Lotus Elan and Lotus Elan Plus 2 Forums

Since Lotus elan where built from the 1960's were there assembled with Whitworth size nuts and bolts or did the use USA standard sizes ?

No Whitworth threads were used on Elans to my knowledge, UNC were used on tapped threads in cast iron and aluminium.
Generally bolts with nuts had UNF threads but there are some other electrical fitments that used BA and some block fitments had NPT threads, the Weber/Delorto carbs had metric threads.

correct. nothing whitworth

The adjusting nut on the clutch slave cylinder rod fits a Witworth spanner but the rod and nut are unf threaded

cheers
Rohan

I've heard the term 'Whitworthless' used now and then in discussions of old motorbikes. Sounds like Lotus had at least a little bit od sense when it came to fasteners.

I had understood that apart from minor differences in thread profile UNC and Whitworth were essentially the same, and subject to all the usual caveats were interchangeable?

threads might be interchangeable but the hex nut bit is usually bigger, as i recall from my moggie minor days ...
I had the odd whitworth nut in my tin of nuts which i think got used when i was after a UNC thread .... marginally flatter and wider

Whitworth had a larger head but I think Dad told me that head sizes were reduced during the war to save steel. He's no longer around, can anyone confirm that?

Also, I think, Whitworth spanners were sized by the bolt diameter rather than the head size (AF - Across Flats).

They have different thread forms ,Whitworth is 55? , UNC is 60? . Maybe they can be forced together though .

The instruments use a BA thread for the thumb nuts. I think it was in the late 50's when the conversion from Whitworth began. The Triumph and BSA motorcycles I had in the 50's were Whitworth, and my 1964 289 Cobra had a mix of threads.

I work with all thread types in our restoration activities and Whitworth and Unified (UNC/UNF) threads are not the same, although you can force a UNC screw into a WW thread and a UNFscrew into a BSF thread. But nobody on this forum would do that, would they? Something that really pisses me off when we get a vehicle in that's been "restored" is when the previous restorer has used a mixture of different threaded fasteners in assembly. It means you are constantly changing spanner sizes which wastes time, if nothing else.

In answer to question about changes in diameter across flats, it is correct that pre-WW2 BSW nuts and bolts had larger diameter heads. The generally accepted reason for the change was an order from the Ministry of Supply to save material. We have a pre-war bus chassis (technically not pre-war as it was assembled in 1947) which uses these larger nuts and bolt heads and it is a PITA as replacements are very hard to get, however I always replace like for like where I can but sometimes a compromise is necessary. But mixing BSW, Unified and metric on the same vehicle - never lol

Nigel F.

Whitworth and BSF = 55Deg Thread Form
BA = 47.5 Deg Thread Form
American and Metric = 60Deg
That's what my old Moore and Wright
thread form gauge says.

I'm currently working on a 1972 Elan Plus 2 that's been in the same ownership since 1980 when the first owner, a lady sold it. The engine is a Big Valve Twin Cam and I have found the long and short Engine Mount bolts in to the Block are Whitworth sizes, as are the longer (3/4") but not the 1/2" Sump Bolts. I thought the first one was just a coincidence but I believe they were fitted deliberately now that I've found all of the same sizes are a Whitworth. thread..
Don't shoot the messenger !!!

Derek.

UNC - Whitworth threads are mostly interchangeable,
but the 1/2" thread is not... UNC 1/2" is 13TPI. Whit is 12TPI, all the rest are the same.

Always use coarse thread in Aluminium castings etc... Never use UNF thread in Aluminium.

I would be very surprised if any threads are Whitworth on a Lotus and even more surprised if any Ford engine parts were. The UK car industry had moved on long before then.

For what it's worth This is from Wikipedia

Current usage
The standard tripod mount on all SLR cameras and, where fitted, on compact cameras, and therefore on all tripods and monopods, is 1/4 Inch Whitworth. Larger format cameras use 3/8 inch Whitworth with tripod adaptors from 1/4 inch Whitworth if necessary.[citation needed]

The widely used (except in the US) British Standard Pipe thread, as defined by the ISO 228 standard (formerly BS-2779), uses Whitworth standard thread form. Even in the United States, personal computer liquid cooling components use the G1⁄4 thread from this series.[citation needed]

The Leica Thread-Mount used on rangefinder cameras and on many enlarging lenses is 1+17⁄32 in by 26 turns-per-inch Whitworth, an artifact of this having been developed by a German company specializing in microscopes and thus equipped with tooling capable of handling threads in inches and in Whitworth.[citation needed]

The 5⁄32 in Whitworth threads have been the standard Meccano thread for many years and it is still the thread in use by the French Meccano Company.[citation needed]

Stage lighting suspension bolts are most commonly 3⁄8 in and 1⁄2 in BSW. Companies that initially converted to metric threads have converted back, after complaints that the finer metric threads increased the time and difficulty of setup, which often takes place at the top of a ladder or scaffold.[citation needed]

Fixings for garden gates traditionally used Whitworth carriage bolts, and these are still the standard supplied in UK and Australia.[citation needed]