Backing up with the overdrive engaged will destroy some internal
components, yes - namely the roller clutch.
However - there are a pair of switches on the top of the gearbox
(only one switch on very early boxes) which "cut out" the electrical
circuit when the gearbox is in reverse or first (or 2nd or 3rd on
early boxes).
It's possible to override the circuit, of course, and thus risk
destroying your OD by reversing with OD on ... but I think you would
have noticed grinding and gnashing metal sounds by now if that had
happened.
My guess is that the overdrive doesn't work for other reasons, and
having the switch engaged is not making a difference.
Some common causes of overdrives not functioning are, in no particular order:
low gearbox oil level;
incorrect adjustment of solenoid travel;
faulty wiring in circuit;
faulty relay;
faulty switch;
faulty solenoid;
dirt/crud/sediment blocking passages in OD unit;
As you can see - the fault is most likely related to either the
electrical circuit or to the oil. Those are the best things to check
out first.
Of course, it's also possible that internal components have failed,
but these things really are pretty beefy, and will last next to
forever if not abused outright.
When you do get around to checking out the solenoid, be sure to read
up on it first, as you can quickly destroy even a brand new one if
you go about it wrong. (and they ain't cheap!!).
I have scanned the factory manual for A-type ODs - get it in PDF from
http://www.thelittlemacshop.com/trsite/download.html
The manual is for earlier cars, but it's the same unit as a TR4.
HTH!
Dan
>So I'm sitting with the boys this morning, looking at car photos on
>the laptop.
>We get to the photos of my TR4 provided by the PO before I bought
>the car. When
>I bought it he told me the overdrive didn't work, perhaps I know why -- I
>noticed that in every photo of the interior, the overdrive is switched ON. Not
>all photos are from the same day, so I'm guessing he drove with the
>O/D on most
>of the time -- and probably enjoyed backing up with the O/D on also.
>
>To refresh my memory, backing up with the O/D engaged = bad. Right? Just
>thinking about fun projects to do in the driveway this summer. ;-)
>
>--
>Steven Newell
>Denver, CO
--
* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
Dan Buettner - Des Moines, Iowa - mailto:danb@thelittlemacshop.com
1957 TR3, TS15098L, now with an O! Undergoing frame-off restoration
begun 9/99. Currently awaiting warm weather and funds.
1977 Spitfire, FM64159U, with an O. In need of a comprehensive
restoration (again); will probably become a Spit6 or a Spit8.
Visit the Team.Net Triumph list member pages at:
http://www.thelittlemacshop.com/trsite/index.html
Photos, downloads, member bios, and more!
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