Whitworth threads, BMC car restoration question

[Mr Fixit]

HI Group,

I'm in the process of restoring a 1957 British Morris Minor car here in the States, and it has Whitworth hardware. I'm interested in taps and maybe dies for cleaning the existing threads of hardware and fittings that are part of the car.
I would like a recommended source that others have used for taps and dies along with hardware to replace those that have broken during disassembly.

An idea that a buddy suggested was to retap them to UNF or MM and get hardware to fit. I'm not sure this is a good idea, but it was something that sparked some interest, as it would only be for fender mounting, door hinge mounting, etc. not for suspension, engine, or other critical parts of the car.. I still need to look at tables for sizes before repapping the holes would be considered, but just thought I'd toss that idea out to see what the group thinks of the idea.

Now, I have just started to look into this but any help would be greatly appreciated.

TX
Mr fixit for the family
Chris

[nickel-city-fab]

I've had no problem finding Whitworth and BSF tap and die sets brand new on eBay from the UK. Cheaper (carbon steel) sets are available direct from India also. You might also check Amazon.

Here's the set I got, no problems with it at all: https://www.ebay.com/itm/WHITWORTH-T...-/173938500937

And here is another seller with BSF: https://www.ebay.com/itm/22357511742...4AAOSw7GBdHgAu

I would *not* re-tap a Whitworth thread to UNF or MM under any conditions, but that is just me. It is definitely a rare item that was designed with certain thread specs in mind, so I wouldn't change them no matter how trivial. Changing the thread may affect operation and durability, and will certainly lower the value.

[ed_h]

Try this outfit:

https://britishfasteners.com/

I also would not try to retap fasteners. It cant help but make them weaker.

A 57 may not be entirely Whitworth. My 57 MGA has a mix.

Ed

[Tundra Twin Track]

I got some 1/2 threaded rod & nuts from Britishfastners that ed_h mentioned,it’s wasn’t cheap🙂

[The Artful Bodger]

Are you sure your Morrie has Whitworth threads?


A table I found online for the Morris Minor series II, but with the exception of three:

The master cylinder cap
The differential retaining cap nuts
Track rod ends to track rod

There are also a few thread sizes missing, but the spanner sizes are there.

https://www.mmoc.org.uk/Messageboard...hp?f=4&t=51709


Please note on both front and rear suspension replacement parts, they can have a UNF thread instead of the original BSF.
Thread and Spanner Sizes Pt1-5 v4.jpg (171.18 KiB) Viewed 12435 timesThread and Spanner Sizes Pt2-5 v4.jpg (122.36 KiB) Viewed 12435 timesThread and Spanner Sizes Pt3-5 v4.jpg (152.96 KiB) Viewed 12435 times

[Mr Fixit]

Artful Bodger,

That is a chart that I can make use of, Thanks ! You are correct the car has Whitworh and BSF hardware for sure. When I read the threads on the boot latch screws I get a 1/4" with a 26tpi which is not a UNF that I see, so yes it is a mix of hardware. I'll take everyone's advice and NOT be re-tapping any hardware to fit UNF or MM hardware. I may use a complete bolt and nut if needed to get it back together, but I'll try to stick with the original as best possible.

TX
Mr fixit for the family
Chris

[Mike Burch]

26TPI is the standard brass thread, in any diameter.
Don't confuse Whitworth with UNC. It's easy to confuse the two, as the pitches of the common sizes are the same except for the 1/2" diameter (Whitworth is 12TPI, UNC 13), but the thread angles are different (Whitworth is 55°, UNC 60°). Similarly, UNF and BSF are not the same thing.
I would be very surprised if a 1957 Minor had any Whitworth threads in it. TAB's chart (above) bears this out. Don't be fooled by the spanner sizes being quoted in Whitworth—many of my decades-old Imperial spanners have both Whitworth and BSF sizes stamped on them, just like the chart shows. All that means is that Whitworth bolts had bigger heads than other bolts of the same diameter.
The table shows seven different types of thread, and even different head sizes for bolts of the same thread and diameter. This certainly accords with my own memories of working on British cars in my youth—one never knew which spanner one needed.

[The Artful Bodger]

Mike, I have a small steel toolbox where I keep all my Whitworth tools including those from my Riley owning days.
John

[Mike Burch]

Hi John. I bought my first car in 1963, a 1934 Morris Minor, which was not the famous Issigonis-designed Minor, but rather the fore-runner of the Morris 8. That was followed by a Standard Ten, various Austins, three Rovers (madness!), a Wolseley, a Vauxhall, and a home-brewed topless sports car that had started life as a 1936 Ford V8 and required a complete gearbox rebuild every couple of months. And every one of the wretched things had a baffling collection of fasteners.
Nowadays I am half a century older, and the only thing I service personally is my ancient and blessedly simple Kubota tractor—with metric fastenings!
Cheers,
Mike.

