I think the throttle switch is there to prevent unintended additional
compression braking when flipped to normal. Requiring the throttle to be
depressed to disengage the overdrive prevents an excess of compression braking
coming out of OD, which may not be a big deal in 4thOD in a straight, but can
be interesting in 3rdOD in a high speed sweeping corner. I think it also
reduces strain on the gearbox/OD/drivetrain for the same reasons.
David W. Jones
'62 Mk II BT7 tricarb
Cumberland, RI USA
----- Original Message -----
From: Alan Schultz
To: Bob Spidell
Cc: healeys@Autox.Team.Net
Sent: Saturday, November 06, 2004 4:16 PM
Subject: Re: Overdrive wierdness - I'm not really sure
Bob,
Thanks for the lesson in technique.Hope when I blip the throttle at the
stop light some hot rodder isn't considering it a challenge. I see
little reason to keep the throttle switch. If I plan to pass someone I
could just flip the switch to normal. Seems its the only reason for the
switch?
Bought my 53 BJ8 from a guy living in Madison, WI who had taken it
completely apart years ago. It was a "basketcase" or should I say "boxes
and bags case".
Bob Spidell wrote:
> This should probably be re-subjected to "O/D Technique," I suppose.
>
> Anyway, my O/D tecnhique is a follows:
>
> a) on "upshift" (from straight 3rd or 4th to 3rd-O/D or 4th-O/D) I just
> flip the fascia switch at or near WOT. The result is very similar
> to an automatic transmission upshifting
>
> b) for "downshift" (from 3rd-O/D or 4th-O/D to straight 3rd or 4th) I
> push the clutch in a little (inch or two), rev the engine a little
> and throw the
> switch. If done just right, this results in an almost
> imperceptible downshift;
> the only effect is an increase in engine speed.
>
> I have 140K+ original miles on my O/D, and I've gotten 80K miles--and
> counting--on
> my latest clutch so I think this technique is fairly friendly to the
> machinery.
>
> Alan: yes, that's normal for an O/D. The throttle switch will keep
> the O/D
> engaged until the throttle is opened something like 3/16" measured at the
> stops (probably around 1,500 - 2,000 RPM). BTW, you didn't get your
> "53BJ8" off of eBay by any chance? ;)
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