Author Topic: Douglas Aero 1937  (Read 10362 times)

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Offline Doug

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Re: Douglas Aero 1937
« Reply #50 on: 28 Feb 2017 at 18:15 »
Eric,

With the output sprocket off, there will be a small amount of axial (end) play in the output shaft. With the sprocket on, the spring washer against the seal should eliminate any axial play. There should be very little radial play, or wobble. However the roller bearings are not spaced very far apart and much of the alignment is provided by the fit of the input shaft through the sleeve gear busing. If that is worn, the sleeve gear can wobble on the shaft and the roller bearings do not have a wide enough 'stance' to prevent it. The input shaft should have a small amount of axial play at all times and no perceptible radial play. Again, if the sleeve in the output shaft is worn, you will be able to wiggle the shaft up and down. If you can perceive it (0.15mm) it is worn out.

Yes, there is a rod that passes through the footrests with nuts on the outside clamping everything together. It looks like the face of the footrest and the sleeve have been modified. These should have a face serration to allow angular adjustment. Pictures of mine attached. The serrations for the brake pedal side are almost entirely worn down. I made new ones. I re-cut the serrations on the foot peg arms.





-Doug

Offline Doug

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Re: Douglas Aero 1937
« Reply #51 on: 28 Feb 2017 at 18:18 »
Actually, you may want to ask around about the footrest serration. Perhaps Douglas changed that for the 1937-38 models, because the serrations getting worn and mashed was a chronic problem.   -Doug

Offline Eric S

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Re: Douglas Aero 1937
« Reply #52 on: 28 Feb 2017 at 19:38 »
As for the foot rests, I can see remains of serrations but INSIDE of the right only foot rest. Like if the rod should have matching serrations.
Nothing can be seen on the left.

Any way I will mount it back the way it was. I have more than I can handle for now.

Offline Eric S

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Re: Douglas Aero 1937
« Reply #53 on: 28 Feb 2017 at 19:53 »
I do have a small amount of axial play on the output shaft. (Providing output shaft is where the Sprocket for Primary Drive mounts or larger shaft)
However I have no "spring washer against the seal". Do you have a picture of that?

Providing input shaft is where the Sprocket for Secondary drive  mounts, or small inside shaft, I have no perceptible play between it and the output shaft.
I am not sure to understand what is the "sleeve in the output shaft" though.

Offline Eric S

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Re: Douglas Aero 1937
« Reply #54 on: 28 Feb 2017 at 20:07 »
I am not able to identify the thread size of the screws holding the front brake.
I thought it would be 1/4 26 Tpi BSC but is seems to be just a little bit asmaller and 1/4-26 do not screw there.

The original screws on the bike were Allen socket head screws. Anyone has the information as to the correct head shape on those screws?

Also how can we remove this triangular shape plate. Seems to be locked on the square shaft. Do I have to remove the front wheel?
« Last Edit: 28 Feb 2017 at 20:20 by Eric S »

Offline Doug

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Re: Douglas Aero 1937
« Reply #55 on: 28 Feb 2017 at 21:08 »
Eric,

The original fasteners would be hex head, Whitworth wrench size across the flats. While Allen head socket cap screws were available for the 1920s onward, Douglas did not use them until postwar.

The triangular plate is some sort of modification. So no telling how it was put together. Attached is the very original (and rusty) front end of my 1936 Aero. Also a picture of just the brake backing plate (sorry about the low resolution). The brake arm passes through a bush in the girder fork blade and plugs into a spline inside the brake. A bolt through the center holds the brake arm and shaft from falling out.





Markup of the sleeve gear, labeling the parts. I do not happen to have a picture of the wave washer, but it is of the same design as waver washers still sold today.



-Doug


Offline Eric S

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Re: Douglas Aero 1937
« Reply #56 on: 01 Mar 2017 at 19:30 »
I just remind that the front brake has been changed by a previous owner. I guess they installed Triumph parts to make it more efficient.