[The Artful Bodger]

I think my 20+ year old Falcon has a bit of a mixture but I don't get my hands dirty these days! There is a home brewed topless car of mine at Southwards, it is the one with the wicker body!

[darylbane]

At least your Morris doesn't have a few BSC (cycle) threads thrown into the mix, along with the odd metric, which just about be all of them.

Oops I see it does have a BSC for some plugs, but no BSW (coarse) threads...odd. Maybe they are calling BSC (British Standard Coarse) and not Cycle. Oh, and lets not forget BA for some of those smaller screws.

[Georgineer]

At least your Morris doesn't have a few BSC (cycle) threads thrown into the mix, along with the odd metric, which just about be all of them.

Oops I see it does have a BSC for some plugs, but no BSW (coarse) threads...odd. Maybe they are calling BSC (British Standard Coarse) and not Cycle. Oh, and lets not forget BA for some of those smaller screws.

No, it would be BSC (often, and better, abbreviated as BSCy), the cycle thread series of 1 1/8" diameter and 26 TPI, usually used for motorcycle and tandem steering columns. Impressively, the Morris engineers seem to have used an existing standard thread, rather than invent their own bespoke abomination.

George B.

[Georgineer]

It is important not to get confused between the many thread series which have the Whitworth profile, and British Standard Whitworth (BSW), which is just series of the family. People routinely use the term 'Whitworth' to mean either or both, so it pays to find out which they mean.

Quick history: The Morris Minor Series MM was introduced in 1948 with a 918 cc sidevalve engine and it was all based on Whitworth profile threads, mainly BSF. A nice tempered engine developed from the pre-war Morris 8, but underpowered. After a merger with Austin in the early fifties, the Morris Minor Series 2 was introduced, in 1952 I think, which had the 806 cc Austin series A engine and gearbox, which used Unified threads. It was fussy, underpowered and undergeared. It was horrible! In 1956 there was a body revamp and the Morris Minor 1000 was introduced with the Series A engine increased to 948 cc and a new gearbox. It was a vast improvement. In 1962 the engine size was increased again to 1098 cc and the front drum brakes were increased from 7" to an enormous 8" diameter. Typically for the British motor industry there were no further improvements until it ceased production in 1971.

The upshot of all this is that, broadly speaking, the bodywork bolts are from the Whitworth-based BSF series, and the greasy bits are all from the Unified series, mainly UNF. Yes, there are oddities like the master cylinder plug, but who cares? I never had to replace or repair that thread, or fit it to a bicycle. I'm a bit surprised that the brake light switch should have a NPT thread - I would have expected it to be BSP.

All this is from memory, from my first Minor in 1970 (a 1960 ragtop; I wish I still had it) to the last and eighth some twenty-five years later, so forgive me if I have made any minor mistakes.
Incidentally, my brother had a MM and my sister a Series 2, while father had a Morris Oxford series MO, which was like an inflated version of the Minor. You'd never guess that Grandpa was a Morris Agent!

If you get a chance to see the 1998 film 'The Borrowers' you'll find that every car in it is a Morris Minor, except for the villain's which is a stretch Morris Oxford. It's wonderful!

George B.

[Mr Fixit]

Hi George and the Group,

Again, thank you for the information. I have to say, this hardware is vexing in size and thread, especially when you use the Whitworth wrenches and you assume it's Whitworth, when actually it's BSF or UNF as I have continued to research and find out. When I really study the charts and the hardware that I have just cleaned up, it becomes clearer all the time that it is a mix of threads depending on the application and size..

So the learning process continues.

TX
Mr fixit for the family
Chris

[MaxHeadRoom]

HI Group,

I'm in the process of restoring a 1957 British Morris Minor car here in the States, and it has Whitworth hardware. I'm interested in taps and maybe dies for cleaning the existing threads of hardware and fittings that are part of the car.
I would like a recommended source that others have used for taps and dies along with hardware to replace those that have broken during disassembly.
Chris

Interestingly I may have seen that Minor come off the assembly line, the company I worked for at the time did contracting at the Morris Motors at Cowley factory in Oxford at the time.
I also saw the first MGA come off the line in Abingdon! 😃