Taps and dies, which ones for an AJS 500?

[rcousine]

So, I want a tap and die set to do some general thread chasing and hole cleaning (I shouldn't need to cut any threads from scratch, though).

I ordered a standard BSW tap and die set and...the threads are much too coarse.

I assume the threads on the engine and chassis parts are mostly BSF or BSC, then?

Does anyone know of a good reference on the main chassis and engine threads used on these bikes?

Bike is a 1958 AJS 18CS.

Bonus: I need to recut the triple clamp (fork crown) threads, and I believe that's a 1” thread, but is it BSW, BSF, BSC, or other?

Thanks,

[Rob Harknett]

Most standard fitting sizes will be found in parts lists. ( I've posted this soooo many times, remember and pass on to others ) Standard fittings started late 1920's onwards, they had a pt. no. prefixed STD, About 1953 new parts numbers were introduced. They got a bit lazy and did not give very many sizes in the parts books after approx. 1952. So you need to refer to old parts lists. old part numbers starting STD are easy to covert to new par no's. Just delete STD and add as many zeros it takes to make a new part number e.g. STD 1 + 000001 STD 999 + 000999 simple. To make it easier to find these old part numbers and the sizes. I compiled a master parts list up to approx. 1960 of all the old fittings use up until that date. It shows both old and new part numbers, so just this one list is of use to any bike up to 1960, to refer to, for standard fitting sizes. See here, the book has 3 sections. It is the 3rd section that covers up to 1954. See here;
http://archives.jampot.dk/book/Spares_l ... ements.pdf

[cbranni]

Hi Ryan, most threads in steel (including nuts and bolts) will be cycle thread, that is 26 tpi, axle threads may be 20tpi, threads into alloy will be BSF. The fork crown will be cycle thread.
I am sure there is a company Stateside dealing in taps and dies with British threads if not Tracy tools UK are very good, if you are just cleaning or repairing threads go for the carbon steel but if cutting a thread use the more expensive HSS ones, you may find the 1" x 26 die very expensive.

Colin

[Mick D]

Hi

If the damage to the lower yoke stem isn't too serious you may be successful in re-dressing it with a BSW/BSF thread restoration file - I can confirm the thread to be 1" x 26 TPI BSC.

The BSC thread angle is 60 degrees as opposed to that of BSW/BSF, (55 degrees), but you will get away with restoration for a few threads, (I assume it's just the first few damaged).

You can get the correct die from here:

http://www.tracytools.com/taps-and-dies ... uct_id=983

I guess postage to Canada won't be too bad.

Regards Mick

[Andy51]

Hi Ryan, I would recommend a standard set CEI/BSC (26 tpi/60 deg thread angle) taps and dies 1/4-5/16-3/8-7/16-1/2 in; you don't need high speed steel unless you plan to cut lots of threads using machine tools. A small set BSF taps: 1/4-5/16-3/8 should do it. Others buy as required - BA 0, 1 and 2 might be needed, Burman used non-BSC sizes at times. You must get a set of Imperial thread gauges £6 or so) so you can measure tpi easily. 26 and 20 tpi are almost certainly BSC, others will be BSF (55 deg thread angle) except 1/4 bolt into alloy which are normally BSW. Tracy Tools sell cutters from Coventry die heads plaus holder which are very useful for sorting threads not too seriously chewed up and at a pound or so each are much cheaper than buying large and rarely used large dies - they used to sell mixed sets covering most threads. Read up threads on line-it's a fascinating subject! Cheers, Andy

[rcousine]

Thanks for all the responses; I'll digest them later, but it looks like this is enough info to order everything I'll need, and good advice about the thread gauge.

(with regard to shipping, it's usually pretty reasonable from the UK to Canada, and I'm currently taking advantage of Recent Developments which have made the exchange rate unusually favorable...)

[cfaber]

Hey Andy, do you know about tap sizes on the amal carbs?

[Andy51]

2 BA for screws holding Concentric bodies/tops together (4 off). All other screwed parts (jets, etc) are unique to Amal - probably British Standard Pipe - and I have never measured or made any of them. A good set of thread gauges would allow you to identify these threads, if for example you wanted to get some taps and clean up threaded holes in the carb body. Hope this helps, Andy

[cfaber]

Thanks yeah, I ordered a gauge set.