At some point in the past I could have given you a more authoritative
response. But what the hell - here goes. Years ago I took an overdrive from
a Triumph Vitesse and attached it to the back of my TR6 tranny. It involved
changing a large shaft (input, output??, I forget). It also required a
change in some bearings, which I turned out of bronze. I recall there were 2
overdrives which could have been attached: an earlier and a later, the later
being more comparct. I used the earlier overdrive. I know there are other
overdrives which look similar on MG's and on Spitfires which will not fit.
Fitting the overdrive and tranny assembly betweeen the space frame tubes was
quite a challenge. lt may have been easier with the engine removed. On TR6's
typically the rear end ratio is lower on cars with the overdrive. My car had
the higher rear end. Initially I was concerned about that but the car is so
light and the engine so torquey it was not an issue. It does make the car
nicer on the highway, and I am aware of folks who slalom who like the
electric shift as it is faster and less prone to miss-shift. As to rarity,
there are quite a lot of overdrives on transmissions around, but they seem
to demand a good price. It is hard to say what a fair price is for an
overdrive not attached to a tranny. It will cost you a fair buck to pay
somebody to put it together, and for parts (the shaft). Personally I
wouldn't pay much for one, given these costs. Bye the way, apparently the
correct overdrive also came on some models of Volvo as well. Stephen
> ----------
> From: William Zehring[SMTP:zehrinwa@umdnj.edu]
> Reply To: William Zehring
> Sent: Wednesday, July 22, 1998 8:23 AM
> To: tvr@Autox.Team.Net
> Subject: OD tranny
>
> Dear all:
>
> A regional brit-car mechanic informs me that he has an OD unit that can be
> attached to the existing 4 speed tranny on my '71 2500 (TR6 engined car).
> I believe he said that the only additional part I'd need would be the
> motion shaft. I am not sufficiently familiar with these units, in fact,
> I'm downright dull-witted when it comes to transmissions. Any advice on
> this matter would be greatly appreciated. I know these units are VERY
> rare, and I also know from experience that the OD is a sweet thing to have
> on highway trips. Is there any net-wisdom on this? Is adding the OD unit
> as simple as it sounds? Wouldn't I need a different prop. shaft too??
> What sort of price might I expect for this (I didn't ask at the time)?
>
> cheers,
> Will Zehring
> '71 2500 (on the road by ????)
>
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