Author Topic: Douglas 1928 SW5 or OHV  (Read 8014 times)

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Offline Ryser Kaspar

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Douglas 1928 SW5 or OHV
« on: 19 Jun 2016 at 15:52 »
Hello Friends
I have e problem with my Douglas ca. 1928 SW5 or OHV. The camshaft is brocken an i need e other one. But i dont know is it e SW5 or e OHV. Can any body help me? I live in switzerland.  Engine Nr. is EL 1380.
Greetings.
Kaspar Ryser
Amsoldingen CH
« Last Edit: 19 Jun 2016 at 16:11 by Ryser Kaspar »

Offline cardan

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Re: Douglas 1928 SW5 or OHV
« Reply #1 on: 20 Jun 2016 at 03:53 »

Hi Kaspar,

Wow, that cam really is worn out! It's hard to imagine that it was allowed to wear so far. Perhaps it is not properly lubricated?

The EL prefix is certainly for the DT5/SW5 engine. I'm not an expert on these, but yours seems to be the later "small air-box" version, around 1929-30 build I suppose, but someone here might be able to date it accurately.

The bike is based on something earlier, perhaps Model OC. What is the frame number (on the gearbox platform near the seat post)? The gearbox looks to be one of the Sturmey Archer boxes commonly adapted to Douglases.

I'm not sure about the cam shaft itself, but I think Doug might still have DT cam followers. Have a look in the "for sale" part of the site.

Best regards

Leon

Offline cardan

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Offline Doug

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Re: Douglas 1928 SW5 or OHV
« Reply #3 on: 20 Jun 2016 at 06:17 »
Kaspar,

EL1380 is a Dirt Track (DT) crankcase and the number is high enough to have been shipped from the factory in 1932 (EL1296 shipped in 05Jul32), but essentially is the same as 1930-31 model. It looks to retain the DT cylinder heads and the 'small' airbox. The frame and forks look to be model OB.

Given the wear on the cam, the rest of the internals will require close examination for damage from the wear debris. If the cause was oil starvation, the crankshaft is probably in poor shape for lack of oil. New camshafts are not available, but I have had them welded up and re-profiled in California. As Leon mentioned, new tappets (cam followers) are available.

-Doug

[fix typo. 22Jun16. Doug]
« Last Edit: 22 Jun 2016 at 19:53 by Doug »

Offline eddie

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Re: Douglas 1928 SW5 or OHV
« Reply #4 on: 20 Jun 2016 at 07:43 »
Kaspar,
           As Doug says, it looks as if there may be a problem with the lubrication. Early dirt track engines had a direct feed from the hand pump in the tank to the crankshaft. Later engines (like yours) have a mechanical pump, but to make it possible to prime the engine with oil via the handpump, a non return valve is incorporated in one of the banjo bolts in the air box. Now, if the valve becomes faulty, the oil (pumped by the mechanical pump) can recirculate to the inlet side of the pump without feeding the crankshaft. I suspect that is the problem with your engine - the camshafts seem to be the first to suffer from poor lubrication due to the high loads and the sliding action of the followers - rolling surfaces, like the big ends, need much less oil to survive.
  On our sprint engines, we dispense with the hand pump in the tank, and blank off the non return valve to make sure the oil can only go to the crank.
   The oil pump has 2 stages - the first stage pumps oil to the sight glass (where it is regulated), and the second draws it from the sight glass to the crank. There is also a pressure relief valve in the pump, so make sure that is operating correctly, otherwise, again, oil can recirculate to the inlet side of the pump.
  From the photo of your camshaft, it looks as if it has 6 splines - some camshafts had 6 splines, others had 8! 6 splines were better for finer tuning as, with a 44 tooth gear, they gave 3 options before the figures repeated themselves (8 splines only gave 2 options before repeating).

   Hope some of this helps,
    Regards,
                 Eddie.

Offline eddie

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Re: Douglas 1928 SW5 or OHV
« Reply #5 on: 20 Jun 2016 at 08:01 »
Hi again Kaspar,
                        From the photo of the camshaft, the exhaust cams look reasonable - just the inlets are badly worn. As the cam followers have obviously been offset to the cam, you still have a witness of the original cam profile. If you intend having the cam built up and reprofiled, take a copy of the original before it is ruined by the building up process. In the past, we have reprofiled cams for sprinting by building them up first with steel and ground about .5mm undersize, then built up again with 'Stellite' and ground to the final form. With 'Stellite', there is no need to have them heat treated provided they are run with steel followers. Do not try to run Stellited cams against Stellited followers - that is a big 'No- No!'
  Regards,
                Eddie.
« Last Edit: 20 Jun 2016 at 11:32 by eddie »

Offline Ryser Kaspar

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Re: Douglas 1928 SW5 or OHV
« Reply #6 on: 21 Jun 2016 at 11:57 »
Dear Douglas Friends
I answer with my School english and catastrophal Google Translation! You have to because some very good evidence to put on the road. And I thank you very much for the efforts and good tips. It is a machine that was assembled from different parts. But she makes me happy an i like to bike. On one Hand, it is clear, and I also went on the assumption the camshaft has not enough oil an that this oiling is probably very difficult to handle. I will done better in any case in the future and solve. However, the main Problem is the repair of the camshaft. Without pattern can hardly be reconstructed. I do Need accurate Information, such as the cams are to be made. Apperently there ist no buying. But maybe someone has e drawing or pattern that you may call for the construction. Or ist there someone who can reconstruct my camshaft? So far, thank youe all for your help and insterresting tips and Information. I see, that my Problem ist quite complicated. Regards Kaspar from Switzerland

Offline Doug

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Re: Douglas 1928 SW5 or OHV
« Reply #7 on: 21 Jun 2016 at 17:05 »
Hello Kaspar,

The attached PDF is what I used for getting the camshaft built-up and reground. It is for the "IN OP 20" camshaft, one of the common camshafts fitted to the DT.

