Issue 2.0 – 10/12/15 - 1152 Longitudinal Transaxle Sportscar Gearbox Manual
© 2015 - Xtrac Limited, Gables Way, Kennet Park, Thatcham, Berkshire. RG19 4ZA.
Xtrac Inc, 6183 W. 80th Street, Indianapolis, IN 46278. United States
13
The gear cluster comprises:
•
A layshaft with integral 1
st
& 2
nd
gears. All other drive gears are slide on. Note
the ‘overlapping’ gear order ‘1
st
, 2
nd
, 3
rd
,
5
th
, 4
th
, 6
th
’.
•
Mainshaft with 6 mainshaft gears on 3 hub assemblies plus a reverse gear on
the reverse hub assembly.
•
A single, full length barrel with 3 change gear selector forks and a reverse
gear selector fork, mounted on a selector rail.
Drive is transmitted from the clutch shaft directly to the layshaft, driving all layshaft
gears at layshaft speed. All mainshaft gears are in permanent mesh with these gears
but are not coupled to the mainshaft. The reverse mainshaft gear is in constant mesh
with the reverse idler gear (mounted in the maincase), which itself is in constant
mesh with the integral input reverse gear on the layshaft. A dog ring is engaged with
the selected mainshaft gear by a selector fork, transmitting drive from the gear to the
dog ring, through the hub and into the mainshaft itself. The entire cluster can be
removed as one assembly from the rear of the gearbox (as installed) for ease of
inspection and maintenance. The barrel should be shimmed to ensure it holds the
selector forks and dog rings central to the gear cluster. A cluster setting jig (1152-
999-006A) is available for this operation after gearchange barrel and/or barrel
bearing replacement. It is essential that this is checked periodically. Please refer to
the assembly procedure given in section 5.2.2 - Selector Barrel Setup. In addition,
the dog ring and mainshaft gear dogs should be checked and replaced if the dogs
show signs of damage, in order to avoid inconsistent gear changes and further
damage to other systems. Refer to Appendix B – Dog Damage Sheet for guidance.
4.3.1.
Reverse Gear
Care should be taken when engaging and driving in reverse gear. Whilst the reverse
gear engagement mechanism is via a dog ring (constant mesh gear train), the
gearbox layshaft speed should be allowed to reduce to 500rpm maximum before
reverse gear is selected and engaged. An engine output torque limit of 150Nm
should be applied whilst driving in reverse gear.
