Author Topic: 1932 TT Douglas  (Read 9800 times)

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Offline Doug

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Re: 1932 TT Douglas
« Reply #50 on: 16 Jul 2020 at 03:23 »
Quote
Doug posts an older photo of an interesting bike with an unusual fuel tank "supposed to be Jack Douglas' Works sidecar bike prior to restoration", and another of it after restoration. But is this the same bike? How did it grow an extra frame lug on the lower right chainstay, adjacent to the rear wheel rim? Could it be a different bike Doug?

Well we probably will never know for certain. Regardless of which bike was the ex-Jack Douglas machine, one might expect the trio built would have been similar. As they (the '32 Works bikes) were not standard road frames, nor were they earlier (1926-28 TT/I.o.M. frames) adapted frames one would imaging they were specially built new for the occasion, built together, and all had that footrest lug on the rear chain stay. I think part of that lug remains in the photo you mention, in line with the tire tread. If you look closely, there is a 'fattening' of the chain stay tube where the lug would be. I think it is the part of the lug that wrapped around the tube. If it is the same bike that was auctioned, I don't imagine it would have been too difficult to replace the missing portion during restoration. Colin Clifford also built a replica frame for the Dixon twin-cam, a 'tribute' 1932 Works bike, and a batch of new 1930-32 oil sump castings to support these projects.
 
There is some tenuous circumstantial evidence that the un-restored and restored bike in the auction are the same; beyond the default 50-50 chance (since it is not the Bury Brothers outfit that leave one other bike of the trio). When Colin Clifford sold off his remaining Douglas parts, there was a sole 1934-35 foot shift gearbox for an ohv Dougie; same as seen in the photo. Collin never had a OW/OW1 to the best of my knowledge, and those gearboxes are not very common. It is possible it was surplus when replaced with a more period correct Sturmey-Archer box. Whether it is the ex-John Douglas outfit is a entirely different matter. I do not know the chain of ownership, or what supporting evidence there was to support such a claim.

I say '1932 Work bikes' but as the info I was told about the ex-Bob Jones sprinter being a 1932 frame being suspect, one has to consider that maybe they built new frames in 1930 or '31 and just kept using them over. Or in 1932 they built new (or altered?) frames with taller head stocks and non-Douglas gearbox. If the Motor Cycling reporter got that right; though news reporting in the past tended to be more accurate than what we have come to expect today!

Quote
"Information is sought by a reader about the Douglas sidecar outfit which was built for the abandoned 1934 Sidecar TT and later raced at Brooklands by Jack Douglas. It has a Swill-built Dixon banking sidecar and a 596-c.c. o.h.v. engine, No. 10, the frame number being OF 218.

If the bike the reader was seeking information on used the 1926-28 TT/I.o.M frame (OF prefix) then the gearbox platform would have swept down like a DT, and not sprung directly forward like the 1930-32 Works bikes. Indeed it would have been a lot like a DT/SW5 frame, the major difference being the top tank tube shape and the use of a taper roller bearing head stock vs. the loose bearing balls of the DT/SW5 (that harked back to the RA model). So if OF 218 was really built for the abandoned '34 TT and then later raced by Jack Douglas at Brooklands, then it would have been quite an old frame brought back into service and owed little in common with the 1930-32 Works bikes*. Not that it couldn't have been a entirely different machine. After all C.T. Atkins was still altering and racing a 1926-28 TT/I.o.M. based frame into the thirties and either it or a DT frame then became the basis of his supercharged special in 1936. Or the reader making the query could have been entirely mistaken about the machine's provenance.

-Doug

* Assuming there even were any 1930 Works bikes.


[Clarification. 10Aug20 -Doug]
« Last Edit: 11 Aug 2020 at 00:45 by Doug »

Offline Doug

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Re: 1932 TT Douglas
« Reply #51 on: 25 Jul 2020 at 04:14 »
For those that are unfamiliar, I found a good representative picture of the 'straight' gearbox platform that has been mentioned from time to time in this thread. Compared to a DT gearbox platform seen immediately below.





