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Penguin45
Joined: 28 Jul 2014 Posts: 382 Location: Padiham
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Posted: Fri Nov 03, 2023 12:18 pm Post subject: Thread Help, Please. |
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Wolseley 4/44 gear knob by Penguin 45, on Flickr
That's a picture of the remains of a Wolseley 4/44 gear knob. As you can see, it's got a threaded hole in the centre casting. And that's where the fun starts.
The hole is 0.2555" or 6.49mm. As far as I can work out, the thread is 20 TPI.
5/16" UNC 18 will engage, but not advance.
1/4" UNC 20 is a drop fit - no engagement at all
5/16" W 18 is too big.*
M7 x 1 will fit and advance 3 1/2 turns before binding.
So, what's the thread? Any ideas appreciated.
Chris.
* My only Whitworth tap since a burglary... _________________ '67 Wolseley MkI 18/85, '70 Austin MkII 1800 The Landcrab Forum. |
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Penguin45
Joined: 28 Jul 2014 Posts: 382 Location: Padiham
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Posted: Fri Nov 03, 2023 1:30 pm Post subject: |
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Further to... I found a 1/4" W 20 die, so spun up a bit of bar stock. It's a drop fit, so no go. Logically, it must be 5/16". 5/16" 20 turns out to be a British Standard Cycle thread. Gosh.
Could anyone confirm this thinking before I go spending on taps and dies?
Chris. _________________ '67 Wolseley MkI 18/85, '70 Austin MkII 1800 The Landcrab Forum. |
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Ray White
Joined: 02 Dec 2014 Posts: 6342 Location: Derby
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Posted: Fri Nov 03, 2023 2:16 pm Post subject: |
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It can't be cycle. 5/16" BSC is 26 TPI.
3/8" BSF is 20 TPI.
5/16" BSF is 22 TPI
If that helps? |
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ukdave2002
Joined: 23 Nov 2007 Posts: 4117 Location: South Cheshire
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Posted: Fri Nov 03, 2023 9:18 pm Post subject: |
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Cycle threads can be either 20 or 26 tpi. There are cycle threads on pre war Morrises, the track rod being one.
Dave |
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Ray White
Joined: 02 Dec 2014 Posts: 6342 Location: Derby
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Posted: Fri Nov 03, 2023 9:55 pm Post subject: |
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ukdave2002 wrote: | Cycle threads can be either 20 or 26 tpi. There are cycle threads on pre war Morrises, the track rod being one.
Dave |
Yes, but they would be too big for this.
You could have BSC with 20 tpi in 7/16", 1/2", 9/16", 5/8" etc.
....but not as small as 5/16" |
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Kenham
Joined: 12 Mar 2012 Posts: 209 Location: Kent
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Posted: Fri Nov 03, 2023 10:34 pm Post subject: |
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In cases of trying to find what a thread is ,it is best to dismiss the task of giving it a name. If the thread you are measuring is 5/16th 20tpi then that is what the thread is. Whit, BSF, UNF, BA, cycle thread, whatever , the thread you appear to want is still 5/16 20tpi. I have some very strange taps , all made for some specific purpose no doubt and you will never find them in a thread chart. If you have someone who can cut a thread on a lathe you can try it to make sure before you buy a tap perhaps. |
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Ray White
Joined: 02 Dec 2014 Posts: 6342 Location: Derby
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Posted: Fri Nov 03, 2023 11:22 pm Post subject: |
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The Wolseley gear knob looks rather fragile and very discoloured with age. Understandably, you refer to the "remains".
I wouldn't like to say how long it might last in service before breaking up so perhaps a good replacement would be your best hope. I believe it should be imitation ivory with a chrome bezel at the end.
Good replacements are probably rare.
Best of luck. |
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bjacko
Joined: 28 Oct 2013 Posts: 364 Location: Melbourne Australia
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Posted: Sat Nov 04, 2023 5:50 am Post subject: Wolseley Gear change knob |
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On the 4-50 and 6-90 the knob comes with the shaft to which it attaches. Are you sure it is not a tapered thread?
I imagine most of the BMC cars would have similar installations and use the same threads which at the time may have been unified. _________________ 1938 Morris 8 Ser II Coupe Utility (Pickup)
1985 Rover SD1 VDP |
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ukdave2002
Joined: 23 Nov 2007 Posts: 4117 Location: South Cheshire
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Posted: Sat Nov 04, 2023 11:58 am Post subject: |
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I recently had to figure out what an obscure internal thread was. I sprayed a light lubricant into the thread and filled the thread with glue from a glue gun, before it set I stuck a screwdriver in, 5 mins later when the glue is set simply unscrew, it?s far easier to identify what the male thread is.