As for the leather gland, is it something hidden inside?
I guess I still miss parts as I can't see how a wave washer stuck between the rotary sprocket and the fixed gear box would handle the friction. Don't I need a ball bearing or the like?
Also I have 3-4mm between the gear box wall and the sprocket. Isn't it too much for a wave washer?
« Last Edit: 02 Mar 2017 at 06:59 by Eric S »

Offline Eric S

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Re: Douglas Aero 1937
« Reply #57 on: 06 Mar 2017 at 11:43 »
Hello there
On the front brake, original screws seems to be 26 Tpi and about 1/4 but  I can not screw in a 1/4-26 screw. So what it might be?

Doug that is your "bolt through the center holds the brake arm and shaft from falling out".

Doug again, from what I understood on your previous drawing, I should have a leather gland, a backing washer and a spring or wave washer. If those are 3 loose parts that are taken between the gear box and the sprocket, I am lacking them.
Below is a picture of the shafts out of the gear box. I only have the Sprocket to install there.

I found a round gasket, that comes to be slightly compressed between the box and the sprocket. Is that a decent solution unless anyone can tell me where to get the right parts?

Current spark plugs are NGK BP7EVX. Those are completely worn out. Is this model OK? Bike Works well with it...

Offline cardan

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Re: Douglas Aero 1937
« Reply #58 on: 06 Mar 2017 at 20:06 »

Hi Eric,
It looks like someone has fitted a "modern" lipped seal to replace the original leather seal. Since it has been leaking, I guess you need to replace it. Try to find a replacement before you try to get this one out because the metal casing is often very thin and will probably be ruined if you take it out from the outside.
A gasket of any kind between the case and the sprocket will not work: it won't seal the shaft and it will probably spin with the sprocket and wear the aluminium case away.
Cheers
Leon

Offline Doug

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Re: Douglas Aero 1937
« Reply #59 on: 06 Mar 2017 at 20:23 »
Hello Eric,

Remember when I said "if they used the same design as the 3-speed". Well they did, and they did not. I pulled the sprocket off of my 1936 Aero gearbox and the seal is not the same as the 3-speed. The housing has no external access to the seal, as you can see in this picture. The aluminum comes right down to the journal diameter.



Which did not match you photo at all. So I looked at another gearbox, this for a 1932 Greyhound 4-speed. It has a design like the 3-speed and the section illustration that I previously posted.



Just to the rear of the keys you can see the spring washer. The spring washer and the backing washer behind it are shown below. The leather gland was missing.





With this style, the back of the sprocket has a more pronounced spigot that projects into the end recess of the gear case and bear against the spring.



The 1936 sprocket only has a slight hub. The 1936 gearbox for the Aero has a P prefix, the 1932 gearbox for the Greyhound has a GB prefix. It looks like you have this earlier style gearbox?

The spring has a cross-section of 0.062 thick by 0.093 radial, 1.531 outer diameter, and a free height of 0.200 (all dimensions in inches). The backing washer is formed by rolling a lip. The material is 0.036 thick with a inner flange rolled up to make a overall width of 0.088; the outer diameter is 1.739 and the inner diameter is 1.293 (inches). The lip faces outward, towards the spring.

-Doug

Offline Doug

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Re: Douglas Aero 1937
« Reply #60 on: 06 Mar 2017 at 20:27 »
Eric,

The bolt that secures the brake lever is 1/4-25, a Douglas proprietary thread. They also used 17/64-25 (like for the petrol tank mounting bolts), so you have to be careful.

Picture of the brake arm and bolt in this post:
http://www.douglasmotorcycles.net/index.php?topic=2440.msg8835#msg8835

-Doug

Offline Eric S

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Re: Douglas Aero 1937
« Reply #61 on: 10 Mar 2017 at 19:45 »
Leon

thank you for your expertise.
The round gasket I'm talking about is a round rubber ring. Being compressed it should pressure the shaft out of the box and limit the leak. Being rubber it should be harmless and help for a while.
I'd prefer to have the box opened, the modified gasket inspected and replaced but can not find anybody locally that may do it. Though waiting replies.