These 'straight' platforms showed up on the F/G31 models (example shown), and continued on to the 1934-35 OW/OW1 models. This same lug was used on the thirties Works bikes. A similar - though not identical - lug was used on the short-stroke DT frame on c1932. 

-Doug


Offline cardan

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Re: 1932 TT Douglas
« Reply #52 on: 28 Jul 2020 at 22:26 »
Here's the Bury brothers' 750 Douglas outfit in action at Donnington in July 1935. The caption says W. E. Bury riding - presumably Ted? Bob Currie (CMC June 1988) says the bike's debut was at the same track in May 1935, and the likely build date was 1934. Hard to argue, given the special frame and engine prefixes issued for these large racers that fit in after the 1934 production bikes - see the appendix in The Best Twin. I'd be pretty certain that although they looked like the 1932 TT bikes, they were built after. Probably without the upward-angled inlet ports.

Leon

Offline cardan

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Re: 1932 TT Douglas
« Reply #53 on: 30 Jul 2020 at 07:12 »
More info on the 23 July 1932 outing of the Douglas team at Brooklands, from "All the Years at Brooklands" by Gerry Belton. (Great book - get a copy.)

The Stilltime collection photo from earlier in the thread is reproduced full page, and there is enough detail to note that - since the TT the previous month - the cylinder heads with the angled inlet ports and carburettors "close coupled" have gone, replaced by the vintage setup of carburettors (probably 15TT32 AMALs) close to the central airbox. The air intake atop the airbox has its opening pointing forwards.

I don't have a photo showing the offside of a Douglas actually running in the IOM TT, but anoraks will notice that in the 1932 TT photos posted higher up show cables running towards the front cylinder head, so presumably the carbs were bolted directly to the heads in the TT race.

Belton tells us three Douglases ran in the Brooklands Senior GP (the TT riders C. S. Williams, C. W. (Paddy) Johnston, and Frank Longman), with a fourth Douglas (model unknown by me) ridden by amateur J. H. Fell. Fell finished fourth.

On the same program, C. S. Williams won the three lap senior handicap race on his 494 Douglas at 102.06 mph. This race was on the outer circuit, so unless he swapped out his mudguards, handlebars and braked front wheel I doubt he used the same bike he rode in the Senior GP (on the "road" Mountain Circuit). Still, nice to see a Douglas lapping at over 100 mph. The usual twist: he beat Hewitt (Excelsior JAP) who put in a lap at 115.29 mph and Bickell (Bickell JAP) who managed 112.71 mph, both well above the 500 lap record that had stood since 1929. Winning a handicap race at Brooklands in the 1930s might have been fun, but it didn't "mean" much.

Doug I think the angled-port TT head you posted photos of is an EXTREMELY rare beast.

Cheers

Leon


Offline cardan

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Re: 1932 TT Douglas
« Reply #54 on: 31 Jul 2020 at 00:34 »
Interesting now to revisit the workshop photo higher up in the thread, and comment that the airbox on the engine on the bench has a circular opening for the carburettor mouth. The 1932 TT engines must have had an elongated hole or slot - maybe 3" long? - for the large air manifold. Has anyone seen an original 1932 TT airbox?

Leon

Offline Hutch

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Re: 1932 TT Douglas
« Reply #55 on: 02 Aug 2020 at 04:58 »
Leon,

Thanks for the links to the pictures of Toni Babl at https://www.technischesmuseum.at/

I had a little bit of a look into the racing history of Toni Babl. It seems there is a bit of information here and a bit there, but I have not found a complete list of his achievements. So it appears to be difficult to piece together a definitive list of his racing results and then use this as a means to work out when he was racing Douglas machines, and in particular which machines they were. He was certainly using them between 1931 and 1935, and possibly earlier in 1927 and later in 1936.

On the Victoria website there is the statement that he had 31 wins from 35 “big race” starts. The first reference to Toni Babl winning that I can find is in the 1927 Ratisbona race. If this is correct (I have not found any other information yet to prove or disprove this) then Babl appears to have had 4 Douglas machines – the 1927 one, the 750cc outfit bought in pieces in 1931 with the help of Toni Nöckl and the two listed in the Appendix of Clew’s The Best Twin.

