM
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Interesting article.
"There never was a Rudge-Crocker..." but Crocker had clearly studied the Rudge engine: the Crocker single is by no means a copy of the Rudge, but it has the same general layout, features and look.
The rise of the JAP engine for speedway/dirt track was meteoric. Through the 1930 season in England the Rudge won more-or-less everything of importance, but after the first few meets of 1931 even the top Rudge riders were fitting JAP engines to their machines. Even the very special Works Rudge engines couldn't compete. My guess would be that even the hand-built single cylinder Crockers had trouble keeping up with the "standard" DT JAP engine.
Leon
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A 'Rudge-Crocker' would be a Rudge frame and a Crocker engine combination = never existed.
A search on the net will show 'Rudge-Crocker' examples at the auction houses, which is where and why they exist. MONEY!
The design of the Crocker is certainly based on British engines. It made sense to take a close look at Brit bikes.
Charles Franklin designs were based on British bikes. He died in 1932 and Indian had no one to design anything.
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This is from LA business directory. Fred Schunk was an employee of A H Crocker
(https://www.advrider.com/f/attachments/2023-08-26-4-png.5183067/)
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1936 LA yellow pages. George Beerup and Fred Schunk. Both of these buildings are still standing today. Can be seen on google maps. Beerup shop is now a "Green Cross"
(https://www.advrider.com/f/attachments/2023-08-26-3-png.5183051/)
(https://www.advrider.com/f/attachments/2023-08-26-5-png.5183063/)
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The "dirt track" bike was a very formulaic thing: the Webb DT fork in a frame of very well prescribed geometry with a single-speed countershaft, either with or without a clutch, depending on racing regulations at the time. All this stuff was designed by Australian Alan Bruce in 1928. His racing bike was taken to England in 1929 by Melbourne Rudge Agent Tommy Rogers and presented to the Rudge factory, who used Bruce's fork, geometry and countershaft for the all-conquering 1930 DT Rudge. The fork was put into production by Webb and sold on all speedway bikes up until the 1960s, and the countershaft and geometry could be copied by anyone, so a 1931 DT JAP was just a JAP engine in someone's DT frame. Martin were big manufacturers, and if I recall correctly these were sold by Commerford's - thus the reference to Floyd Clymer importing Commerford-JAP speedway bikes. The Crocker speedway bikes either used these frames, or copies of them, so while not "Rudge" they were more-or-less 1930 Rudge pattern, as were all speedway bikes. But I don't think short-track speedway was ever really big in the US, at least not as big as it was in the UK and Australia.
I'm not sure what to make of some of the Crockers that come on the market these days...
Leon
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The Harley Peashooter frame was also big in speedway in both Australia and the US ,and I notice an auction bike called an Indian 500 ohv speedway bike,seems to have a Peashooter frame.........of course HD also made a copy of the JAP engine (some said it was a JAP) for speedway .
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Victor Martin was the distributor, direct from JAP. He later took over Comerford. His Martin frame was a copy of Rudge. The Comerford had a forged head
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The Crocker frame was built around the Indian engine. This same frame was used for the 1934 OHV single.
The Rudge frame was never used. That would take 2 bikes to make 1. The Rudge DT was last listed in 1933 catalog. The JAP was the king of the track.
This bike has Indian on the tank not Crocker, because it's a Crocker frame but Indian engine.
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Rudge DT was listed in 1933 catalog but it is unknown if any were built. That would make them 1932.
JAP dominated the track by then.
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Rudge DT was listed in 1933 catalog but it is unknown if any were built. That would make them 1932.
No, it wasn't. Your image is from the 1931 Rudge catalogue, which would have been produced in (say) September 1930.
Interestingly the actual bike had some big differences from the drawing: the fat front wheel never made it onto the track (regulations were changed to limit the width of the front tyre), and the gearbox shell (with no gears inside) had been replaced with a countershaft for the 1930 models.
The DT Rudge was listed in the 1932 catalogue (say Sept 1931), with exactly the same illustration as the 1931 catalogue. I bet none - zero - were built or sold. Nor was it in the 1933 catalogue, despite an incredibly potent 6-stud (if I remember correctly) engine having been designed and built to return Rudge to the top of DT racing - the JAP was too good. Rudge withdrew from racing entirely after the end of the 1932 season.
Victor Martin was the distributor, direct from JAP. He later took over Comerford. His Martin frame was a copy of Rudge. The Comerford had a forged head
Mmm... I don't think so.
To my knowledge, JAP didn't make bikes, nor did Comerford? I think you'll find that Martin made the bikes, and Comerford sold them?
Leon
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The DT was last listed in the 1933 catalog with no image. The Rudge site lists the catalogs.
Victor Martin was the only dealer of JAP engines from the factory. The Comerford predates the Martin frame- Rudge copy
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Yes indeed - one mention in 1933 with no illustration and no specs. Worth pointing out that your "1933 DT" post has an illustration from the 1931 catalogue.
What year is your Floyd Clymer/Comerford JAP article? I see Comerford were originally called Comerford-Wallis https://cybermotorcycle.com/archives/speedwaybikes/comerford.htm so presumably the early Comerford bikes were made by Wallis, or from the Wallis design, and later Martin?
Leon
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1931 and 1932 have 1930 specs.
Clymer became 'English Motorcycles' -'Clymer Motors in 1933.
George Wallis designed frames
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1931 and 1932 have 1930 specs.
Rudge? The 1931 DT Rudge used a very different engine from the 1930 DT. It was based on the 1930 TT engine, so it had different crankcase, timing gears, cylinder, and head (with bolt-on plates rather than cast-in pillars to support the valve gear). Also for 1931 there was an option of the standard 1930-type frame, or a new longer wheelbase version. Despite the fab new engine, even Rudge greats were bolting JAP engines into their Rudges after the first few races of the 1931 UK season - the origin of Victor Martin's "Martin JAP". I see that Martin's early brochures noted that the frames were made "Under Licence with Rudge Whitworth Ltd" - interesting that Martin and Wallis/Comerford ended up under the same umbrella.
I wonder why the Crocker DT machine ended up with a cross-over gearbox. Seems like such a bad idea on paper.
Leon
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Cross over was pretty standard US racing practice.....the final drive ratio could be changed in a few minutes.
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Good point - maybe that's the reason. With a massive amount of power from the speedway engine the price is the chains yanking the countershaft in opposite directions at each end.
Leon