Doug thanks one more time. Don't know what to do. Maybe as just said give this rubber ring a try.

As for the bolts, the "bolt through the center holds the brake arm and shaft from falling out" will be re-installed. I wanted to change as it is an Allen head but will leave it as it is a 1/4-25 and can't find a correct hex head bolt in that size.

I will helicoil the 3 screws on the triangular plate and makes them 1/4-26. The original bolts seems to be also 1/4-25.
Anyway since they were Allen and loctited over worn out threads, I had to discard them + I should be able to live with 1/4-26 there.

The drum being a Triumph, is it possible Triumph also used 1/4-25 there?

On the tank I had a missing bolt so got 4 new chromed 1/4-26 bolts and they screw in 4 turns before being hard to turn. Are they bottoming out or are they 17/64-25?

Offline Doug

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Re: Douglas Aero 1937
« Reply #62 on: 11 Mar 2017 at 02:42 »
Eric,

The petrol tank bolts are 17/64-25.

-Doug

Offline Eric S

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Re: Douglas Aero 1937
« Reply #63 on: 11 Mar 2017 at 17:10 »
Doug

I measured the 1/4-25 bolts and they are .232"
Seems a bit small for 1/4"?

Offline cardan

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Re: Douglas Aero 1937
« Reply #64 on: 11 Mar 2017 at 20:08 »

Since they're Allen heads, they might be M6 (6mm x 1mm pitch - 0.236 - 25.4 tpi)!

Leon

Offline Eric S

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Re: Douglas Aero 1937
« Reply #65 on: 12 Mar 2017 at 19:26 »
Well done Leon, it's well a 6mm bolt.
This bike seems to be a sample of every thread size available in the world.

I re-installed the gear box, clutch flywheel, ...
With the knowledge I acquired through the forum and reading period manuals, I came up to the conclusion that my clutch problems might be linked to an overloaded clutch counter acting on the cam plate/cable action.
So I thought I would adjust the springs to a minimum.
But I think I have too strong springs in there.
Using 2 springs (instead of 6) and screwing in the adjustment nut just 1 turn, I have the plate out of its location but the clutch seems to function and I can turn the primary chain sprocket by hand without turning the engine (so Clutch is well off)
Screwing more prevent that and turning the sprocket turns the engine.
I did not started the engine yet and did not tried "live" but I am really wondering if the sprins are OK.

They are 40mm/1.57" and wire is 0.80"/2mm


Offline Eric S

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Re: Douglas Aero 1937
« Reply #66 on: 13 Mar 2017 at 21:54 »
Looks like the tank bolts has been helicoiled that would explain the 1/4-26 Tpi bolts fits.

I also noticed the engine bolts fits into inserts that I do not have on the gear box where bolt screw into aluminium. But the inserts are the correct thread size.

Offline Eric S

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Re: Douglas Aero 1937
« Reply #67 on: 15 Mar 2017 at 19:21 »
Does anybody have any idea regarding the clutch springs discussed just above?
Are they too strong?

Offline Doug

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Re: Douglas Aero 1937
« Reply #68 on: 15 Mar 2017 at 22:34 »
Eric,

I don't know that anyone bothers to measure them. New ones are available to LDMCC member via the spares department.

As for the engine and gearbox mount. The engine is supposed to have the steel inserts, the gearbox was tapped directly into the aluminum.

-Doug

Offline Eric S

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Re: Douglas Aero 1937
« Reply #69 on: 16 Mar 2017 at 10:01 »
Thanks Doug
I will check with the club.

I noticed a play on the rear wheel sprocket. Do I have a torque converter here?

