Seems like everyone who is anti-overdrive is quoting John Twist. I
saw that blurb he wrote about overdrives on the NAMGBR web page before
it was printed in the "Driver." I wondered what his logic was. So after
he announced his recovery from his illness and surgery I wrote to him
and asked him. In his reply he said that he'd never seen any evidence
pro or con, it was strictly unsupported opinion. I offered him my own
gas mileage results (about 15% increase in mpg) and suggested that the
SAE might have some wear data. I haven't heard from him since.
Considering the above, while I'll bow to Twist's experience and
knowledge on how to fix LBCs I don't believe he knows anything more than
many others of us about whether or not overdrives save wear and tear.
It seems self-evident to me that (all other things being equal) if the
engine doesn't have to turn over as many times per mile while the OD is
engaged, it's useful life will be extended. We generally compare engine
longevities in terms of miles driven between overhauls. The fewer
revolutions the engine turns per mile driven should result in more miles
driven between overhauls. Seems like elementary logic to me.
Keith, I put an overdrive in my `70 B because I wanted to get better
gas mileage, increase the car's driving flexibility and I wanted to
extend the engine's useful life; not because I wanted to brag about it.
Quite frankly, I resent your reiteration of your charge that I and other
OD users would be so air-headed as you seem to opine that we are. That
was an opinion you should have kept to yourself.
--
Charley Robinson
Kerrville, TX, USA
NAMGBR 8-3530
`69 B Roadster
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