Recent Posts

Pages: 1 2 3 4 5 6 7 8 9 10

Anyone know how much backlash is permitted on the final drive bevel gears. With first gear engaged and the input shaft held stationary I can move the final drive sprocket about 3/16 inch - is this OK?
Also how may shims are needed between the sprocket housing and gearbox casing.


Wheels are back in frame and fork, lamp stays are made.
The rear wheel is now of original 19" instead of 18". So the stays are too short. On pictures the stays are different; I would like to get informations  about the kind of the stays and the fixing of the alloy guard.

Dougs bronze bush mod was a success, thanks Doug.
The case hardening near the end of the hub caused me a few headaches!
I could now do with addressing play in the rollers, so does anyone know where I can obtain oversize 3/16 x 3/16 ones?
Douglas Motorcycles - General Discussion / Re: S.L. Bailey
« Last post by Hutch on Yesterday at 07:51 »
Oh I forgot to add, the bore of the grey plastic eccentric part is 60.8mm.

Also, thinking about the possible De Saxe setup on the Bradshaw / Bailey engine, I don't think my demo system would give enough offset to be worthwhile, unless maybe slipper pistons were used so that their bore could overlap the cylinder holes in the crankcase by an amount and more offset of the barrels could be gained. The "spigot" on the barrel would then not be a full circle tho', but maybe that is not a major issue on a racing engine?

Douglas Motorcycles - General Discussion / Re: S.L. Bailey
« Last post by Hutch on Yesterday at 06:54 »
As Bradshaw machined the barrels from most likely round steel stock, he could have easily offset the "spigot" on the barrel that goes into the crankcase recess. To line up the front and rear barrels would require them to be offset inwards by 1/4". I found this was not quite possible, but you can get close. I think I noticed that in the literature it was stated that the barrels were not quite on the crank centre line - is this the slight offset that they were talking about? I will have to re read the previous posts carefully.

I didn't have any suitable steel laying around, but I did have some PVC. Not quite up to building an engine with (!) but ok for a demo. A bit of playing on the lathe and this mockup is the result. The conrods can be central to the pistons and  if you offset the front barrel toward the timing side and offset the rear barrel towards the drive (flywheel) side you can end up with the barrels almost in alignment with each other (not quite, about 1/4" offset, but maybe close enough?). If you wanted to be brave with the machining you could get closer, and if you were to machine the cases slightly you would be able to get them aligned. Note that this setup would not be able to be used with a standard crank but would require the 3 throw crank to be used, as previously stated by Leon.

If you offset the barrels the other way, i.e. front towards the drive side and rear towards the timing side, it appears you could possibly use the standard crank and the barrels would be offset from one another by 3/4" or more. The centre to centre distance between the rods on the standard engine looks like about 1 3/16", so not perfect alignment but possibly better than the standard setup with regards to conrod / piston alignment.

If Bradshaw used detachable heads, then the front and rear barrels could be swapped and inverted so the offsets could be outward to use a standard 2 throw crank and inwards for a 3 throw crank?? So possibly the Bradshaw / Bailey OHV engine was used in both configurations??

The Bradshaw / Bailey OHV barrel and head conversion therefore appears to be able to be used with a standard crankcase with either 3 throw cranks and special pistons and rods (i.e. 3 rods) or with the standard 2 throw crank (and possibly standard pistons and rods). I wonder if they had thought of selling it as a conversion? Also did Bailey take the engine parts with him to Australia to put on a standard 2 3/4 HP, or did they stay in the UK?

Can this eccentric barrel idea be used to get a De Saxe setup? Yes it appears to be able to do this but I need to do some playing to see if it can get the offset shown in Doug's picture of the engine.


Douglas Motorcycles - General Discussion / Re: S.L. Bailey
« Last post by Hutch on Yesterday at 06:04 »

Thanks for the much better image of Violet !. Yes I think it could be her on AD 5724, especially as there is probably about 6-7 years between the pictures of Violet with Eric and the Brooklands picture. Fingers crossed a better picture of either her or Kate turns up so it can be confirmed either way. Looking forward to seeing how you go in the Brooklands Museum Archives.