Cam_weld_grind.pdf

-Doug

Offline shuswapkev

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Re: Douglas 1928 SW5 or OHV
« Reply #8 on: 21 Jun 2016 at 22:14 »
heres a fairly simple cam grinder...that could even be made a lot simpler

https://www.youtube.com/watch?v=xZqWYG1Q5DQ

Offline Ryser Kaspar

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Re: Douglas 1928 SW5 or OHV
« Reply #9 on: 25 Jun 2016 at 08:19 »
Hello Doug
This camshaft drawing is very, very helpful and we will see, if it's possible to rebuilt my malfunction camshaft. But now, we must be shure, that is the right engine. Is my engie for shure e DT engine? And the cam folower, what for e radius they have? We think, we can rebuilt there. The camshaft become too Little oil. It's possible to make e oil line in to the Region of the camshaft? I thank you very much for your help. Kaspar

Offline Ryser Kaspar

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Re: Douglas 1928 SW5 or OHV
« Reply #10 on: 30 Jun 2016 at 17:05 »
Hello Douglas Friends
Can know anybody the radius from the cam folower of the engine DT5 of 1927/29? Built  of the Picture of my first ask two weeks ago. Thanks for all answers.

Kaspar from switzerland.

Offline Doug

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Re: Douglas 1928 SW5 or OHV
« Reply #11 on: 30 Jun 2016 at 20:47 »
Kaspar,

As seen via the link Leon provided, they are flat. No radius. The angle is 8.5 degrees from the axis of the tappet stem.

-Doug

Offline Ryser Kaspar

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Re: Douglas 1928 SW5 or OHV
« Reply #12 on: 01 Jul 2016 at 06:28 »
Hello Doug
Thank you very much for the answer. I shink, now we can go to work, maybe the machine is ready to go on the saison 2017.
Thank's all Douglas friends. I send e message, when the bike is on good health.

Kaspar

Offline Ryser Kaspar

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Re: Douglas 1928 SW5 or OHV
« Reply #13 on: 27 Jul 2016 at 16:28 »
Hello Friends
The reconstrucion of my 500er camshaft is in work and i think to finish the machine in some wheeks. Thanks for all the requestions.

Is it possible, that any Douglas owner have e drawing of e 600er camshaft? I have to buy e camshaft, where must rebuilt. I can't there Need myself. I can send Pictures with mail.

Kaspar

Offline Doug

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Re: Douglas 1928 SW5 or OHV
« Reply #14 on: 27 Jul 2016 at 17:28 »
Kaspar,

A 600 DT camshaft? There were several different profiles of camshafts for the DT and the other OHV models; "IN OP 20" being one of the more popular ones. However Douglas did not make any distinction between camshafts for the 500 or 600. Any of the period DT camshafts could be used in either displacement without alteration.

The factory or a tuner may further tweak the timings to best suit their (or a client's) engine. But the factory did not bother for the standard 'over the counter' DT model. You might get to pick from a few available cams on offer, then what you did with it was your business. Only if you paid extra or were you a Works supported rider did your camshaft get special treatment. But what those timing values may have been are lost to history. And they would have been fuel, compression, and exhaust system dependent; to name a few variables.

The standard timings were not that aggressive. The "IN OP 20" cam used in some DTs was also used in later single carburetor road models. My 1934 OW1 (600cc) has one, and it is a very nice mid-range cam for road use.

-Doug

Offline Ryser Kaspar

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Re: Douglas 1928 SW5 or OHV
« Reply #15 on: 28 Jul 2016 at 06:36 »
Dear Doug
Thanks for your comments.
I bought the 600er camshaft for a few weeks, because I thought it might serve me as a model for my 500er. But that is constructed differently. Therefore, it doues not serve me and I would resell. By the seller of the camshaft were other parts vor the 600er, they were stil present., which he would sell. I try to insert a picture of the camshaft. Or I can send you per mail.
Kaspar
« Last Edit: 28 Jul 2016 at 06:46 by Ryser Kaspar »

Offline Doug

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Re: Douglas 1928 SW5 or OHV
« Reply #16 on: 29 Jul 2016 at 03:33 »
Kaspar,

The camshaft is just an earlier drive type. They started out with the taper, then sometime around 1928 changed to a spline drive. It will fit in the later engines with the appropriate drive gear, but the later cams did have an advantage of a slightly wider cam lobe. As the cams are prone to wear, they need all the surface area they can get!

The frame looks like an OC model, with some modifications. The front forks look like later S6 model. The crankcase could be OB or OC. I do not know if the OC still had the small aperture for the magneto drive. The prefix code on the crankcase will tell. If it is OE it is OB model, if it is ED it is OC model. There are a few other options, but likely it is one of those two.

-Doug

Offline Ryser Kaspar

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Re: Douglas 1928 SW5 or OHV
« Reply #17 on: 29 Jul 2016 at 05:40 »
Doug
Very thanks for your answers. The camshaft is me, the other parts have my friend. All the parts are to buy. I must show, which prefix code is in.

Kaspar

 

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