Carroll
As nobody else appears to have responded to your query I will add what I
believe to be the situation.
When BMC was formed it was decided that a replacement for the large
saloons was needed. This was chosen to be an Austin and took the form of
the A90 BN4 Westminster. The engine, gearbox and rear axle were all new
developments but ironically built in ex Morris factories who for some
unexplained reason were allowed to keep the Morris name. Morris
Transmissions in Coventry made the rear axle and I believe the gearbox
for the A90 Westminster. Not to be confused with the earlier A90
Atlantic.
When the 'Austin' parts were being phased out as part of BMC
rationalisation the 100 had to take on the new major units. The later
BN1s had the later 5 stud Hypoid Rear Axle and these ended up with very
strange set up of larger brakes on the rear than the front. Not the way
that Healey would have designed a car! However the A90 axle was too wide
so the 100 ended up with a unique narrower casing and shorter half
shafts. The differential unit however was the same but with a range of
possible ratios.
This rear axle went into the BN2 but with the modifications that had
been applied to the A90. The oil filler was moved and the hub threads
were now left and right handed.
The gearbox on the BN2 was basically A90 but as the saloon had column
change a unique side entry gear lever system was developed. Actually
this was later used on a more sporty version of the A90 the A105.
However the A90, if it had an overdrive at all, did not use the Laycock
so the mounting and third motion shaft on the BN2 are again unique. The
gear ratios are not all the same so again there are variations.
Moving on, the 100/6 might not have happened at all except that BMC
management wanted to stop the 100 engine production. As it turned out
this did not happen but by then the big Healey was committed to the 6
cylinder engine. The 100/6 and 3000 continued to use BMC major units
mostly derived from the big BMC saloons. These went through to A95 and
A110 etc. with a whole host of badge engineered versions such as
Wolsley, etc. etc.
As it happens the only significant 'Austin' part that continued was the
front suspension. This started life in the early A40 Devon and continued
with minor modification right through to the A110.
Other than the early BN1s perhaps our cars would have been more
accurately named from a technical standpoint BMC-Healey!
All the best
>Does anyone know what the transmission that was used in the BN2 was
>originally built for? I can't imagine that given the limited number of
>BN2's made,
>it was designed by or for Healey.
>
>Thanks in advance,
>
>Carroll
>
--
John Harper
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