The question of the Bradshaw / Bailey OHV conversion was playing on my mind a little.......2 or 3 throw crank, De Saxe or not?? etc,  so I thought I would do a bit of an experimental mock up to see how they might have put their engine together using a standard crankcase from 1912. Now I don't have a 1912 crankcase so I used a 1919 one which for the purposes of these experiments should be ok. If anyone knows of significant differences between the 1912 and 1919 crankcase that would render my theories as incorrect please let me know! :-).

Most Douglas enthusiasts would, I think be familiar with the normal 2 3/4 HP setup with regards to the barrels and conrods and crank. That is, the conrod is offset to the piston centre line. See picture A below. This was done to reduce the rocking couple between the front and rear cylinders and hence reduce engine vibration. This results in the barrels to being offset from one another by 1/2" or so.

A conrod offset from the piston centre line would not be a good feature to have for a "high" performance engine due to the eccentric loading on the conrod. This would obvious lead to flexing and fatigue of the conrod and uneven wear on the big end bearing etc. (which is a common problem on 2 3/4HP engines I have seen). If you flip the pistons over on the rods (Picture B attached) you can more or less get them in line, but due to the offset of the barrels in the crankcase (required because of the web in the crank between the two big ends, you cannot assemble the engine without serious machining work. The period articles on the Bradshaw / Bailey OHV engine of 1912 appear to state that a standard crankcase was used - so how did they improve things and use conrods inline with the centre line of the pistons?
Douglas Motorcycles - General Discussion / Re: S.L. Bailey
« Last post by Doug on Yesterday at 01:07 »

Slight correction to the use of "Sopwith". I see now it could be read as the firm Sopwith, when in Jeff Clew's book the reference pertains to a job interview with Tom Sopwith at the 'Bear' Hotel in Esher. I have made an edit to the previous post, highlighted to show the change.

Douglas Motorcycles and Parts Wanted / Re: DT/SW ad TT carbs
« Last post by desmobikes on Yesterday at 00:45 »
If you end up with the early 2 3/4 carb I,d be interested in buying it. Bob
Douglas Motorcycles and Parts Wanted / DT/SW ad TT carbs
« Last post by roger h on 11 Oct 2019 at 22:41  »
Wanted - I'm looking for a pair of AMAC carbs for my SW5. I have a pair of TT carbs for a 90+, and a carb from an early 2 3/4 hp for exchange, part ex, or can pay cash. Thanks, Roger
Douglas Motorcycles - General Discussion / Re: S.L. Bailey
« Last post by Brooklander on 11 Oct 2019 at 22:08  »

Thank you for the source, I have the same problem with dates in Jim Sheldon's Veteran and Vintage Motor Cycles!. 
Sopwith Aviation went into liquidation in September 1920 so it would have been ABC Motors (1920) that Moore joined in 1922.  They were part of the Hadfield Bean group and had gone into the production of the ABC car to use up some of their spare  manufacturing capacity  built up during the war.  Jim Shelton also thought that ABC Motors (1920) were producing the motorcycle and bought shares in the company which promised rich returns on the investment with guaranteed orders for 4000 cars from the parent company each with a 30 profit.
There were problems with the car production but these were mainly due to the parent company forcing the use of heavier transmission components in what was essentially a cyclecar.  Would Moore have attempted to sort out such problems?

However, I have just found a picture of an ABC motorcycle with the registration P 1 HB which opens up the possibility that the original ABC Motors sold a licence to manufacture motorcycles to Sopwith rather than an exclusive licence.  The wording of the transfer of assets to the new company include the motorcycle so Moore could well have been enticed from Douglas in early 1922 to sort out those problems.

Graham Walker left Norton in 1923 following his use of Webb forks in the TT and Moore replaced him.for the 1924 season.  Bristol based George Tucker won the sidecar TT in 1924 with Moore as passenger.  Quite what he did in between we will probably never know.

Pages: 1 2 3 4 5 6 7 8 9 10