My 2 cents worth on this thread are that, YES, an overdrive-ratio 5th gear
(either 5th or OD) is a worthwhile conversion for two main reasons: (1) the
wear & tear on the engine is less at the lower highway rpm, and (2) the NVH
level is greatly reduced.
Having owned/driven both non-OD and OD MGBs on many long (500mi) 4-lane
Interstate-type A-to-B trips at 70-75 mph (110-125 kph) (short story:
university far away from girlfriend), the lower NVH of the OD cars was MUCH
more restful. More importantly, the rod bearings of the OD cars did not
wear nearly as fast as the non-OD car's rod bearings, a very important
factor. Other reciprocating engine parts also lasted longer.
As far as 5-speed vs. OD goes, my preference is for OD as it is original
factory fitment and the value of the car increases with only a relatively
minor net cost for the OD box after selling the non-OD box. The 5-speed
conversion will result in a lower value increase and a significantly higher
net cost. Either job will result in benefits to the ears and to the engine
and the reliability of both are comparable.
Dave Q.
Neuhorst, SK, Canada
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