Offline Chris

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Re: Douglas Aero 1937
« Reply #70 on: 16 Mar 2017 at 10:03 »
HI Eric
   I have just measured six clutch springs purchased at different times over the years from LDMCC spares. No two are identical. These are a fairly fast moving item and have been purchased from different sources probably on the basis of samples supplied as patterns. The lengths vary between 35.68 and 37.35mm, appreciably shorter than your springs of 40mm. Diameter of coils vary between 12.64 and 13.19mm. The wire diameter also varies between 2.01 and 2.12mm. The subject of clutch springs has been discussed previously on the Forum as other members have experienced difficulty with clutch operation. From my experience with four different models with flywheel clutches none of them needed more than four springs to function well even including a 350cc CW with passenger sidecar.
Chris.

Offline Doug

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Re: Douglas Aero 1937
« Reply #71 on: 16 Mar 2017 at 14:10 »
Eric,

Quote
I noticed a play on the rear wheel sprocket. Do I have a torque converter here?

Do you mean a shock absorber or cush-drive? If so, no, the rear sprocket is supposed to be rigidly mounted to the rear brake drum/hub/wheel. Having said that, it is only pressed on to a knurled portion of the brake drum. There are several key/blocks that transmit the torque.

-Doug


Offline Eric S

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Re: Douglas Aero 1937
« Reply #72 on: 16 Mar 2017 at 16:08 »
I don't really know what I mean !
But shock absorber or cush-drive seems to be what I had in mind.

 A friend told me that if the large toothed wheel (with the chain on) moves on the drum where it is installed, then it might be a torque converter.

If it is supposed to be rigid, looks like a new field to play with...
« Last Edit: 16 Mar 2017 at 17:35 by Eric S »

Offline Eric S

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Re: Douglas Aero 1937
« Reply #73 on: 02 Apr 2017 at 18:38 »
I tested the bike with 2 springs (out of 6) on the clutch, tightened just the minimum I could.

Worked fine but gears still cracks and when going up hill on 4th, the clutch slipped so I had to come down to 1st gear. (steep road) and went back home safely. I hadn't a chance to make more tests as I have to another toy to play with for now.
Cracks seems to be manageable though. Will make more tests later.

Now I also have an elecrical problem. The bike's harness is a real mess with blue wires connecting to reds. Ground being any color but never black !

Dess anyone has a wiring harness plan or drawing fopr a 1937 Aero?

Offline Eric S

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Re: Douglas Aero 1937
« Reply #74 on: 11 Apr 2017 at 11:05 »
I am sorry that nobody can help with a wiring diagram for my bike.
I can not find a regulator before the dynamo. Are we suppose to get one?
I do a have a diode leaving the amperemeter. Is this replacing the regulator?

Offline eddie

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Re: Douglas Aero 1937
« Reply #75 on: 11 Apr 2017 at 11:43 »
Eric,
        I don't have any first hand information regarding the wiring on an Aero, but I would assume that it is much the same as that on a 1930 S6 as both machines are fitted with 'Pancake' generators. The S6 has a single wire from the generator to a cutout that prevents battery voltage draining back through the generator windings at low engine speeds. The other side of the cutout is wired directly to the ammeter, and then linked to the lighting switch input terminal. The other side of the ammeter is wired to the live side of the battery. The only provision for voltage regulation is via a ballast resistance on the lighting switch.
    As your bike already has a diode fitted, it would appear that the original cutout has already been superceded. If your bike is fitted with an electric horn, it should be wired directly to the live side of the battery - not through the ammeter!
  Hope this is of some help,
   Regards,
                Eddie.

Offline Eric S

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Re: Douglas Aero 1937
« Reply #76 on: 11 Apr 2017 at 12:11 »
Thank you so much Eddie
Yes the bike as an electric horn and is wired directly from the battery.
I am forwarding the rest to my helper as I am not able to grasp all the details here.

Offline Doug

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Re: Douglas Aero 1937
« Reply #77 on: 11 Apr 2017 at 14:47 »
Eric,

I have not yet seen a handbook published for the Aero models, just parts lists. So neither have I seen a wiring diagram. It would have to worked out from contemporary systems.