Dave
Last edited by ukdave2002 on Sat Nov 04, 2023 12:02 pm; edited 1 time in total |
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Penguin45
Joined: 28 Jul 2014 Posts: 382 Location: Padiham
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Posted: Sat Nov 04, 2023 12:01 pm Post subject: |
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Ray White wrote: | The Wolseley gear knob looks rather fragile and very discoloured with age. Understandably, you refer to the "remains".
I wouldn't like to say how long it might last in service before breaking up so perhaps a good replacement would be your best hope. I believe it should be imitation ivory with a chrome bezel at the end.
Good replacements are probably rare.
Best of luck. |
You should see the other side! It isn't there... The plan is to remake it for my club member. I can turn up a new centre insert and resin cast the outer. Who knows, there might even be a bit of demand for them. And no, there are no replacements to be had.
M8 was also suggested as a possibility. Wolseley was a Morris company from 1927 onwards and did some very strange things with metric threads. Anyway, it would engage the first turn of the thread but was too fat to advance. 1.25mm pitch on the M8, 20tpi translates to 1.27mm, so close but not quite.
Tracy Tools have 5/16" 20tpi taps and dies at a sensible price, so I suppose there is nothing for it but to invest.
Kenham is quite correct, the name is irrelevant - the object doesn't care. Anyway, lathe, mill and welder and you can make anything.
Cheers,
Chris. _________________ '67 Wolseley MkI 18/85, '70 Austin MkII 1800 The Landcrab Forum.
Last edited by Penguin45 on Sun Nov 05, 2023 5:21 pm; edited 1 time in total |
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Penguin45
Joined: 28 Jul 2014 Posts: 382 Location: Padiham
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Posted: Sat Nov 04, 2023 12:04 pm Post subject: |
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ukdave2002 wrote: | I recently had to figure out what an obscure internal thread was. I sprayed a light lubricant into the thread and filled the thread with glue from a glue gun, before it set I stuck a screwdriver in, 5 mins later when the glue is set simply unscrew, it?s far easier to identify what the male thread is.
Dave |
Genius. Heads for garage...
C. _________________ '67 Wolseley MkI 18/85, '70 Austin MkII 1800 The Landcrab Forum. |
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Penguin45
Joined: 28 Jul 2014 Posts: 382 Location: Padiham
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Posted: Sat Nov 04, 2023 1:09 pm Post subject: |
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Returns...
Wolseley 4/44 gear knob by Penguin 45, on Flickr
Brilliant - all is revealed. 11 turns over 1/2", so 22tpi and tapered. Therefore, it must be a 5/16" 22 BSF tapered thread.
Tracy Tools have the taps. I can't recall ever having cut a tapered thread, so if there's any special techniques involved I'd be grateful for the information.
Dave, you're a genius.
Chris. _________________ '67 Wolseley MkI 18/85, '70 Austin MkII 1800 The Landcrab Forum. |
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petelang
Joined: 21 May 2009 Posts: 448 Location: Nottingham
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Posted: Sat Nov 04, 2023 2:13 pm Post subject: |
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Shame there isn't a "Like" button as I reckon that from Dave was well worthy of one. Stuck that in the memory bank for future reference. _________________ Daimler Fifteen 1934 (now sold)
Armstrong Siddeley 15 Long 1933
Daimler V8 250 1969 |
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peter scott
Joined: 18 Dec 2007 Posts: 7124 Location: Edinburgh
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Posted: Sun Nov 05, 2023 10:05 am Post subject: |
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petelang wrote: | Shame there isn't a "Like" button as I reckon that from Dave was well worthy of one. Stuck that in the memory bank for future reference. |
+1
Peter _________________ http://www.nostalgiatech.co.uk
1939 SS Jaguar 2 1/2 litre saloon |
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Ray White
Joined: 02 Dec 2014 Posts: 6342 Location: Derby
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Posted: Sun Nov 05, 2023 2:28 pm Post subject: |
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William Morris bought the Hotchkiss plant in 1923 and renamed it Morris Engines. A legacy of this was the use of obsolete threads. M8 x 1 is one such thread and is what MG used for the gear knob on my TC.
Unlike the 5/16"BSF thread on your Wolseley gear knob it is not tapered.
Well done Dave. You have cleverly shown that necessity is the Mother of invention. |
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