Thead forms for 1969 Starfire

[iansoady]

I have a 1969 Starfire rolling chassis fitted with a Suzuki DR400 engine (I know, I know...). Can anyone tell me whether the threads in the cycle parts should be BSW/BSF and CEI or are they Unified? It currently has an assortment of fixings (including metric!) and I'd like to fit the correct ones.

[Ian C]

May I suggest you get hold of a copy of the 1969 parts book. In that you will see the part numbers for everything including fasteners which should help in cross referencing the threads, lengths etc.. I mention this because you will find a good mixture of thread forms.

[Mike40M]

And some BA too.

[iansoady]

Thanks, I do have a copy of the parts book but it only seems to mention the lengths of bolts etc not their threads. I'm not a purist (as may be gleaned from the choice of engine) but just want to achieve some consistency. I think the only BA threads left will be the control lever clamps!

[Greenfield]

If you google 'BSA & Triumph fastener list', it should give you what you need.

[iansoady]

Thanks, I think I had one of these in the past but you've reminded me. Still a bit of a pain going from one document to another but at least the info I'm looking for is there.

As I thought it's a mixture - for example, fork end cap bolts are UNF while engine mounting bolts CEI. I suppose like Norton they changed when convenient but didn't try for consistency.

[AltcarBob]

1969 is in the middle of BSA/Triumph changing from British imperial threads to US imperial threads. I don't know if BSA ever got round to a complete US imperial change, probably not due to the company collapsing around everyones ears.

[V500]

To be accurate (or even pedantic!) there's no such thing as US Imperial threads. The US uses the SAE threadform system measured in Imperial units (like most of their stuff) but it's not an Imperial thread.

[iansoady]

I always wonder why the Briotish automotive industry went down the rabbit hole of SAE when it might have been far more sensible to go straight to metric. Not that I'm a great fan of that......

[V500]

In two words, Lend-Lease (or as some prefer Lease-Lend) showed that there was a need for standardisation and conformity, given the problems of the British being made to use SAE forms, and Americans doing their best to understand all the various "Limey threads".
Post war, the slogan was "Export or die" so to sell into the US market equipment and vehicles etc the buyers would expect to be able to work on the stuff using their existing tools. Obviously the change to SAE took some industries a lot longer than others, but Metric was a distant plan on the horizon at that stage.