-Doug

Offline Eric S

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Re: Douglas Aero 1937
« Reply #78 on: 12 Apr 2017 at 05:49 »
Thank you Doug.The bike has been well modified so I am even wondering if a wiring diagram would really help.

Eddie, can you explain briefly the reason why the horn must not go through the ammeter for my personal education?

As for the ballast, I have no idea the way it looks. What I am looking for here?

On the ammeter, I have on one side a direct wire from the + on the battery, and the diode going down (to the dynamo but did not checked it). On the other side of the ammeter, a wire goes to the lighting switch input terminal.
You showed it slightly different with dynamo and lighting switch on the same side and + on the other side.
Does it makes any importance there?
« Last Edit: 12 Apr 2017 at 07:01 by Eric S »

Offline eddie

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Re: Douglas Aero 1937
« Reply #79 on: 12 Apr 2017 at 07:31 »
Eric,
       It is normal practice to wire the horn direct to the battery as the ammeter is probably only rated at about 4 amps and the horn's start up load could easily exceed that.
     The ballast may be a ceramic coated resistor or just a coiled bare wire between 2 terminals on the switch.
      The ammeter should have just the battery connected to one side - the generator lead (with the diode) and the connection to the lighting switch go to the other side of the ammeter. Wired this way, the ammeter will read the current either going to the battery (charge), or being drawn from it (discharge) - thus giving a continuous reading of whether you have enough charge going to the battery (very important on the Aero as those pancake dynamos often didn't keep up with the drain of a headlight bulb!). One of our local Club members had a 600 Aero that had a reputation for going well, and would often be seen disappearing into the distance - until nightfall - then his battery would go flat within about 15 miles - at which point, he would have to rely on following someone else's taillight!
   Regards,
               Eddie.

Offline Doug

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Re: Douglas Aero 1937
« Reply #80 on: 12 Apr 2017 at 17:50 »
This is all that remains of my Aero wiring harness. with the exception of the headlamp dip lead, it had been cut where the main bundle left the headlamp shell.








-Doug

Offline Eric S

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Re: Douglas Aero 1937
« Reply #81 on: 12 Apr 2017 at 18:44 »
Is this white curved part with a wire around it a ballast?

Offline Eric S

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Re: Douglas Aero 1937
« Reply #82 on: 14 Apr 2017 at 12:13 »
I played a little bit and wrote down the harness as it is with colors for the wires.
Beside the diode to dynamo wire that has to be linked to the other side of the ammeter as Eddie required, did any of you see any big mistake or useless connections?

Offline Eric S

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Re: Douglas Aero 1937
« Reply #83 on: 14 Apr 2017 at 12:18 »
Here is the dynamo, can you let me know where I can plug the earth and the "diode" wire (sorry picture is up side down)?
On the lighting switch, do you see a ballast (picture again not straight) ?

Offline eddie

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Re: Douglas Aero 1937
« Reply #84 on: 14 Apr 2017 at 15:36 »
Eric,
       As we are looking at the photo of the dynamo (upside down) - the terminal at 4 o'clock is where the diode wire should go. The terminal at 9 o'clock has been added, but is not needed - the dynamo is designed to be earthed via the crankcase and frame.
 Looking at the lighting switch, I am assuming that it is a 3 position switch - that is 'Off - Sidelight - Headlight', and that the switch was photographed in the 'Sidelight' position. If that is the case, your wiring diagram looks to be correct, but with that Lucas switch there is no provision for switching in a ballast resistor. If you have a speedo fitted, the speedo light should be wired to the same terminal (7) as the taillight.
  Bearing in mind that the output from those 'Pancake' dynamos is pretty dismal, you should get away with leaving it permanently connected - it is very unlikely that it will boil the battery dry.
  Regards,
                Eddie.

