Author Topic: 1932 TT Douglas  (Read 5282 times)

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Offline cardan

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1932 TT Douglas
« on: 09 Aug 2014 at 11:40 »

Searching for 1932 TT Rudge info, I came across this rather nice illustration of the 1932 TT Douglas motor, from the Motor Cycle of June 23, 1932.

The drawing shows the neat arrangement of the twin carburettors, close coupled to the cylinder heads but still drawing air from a central airbox, in the time-honoured manner dating back to, at least, the 1923 TT bikes (RAs). In fact the main mechanic features of the motor are not too dissimilar to the RA and its progeny - the TT and DT.

Leon

Offline cardan

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Re: 1932 TT Douglas
« Reply #1 on: 10 Aug 2014 at 11:48 »

And here's the beast itself. Note the Webb fork and non-cross-over gearbox.

Prior to the race the chances of the Douglas team were summarised thus: "The Douglases are not quite ripe, and their jockeys are not 80 m.p.h. men." These observations were confirmed in the race itself. Cammy Nortons finished 1, 2 and 3 in 1932 Senior T.T., with the Rudges best of the rest.

Leon

Offline oil baron

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Re: 1932 TT Douglas
« Reply #2 on: 10 Aug 2014 at 22:53 »
Hi There Leon

Just a few thoughts on the machine,  I wonder what brakes were used as they do not appear to be Douglas, so were they using Enfield or similar proprietary hubs.  The machine does not have a flywheel clutch, and being a non crossover box, I suspect is it using a Sturmey Archer box set up as was fitted to the very similar looking Dr Joe Bailey/Len Cole and later Colin Clifford 750 cc sidecar outfit.  Though that machine seems to use a modified small air box and conventional carb set up rather than that shown in the first picture, the crankcase and sump appears the same. It also appears to use standard 8" Douglas brakes, with the front brake on the left-hand side. otherwise the machine is looks very similar to the one shown in your post, apparently a total of 3 machines were built.

Thanks for the interesting posts Leon

Regards  SteveL
Steve L

Offline oil baron

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Re: 1932 TT Douglas
« Reply #3 on: 10 Aug 2014 at 23:03 »
Hi Leon

Found a better photo of the Dr Joe Bailey/Len Cole/Colin Clifford machine, It uses the same air box as your first photo, but with a conventional carb set up, interestingly the boss at the bottom left-hand side is for mounting the gear change lever.  See the photos on Bonhams Website

http://www.bonhams.com/auctions/19766/lot/322/

Regards  SteveL

Steve L

Offline Doug

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Re: 1932 TT Douglas
« Reply #4 on: 11 Aug 2014 at 00:45 »
The 1931-32 Douglas works machines allegedly used Douglas brakes, but they were 9". However I have not seen inside one to see if they used the Douglas band brake. The gearbox was a Sturmey-Archer unit explicitly made for Douglas. Initially with an external posi-stop gear change as see in the Bonham auction advert and then in mid 1933 or '34 with an integral posi-stop like used on Norton 'dollshead' 'box and the Norton retrofits in Douglases favored by the vintage sprinters. Examples of these Douglas-Sturmey-Archer gearboxes survive, but were only used on the Works machines and are very rare. Hence folk modifying Norton 'boxes.

The machine in the Bonhams auction is not Joe Bailey's machine (which was a 1926-28 TT model). It is one of the Works sidecar machines. It was assembled and sold at a Bonhams auction a few years back by Collin Clifford. Then in 2012 it was in the sale again. Bailey's machine initially went to his son, who then after a few years sold privately to a Douglas enthusiast.

I know of about three of the 1930-32 Works bikes. The outfit, a solo, and a Works frame built into a sprinter. There was a fourth, the Bury Brothers outfit, but that burned up in the National Motorcycle Museum fire and disappeared. I think I read somewhere that in 1933 they just used the '32 machines and in 1934 the factory had no official involvement, but they did lend the same machines (which at some point received updated gearboxes) to private entries. The engines were described as sounding a bit "flat" by the journalists (I forget which year this was quoted, but I don't think it matters in the results!), and the entries did not gain any merit.

They used a wider angle between the valves than the earlier DT/TT. From what I can tell (an this is still a bit of a learning curve) the 1930 machines had horizontal ports. In 1931 the exhaust ports pointed downward. In 1932 the inlets also pointed downward (or up if going with the flow.) The inclined inlets can be seen in the engine photo Leon posted.

-Doug


[fix typo. 11Aug14  -Doug]
« Last Edit: 11 Aug 2014 at 12:11 by Doug »

Offline cardan

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Re: 1932 TT Douglas
« Reply #5 on: 11 Aug 2014 at 11:36 »
Here's the description of the 1932 TT Douglas from The Motor Cycle in May 1932:

"LAST week the first of the T.T. Douglases was to be seen down at Brooklands. C. T. Atkins, the well-known Douglas exponent, who is largely responsible for the "upbringing " of this model, was putting it through its paces over the half-mile for the first time.