At least one website cites that Babl was killed in practice for the Eifel race at Nürburgring  in 1936 on a Douglas rather than a DKW. One would have assumed he would have been practising on a DKW rather than a Douglas at the time? This is a mystery that I have not found any answers to. The politics of the time may be of influence here?

To get an idea of some of the races Toni participated in here is a newsreel of the day for Klausen Hillclimb in 1934 where Toni won his class. Pity we don’t get to see the full length of the material Pathe would have filmed;
https://www.youtube.com/watch?v=6Qho8wskWA0

Results I have found so far – please let me know of any additions of corrections;
•   1927 Ratisbona -Bergrennen  Douglas (what model?)
https://www.automobilclub-muenchen.de/dateien/echo-2004-02.pdf
(page 22)
https://de.wikipedia.org/wiki/Ratisbona-Bergrennen

•   1931 international Freiburg berg-Recordrennen 1st Victoria 600cc
http://victoria-rad.de/?p=3366

•   1931 Kesselberg Victoria KR 6 600cc
http://victoria-rad.de/?p=3366

•   1931 Thiersee Douglas 750 cc
http://victoria-rad.de/?p=3366

•   1932 Kesselberg Douglas 750 cc
•   1932 Freiburg (by 4?)
•   Taunus-rennen (Feldberg?)
•   May 26th 1932 Gaisburg (Saltzurg) Sidecar up to 1000cc 1st Douglas (also ran Victoria 600cc)
https://www.automobilclub-muenchen.de/dateien/echo-2004-02.pdf
(page 23)

•   11th September 1932 Lietmeritz, broken front axle crash. Toni Nöckl died as result of his injuries. Douglas
http://victoria-rad.de/?p=3366

Babl out for all of 1933 with shoulder injury from crash

•   1934 Kesselberg 1st Douglas
https://www.technischesmuseum.at/motorsport-in-oesterreich/person/articleid/1794

•   1934 Klausen hillclimb Douglas
https://www.technischesmuseum.at/motorsport-in-oesterreich/person/articleid/1794

•   1934 Feldberg Mountain Race 2nd 600cc Douglas Julius Beer
https://nl.wikipedia.org/wiki/Feldbergrennen
http://www.feldbergrennen.de/feldberg%20-%20bergpreis%201934.htm

•   12August 1934 Luckendorf - Bergrennen under 600cc 2nd Douglas and over 600cc 2nd Douglas
https://www.yumpu.com/de/document/read/59436058/abschlussberichte-von-1923-2017
https://docplayer.org/45501580-Walchensee-ziel-start-kochel-see-km-st-72-km-67.html

•   1935 Feldberg Mountain Race 1st 600cc Douglas Julius Beer (stated as a “G33” Douglas?)
https://nl.wikipedia.org/wiki/Feldbergrennen
http://www.feldbergrennen.de/feldberg%20-%20bergpreis%201935.htm

•   1936 2nd place, Hanoverian Eilenriedoren DKW (Eilenriede Rennen at Hannover)
https://de.wikipedia.org/wiki/Toni_Babl

•   Solitude Stuttgart Leonberg 600cc 1st DKW
http://www.solitude-historic.de/sr02-his-r22-37.htm

•   26th April 1936 Barcelona GP DKW 600 with Julius Beer
I have misplaced the reference to this one therefore need confirmation…..

•   3rd May 1936 Swiss grand Prix 1st 600cc DKW
http://www.hammondlighthaulage.co.uk/racingmemo/M%20GRAND%20PRIX/MGP-PALM-SUI.htm

•   24th May 1936  Kölner-Stadwald Rennen DKW  600 cc
https://www.kuladig.de/Objektansicht/O-120305-20150330-2

•   June 11-13th 1936 Nürburgring Crash in practice for Eifelrennen on DKW or Douglas?
http://www.motorsportmemorial.org/focus.php?db=ms&n=3330

https://de.wikipedia.org/wiki/Liste_t%C3%B6dlich_verungl%C3%BCckter_Motorradrennfahrer
https://digi.ub.uni-heidelberg.de/diglit/hnn1936/1395?&navmode=fulltextsearch&leftcolumn_compactview_hidden=0

So not a complete list yet. Will update it if I find any more information - looking in particular for pictures of the machine Babl supposedly used in 1927!

cheers

Ian

« Last Edit: 03 Aug 2020 at 06:18 by Hutch »

Offline cardan

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Re: 1932 TT Douglas
« Reply #56 on: 03 Aug 2020 at 03:28 »
Phew - that's a lot to take in.

