The standard Whitworth?

[Mick_Anik]

Does anybody know why Morris incorporated nuts and bolts of this spec, especially around the suspension?
Did they hold shares in a spanner company specialising in Whitworth sizes?

I found this on the net:

Sir Joseph Whitworth proposed this thread in 1841. This was the first standardised thread form. The form of the thread is shown in the diagram. The principal features of the British Standard Whitworth (BSW) thread form are that the angle between the thread flanks is 55 degrees and the thread has radii at both the roots and the crests of the thread. The relevant standard for this thread form is BS 84: 1956. The thread form is now redundant and has been replaced by Unified and Metric threads. The British Standard Fine (BSF) thread has the same profile as the BSW thread form but was used when a finer pitch was required for a given diameter.

And this - there's a Whitworth society! Definitely an interesting chap:

http://www.whitworthsociety.org/history.php?page=2

[bmcecosse]

It was the standard thread used in Britain at the time - only natural they would use it!!

[Blaketon]

Not at all common nowadays (Even UNF/C is harder to find nowadays - I recently got some from http://www.spaldingfasteners.co.uk/). The Traveller has some BS/W & some Unified (UNF/C).

During WW2, the American system became popular (ANF/C) and this is the basis of UNF/C, which is what later British cars used, before going metric. Clearly the Minor, as an older design, kept BS/W longer than models introduced when UNF/C was established. The front suspension, being Minor specific (Esp. after the Wolseley 1500/Riley 1.5s were dropped), would not have been changed on grounds of cost. Engines were shared with other models and the 948/1098 came in when UNF/C was more widespread, hence that system was adopted.

A Zeus book is a useful thing to have.

[bmcecosse]

I have Zeus as a pdf if anyone wants a copy!

[Dean]

Please BMC!

[Alec]

Hello Mick,

just the other day the young lad who works for us had the crank fall off his bike (Fairly modern sports bike) He asked if I had a nut to fit. I looked at it and thought, I'll try 8mm, h'm no good, 3\8" UNF, no good either, it turned out it is 3\8" BSF, so some relatively modern engineering still use the Whitworth standard. Cycle threads are another lot again.

Alec

[Blaketon]

All truly modern bikes would be metric. Cotter pins went out during the 1970s and since then there have been square taper cotterless (Usually 8mm) and these have given way to Octalink/Isis (Metric again) and now there is "Capless", where the bottom bracket axle is attached permenently to the right crank and is splined into the left crank (Bearing cups are "External") and held on by a cap and two M6 allen screws.

British bikes still have the BS 1.37 X 24TPI bottom brackets of 68mm width (Some mountain bikes are 73mm) and pedals threads are still 9/16" (Or 1/2" for BMX) but everything else will be standard metric, apart from the rear gear hanger, which is 10mm fine (1mm pitch).

[Alec]

Hello Blaketon,

I paid no attention to the make, but he went off home quite happily with a 3\8" BSF nut holding the crank on.

Alec

[nigelr2000]

Yes Please BMC

[Blaketon]

Hello Blaketon,

I paid no attention to the make, but he went off home quite happily with a 3\8" BSF nut holding the crank on.

Alec

Was the end of the axle square taper or did it have cotter pins?

Square taper cranks can work loose and need to be done up to something like 30 - 50Nm. If they work loose, the relatively soft aluminium of the crank moves about on the steel axle and the taper can get damaged. When that happens, its a job to keep them tight and often they are scrap.

[mike.perry]

I had a Williams crank axle which was splined. It didn't matter how tight I did the bolts up, the cranks kept coming loose, once in a time trial. I ditched them for a Campagnolo crank set which never needed touching apart from an occasional packing of the bearings with vaseline. (Less friction than grease)
Yes Please Roy

[rayofleamington]

I have Zeus as a pdf if anyone wants a copy!

Of course you'll need their permission due to copyright law.

[Alec]

Hello Blaketon,

this was the square taper, cotter pins, if my memory serves me correctly had a much smaller diameter nut.
The crank had already suffered as I suspect the nut had been loose for some time before it actually fell off.

Alec

[linearaudio]

I have Zeus as a pdf if anyone wants a copy!

That is a very splendid offer, Sir! How do we proceed?

[rayofleamington]

How do we proceed?

by purchasing a legal copy?

[Mogwai]

there's a lot of info on this site http://www.enginehistory.org/british_fasteners.htm

[linearaudio]

This modern-odd-thread thing caught me a couple of years back when a work mate had a fishing "pod" which had bruck. I remade one of the joints, thereby discovering that 5/16" bscy is still used in some modern applications! Why, oh why, would anyone be designing around an oddball like that nowadays? (no slur intended upon the bscy society).

Unfortunately, the pod manufacturer discovered what I had done in re-making the part, and took me to court for Patent infringement

[rayofleamington]

Does anybody know why Morris incorporated nuts and bolts of this spec, especially around the suspension?

Not only was the standard 'the norm' at the time but it was an excellent standard. In the days before Torque wrenches were common place, the size of spanner + skill of fitter determined what torque would be applied. Whitworth not only standardised the thread form but also standardised the head size for each bolt/nut. This allowed standardising of tools and more chance of using the right torque.

Over a century later the wonders of FEA has shown that the ideal thread angle is... Whitworth standard (Superior to UNC/F and Metric thread forms).
The advantage of Metric threads relates to standardisation - not only is it globally accepted now (even the old US of A is catching on), but with bar stock now being mainly metric the use of a metric standard thread is the only sensible route.

Often people get annoyed to find 'Whitworth' fasteners (because of needing a different spanner) without understanding that not only was it normal in its time, it was world leading and although it's now nearly defunct, it still is superior.

These days car parts are made to a cost and it's now common to save a millionth of a penny by making a head size 'undersize' for the thread. This didn't make me chuckle when heads round off on modern cars - e.g. a top engine mount on a FWD that's squeezed next to the inner wing with no access to recover it. 4 hours of effort (on top of the effort to do a cambelt on a 6 year old car) all because someone decided to cut a bit of a corner with the head size on a bolt.

[Mogwai]

there are also fewer spanner sizes needed for a given range of bolt diameters compared to metric or unf meaning less tools to carry around in the toolbox

[linearaudio]

I whole heartedly agree! I have a range of ancient Whitworth spanners, which all fit and work perfectly. The spanner proportions seem far more robust than modern stuff, and no nasty chrome plating to peel off (ouch!)