Todd :
Overdrive was available from at least very early TR2, don't recall offhand
if TS2 had it or not.
If your car was so equipped by the factory, there will be an "O" at the end
of the commission number. However, OD was sometimes installed by dealers
and owners, who should not have added the "O". Normally, there would be an
OD operating switch on the dash, next to the heater switch (or where the
heater switch would be if you had a heater <g>). This was a simple
push-pull like the wiper switch on early cars, but it was changed to a
distinctive toggle switch with a rather large teardrop shaped body at some
point, perhaps at the change to TR3.
But of course after all these years, the presence/absence of a dash switch
may or may not reflect what is actually installed. Looking underneath the
car, a OD-equipped car will have a rather large (3") brass drain plug just
forward of the gearbox mount/crossmember. A non-OD car just has an empty
space, with the gearbox tailshaft casting above it (no drain plug).
The stock OD ratio was .82, which means at 70 mph your engine will only turn
2950 rpm instead of 3600 (assuming standard gear ratio and original Michelin
X tyres). Possibly not too big a deal, if you don't plan any long trips at
high speeds, but I certainly love my OD.
The best way to add OD is to buy a complete gearbox already equipped with
the OD. The original TR2/3 boxes are unfortunately rather scarce and
expensive here in the US, but fortunately the later 4-synchro boxes are
still available used from the UK, and will fit with only very minor
modifications (drill two new holes in the crossmember).
Otherwise, you will need the OD itself, the adaptor plate to the
transmission, the mainshaft to suit your transmission (different between
3-synchro and various versions of 4-synchro), and either a top cover that is
already drilled and tapped for the isolator switches (some early ones were,
with brass plugs in the holes) or you will have to drill and tap the holes
yourself. You'll also need the switches themselves, a relay (ordinary fog
light relay will work), and an operating switch, plus the wires to connect
them together. Different speedo cable (but the speedo itself doesn't need
to change unless you are installing a very late gearbox).
There are several vendors around that still specialize in OD repairs and
parts, check out the Monster List at
http://www.team.net/sol/britpart.html
I believe Rimmer Brother's still sells used OD 4-synchro boxes taken from
later cars in the UK, and they usually have a "free shipping to the US"
special every summer ...
http://www.rimmerbros.co.uk./
Note that the Laycock overdrive used in the TR2/3/4/5/early 6 is known as an
"A-type". You don't want the "J-type" used in later TR6 (and other cars),
as it's much more difficult to fit to a TR3.
Yet another possibility is a conversion to a Toyota gearbox with a manual
OD. Herman van den Akker is selling (or will be soon) a kit to adapt the
Toyota box to the TR2-6, or you can buy a complete converted box (which
still requires other modifications to the car) from New Zealand (can't
remember the name offhand).
None of these options are cheap, you're probably looking at $800-$2000 just
for parts ...
Randall
59 TR3A daily driver TS39781LO
63 Sports 6 rustoration project HB7826LCV - with OD on the wish list
> 1) When did TR3's start coming with overdrive, if ever?
>
> 2) How do you tell if you have overdrive?
>
> 3) If you don't have overdrive, what's the best way to install it? What
> do you need to do it?
>
> 4) I think I've read somewhere that the overdrive gives you ~25% increase
> in tire rotation versus no overdrive at the same rpm. How big a deal is
> that? When I get done with my restoration, am I gonna immediately wish
> I had overdrive on my TR3A?
/// triumphs@autox.team.net mailing list
/// To unsubscribe send a plain text message to majordomo@autox.team.net
/// with nothing in it but
///
/// unsubscribe triumphs
///
/// or try http://www.team.net/cgi-bin/majorcool
|