Author Topic: Alwyn's 1948 T35  (Read 13340 times)

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Offline alwyn

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« Last Edit: 26 Mar 2008 at 14:33 by alwyn »
Quotable Quote - "640 k should be enough for anybody"! - Bill Gates - 1981.

Offline Dave

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Alwyn's 1948 T35
« Reply #1 on: 28 Apr 2004 at 23:00 »
Thatís a fine looking machine Alwyn. Can you tell us about the restoration and/or its history?

Offline alwyn

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Alwyn's 1948 T35
« Reply #2 on: 01 May 2004 at 04:17 »
Quote from: "dave"
Thatís a fine looking machine Alwyn. Can you tell us about the restoration and/or its history?


Thanks Dave,
Unfortunately there is not very much history known of the bike except that it was bought new in South Australia c 1948/49. I acquired the bike in 1999 from the guy that did the restoration after seeing the advertisement reproduced here, in the magazine "Just Bikes" - it was featured in colour on the cover of the particular issue and having owned a Mark 3 of the same era as a young petrol-head, I found it just too hard to resist.



The credit for the restoration must go to Greg Burns of Wattle Park in SA. Greg is an engineering draftsman with a penchant for meticulously restoring motorcycles, specialising in Puch.

Greg sourced many of the replacement parts needed for the Douglas through his membership of the London Douglas Motor Cycle Club Limited (of which I am now a member). He visited the Club personally during a trip to the UK. He began the restoration in 1989 or 1990 and completed it in August 1999 - he also completed a number of other restorations during the same period.

Unfortunately, Greg kept no photos before or during the restoration but he has told me the bike was in a pretty poor state of repair when he acquired it. However, the tinware and tank must have been pretty well preserved because no sign of rust or panel repair can be seen beneath the lustrous finish.

Among parts sourced in England were replacement cylinders and cylinder heads - these were originally fitted to a defence forces auxiliary generator or water pump motor and are standard bore. History relates that apart from manufacturing thousands of Douglas motorcycles for UK Forces during WW1 part of the Douglas company's war effort during WW2 was the production of many of these particular 350 cc horizontally opposed twin cylinder motors for various uses by the forces. They were apparently a very reliable unit as a stationary engine.

Since I aquired the bike, it has clocked more than 4000 miles. The only post restoration modification carried out has been the modification of the crankcase breathing system. The original crankcase breather is moulded into the cast aluminium alloy cover over the timing and camshaft gear compartment of the crankcase at the front of the motor the exit of which terminates in a downward facing hole at the base of the casting. This spewed such quantities of oil as to be quite a nuisance, an inherent fault I can well remember contending with on my original Mark 3, c 1950/51, pictured here.



The modification involved plugging the original breather, (horror of horrors, a piece of wooden dowel suffices!) - and the modifying of the oil filler cap by raising it with a 1" diameter m & f brass nipple. See the  photograph here.



A copper tube spigot is brazed in to the side of the nipple. A plastic hose is connected to the spigot and in turn is coupled to a flat plastic bottle acting as an oil catcher fitted beneath the toolbox. A second hose from the receptacle breathes engine vapours downward toward the ground.

The modification works quite effectively but I have recently read a report that indicates I have inadvertently stumbled upon a remedy that is not recommended by those who have raced the machines, as they still do at club level in the UK. Reasons were not expounded upon in the report but if you or anyone at all has a comment about this, I would be grateful to receive it.
Quotable Quote - "640 k should be enough for anybody"! - Bill Gates - 1981.

Offline Doug

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Alwyn's 1948 T35
« Reply #3 on: 01 May 2004 at 05:17 »
I have heard tell that when you have a long tube like this for a breather you can create an extractor effect that will actually pull more oil vapor out than a short and otherwise low velocity flow breather.  But if you keep an eye on the oil level, I can not see the harm.  You can always pour the reclaimed oil back in!  Perhaps racing, with more blow-by and higher RPM, aggravates the problem.  But at club level, I would have thought the races too short to worry about running out of oil.  And you could check the oil before every race.  

-Doug

Offline maverick65

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Don't waste that oil!
« Reply #4 on: 29 Oct 2004 at 10:31 »
Quote from: "Doug"
I have heard tell that when you have a long tube like this for a breather you can create an extractor effect that will actually pull more oil vapor out than a short and otherwise low velocity flow breather.  But if you keep an eye on the oil level, I can not see the harm.  You can always pour the reclaimed oil back in!  Perhaps racing, with more blow-by and higher RPM, aggravates the problem.  But at club level, I would have thought the races too short to worry about running out of oil.  And you could check the oil before every race.  

-Doug


On my MkI I have a 1" pipe running up under the tank (drains most oli back down into the crankcase again) then to a bottle sitting on top of the rear swinging arm, under the toolbox. But you can also get rid of this bottle and direct the pipe outlet onto the chain just behind the drive sprocket - keeps the chain oiled, so any oil that does get blown out isn't wasted!

Maverick65
Doug Cross  Tel *44 1229 885420

Offline tck

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Re: Alwyn's 1948 T35
« Reply #5 on: 09 Aug 2013 at 11:07 »
Breathers are an 'Entry ' topic with Vincent owners more is 'spouted' about them than any other subject although a horizontal twin I guess the Douglas crankcase pressure also varies if it does then a simple PCV valve in the breather will after initial setup keep a slight vacuum in the crankcase and the oil in I use a I" by 3/4" dia STANDARD (American car part) line ball valve  V148 in my 1" breather pipe.  Alternatively with a little ingenuity you could fit a BMW (I think that's a German company that copied the Douglas design about 100 years ago) flap valve (that's about the size of 6 50p pieces stacked ) somewhere on the filler spout

 

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