Speedo drive ratio for A10

[KeithS]

Does anyone know what the speedo ratio is for 1956 A10? I am considering getting a speedo for an Enfield as they are cheap and mine is stuck at 30 mph!

[trevinoz]

Ratio is 1440 revs per mile.
I think Enfield speedos are 2:1 which is about 1600 revs per mile.

Trev.

[KeithS]

So 1.8 to 1 then?

[wilko]

If you live here in Oz Keith I'll fix it for nothing. I pull them apart for the fun of it.The four leaf cam spring needs re setting, or your speedo drive is stripped. Check the rear drive first.

[KeithS]

Thanks but I'm in UK. Can't even open the speedo. Have been soaking the threads in penetrating oil for two days now. What do you use to get the bezel off the can?

[trevinoz]

They can be very hard to remove.
A rubber strap device, like an oil filter tool, can work.
You could try protecting the surface and grabbing the bezel with a stilson or large multi grip.
Last resort is to cut it off!

Trev.

[chaterlea25]

Hi All
Search for old replies on this topic
I use a layer of double sided stiky tape carefully wrapped around the bezel, then wrap a length of webbing strap around this catching both ends in a vice jaws
then grab the body and unscrew  ????

Works for me
John

[wilko]

Before you pull it apart, spin up the speedo in the right direction to see what happens. I use the end of an old cable in the chuck  of a drill. If a drive is stripped or a broken cable the needle will stick at whatever speed it was last doing. Looking at the speedo face the drill should spin in the same clockwise direction. In other words the drill should be in the reverse direction??? Are you  confused yet?

[KeithS]

If you live here in Oz Keith I'll fix it for nothing. I pull them apart for the fun of it.The four leaf cam spring needs re setting, or your speedo drive is stripped. Check the rear drive first.

Thanks.
I got the bezel off with the help of blowtorch and chain wrench (doing no damage in the process!)
Removed the speedo needle without damaging the face.
I'm now looking at a lot of brass and stuff.
How do I find and reset this four leaf cam spring?

[chaterlea25]

http://www.hells-confetti.com/Technical%20data/Jaeger%20Instruments/Jaeger%20Chronometric%20Overhaul.pdf

HTH
John

[wilko]

I couldn't explain it better! The four pronged cam springs often over time  fail to lock in place, so i remove them and bend them downwards so they lock in place on their respective wheels. You'll need a magnifying glass and steady hand to remove and replace the two tiny screws that hold it in place. DONT overtighten these two screws or they will break and make the chassis useless. i use those tiny jewellers screwdrivers. I'd love to see an old youtube of these tiny parts being manufactured! The tiniest screws are the ones holding the spring in place.

[Gerry]

Hi Keith, Guys, Funny thing is I had just had the same problem undoing the bezel on a chronometric yesterday!! What I did was tightened a hose clip (jubilee) onto the body or case and held it gently (not too tight) in the vice with the adjusting screw against the jaw to stop it turning. Then I used a second hose clip carefully around the bezel, tricky to keep it on centrally, then used a large multigrips pliers on the hose clip and wallah...off it came with no damage to the case or bezel and no heat required. To remove the needle I made a puller from a 1/4" nut with the side cut off and ground the bottom of the nut pretty thin and cut a groove in that part to slip between the face and either side of the needle spindle, then tapped a 4BA thread in the top section and fitted a screw into that with a fine point on its end. Tightening the screw forces the needle off the spindle. Cheers. Gerry in Oz

[chaterlea25]

Hi Gerry,
A pullet with an extraction pin/screw like yours can damage the spindle as its hollow with another pin rotating inside it
I just have a hooked piece with a groove that catches under the needle boss, one end is held in the vice and pull on the speedo
HTH
John

[KeithS]

All good stuff about dismantling. Bearing in mind the comments about hollow spindle in last post, how is the needle meant to stay on when reassembled? I've just pushed mine back on. Will probably see it bouncing around the speedo after a few yards of riding!?

[wilko]

It's a taper fit. Just give it a tap! Make sure it's all the way back to zero by turning the drive backwards to it's normal rotation.