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Driven Nuts !

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Robdavies
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Driven Nuts !

Post by Robdavies » Thu Sep 05, 2019 3:42 pm

Hello,
Regarding the Daimler 15, 1937.
Just a quickie, does the near side/portside rear axel nut,11/16 unfasten clockwise or anti clockwise.
The thread is very rusted and slightly damaged so its hard to tell, but it might undo the "wrong way" due to wheel rotation.
Better to know before heaving on it the wrong way.
Cheers to all, Rob.

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Robdavies
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Re: Driven Nuts !

Post by Robdavies » Fri Sep 06, 2019 1:18 pm

Well, after a great deal of cleaning and checking I can tell you that the near side 11/16 axel bolt on a Daimler 15 unscrews anti clockwise in the normal way.

chrisjb
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Re: Driven Nuts !

Post by chrisjb » Sat Sep 07, 2019 7:37 am

I assume that it has a split pin to lock the nuts. I had a nut on a spare axle which would not budge. Usual soaking for days, heat etc. In the end I drilled parallel to the thread and then split it. Replacement castellated nuts are readily available/
Chris

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Robdavies
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Re: Driven Nuts !

Post by Robdavies » Sat Sep 21, 2019 3:56 pm

Hello Chris,
Yes, they do indeed have split pins.
By the way, where are 11/16 whitworth nuts available, it's an odd, little used size and when I was doing a "just in case I b****r it up" replacement search I couldn't find any.
Cheers Rob.

chrisjb
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Re: Driven Nuts !

Post by chrisjb » Sun Sep 22, 2019 8:43 am

Hello Rob
You're right they are not a "usual" size. My LA10 has 3/4" and they are readily available. I have found a source for you and it might be worth digging around.
https://www.ebay.ie/usr/tonytot350m?_tr ... 7675.l2559
Chris

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Robdavies
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Re: Driven Nuts !

Post by Robdavies » Tue Sep 24, 2019 3:55 pm

Hello Chris,
Thanks for your note, I found them but they are 11/16 bsf.
Now all of the rest of the car is bsw so I need to get my thread gage out and check to see exactly what I have.
I assume both bsw and bsf are measured the same way, so a 11/16th spanner would fit both.
I'm still getting used to the dark magic used by the Whitworth wizards.
Cheers.

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Re: Driven Nuts !

Post by Vortex O'Plinth » Tue Sep 24, 2019 6:44 pm

Typically BSW hexagons (bolt head or nut) are one size larger than the corresponding BSF nut or bolt. Unlike Unified thread fasteners where the a spanner size is quoted as the size across flats of the hexagon, Whitworth spanners are quoted against the bolt diameter, so for example a 7/16" BSW spanner also fits a 1/2" BSF fastener. Whitworth spanners were often marked with both the BSW and BSF sizes.

So, in your case an 11/16" BSW spanner will be too large for an 11/16" BSF nut, which will need a 5/8" BSW wrench.

In recent years the one size difference in spanner size has not always been adhered to and you will occasionally find that the same spanner will fit both BSW and BSF fasteners of the same diameter, however on pre-war cars this is unlikely.
Nick

"Open the pod bay door Hal".

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Robdavies
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Re: Driven Nuts !

Post by Robdavies » Fri Sep 27, 2019 7:05 am

Hello Nick,
Thanks for that,
I have pretty much managed to digest the secret law of Whitworth re nut/spanner sizes ie a nut advertised as 11/16 bsf is smaller than the 11/16 bsw I'm looking for, but is the bolt thread the same diameter and pitch, but a smaller / less massive nut used ie smaller measured across the flats, hence smaller spanner size.
I read that it was something to do with saving metal due to the war that the sizes were changed but I don't quite understand how it would make a diffrence, however maybe I just had too much cellulose thinners in my bloodstream when reading that particular entry on Google!
Thinking about UNC and UNF being different, at least I think so.
Maybe I just worry too much .....
All the best Rob.

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Re: Driven Nuts !

Post by qantasqf1 » Fri Sep 27, 2019 10:56 am

This website below explains all. The only commonality with BSF and Whitworth threads is the thread angle, being 55 degrees. Naturally the thread pitches are different.
The story of the evolution of these thread forms is interesting. The genesis of the Whitworth thread goes right back to the early days of the Industrial Revolution while the BSF thread form arrived much later on, by which time the quality of steel had improved allowing the larger shank diameter; hence, for instance, 1/4 BSW nuts are equal in spannering size to 5/16 BSF. FWIW a thread angle of 55 degrees is technically better than the Unified thread angle of 60 degrees and I don’t know why 60 degrees was settled on after WW2 when the issue was resolved (hence the word Unified) unless it made production easier. Certainly Packards had a hell of a job organising tooling for cutting these strange British screw thread forms for their R-R Merlin engines because no one in the UK and US governments and manufacturers had discussed the differences before the war (presumably because no one ever considered it).
Sorry if this got a bit tedious!

https://journeymans-workshop.uk/whitworth.php

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Robdavies
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Re: Driven Nuts !

Post by Robdavies » Fri Sep 27, 2019 6:22 pm

Hi,
Nothing tedious there friend.
Seriously I could talk screw threads all day, and maybe one day I may even understand them.
I do remember reading about the licence built Merlin engines.
Our American cousins are still rather wary of English engines, hence the number of Jaguars with local V8 engines.
It's a beautiful world, Rob.

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