What is clear is that Babl's 750 Douglas was a very fast machine. It seems he started racing it in the second half of 1931.

"Soon the Victoria was no longer fast enough for them. Nöckl [Babl's passenger, until he was killed in a crash in Sept 1932] discovered the fast Douglas 750cc in England. It was purchased at enormous cost and delivered in individual parts. The two of them did the assembly themselves. Financial support was provided by Babl's parents, who had a well-running carpentry. Now Toni Nöckl moved to Miesbach and the two were together every day, screwed [sic!], trained and improved constantly. The team should not remain unknown for long. In 1931 Toni Babl's star rose. It was his first mountain race and it was in the motorcycle mecca of the legendary Kesselberg. With its Victoria 600 still at the start, [Babl was] faster than the stronger 1000 class. But the 750 cc Douglas was now ready to race. There followed victorious races with new records in both classes. Nöckl proved to be an acrobat in the sidecar and also had a large share in the victories."

I wonder if this fast, expensive, 750 Douglas that was raced so successfully by Babl/Nöckl through 1931 and 1932 was the bike Jack Douglas was racing on the Mountain Circuit at Brooklands in April 1931? I suspect so, or maybe a sister bike. The specs were likely along the lines of the 1931 Senior TT entries.

A photo of Jack Douglas at Brooklands would be most illuminating.

Cheers

Leon

[Edit: If you didn't notice immediately that Babl was a real racer, look again at the photo!]

Offline Hutch

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Re: 1932 TT Douglas
« Reply #57 on: 03 Aug 2020 at 23:57 »
Photos of C.T Atkins and Ben Bray at the Senior TT in 1931 (used with permission from the Alexander Turnbull Library, Wellington, New Zealand).

Cheers

Ian

Offline cardan

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Re: 1932 TT Douglas
« Reply #58 on: 04 Aug 2020 at 00:15 »
Oh very nice Ian! I suspect these 1931 Senior TT bikes and the larger-engined Babl bike (immediately above) had something in common...

Let me raise you, with a pic of Max Reheis on his (his? I suppose he could have borrowed it from Babl, although I doubt it) 750 Douglas at the Kesselberg Hill Climb in Germany, 15-16-17 June 1934. Toni Babl also rode in this event (as you've noted above), and in one class used a 600 Douglas - probably the one with the 6/H engine listed in the appendix to the Best Twin. Note the pivot for the gear change lever on the frame, as we've seen before in the "workshop photo".

Ian I wonder is your photo of "possibly Toni Babl" actually Max Reheis? Many similarities in man and machine - tank-side rev counter, tapes inlet ports, brace front guard and so on.

I wonder how many of these "big" racers Douglas built around 1934?

Cheers

Leon

[Edit: Although the photo I posted earlier of Babl on the Douglas outfit No. 78 is said to be at Kesselberg in 1934, I don't think it's taken at the meet discussed here. Babl's 596 Douglas at this meet was no. 204, and his 746 Douglas was no. 234, however it's possible he was still riding the "old" (1931) 750. As usual, photos needed to tell the full story.]
« Last Edit: 04 Aug 2020 at 00:35 by cardan »

Offline cardan

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Re: 1932 TT Douglas
« Reply #59 on: 04 Aug 2020 at 02:08 »
Here are photos of Babl on his 596 Douglas no. 204 and his 746 Douglas no. 234, take on the same day (Kesselberg, Germany, 17 June 1934) as the photo of Reheis on his 746 Douglas no. 185. A bit small and blurry, but both appear to be deep-tank bikes, build date c1934.

Leon

Offline Hutch

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Re: 1932 TT Douglas
« Reply #60 on: 04 Aug 2020 at 03:18 »
Great picture of the big tank Douglas at the 1934 Kesselberg Leon!....and more questions :-). I don't know. I think the Douglas could be the same machine but obviously at different times as some features such as the lights / number plate / screen in front of the engine are different - or as you say another 1934 big tank machine has come out of the woodwork? (EDIT:- I'm erring towards them being the same machine.)