Offline Doug

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Re: Douglas Aero 1937
« Reply #85 on: 14 Apr 2017 at 17:12 »
Yes, the white thing is a half-charge resistor.

A ballast resistor is (I think) a resistor used in the specific application of older coil ignition systems with mechanical points.

Here, it is a half charge resistor to prevent over charging of the battery (or accumulator in English). Which is a bit silly, as Eddie says, the output of the BTH pancake dyno is so feeble that overcharging is farce. I suppose back in the day if you ran all day and every day with little night time running the lack of headlamp load could over charge and boil the battery dry. But these days the systems are under-performing (if even working!), the usage is occasional, and often the headlamp on during the day as a daytime running light.

-Doug

Offline Eric S

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Re: Douglas Aero 1937
« Reply #86 on: 14 Apr 2017 at 21:25 »
Eddie

I have an earth wire linked to the 9 o'clock terminal. Should I remove this wire or leave it plugged?
Yes its a 3 positions switch and it's well set on sidelight on the picture. And it has no speedo.
When you said I "should get away with leaving it permanently connected", do you mean that I can leave it permanently connected? Or stay away to leaving it ...?

Do I understand well that the ballast (or half charge resistor) should regulate the voltage so as not to overcharge the battery?
When I bought the bike I've been told that the battery charging by the dynamo was very low so, as Doug pointed, overcharging is not a problem !

I tested the dynamo and I read an 8V output when accelerating the engine a little bit. Sounds to be not too bad but is it relevant or should we check Amps?
How can I check, when everything will be connected and battery installed, that the battery charges beside reading he ammeter. How can I get a value on my meter?
Somebody tested the battery with engine running, connecting on the battery connections and said it was "not charging"?

And is the way the ammeter is wired now, is it possible that the ammeter gives false or no reading?
« Last Edit: 15 Apr 2017 at 17:09 by Eric S »

Offline eddie

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Re: Douglas Aero 1937
« Reply #87 on: 15 Apr 2017 at 11:11 »
Eric,
         As I have already said, an earth wire from the generator is not necessary as the unit is earthed through the crankcase to the frame.
   Originally, the Aero models were fitted with a Miller lighting switch that was designed to have a ballast resistor (half charge resistor) incorporated in the wiring. Turning the switch to the headlight position would also bypass that resistor so that the full charge rate went to the battery - your Lucas switch does not have that facility, so I would suggest that you should connect the generator via the diode to the ammeter. Connect it to the opposite side of the ammeter to the battery - then any power coming or going from the battery will register on the ammeter. The way it was wired (with the battery and generator on the same side of the ammeter) meant that any charge going to the battery didn't have to go through the ammeter, so the ammeter wasn't reading it.
  When you have everything wired up as I suggested, you can run the engine and see on the ammeter how much charge is going to the battery with the lights off. If it is in the region of 2 - 3 amps, the battery should cope with that. If it is more than 3 amps, you may need to insert a ballast resistor in the generator wire - in order to then get the full charge rate with headlight on, you just need a simple on-off switch wired across the resistor so that you can bypass the resistor when you have the headlight on (thus replicating what the Miller switch did).

  Regards,
               Eddie.

Offline Eric S

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Re: Douglas Aero 1937
« Reply #88 on: 15 Apr 2017 at 17:45 »
Eddie

I well understood that this wire was useless but it is here. So I will see if it's easier to leave it or remove it.
As I like to understood what I am doing, I came to the  terminal at 9 o'clock and checked it for earth. And it is, as expected. So far so good, it was easy.
I then checked the  terminal at 4 o'clock the one that has the "dioded" wire coming down from the ammeter with +. But this terminal is earthed too. Am I missing something here?
Is it normal due to the nature of the dynamo and the way it works (earth until it comes in production)?
The Diode being supposed to "block" the + going down to the dynamo?
« Last Edit: 15 Apr 2017 at 18:07 by Eric S »

Offline eddie

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Re: Douglas Aero 1937
« Reply #89 on: 15 Apr 2017 at 19:54 »
Eric,
       The terminal at 9 o'clock is showing a connection to 'earth' because there is a connection through the armature windings. If you were to lift one of the brushes, it would show 'no connection'.

