Author Topic: 1920 sturmey archer 2sp gearbox  (Read 155 times)

Offline rick-chuck

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1920 sturmey archer 2sp gearbox
« on: May 11, 2018, 05:20:43 PM »
Would any of you know where I could obtain a repair manual for a Sturmey Archer 2 speed gearbox, # TS11973, I believe was produced in 1920. Cheers, Rick

Offline cardan

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Re: 1920 sturmey archer 2sp gearbox
« Reply #1 on: May 11, 2018, 11:57:05 PM »

At best I think there might be a parts list - no repair manuals as such back then.

But it's a very simple box. What's the problem?

Leon

Offline iansoady

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Ian
1952 Norton ES2
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Online 33d6

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Re: 1920 sturmey archer 2sp gearbox
« Reply #3 on: May 13, 2018, 03:11:20 AM »
 Two speed hand change gearboxes are an ideal introduction to gearboxes as a whole. After all they are the simplest box of the lot aren't they. Nevertheless they will teach you a lot about the basics common to all boxes. The clutch, clutch operating mechanisms, importance of mainshaft end float, indexation (or lack of it in some cases) and so on. Once learnt the basics transfer across to all boxes. The methods may differ from maker to maker but the principles don't.
In your case Sturmey Archer never did repair manuals. The only Sturmey Archer factory material you can get is an illustrated maintenance and spare parts list as Ian advised above and BMS is as good a place as any as he also advised.
All is not lost though.
The solitary original, factory written and illustrated article on Sturmey Archer overhaul I've ever seen in many years of playing with Sturmey Archer boxes  was written in the early 1930's for a weekly publication "Motor Cycle Repair and Upkeep" published by George Newnes Limited. This was one of those weekly part by part D.I.Y. publications still found in newsagents today. Someone republished it in the 90's and it still pops up in eBay on a regular basis. A full set is held in the VMCC Library and for a fee they will copy off the Sturmey Archer chapter for you.
This article does not mention your two-speeder in particular but regularly refers to points of concern in early S/A boxes.
You haven't said what repairs yours needs. We may be able to help if you expand on your concerns a little.

Offline john.k

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Re: 1920 sturmey archer 2sp gearbox
« Reply #4 on: May 13, 2018, 03:23:08 AM »
The biggest catch is ball bearings in odd sizes,which cant be replaced ,unless you make them......The more common LS type have a double ball bearing incorporated with the sleeve gear,and the price of a new made one will lift your hair off.

Online 33d6

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Re: 1920 sturmey archer 2sp gearbox
« Reply #5 on: May 13, 2018, 06:32:53 AM »
I have a vague memory that the two speeder didn't have the usual S/A factory own double bearing arrangement but used a standard size commercial bearing instead. Many years ago I had an elderly friend who could no longer cope with his bottom of the range direct belt drive single speed Levis 'Pop' Eventually he found a correct for year two speed S/A box and fitted it to move up a notch in the Levis range. This gave him a year or two more riding. It was having a clutch and not having to do a push start at every traffic light that thrilled him.  Much to his discontent it leaked ferociously through the bearing and over the belt. I remember him being confident he could replace what was there with an identical sealed version which would solve the problem.
Unfortunately he became too frail to ride anyway so we never followed through. The 'Pop' was a lovely little bike. It remains the only motorcycle engine with a one piece crankshaft on which I've done a car style crankshaft grind plus make a new bronze bush big end. All in a tech school night class.

Little did I know that many, many years later I'd being following in his footsteps with my own small vintage two stroke with an Albion two speed box.   

Offline rick-chuck

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Re: 1920 sturmey archer 2sp gearbox
« Reply #6 on: May 13, 2018, 06:15:46 PM »
I don't have an issue with the box at this time (that I have found) but being an experienced mech, I've learned to find reference material before digging into something I'm unfamiliar with (example: the notorious "sproing" heard as a part goes flying off into oblivion during disassembly). A parts manual is very useful as a guide and will suit me well. Are any parts available for these, clutch being one, and can a chain to belt be changed to chain to chain? This box shifts well and the shafts seem to turn properly with no bind or slop, bearings seem servicable. Shaft end play? How much? Pics of the unit, and the 88cc engine that will run it. Maytag washer engine.

Offline mini-me

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Re: 1920 sturmey archer 2sp gearbox
« Reply #7 on: May 13, 2018, 08:29:21 PM »
Quote
(example: the notorious "sproing" heard as a part goes flying off into oblivion during disassembly)

The correct technical term is 'pingfukkit' ;D

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Re: 1920 sturmey archer 2sp gearbox
« Reply #8 on: May 14, 2018, 01:50:28 AM »
On other S/A boxes the belt pulley and gear box sprocket are interchangeable. Can't see the two speeder being any different.
Mainshaft end play is trickier. Other S/A boxes have a bronze thrust washer fitted on the mainshaft to minimise end play when the clutch lever is pulled in. Otherwise instead of the clutch plates separating the whole clutch and mainshaft move together as one. This means the plates don't separate and the clutch drags. The more the thrust washer wears the more the drag. Its a simple fix but many owners don't diagnose the problem properly and moan of a rubbish clutch when the problem isn't  the clutch at all but a worn internal thrust washer. Again I can't see S/A doing anything different in their two speed box.
As for precise end float measurements S/A never provided pedantic figures. An experienced fitter knew by feel (fat lot of good that is nowadays). For an overall view of how Sturmey Archer approached their product you should carefully read the Newnes article I mentioned previously.
Also the clutch outer cable stop on the end of the gear box is supposed to be a trace loose so it rocks slightly. Theoretically this is so the inner cable is automatically centralised for maximum efficiency. I've yet to see one work effectively for any length of time without constant fiddling.

Best of luck,

Offline john.k

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Re: 1920 sturmey archer 2sp gearbox
« Reply #9 on: May 14, 2018, 09:34:57 AM »
One thing in general about Sturmey boxes with a quick worm thread clutch throwout is never have the pushrod so short that the end of the quick thread worm can contact the mainshaft.....at least you will mushroom the mainshaft and thread,and at most the box will burst apart...This throwout carries on thru all the Sturmey descendants to the Laydown box of  1956.......This box seems to have been taken from a restored machine,so its likely in good operating condition.