Not unknown for machines to be raced on the same day as an outfit and a solo......but if Babl was to loan a special machine to Reheis he would have had to have been a very good friend I would think! (also I guess, just because Babl ordered two special machines from Douglas doesn't mean he was the full owner of those machines?)

I have added a 3 way comparison picture of Reheis, the person on the dual headlight big tank Duggie and Babl from the Victoria website. I cannot say one way or the other. - I will leave that to someone better at facial recognition than I ! :-)


Cheers

Ian
« Last Edit: 04 Aug 2020 at 03:52 by Hutch »

Offline cardan

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Re: 1932 TT Douglas
« Reply #61 on: 05 Aug 2020 at 00:21 »
I'd be pretty sure "the man on the twin-headlight bike" is Max Reheis, but I don't think it matters very much. We know he had a "big tank" 750 Douglas at an event in 1934, when Babl was competing with his two machines.

Like Babl, Reheis raced Douglas machines before his "big tank". At an event in 1932 he was riding a pretty stock-looking Douglas - very G31 with a single carburettor (see no. 83 below - unfortunately he must have entered late because Babl on no. 81 is the highest entry number in the program). In 1933 Reheis rode something much more interesting: the photo shows him at the Semmering Hill Climb in September on no. 60. Could this be his "G31" fitted with a hot engine? Or some iteration of Babl's 1931 racer? Babl sat out 1933 after the crash that killed his passenger in 1932. No idea!

What is clear is that Austria/Germany had a couple of enthusiastic Douglas riders in Babl and Reheis, and they got their hands on some pretty interesting machinery.

Leon

Offline Hutch

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Re: 1932 TT Douglas
« Reply #62 on: 06 Aug 2020 at 03:20 »
Very Interesting information and great pictures of the Reheis Douglii, Leon!,

I noticed that the Reheis bike does not have the big finned sumps of the works bikes, but does appear to have a mechanical oil pump and oil feed from the bottom of the crank case (also some other engine features similar to the earlier Reheis machine (?)). The oil maybe is held in the saddle tank (between them?) and might explain what appears to be 3 filler caps on the big tank?. I have not seen any other of the big tank bikes with this feature.

 
The list of engine numbers in Clew is fascinating. Tempting to think that the engine number on the Bury Bros bike was 7/F 1 (rather than 7.E 1 in the Classic Motor Cycle article), as this would tie the Babl bike to the Bury bike (which debuted in May 1935) rather nicely. Ireckon if they stamped 5/ on the 500s, 6/ on the 600s, 7/ could be a lazy stamping of 75/

You may be close to the mark there Leon, the Reheis bike does appear to have some very similar features to the Bury machine. A) Unused lug, B) Unused rear stand lug (not needed for an outfit but also not used on Reheis machine (indicating dual use as an outfit?), C) What appears to be a join in the tube?? and D) Tap on tank on the Reheis machine and what appears to be an unused fitting in a similar location on the Bonhams machine in 2007.

EDIT:- I had a closer look at "C" and it appears to be racing number plate bracket on the Bonhams bike not a join and coincidentally on the Kesselberg Bike of Reheis there is a shadow there - so I was reading too much into it! (silly me).

Tank on Bonhams machine does not have the third filler cap (or whatever it is) that the Reheis machine appears to have - but there is something mounted in a similar location - hard to tell from the Kesselberg picture. There is nothing in this position on the Bury machine in the TCM article from 1988. So the Reheis machine and the Bury bros. outfit would appear to be  fairly similar in quite a few areas from the old grainy pictures we have.....

I found another poor picture of Babl but the person in the picture looks more like Reheis ! :-)
cheers
(Edit:- Fixed some typos in text and picture)
Ian
« Last Edit: 06 Aug 2020 at 10:28 by Hutch »

Offline cardan

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Re: 1932 TT Douglas
« Reply #63 on: 08 Aug 2020 at 02:00 »
Hi Ian,

Yep there's a lot of detail that could be studied! In particular I'd love to study in detail an original pair of pannier tanks. I wonder if the fittings you highlight are related to linking the two sides together.

