I had some problems mailing this, hope it gets to you all.
neil.cairns@virgin.net wrote:
>
> Skye Poier wrote:
> >
> > > WARNING, another 'story'
> >
> > Keep them coming Neil -- I enjoy them!
> >
> > SKye
>
> Bedtime Story For MG Nuts. ( Original from Roger Furneaux
> MGCC 'T' Register, UK.
> Modified by Neil Cairns!!)
>
> It all started in 1915, when Hotchkiss, a FRENCH manufacturer of
> machine-guns, moved to England to get away from the Bosche, who were at
> that time winning WW1. Hotchkiss built a new factory in COVENTRY, with
> finantial aid from the UK government. The guns were a vital part of the
> armament supply to the troops, but a safer base was needed away from the
> advancing Hun.
>
> After WW1, ( England 1, Germany 0,) the firm found itself with no work,
> so they approached William Morris, for whom they built a copy of an
> American engine under licence, for the Bull-Nose Morris Oxford and
> Cowley. The firm had never made an engine in its life, but their
> expertise in machines was a great asset. They did such a good job of the
> engines and gearboxes, Morris brought them out, lock stock and barrel so
> to speak, in 1923.
>
> It was common in the early Industrial Revolution for companies to have
> their own theads on nuts and bolts. In the UK three had eventually been
> standardised for the motor industry, British Standard Fine, BSF; British
> Standard Whitworth, BSW; and British Standard Pipe Thread, BSP. All used
> the Whitworth thread form. The USA was developing its ANF and ANC
> system, but the European Continent had mant variations of metric
> threads, that would eventually lead to the ISO Metric system. There were
> other threads, British Association, BA, a tiny system used in
> instruments, and some UK firms were coyping the Americans, but calling
> the system UNF and UNC, Unified Coarse and Unified Fine.
>
> Hotchkiss had their own metric thread system for the manufacturer of
> their guns. They continued to use these taps and dies on the engines
> they made. But as time advanced, the more logical system on a 'Unified
> Common Thread' for all machines was developed. In the UK the heads of
> ALL the nuts and bolts were made BSW sizes. This was handy as the BSF
> head size for the BSW equivalent was the next size down. This mattered
> not, as the mechanic only needed one set of spanners. Even BSP used the
> spanner sizes, ( on sump plugs, etc.)
>
> Morris's Nuffield Empire was not to be left behind, Morris Engines
> Branch, as Hotchkiss became once purchased, use BSW heads on their
> unique metric nuts and bolts. So Morris engines could be stripped and
> rebuilt with those normal set of spanners.
>
> Now, not only Morris used Morris Engines Branch Engines, so did Wolseley
> and MG. It would have cost a small fortune to re-engineer the automatic
> thread cutting machines of Hotchkiss, so these old French Metric threads
> were used on Morris until 1954, MG until 1955 and Wolseley until 1956.
>
> In the MG context the XPAG engine and its gearbox were the last to use
> these odd metric threads, the XPEG being the same, but bored out, unit.
>
> Are these old metric the same as modern ISO? Well, some are and some are
> not. The ancient metric threads were in two pitches, ( distance between
> the tops of the thread,) these were standard & fine. The standard
> Hotchkiss thread DOES match the modern ISO, especially in the common
> sizes. The fine does NOT match up, though the most common 8mm x 1.0mm is
> still available. The thread angles are 60 degree throughout.
>
> Mad Metrics, the bolt supply specialist run by Roger Furneaux, can find
> you the nuts & bolts you may need. These 'Mad Metric' threads are used
> in the MG;- TA, TB, VA, SA, WA, TC, TD, TF, YA, YB, YT; Wolseley;- 4/44,
> Ten/40, Twelve/48; Morris;- Eight, Ten, Twelve, Fourteen, Twenty, Series
> 'M', Minor, Minor series MM, sv Cowley and Oxford.
>
> In the XPAG;-
>
> Dia & pitch equivalent location BSF spanner size
>
> 5mm x .8 ISO metric fan blades 8mm or 5/16"A/F
> 6mm x 1.0 ISO metric Oil pump bolts 1/4"
> Tappet chest cover or 5/16"
> 8mm x 1.0 ISO fine Front of sump,
> long head rear of sump,
> long slotted head, rest of sump,
> Bell housing,
> Gearbox remote studs,
> Rocker shaft small,
> Small water pump studs,
> Back axle casing,
> Manifold studs,
> Timing cover,
> Little end pinch bolt, all 1/4" or 5/16"
> 10mm x 1.5 ISO coarse Cylinder head studs 3/8"
> Rocker shaft large 7/16"
> 12mm x 10.5 no equivalent Main bearing stud 1/2" or 9/16"
> 10mm x 1.5 ISO coarse brass plug in sump 1/4
> 12mm x 1.5 special, no equivalent Oil gallery plugs
> with screwdriver slot.
> .383" x 28tpi 1/8" BSP Oil pipe block to head 7/16"
> .518" x 19tpi 1/4" BSP Oil filter pipe bolt. 1/4"
>
> And for information...at chassis number TD12285 the wheel studs,
> driveshafts, and back axle threads were changed to UNF, ( ANF.) The rest
> of the chassis continued with BSF threads. UNF uses A/F heads.
>
> Roger is on UK 01932 243534, phone & fax.
>
> Neil.
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