Renault
UN1-16 Transmission - The
Lotus Esprit X180 Gearbox
Cut Through of
the gearbox
The Lotus Esprit
X180 featured a Renault UN1-16 gearbox. The Citroen unit, used in
the older Giugiaro Esprit S3 was replaced to safeguard future supplies
of gearboxes, for increased Esprit production. The Renault unit
was used in the Renault 25 and the Alpine GTA, but with the combination
of ratios slightly altered for Lotus requirements. It is a fairly
conventional two-shaft unit; the clutch drives the top shaft, which
passes above the differential, with drive then travelling through
one of five pairs of gears, or the reverse gear train, to exist
forwards, via the bottom shaftt, into the differential.
All five forward
gears have synchromesh engagement. The gear lever is linked to the
transaxle via two push-pull cables, attached to selector shafts
within the tranaxle. Fore and aft lever movements make each cable
move in the same direction, transverse movements in opposing directions.
Thus, each lever position gives a unique position of the cables
relative to each other and to the transaxle casing, which enables
the selector shafts to engage the gears.
To spread the
costs of Federal re-certificattion, the first year's production
of the US specification Esprit retained earlier, 9kg heavier 5 speed
Citroen transmission. This had a lower torque capacity, insufficient
to cope with the power of the 1989 model year US Lotus Esprit, so
all cars had to Renault transaxle. It drives through a 235mm (9.25
inch) singleplate diaphragm-spring clutch, hyraulically operated.
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