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Thread: My 1938/39 Triumph. A Retrospective Review.

  1. #1
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    Default My 1938/39 Triumph. A Retrospective Review.

    By special request here is a retrospective Member Bike Build.

    Axeric requested some more details and has suggested that others may be interested in my Speed Twin (also known as a 5T) so I thought I would post a short summary about how I got it from a few pieces in to a complete bike.

    But first though a brief summary of the history of Triumph for those on here not familiar with the marque. My apologies to those of you who already know this, if you do please skip past it.


    1887. Triumph Cycle Company Ltd registered and were selling imported bicycles.

    1889 Bicycle manufacturing started. Company moves headquarters from London to Coventry.

    1902 first motorcycle made using a clip on Belgian Minerva engine.

    1905 First all-Triumph machine produced this was also the first 100% British motorcycle.

    1915 to 1918, production became focused on the Allied war effort. More than 30,000 Model H bikes were supplied to Allied forces in World War I.

    November 1940. The Coventry factory was destroyed by German bombers so production was moved to Meriden about 8 miles away and production resumed in 1942. Note, when this happened all of the factory records relating to individual machines before November 1940 were destroyed so there are minimal records in existence for before this date. (note this fact as it is relevant to my bike)

    1983 when Triumph went into receivership John Bloor bought the name and manufacturing rights and set up what we know as the modern Triumph company based in Hinkley (about 16 miles from Meriden). This means that Triumph has produced motorcycles since 1902, making it the world's longest continuous production motorcycle manufacturer.




    A note about British bike model years. Manufacturers showcased their new models for the coming year at the Earls Court Motorcycle show. This show is in autumn so the next years model is actually introduced in the previous year.

    My bike was originally registered in October 1938 but it is a 1939 model.


    My Bike

    I acquired the first parts for my bike in the very early 90's. I got a frame, forks, wheels, brakes, seats and a small number of small parts. The main items missing were engine, carb, magneto, transmission, oil & petrol tanks, mudguards, toolbox, headlamp, handlebars and controls. Also there were no fasteners.

    Its worth noting that in the UK a registration (title) is based on the frame number.

    Quite a few people told me that an incomplete pre-war Speed Twin (pre WWII) was as hard as a basket case gets. They were probably right at the time. In very recent years there are some very good quality reproduction parts available so some items are not so hard now. There are still some very hard bits though even now.

    At the time I got the bike it was pre-internet so I put some ads in magazines looking for parts as well as looking at autojumbles/swap meets. I ended up getting a 5T engine and a T100 engine, 2 gearboxes and primary drive plus a speedometer, all for what would now be considered bargain prices.

    Fast foreward to the last few years and there is a guy who used to have a website dedicated to these pre-war Triumphs. He is considered to be something of an expert on Triumphs of this era and he has a database of frame and engine numbers, dates of registration etc. This is useful because, if you remember the text above, the original Triumph records were destroyed in 1940. These bikes did not have matching frame and engine numbers when they came out of the factory. Engines were taken off the pile in whatever order they happened to be in and put in the next frame on the production line. As it turns out there is a known original machine with a frame number 27 away from mine and an engine number 33 away. Amazingly, by total chance, I have got an engine that is exactly the right number for my frame.

    Whilst I now had an engine and transmission I was still missing lots of stuff, lots of it 1 or 2 year only parts so I kept looking whenever I had a bit of spare cash (note its only in the last few years that I have a bit more spare cash). I turned up a couple of the items, most memorably an oil tank at a local autojumble (swap meet), the oil tank is a 2 year only item and as rare as hens teeth.

    Around 2009 I decided to get stuck in and get the bike finished. I took some pictures and so here are a few.

    First are some of the very few "before" pictures that I have.








    This next one was taken in 2006 when I did a bit to get the frame painted and the wheels built but not much more.






    Then the pictures pick things up in 2009









    This rocker box needed replacing




    I used this one but got the extra breather hole welded up that someone has added before I got it.



  2. #2
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    Default Re: My 1938/39 Triumph. A Retrospective Review.

    Coming together.




    I picked this chaincase up in the mid 90's and it is in good condition other than a small crack which i got welded at the same time as the rocker box.








    You might wonder why I chose to highlight these oil pipes?

    The reason is that they are a little unusual in how the rocker feed is controlled. Pre-war was different to post war in that pre war the feed to the rockers was from the oil feed to the crank. Post war it is from the scavenge side of the system.

    You will see 2 pipes, one is the feed to the rockers and the other goes to the oil pressure gauge.




    The smaller pipe is for the rockers but it needs a pressure regulator to make sure that the rockers donít get too much and the crank doesnít get starved. This is achieved by running the oil through the brass fitting with the banjo union then through the small round gauze filter and then through a screw thread inside the barrel shaped brass fitting. You can regulate the rocker feed by varying the amount of screw thread that the oil has to get through.

    Its an unusual arrangement but it seems to work.






    I thought that a new Morgo oil oil pump was a good idea.






    More to come another evening.

  3. #3
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    Default Re: My 1938/39 Triumph. A Retrospective Review.

    The engine came with a carb that looked at first to be the right type. When I had a closer look at the carb it was not in great condition. Also, on closer inspection it wasnít the right spec for my bike. As it happens a company called Burlen Fuel Systems own the brands Amal, SU, Zenith and Weber and manufacture new carburettors to the original specifications.






