Paul Brandsema wrote:
I'd like to know whether there is a preferred method for engagement of OD in
a
TR4, or any other car with similar OD setup. I've always just flipped the
control lever on the column to engage. Sometimes it results in something of
a
jolt. Well recently, and by accident, I engaged the clutch slightly, engaged
OD and then released the clutch. Now I did not depress the pedal as much as
if I was shifting, but just enough to disengage trans from engine for a
moment. The result was a very smooth shift into OD. Of course that may be
my
answer. Even though this might result in a very small amount of wear to the
clutch, am I getting any benefit by not jolting the trans into OD?
Paul - you'll get many variable opinions on "the best way" and AFAIK, there
isn't one. I take the view that the avoidance of any snatch on overdrive
in/out switching on acceleration or overrun is a good idea. The Laycock unit
itself is highly resistant to abuse and I mostly slightly dip the clutch - but
not always. I spent the day with Fred Thomas in January in my 2000 and I
recall him saying he'd never seen anyone using O/D like I do. Wonder what he
meant???? Maybe it was our sinuous little UK roads?
My habit is to go to O/D third under power without clutch dipping and then
straight into O/D fourth. I often disengage on a trailing throttle without the
clutch at low road speeds (like prior to turning a corner) but clutch dip at
higher roadspeeds and blip the accelerator to keep engine revs up. I
double-declutch anyway as I learned to drive on a wide ratio crash gearbox.
But using the clutch as you described does avoid transmission 'clunk' and
there's lots of 'clunk' potential in an IRS Triumph driveline - not to mention
load reversals on the diff nose, quill shaft bearings and diff mounting points
which were always design weaknesses. In my book, there are two ways you can
use an overdrive. For more gentle motoring, flicking it in and out while
keeping the engine around its maximum torque band makes for economical and
pleasurable motoring and avoids high revving and fuel consumption penalties.
Alternatively, use O/D at the upper end of the normal rev band for more
spirited travel. I much prefer it overall to a five or six speed manual box.
Of course, on TR's you have O/D in 2nd gear as well, so you can really start
to play tunes on it depending on traffic conditions and the type of road.
FWIW..... Forum anyone?
Jonmac
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