"ALTHOUGH, at first glance, the Douglas resembles the standard 494 c.c. production model, in actual fact it is entirely different. The cooling area of the barrels and cylinder heads has been considerably increased, even down to the extent of finning the rocker standards, which are cast en bloc with the heads. The 14 mm sparking plugs are centrally disposed between the rocker standards, while the inlet ports lead up from the two carburetters at an angle of 20 degrees to the horizontal. The well-known Douglas air-balancing chamber is, of course, incorporated.

"DRY-SUMP lubrication is employed, a large finned aluminium sump being bolted to the bottom of the crank case. A departure from the normal Douglas practice is the fitting of a Sturmey Archer four-speed gear box, the pedal for the positive foot gear change being neatly mounted at the bottom of the air-balancing chamber. With this gear box the final chain transmission is on the near side, where a large chain sprocket is mounted on the drum of an extremely powerful 9in. brake, heavily ribbed, and well protected from wet.

"THE whole engine unit is mounted in a particularly rigid duplex-cradle frame, fitted with a steering head much larger and longer than has hitherto been favoured by the Douglas people. Special Druid forks are used in conjunction with a heavy type and business-like Enfield front brake and hub assembly. The brakes are interconnected and operated by a near-side pedal. Finally, a large, sloping two-section built-up tank, holding four gallons of fuel, is mounted on the lower tank rail.

"A MEMBER of The Motor Cycle staff who was allowed a short trial trip found that the machine possessed immense power and terrific acceleration from low speeds. The gear ratios were very close together, and it was most difficult to appreciate the difference between top and third gears. But the outstanding feature was undoubtedly the steering over a bumpy road. The machine was rock-steady, and gave the impression that it was absolutely light in weight, so easily did it handle. The brakes were superb, being both light and extremely powerful in operation."

A couple of comments. Re the front fork, it looks much more Webb than Druid to me. Until about 1930 Druid were still using twin side springs on some of their forks, but the "go faster" model was the ES (enclosed spring) that looked a bit like the Webb but had an enclosed central spring. Of course the fork could have been changed between testing at Brooklands and racing in the IOM a month later. Re the cooling fins: those cylinder look like OB items to me (OK, the fin shape is OB), and at least some TT heads from about 1926-7 on had finned rocker standards.

Leon

Offline oil baron

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Re: 1932 TT Douglas
« Reply #6 on: 11 Aug 2014 at 20:59 »
Hi Leon

I suspect that in the photo you published it also had an Enfield rear hub as well, if you compare the position of the rear brake actuating lever with the photo of the 750cc outfit which uses the 9'' Douglas brake.  On that machine the brake actuating lever operates through the brake anchor point in normal Douglas fashion, whereas the TT machine has a separate actuating arm, and the brake diameter certainly looks smaller than 9",  Interesting!
Keep up the good work

SteveL

Steve L

Offline cardan

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Re: 1932 TT Douglas
« Reply #7 on: 11 Aug 2014 at 23:32 »

Hi Steve,

Yes the rear brake on the 1932 TT bike doesn't look like the Douglas "TT" item (9" brake drum with bolt-on sprocket, usually on the off side of the machine), so given the parlous state of Douglas in the early 1930s it is likely to be a bought-in item. Since the fornt brake is named as Enfield in the Motor Cycle article, the rear could well be Enfield as well.

The restored sidecar works racer is an interesting machine, but keep in mind it is "restored". If you read the Bonham's description carefully, it doesn't promise exact originality anywhere, so there is some scope for fitting parts that are in keeping with a racing Douglas of the period. The problem of reproduction racers has been a huge problem with sorting out the (genuine) 1932 Works Rudge. I've given up looking at photos of restored machines, because most seem to be relatively modern recreations.

Cheers

Leon

Offline cardan

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Re: 1932 TT Douglas
« Reply #8 on: 19 Nov 2018 at 20:27 »
Here's the description of the 1932 TT Douglas from The Motor Cycle in May 1932:

"LAST week the first of the T.T. Douglases was to be seen down at Brooklands. C. T. Atkins, the well-known Douglas exponent, who is largely responsible for the "upbringing " of this model, was putting it through its paces over the half-mile for the first time... special Druid forks are used...

I found a photo of Atkins at Brooklands in May 1932. While the powerplant is certainly the 1932 TT job, the cycle parts are pure "outer circuit", with no front brake, dropped bars, and so on.

Indeed the front fork is Druid ES - changed to Webb for the TT.

