The transmission systems on the Lotus Carlton/Omega are bullet-proof to a greater extent with the exception of one piece. The following areas should be checked:
Clutch & Bell Housing
This is one major Achilles' Heel on the Lotus Carlton/Omega. The clutch mechanism is different to most cars and this has introduced a weakness. The clutch pivot pin or the bell housing can fail causing significant damage and expense. This is widely acclaimed as the weakest part of the car and the fault is caused by stress fractures in the aluminium bell-housing or the retaining bolt for the pivot pin shearing off. Check for the clutch depression being heavy but smooth, if it is light, notchy or squeaky, exercise caution.
Clutch failure with the above faults is indicated by depression of the clutch pedal and the pedal not returning, but staying flat to the floor. In any instance, the clutch fork, pressure plate, friction plate and pivot pint will need replacement and possibly the bell housing too.
Look for indications of this work on service history.
Later cars should have had revised bell housings fitted from new, with earlier cars having has them changed under warranty but they still fail.
Gearbox
The gearbox has the internals of the same 'box as used on the Corvette ZR-1. This item is bullet-proof and should give no trouble. The gearbox can be noisy at idle with gear chatter but this is not an issue for concern, it is an inherent characteristic of the gearbox. The gearbox is fairly prone to leaking transmission fluid.
The rubber gaiter on top of the transmission tunnel (underneath the leather one) will most likely be split causing increased road noise and heat inside the car. This can be replaced with a standard item.
Propshaft, Differential and Drive Shafts
The only item to check on this part of the car is the differential. In extreme cases, the differential can whine when the car is moving. It is possible to re-condition the differential.