Talk Morgan Forums Thread Like Summary - Whitworth or Metric?

I started puttering with the bumper tube assemblies on my 1958 4/4 since the next big job will be to replace them. None of my SAE sockets would fit so I used an adjustable wrench to loosen two of the bolts, the ones up front ( so I had room for the wrench) but the rest are waaaaay back there and I figure that I'll probably need sockets and a ratchet to get them off and install the new assemblies.
It occurred to me that these might be Whitworth size bolts, or maybe they are metric? If I do need a set of Whitworth sockets, I'd better order them soon, however I wanted to check with you folks to ask, when did Morgan start using metric sizes? Were they still using British Standard or Whitworth in 1958?
Thanks in advance.

Whitworth is a British standard, the original one in fact. Later to become BSW (british standard whitworth) it generally became the course thread option and BSF the fine. Roughly equivalent to your UNC and UNF respectively, indeed UNC and BSW threads will work with each other as pitch is usually the same. Whitworth used to normally have a larger bolt head size than BSF, thread size for size, but during WW2 it was reduced to match the narrower BSF bolt head size to save metal and simplify tooling, so any BS spanner (wrench) of particular thread diameter would fit either.

Most body and suspension fixings on Morgans have been for some time UNF, spanners and sockets for which are marked in AF (across flat) sizes, although I believe before that Morgan used BSF fixings. Full imperial socket sets cater for all three hex head standards, original Whitworth, BS and AF. As there is a spill over some BS sockets will also be marked with a smaller thread diameter Whitworth (W) as they share the same hex head size. This is equally true for imperial spanners.

Hope this doesn't leave you too confused

With a look at my 2018 Plus4 there is a simple rule:

Engine and gearbox are Mazda, so metric. The rest is Morgan = imperial. That would work for a mainrule at a modern car. But there are some points with riveted and pressin nuts with metric M6 (for 10mm spanners).

Also a point: if a car gets older there are a lot of wizards around which cut and change things Just for their taste and work.

Greets René

So both worlds of spanners would be a good idea.

The bolts that hold the front bumper tubes/mounts are BSF.

David Byrne

Here's a chart relating BSW/BSF to actual bolt head size in metric and inch.

Lots are very close to actual standard sizes to the point that your current sockets/spanners may work at a pinch to get the bumper supports off if they're not too rusted or put in by a gorilla! 🙂







K

You also need to remember thread angles

The Unified series has a thread angle of 60 degrees

BSW, BSF and BSB have a thread angle of 55 degrees apart from BSC which has a 60 degree thread angle.

Personally I wouldn't use UNC fasteners on Whitworth threads but that's just me

Arwyn