The Tommy Atkins track Douglas was campaigned at Brooklands and elsewhere, first by Atkins himself and in 1937 by legendary Norton tuner Francis Beart. For most of its outings the bike was fitted with a supercharger above the front cylinder. At Brooklands - fitted with Brooklands "can" silencers - it was notably noisy. For sprints and hillclimbs - with twin megaphones - the noise was close to unbearable.

The 1932 TT-pattern motor - with its upward-angled inlet ports - was used in both normally-aspirated and supercharged versions of the bike. The unusual ports can be seen in the photo of the bike from the front.

Cheers

Leon

Offline Doug

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Re: 1932 TT Douglas
« Reply #9 on: 20 Nov 2018 at 03:41 »
Some pictures of a 1932 TT cylinder head.

There seems to have been a machining error drilling for the rocker spindles!






Here you can see the angulation of the ports to good effect.






Rather than the 'diamond' head gasket groove, a spigot on the cylinder fitted into a recess in the cylinder head.



Here is the cylinder. Note too, the cylider base does not envelope fully the cylinder studs.




Comparison to a DT cylinder head. The included valve angle is greater and so the rocker spindles (and perches) are wider to accommodate. The DT is 82 degrees and the TT is more like 90 degrees.



The perches are also taller. Perspective in this view diminishes the apparent difference in width between the two.




The rocker arms need to be longer, and were entirely different forgings. Again, a comparison to DT rocker arms.










-Doug

Offline cardan

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Re: 1932 TT Douglas
« Reply #10 on: 20 Nov 2018 at 06:12 »

Nice one Doug - those parts are obviously quite specific to the 1932 race bikes. Under the funny airbox, was the bottom end of the motor laid out like a DT, or was it "twin cam" like some of the racers in the late 1920s?

Here's a photo from Peter Carrick's Douglas book, where it is captioned "A 1923 TT model being assembled in the Douglas race shop".

Clearly not 1923. The bike is 1932 TT-pattern - as is the motor on the bench - but the mis-matched front and rear rims and the rocking pedal for the gearchange on the frame (rather than the lug for it cast under the airbox) add to the mystery.

Cheers

Leon

Offline Doug

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Re: 1932 TT Douglas
« Reply #11 on: 20 Nov 2018 at 12:41 »
Leon,

Regarding the picture from the Peter Carrick book, the airbox does look like it may have the lug for the foot shift pedal. Apparently unused because of the presence of the rocker pedal on the frame. 

The engines were single-cam. The Dixon twin-cam engine appears to have been short lived and in my opinion never stood a chance due to design flaws. I have seen a 1931 engine up close (inlet port horizontal and exhaust pointing downward.) The aluminum crankcases look to have been slightly reinforced versions of the DT type. Other than extra ribbing around the cam bearing boss and whatever was done at the bottom to facilitate the sump, it looks 'standard' DT.

I have also heard that the factory cast the drive side half of the crankcase in bronze to strengthen it. This is plausible, as cracks around the main bearing boss were not unknown. One example has been seen in photos with both the drive and timing side cast in bronze, but otherwise following DT practice. However one has to be careful as there was an individual about twenty five years ago making replacement casings in bronze that developed a reputation for making replica factory race machines that subsequently were passed off as the real thing! So I am not sure if the replicas copied the factory use of bronze, or were used to create the legend of the factory using bronze.

-Doug




Offline cardan

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Re: 1932 TT Douglas
« Reply #12 on: 20 Nov 2018 at 21:03 »
Thanks Doug - shall I wait for the racing Douglas book?

Here's Francis Beart at Gatwick in AUgust 1937. Supercharged Douglas + megaphones = spectators in pain!

"Francis Beart - A Single Purpose", another Jeff Clew book, plots the evolution of the Atkins 1932-TT-pattern track bike after Beart acquired it from Comerfords in mid 1937. He ditched the Douglas flywheel clutch and cross-over gearbox for the usual Norton/SA conversion, rebuilt the motor with new atmospheric cams, and rebuilt the supercharger and reconfigured the inlet system. At the end of the year it went bang and he sold it on.

When he bought the bike it came with spare 600 and 750 cc motors, but I don't know if they were also 1932 TT style.

Leon

Offline cardan

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Re: 1932 TT Douglas
« Reply #13 on: 23 Nov 2018 at 04:13 »

Here's the missing link between the Tommy Atkins 1932-TT-based outer circuit racer and the Francis Beart version.

The Stilltime Collection has four photos of Tommy Atkins (?) with the bike in supercharged form, but still with the Douglas transmission (flywheel clutch and cross-over gearbox): http://www.stilltimecollection.co.uk/search/a/0-0-3-20-0-0-0-3-3-1,2,3,4-0-1-atkins.html

Quite a beast.

Leon

 

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