Interesting to revisit Atkin's May 1932 Brooklands track bike that appears near the top of the thread https://www.douglasmotorcycles.net/index.php?topic=5444.msg27514#msg27514   "Big tank" in many ways, but with cross-over gearbox (and hence rear lugs to mount the RH brake plate) and probably longer in the frame too, with even the front valve gear within the frame cradle. Also of interest is the hand gear change - no need for foot change on the Outer Circuit - which seems to mount to the tank rail of the frame.

Amongst Doug's survivor photos, the "said to be Jack Douglas" machine (now restored as "no. 34") has a lug on the tank rail that could have been for hand change. Also the front valve gear protrudes past the frame - the machine looks shorter than the Atkins bike, as it would have to be if it were raced on the Mountain Circuit (which had corners!) by Jack Douglas.

The bike in the "workshop photo" has a plain tank rail. Plenty of variants!

Anyway, here's Atkins (no. 8 ) at the start of a handicap event at Brooklands, 1 July 1933. Presumably the same bike he rode in 1932. The supercharged bike was probably a later frame.

Cheers

Leon
« Last Edit: 08 Aug 2020 at 02:11 by cardan »

Offline cardan

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Re: 1932 TT Douglas
« Reply #64 on: 12 Aug 2020 at 03:56 »

http://www.stilltimecollection.co.uk/detail/40127-tpt-bike-racing-bmcrc-douglas-rider-williams.html

Williams at Brooklands in 1932, from the Still Time Collection. Presumably his 1932 Senior TT mount.

Leon

Offline cardan

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Re: 1932 TT Douglas
« Reply #65 on: Yesterday at 07:20 »
Leaving aside the 1931 machines, with their G31-ish frames and lower tanks, I think the "big tank" bikes discussed in this thread have their origins in one of the following three groups of machines:

1. The 1932 Senior TT machines. Three or possibly four machines built specially for the IOM Senior TT in June 1932. These bikes have rather unique specs, notably angled inlet and exhaust ports with carburettors fitted directly to the head, deep pannier tanks, non-cross-over Sturmey Archer gearbox and clutch, Webb fork and 8" Enfield brake on the right side. They had their first outing at the TT, and returned to road-racing events at Brooklands the following month with the induction side of their engines returned to "vintage" spec. Beyond the Brooklands events, the only possible glimpse of one of these bikes is in the hands of Bejarano in Spain: his bike alone alone has the right-side 8" brake, and his engine is likely to the spec as run by the works team on the Mountain Circuit at Brooklands in July 1932. [Edit: The bike in "the workshop photo" has a Webb 8" brake, so is likely a 1932 TT bike, after conversion to "vintage" intake arrangement.]

2. Tommy Atkins' Brooklands track machines. Although he raced a "TT style" machine in 1930 and a "Judd style" machine in 1931, his first "big tank" machine in April 1932 used a 1932 TT motor in a plated frame fitted with Druid ES fork. Various tanks were used, depending on the event. A later machine was similar, but fitted with a supercharger. Both bikes used the Douglas cross-over gearbox (with hand change) and flywheel clutch, mounted in frames to suit, built using a DT-style greabox mounting lug, and hardware for right-hand rear brake. When Francis Beart acquired the supercharged bike he converted it to non-cross-over drive. In 494 form at least, the 1932-TT-style angled-port cylinder heads were used in both atmospheric and supercharged versions.

3. A small number of 596 and 746cc sidecar racing machines built for favoured riders, mostly around 1934. Although these bikes looked similar to the 1932 TT bikes, they used a (Douglas?) drum brake at the front, on the left side of the fork. The "story" is that three bikes were built, but this may be apocryphal. In the UK the Bury brothers raced one, Jack Douglas is said to have raced one (to be verified - he certainly raced a Douglas outfit in 1931 but this would have been to an earlier design), and it's possible that C. P. "Clarrie" Wood raced another. (Jeff Clew in "British Racing Motorcycles": "The last official TT entry was made in 1932... Several private owners continued to race Douglases, usually at Brooklands, Donnington, and sand-racing venues. At Donnington the Bury brothers raced a 750 cc sidecar outfit; similar to the one used on the sand by C. P. Wood, but this machine was never quite a match for their opponents.") On the continent, there were at least three more machines: a 596 and a 746 in the hands of Babl and a 746 in the hands of Reheis.