    By now I was starting to become a pre-war Triumph geek and had gathered information from numerous sources and filtered it to get what I believed to be the correct specs for my bike. I had thought that Harry Woolridge's book was definitive and it mostly is and is mostly backed up by Roy Bacon's book. However it turns out that speaking to Burlen was a good move because they have copies of the original Amal factory records and the guy that I spoke to pulled up the original 1938 factory hand written spec sheet for the carb for my bike. They also told me that the carb that came with my engine was from a Matchless G3L from 1946 to 1950 based on the code stamped on it.

    The carb that I required is a type 76, according to the Amal Spec Sheet, and is stamped with the number "76W/1DA". It is apparently unusual in that it has a 15/16" bore at the air intake end but a larger bore at the engine side of the carb. This size body is not available anymore but it would be an easy job to bore it out if you were that way inclined although I am not sure of the advantages of this. A lot of people are not aware of the differences between a type 76 and a 276. Most people call all of the pre-monoblock carbs Type 276's and are not aware of the type 76 that preceded it. Both carbs are similar but the type 76 has a different body which had air holes around the base. The 276 did not have these air holes and used a different method of drawing in emulsifying air.

    The Amal record states a 107.5 needle jet but half sizes are not available any more so 107 is the closest current alternative. The spec for my 1939 Speed Twin is:

    Type 76/ in 15/16Ē with a flange fit. The float chamber is on the right with a bottom feed nut & nipple connection. Float chamber tilted at 7 degrees. Jets are 140 main, 107.5 needle jet and a 3 slide.

    So to cut a long story short, I was able to buy a brand new carb for my bike in a spec that is very close to the original.




    The bike also came with the correct MO1 Magdyno which I sent to Tony Cooper to be refurbished.










    The magdyno fits on a platform at the rear of the engine.




    This is one of the distinguishing features between pre and post war Triumph twins. Post war used a separate mag and dynamo with the dynamo in front of the engine.

    Here is the magdyno in place.



    John

  4. #4
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    Default

    What a great project John! Thanks for posting all this, it's fun to watch something other than an American bike come together....Triumph really was "modern" in the day!
    Pisten Bulley is Harry Roberts in Vermont.

  5. #5
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    Default

    I have found that I really like these serial build threads. John does one of the best jobs I have seen in telling and offering photos but also mixing in questions that both get direct answers or that generate on-going discussion. Great job John.

    Mike Love
    AMCA # 19097

  6. #6
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    Default

    Thanks for the nice comments guys. This thread will be shorter than the HD one because the bike was finished a while ago.

    The next instalment will be tonight (UK time).

    John

  7. #7
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    Default Re: My 1938/39 Triumph. A Retrospective Review.

    When I got the mag mounted i came accross a problem. The mag pinion would not grip on the taper on the magneto shaft.

    Offering the pinion up to another Lucas magneto it was fine so the problem is that the taper on my Lucas MO1 was very slightly undersize. The other problem (obviously) was that I had already had my magdyno refurbished.






    The easiest solution was to get a small local gear manufacturer to make me a new pinion.





    However.

    This led to another problem.

    The gear manufacturer said that he couldnt cut the thread in the middle for the extractor. Instead he said he would just put 2 threaded holes in it for an more conventional extractor.






    I offered the pinion up and it fitted fine. I screwed an extractor on (by hand) and removed the gear and saw that the case was broken. I couldnt believe it, I had not used any force. I screwed the screws into the pinion and then backed them off a couple of turns. I still cant work out exactly how it happened.




  8. #8
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    Default Re: My 1938/39 Triumph. A Retrospective Review.

    First I did this:








    Then I cut a thread in the centre of the new pinion for the correct extractor.


    Then it was just a reassembly job. Whilst I was at it I changed the timing gears for ones that hadnít been drilled out like the ones that came with the bike.








    And then, finally, I could time it.




    John

  9. #9
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    Default Re: My 1938/39 Triumph. A Retrospective Review.

    Here are some pictures of the seats.












    Whilst going through my pictures I found a picture of this.




    I took picture this from an ebay advert and then copied the pipe.

    I found this picture of the new pipe along with some other stuff ready to go for plating. I am a bit paranoid about sending small parts to the platers so I do this with them and send an itemised list cross referenced to the picture. (Maybe I am a bit OCD?)




    Here is a different batch of parts fresh back from the platers.




    John

  10. #10
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    Default Re: My 1938/39 Triumph. A Retrospective Review.

    Instruments.

    I acquired this speedo in the 90's when I got the chaincase. I asked the guy with the chaincase if he had any more stuff and he disappeared into his shed and came back with this.




    The speedo is not too rare although it was still a good find.

    I got the ammeter with the bike. Whilst it looks similar to lots of other Lucas ammeters it is quite a rare item, 2 year only I think.




    The oil gauge was an ebay item.







    You can just see the faded WARNING sign in the second picture above.

    It was miss described on ebay and I got it for (I think) about £100 which is a good price. It is a one year only item. Its made by Eureka but has the Triumph branding on it. The 1938 Speed Twin had a similar gauge but it only went to 120 psi. The T100 was introduced for 1939 and needed a higher pressure gauge and so both the Speed Twin and T100 were fitted with the same gauge. The post WWII bikes had a different gauge altogether which lasted until about 1949 (I think thatís the right date without looking it up) when the pressure gauge was dropped from the bikes because dealers were fed up with people coming along and saying that their oil pressure was lower than the gauge said that the minimum should be.

    Note, after about 20 miles of riding my bike, when its fully warmed up, the oil pressure reads about 25psi at tickover and thatís with an upgraded oil pump so I imagine that the "minimum 35 psi" warning caused lots of queries for dealers.

    I sent all 3 gauges to Ian Bartrum who did a great job. However when they first came back to me there was a problem with the oil gauge, can you spot it?




    However I sent it back to him and he sorted it out straight away.




    John

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