[Healeys] Battery isolation switch - curious

[John Harper]

Alan

I believe that BMC used a 'form fit and function' approach to changes. If a
change was made by say Lucas that did not change F,F, or F then they would
have no need to change their part number. Lucas often added a letter suffix
to their part number when changes took place but not all letter changes
resulted in BMC part number changes. A fictitious example was where an
internal insulator was initially made of a black resin based material but
for production improvement Lucas changed over to nylon. So long as this did
not change the F,F or F and BMC approved the alternative material then BMC
would make no part number change.However very minor concessions might be
made if this reduced overall costs whilst maintaining customer service

There might be another reason for unusual changes. At the merger forming
BMC almost all the Morris, mainly numeric, part numbers were converted the
the Austin alpha-numeric system. A part used on both Morris and Austin
vehicles would become the Austin part but with so many changes to make,
some errors crept in and these were noticed and corrected well after the
merger as they were discovered. I am not saying that the battery switch was
one of these but this might explain other anomalies.

I am curious about the same part number being used for a BSF and a UNF
bolt. As you know BMC had a system where the main technical information
relating to a fitting was coded into the part number. Austin (BSF) fittings
had fairly random part numbers where knowing the part number did not help
in identifying a fitting. I have a full Atlantic parts list. Would you
please send me the details of where these queries can be found so that I
can have a closer look please.

Best regards



On 19 March 2013 06:29, Alan Seigrist <healey.nut at gmail.com> wrote:

> BMC and Austin parts numbers often didn't change if the effective function
> and mounting didn't change.  In the case with the switch, I believe the
> only difference is the length of the knob.
>
> For my '51 Austin Atlantic, in one or two instances it uses the same part
> number for a 1/4" BSF bolt and a 1/4" UNF bolt, and the only way you would
> know the difference is to look in the parts book where it actually
> specifies 1/4" UNF bolt in the parts description , just for that one use of
> the part number.
>
> Of course, I always defer to John Harper on this type of thing!
>
> Best,
>
> Alan
>
> On Tue, Mar 19, 2013 at 2:13 PM, <fiat500f at aol.com> wrote:
>
> > Hmm.  I was looking at a Lucas site today and found something that
> > conflicts
> > with the factory parts books.  Concerning the battery kill/isolation
> > switch in
> > the boot.  The Lucas book/site says that it's Lucas number 76605 for BN1,
> > BN2,
> > and BN4 (1957 only), then after that, the cars use 76604.  In the BN1/2
> > parts
> > book, it says the switch is factory number 1B2804, but I noticed that in
> > the
> > factory BN7/BT7 book, it's ALSO listed as 1B2804.  So Lucas says the
> switch
> > changes, but the factory says it doesn't?  I know the switch are very
> > similar,
> > but, they are different.  But no later part number change by the factory.
> > Yeah, yeah, it's Healey minutiae, but, I was wonderin'.... :)
> >
> >  - Paul B.
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-- 
Best wishes

John Harper

AHC UK 100 Register Secretary