Yes there was variation in the spec of different bikes, and because they were racing bikes stuff was changed over time, and because they are interesting bikes things get changed back to someone's idea of "correct" spec during various restorations.

Original photos anyone? Jack Douglas at Brooklands would be good, or Clarrie Wood beach racing? Something outside of a Groups 1 to 3?

Cheers

Leon
« Last Edit: Yesterday at 23:27 by cardan »

Offline Doug

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Re: 1932 TT Douglas
« Reply #66 on: Yesterday at 17:18 »
Another possible reason for the absence of the 1932 Works cylinder heads (angled inlet ports) on later machines is they were made for the short-stroke experiment of the 1932 Work team. That not being particularly successful, for whatever reason, they simply did not make more copies. The sidecar machines of 1933 likely reverted to the long-stoke engine, being seen as more advantageous for torque and besides might have had more component parts laying about the factory. Also a 600 and 750cc engine gets more difficult to arrange with the 68mm short-stroke crank; having to go further 'over square' with the bore than they would have been accustom to at the time. Though, they did do it with the 1921-23 S2 Sports model... Not that the '32 heads couldn't have been made to work with a long-stroke cylinders and crank; but perhaps they concluded the head design was faulty.

The short-stroke cranks were also tried in a 1932 Dirt Track model. That did permit a shorter wheel based frame; something like 2~2-1/2  inches shorter than a standard DT frame I think I read somewhere. But it was not enough to hold off the Rudges and other singles that had shorter wheel base frames that favored the new foot-forward riding style. Whether the short-stroke DT inspired the 1932 Works bikes, the surplus 68mm stroke cranks inspired the short-stroke DT, or both were developed concurrently, I don't know. Other than shorter barrels and rods, the short-stroke DT used conventional DT cylinder heads and the 'standard' diamond head gasket joint. The shorter rod forgings surplus from all this went on to be used in the Blue Chief side valve engine, that developed into the 500/600cc Aero models. While I am not sure when the 68mm cranks first appeared (ignoring the S1/S2 and RA), the shorter rods were being used in the F/G31 road models with the standard 82mm stroke crank. So those would have been available in late 1930 at least. The same lower end assembly was used in the 1934-35 OW/OW1 models.

-Doug

Offline cardan

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Re: 1932 TT Douglas
« Reply #67 on: Yesterday at 23:24 »
Hi Doug,

Excellent point about the bore/stroke, and one I hadn't thought of.

The 1931 Works Douglas TT bikes were said to be "square", so 68 x 68 for the 494cc "500", as for the 1932 Works bikes. Presumably, then, the bigger racers were 68 x 82 for 596cc and 72 x 82 for 746 cc. Better photos might get us a glimpse of a 596 with angled ports? But hard to get the plumbing right with carbs close to the airbox.

Reading about practice for the 1932 TT there is a comment that one of the Works Douglases "couldn't decide whether to run on one or two cylinders" on the corner where the reporter was sitting. This reminded me of the development of the twin carburettor bikes in the early 1920s (see the thread on Les Bailey) and the problems they had with getting correct mixture across the rev range. I wonder if the carb-on-head updraft setup was a bit fussy at the Isle of Man, or any other track with slow corners, such as the Mountain Circuit at Brooklands (which had a hairpin at the Fork)? Perhaps this explains the reversion to the "vintage" carb setup in the lead up to the 1931 TT, and again immediately after the 1932 TT. Not enough development? But let's guess the angled ports gave good power, thus Tommy Atkins using them on his track (outer circuit) machines at Brooklands where the corners were taken on full throttle!

I'll do a little edit in my post above to point out that the bike in the "workshop photo" has an 8" Webb brake on the right, so is likely one of the 1932 TT machines, but after the TT in June.

Cheers

Leon

 

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