  Eddie.

Offline Eric S

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Re: Douglas Aero 1937
« Reply #90 on: 15 Apr 2017 at 19:58 »
Eddie

sorry I was talking about the other terminal being on earth. The one at 4 o'clock with + wire with diode.
(Actually both terminals are on earth)
Is that normal?

Eric

Offline eddie

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Re: Douglas Aero 1937
« Reply #91 on: 15 Apr 2017 at 20:08 »
Sorry Eric,
                Yes, it's the terminal at 4 o'clock that is connected to the armature windings. With a test meter it will show as being connected to earth due to the low resistance of the windings.

  Eddie.

Offline Eric S

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Re: Douglas Aero 1937
« Reply #92 on: 19 Apr 2017 at 15:12 »
I road tested the bike and although the dynamo seems to output 8V as I measured it some day ago, the ammeter says "0". When lights are on, it goes down to -2,-4.
Is it possible to get an output of 8V but not charging?
For now I am using traditional bulbs. I may change for LEDs to improve battery life but would like to find out if dynamo charging can be fixed.

Offline eddie

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Re: Douglas Aero 1937
« Reply #93 on: 19 Apr 2017 at 17:00 »
Eric,
       It is possible to have 8V with very little amperage, but very unlikely. If the ammeter is showing '0' going to the battery, but -2, -4 with the lights on, it begs the question "Are the generator and battery wired to opposite sides of the ammeter?"  If not, then the power is not going through the ammeter, so it can't possibly give a reading.
 To check whether the generator is working, disconnect the battery, start the engine with the lights turned on, if they light up then the generator is working.
  Eddie.

Offline Eric S

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Re: Douglas Aero 1937
« Reply #94 on: 19 Apr 2017 at 19:38 »
Per your previous instructions I wired the + from the battery on one side of the ammeter and the dioded wire (to the dynamo) and the wire to the switch to the other side.
I will test the lights with no battery.

Offline Eric S

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Re: Douglas Aero 1937
« Reply #95 on: 25 Apr 2017 at 09:20 »
Eddie

I tried running the bike without the battery and the dynamo do not power the lights ! I had not a chance to measure the output out of the dynamo though.

Eric

Offline eddie

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Re: Douglas Aero 1937
« Reply #96 on: 25 Apr 2017 at 10:47 »
Eric,
       Try running the engine with a bulb connected directly between the terminal at 4 o'clock on the generator and earth - this will establish whether the generator is working. If the bulb doesn't light, there is a fault with the generator. If it does light, do the same with the bulb wired to the other side of the diode and earth - to make sure the diode is wired the right way round!
      If there is no output from the generator, you will need to investigate further - one of our members had a similar problem and that turned out to be a faulty magnet in the generator. I see from the photo of your generator that it is of the later type with a single full circle magnet (earlier models had 2 half round magnets). Now, this magnet should have 4 poles at 90 degree intervals. If you pass a compass around the magnet, it should show the 4 poles equi-spaced - if you get an odd swing of the compass at any other point, there is probably a crack in the magnet at that point - this will cause the generator to internally produce a rogue output that opposes the main output - thus considerably reducing the amperage. Another method is to put a sheet of paper over the end of the generator and sprinkle iron filings on to it - the iron filings will then align to show the magnetic field (just like we used to do in science lessons at school!).

  Hope some of this helps,
                                        Regards,
                                                      Eddie.

Offline Eric S

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Re: Douglas Aero 1937
« Reply #97 on: 27 Apr 2017 at 05:40 »
Eddie

thank you again for your help. I have been preparing and now leaving for a 2 weeks trip to Morocco (not with the Douglas !) and I will do more testing when I am back.

Best Regards