It appears that Rootes, going back to the days of the early Rapiers, intended
the overdrive to allow for better acceleration rather then higher top speeds.
Whenever an overdrive was fitted, the rear axle ratio was made higher, thus
keeping the top speed about the same between the overdrive equipped cars and
the non-overdrive cars. This would make sense given the types of roads in
England back in the fifties and sixties. It also made sense, from a British
point of view, for America. Where even though the roads were long and
straight, most states had a 65MPH speed limit back then. The Brits probably
didn't really understand that the 65 MPH limit was widely and normally
exceeded outside of the East coast.
The problem we are now dealing with is the fact that the designers of the
Alpine never foresaw 70+ MPH cruising speeds. Thus to keep up with modern
traffic, some creative modifications are needed. The 3.89 with an overdrive
should be no problem- the '68 Rapier (Alpine GT) came factory equipped that
way. The 1725 produced about the same horsepower as the Alpine V while the
'68 Rapier body weighed only a little bit less.
Jan Eyerman (Rootes collector for 40+ years)
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