Newby questions please be gentle

[Magnetoman]

they'd be arguing about whether the speedo was calibrated in Furlongs or Leagues per hour

Hey, I'd hate to trailer my matching numbers, 0 miles, Vincent to yet another concours and lose points because the speedo was attached with 0 BA if it should be 6 mm. Surely everyone reading this will sympathize.

 

[Howard]

Ain't got matching numbers or a trailer.
I went to the VOCSC open day, and almost before the engine had stopped two guys appeared next to the Egli. One said "We were just saying all these Vincents look alike ....... then you turned up!" I didn't know whether to thank them, or hit them.
If the bolt fits, use it.

H

 

[Magnetoman]

.One said "We were just saying all these Vincents look alike ....... then you turned up!"

I'm glad you agree on the importance of this. You suffered exactly the sort of insult I want to avoid if someone notices I have BA when all the other Vincents have metric.

 

[clevtrev]

I know the origins of the chronometric, but there were plenty of decades after that for Imperial threads to worm their way into production. The mounting studs could have made the switch for reasons of production efficiency without affecting any other part of the design. For what it's worth, KTB lists these as BA. However, it's easy enough to put a few of those studs under the microscope to measure the thread form to know for sure, which is what I'll do within the next couple of days unless someone beats me to it.

I`ve already done that, so don`t bother. You will find the threads are 60 degrees, not 47 1.2. Here`s a little more information, showing that the thread KTB tells you is 15/32 x 26 TPI. is actually M12 x 1 mm pitch. So don`t believe all you read. Check things properly.

 

[clevtrev]

I should have said, that was a Smiths drawing.

 

[Magnetoman]

So don`t believe all you read. Check things properly.

Thanks for posting that drawing. However, since it only shows the internals I'll probably waste a few minutes looking at the external studs anyway. I have a couple of housings in a box so it's easy enough to do.

 

[A_HRD]

So following-on from that logic, are we to assume that the speedo build holder union nut is not 5/8 CEI (as per KTB) but M16 x 1?

Peter B
Bristol, UK.
WANTED: Series 'A' Front Frame.

 

[Dean Grace]

Thanks Simon I'll have a look into those DVR2's.

LOL Howard I thought it was calibrated for Cubits

 

[Magnetoman]

I'll probably waste a few minutes looking at the external studs anyway. I have a couple of housings in a box so it's easy enough to do.

I got back from the east coast last night (where I had a very pleasant lunch with a bunch of VOC members -- thanks guys) and couldn't stop myself from heading straight to the garage to look at one of the studs under the microscope. So, is it metric, or is it BA? The answer is .... (wait for it) ... I don't know.

The depth of the threads is small enough that the faces look rounded (i.e. BA-like) whether or not they actually are. And you might think that 47.5-deg. would look significantly different than 60-deg., but not sufficiently so that I would base a conclusion on just looking. That means taking a few photos, transferring to my computer, opening in Photoshop... Having other things to do, and not needing to trailer my matching numbers, 0 miles Vincent to a concours anytime soon, getting a definitive answer to this has moved to a lower position on my to-do list.

 

[bmetcalf]

Trev, at the helicopter transmission factory that I worked at in 1966, they had what I think were called optical comparators to check tooth profiles, etc. Is that what you have?