Hi John,
I had a discussion with John Esposito (www.quantumechanics.com) on this
subject and I believe what he said was that either O/D can be used in
second, third, and fourth gears, it's just a question of adding the
witches to control it. The switches turn the O/D on and off. The O/D
doesn't know which gear the transmission is in. I don't know why the
stock J type was set up for only third and fourth.
He also said that the A type was stronger in the sense that it could
tolerate larger torque but that it was an old technology and had a lot
of mechanical parts that could fail or be contaminated with dirt and
then fail. The J type was a more modern design and was largely hydraulic
and was less subject to internal parts failing or contamination with
dirt. The J type was however smaller, weaker, and less able to tolerate
high torque. That may be why the stock J type O/D was not enabled for
second gear. Racers favor the A type.
He also added that the A type should not present any problems if it was
rebuilt correctly. In his opinion, Triumph would have continued with the
A type had it continued to be available. It was discontinued so they
went with the J type.
He said that for a daily driver and if reliability was the only concern
he would use a modern 5 speed conversion which he also sells. He also
said that an O/D was just a lot more fun to drive than a 5 speed.
I have both an A type for my TR250 and a J type (from a Volvo) for my 71
TR6. Neither are installed at this time. Ask me in a year or so. I may
have some first hand opinions :-)
I am no expert in any of this -- I'm only passing on what I understood
John to say. Others may have other opinions.
Don Malling
John & Allison Cyganowski wrote:
> Hi All-
>
> I have heard that the A type overdrive has more functionality than the J
> type. What gears can you use the A overdrive in? What gears can you use the
> J overdrive in?
>
> John Cyg.
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