[phutton]

The first thing to ask is whether your machine is a 1932 Model, registered in 1931? The model year started in September, so there were often 1931 registered machines from the 1932 MY. The frame and engine numbers will tell you if this is the case. Marstons changed over to BSF threads for the 1932 range, so some 1931-registered machines will have BSF threads.

The other possibility, of course, is that a previous owner could not find a BSCY screw, so used a BSF nut and bolt!

P.

[Greybeard]

My mistake  - brain not fully engaged I was thinking of 20 tpi Whitworth threads - you'll find the odd one.

Steve

[oggers]

Steve

Not sure what you mean. 5/16ths is 22 t.p.i. for BSF which is Whitworth fine. Nothing in BSW which is 22 tpi. I know some will be BSC/CEI on a model 9, just pointing out that as per most Brit bikes, it is not always obvious what the thead will be.

[Greybeard]

Welcome to the world of strange thread forms  You will come across several different types on old machinery - Cycle thread will no doubt be the commonest one, BSF much less so. I would guess that the 22tpi youve found could well be a Whitworth Fine (a Whitform thread). I cant think of any 22tpi BSF at the moment. You will also come across BSP for any threads associated with oil or fuel pipes/plugs and BA threads for smaller fittings. Spark plug threads will be 14 or 18mm metric as they were first designed/patented by the French! Whitworth threads tend to be used when threading into aluminium.
As far as stainless nuts and bolts go, I resort to making my own which is time consuming especially if you finish them all with radiused heads and polish them. Im finding whitworth hex bar in stainless more difficult to find in some sizes.
I have used ACME Stainless for over 30 years for some parts. Clay is very helpful and can make one-offs to a pattern. Tracy Tools are an excellent scource of taps and dies though I would recommend that initial thread cutting is done on a lathe and given a final clean up with a die.
Its a huge subject and I would suggest starting by resrearching older texts on the subject and a good thread guage, magnifying glass and calipers 

Good luck. Steve

[oggers]

Vic

Not sure all fasteners are BSC/CEI. I pulled a hex screw from the rear carrier earlier and it was 22 t.p.i. measured with a thread gauge - suggesting BSF. Doubtless others will be different!

[VicYouel]

I would recommend that you make contact with one of our UK club  regional groups and consult an experienced member  for advice...... the Pitmans books are quite useful as are the parts lists our club sells.

Nothing wrong with using stainless fittings .....cycle threads for that year if you can get them. We do sell some of the specialised fittings on our club shop

Vic Youel

[oggers]

Folks

I have recently become the very proud owner of a 1931 model 9. It appears to be in sound mechanical condition, but fair to say that paintwork/engine exterior/frame etc. would benefit greatly from a restoration. As such, and not being familiar with the marque, a few questions if I may.

I would like to strip the machine down to the frame. I have various photocopied old Sunbeam manuals from the PO which are very good, but nothing which particularly details the orderly sequence of dis-assembly into component parts to get to just the frame - a Haynes manual type of thing if you will. Has anyone any ideas here please? I like instructions! At this stage, I won't be stripping the engine or the gearbox.

I am tempted to replace various external fasteners with stainless. Are these readily available please?

Who do we recommend for parts please? - this club shop excepted obviously!

Any advice as to how to look after the bike would also be greatly appreciated.

Kind regards

Mark