Britbike forum Forums British Motorcycle specific Brands Panther forum Thread Form

G'day All,
Can some one enlighten me on the thread form on Panther 350 Fork yokes? I am very familiar with all the British thread forms but some one has screwed UNF screws/bolts into the holes and made a hash of it. Before I going putting a BSF or BSCY tap into the holes to clean them up and with my luck I would pick the wrong one. Ken.

Order the correct bolts and check the thread with a thread gauge, then buy and use the matching tap.

I have got all the bolts, and all the taps, But which ones? Ken.

I am not familiar with Panther but on other marques the threads are often listed in the parts list.

I would doubt that the threads are Unified form.

John

Which forks? Dowry or Panthers own? More information please.

Sorry, finger trouble. Dowty, not Dowry.

Dowty forks they are Villiers.

I looked through what I have on Dowty but as expected not a mention of thread type anywhere. Diameter yes. TPI, no.
Nevertheless, as Dowty were an aviation firm that initially made their name with internally sprung undercarriages and the Dowty Tele fork was their sole try at anything motorcycle I would expect them to use the taps and dies they already had in their factory so far more likely be BSF, not cycle thread.
I expect you can confirm this by measuring other threads on the forks. Nothing 1/4” of course as both 1/4” BSF and Cycle are 26tpi but what about the steering damper rod. From memory that is 5/16” so should be the same diameter as your problem butchered bolts.
Having said all that Dowty being aviation based can spring funny surprises on you as the aviation world sometimes liked to use non standard thread pitches to ensure only the right quality of fastener was fitted in sensitive areas. It pays to check very carefully.
Sorry I can’t do any better. I have careful instructions on care and maintenance but no actual advice on what thread form.

As a bit of nit-picking detail, Dowty also made rear suspension units for the MkVIII KTT Velo, as well as the front forks, of course.

Source is the Dowty company website https://www.dowtyheritage.org.uk/co...up/dowty-motorcycle-oleo-shock-absorbers

I'm a great fan of Dowty because of the Dowty washer - an inspired invention. O-ring captured in the centre of a steel washer.

I'm just here to correct obscure facts, and I'm afraid that I am no help whatsoever with the Panther fork thread question.

A Velocette guru who has experience with late KTTs may know.

(Later)
I came across this, it appears to apply to KSS with Oleomatic forks, It refers to 5/16" BSF bolts on the fork crown.
https://dunhackin.com/index.php/vel...smantling-velocette-dowty-oleomatic-fork
from Phil in NSW

Damn you, Mr Snail sir. I've been trying not to get sucked down the Dowty rabbit hole again and your're not helping!
Finding basic Dowty strip and reassembly instructions is fairly easy. What is much harder is getting factory specifications, dimensions, tolerances and the like.Now beingr half a century or so old the average set of Dowty's is usually in rather more need than a good service and new seals but where to go and what to do.
As it happens I had trudged down this track a few years ago grinding to a halt when I found that when it folded, the Dowty Group had gifted all remaining records, correspondence and so to the Gloucester Heritage Archive operated by Gloucester City Council.. Some 180 odd large boxes of it. Unfortunately there were no funds available to sort and catalogue all this material so there it lay. It may contain useful Dowty Fork information; but it may not. Who knows. It was a dead end.
Now you come along Mr Snail so I go back and have another look. They got the funding! They hired an archivist! The boxes are sorted and catalogued! It is accessible! What to do!
Like you I'm Australian.I won't be dropping in there next week..It needs some local Scott/Panther/Velo enthusiast to see if there is any useful held. Any volunteers?
There is a helpful talk on all this on YouTube. Search for Sir George Dowty.
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