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Re: Overdrive Swap

To: Max Heim <>
Subject: Re: Overdrive Swap
From: "R. O. Lindsay" <>
Date: Tue, 05 Jun 2001 15:47:00 -0500
Max Heim wrote:

> I don't think that's the real issue, Lawrie (although Jack does mention
> watching revs)-- it's when you leave the switch in the OD-on position when
> you downshift out of 4th, and are tootling around in second. Then, say, you
> are accelerating madly to merge, and when you pop it into 3rd (or 4th in my
> case) with your foot to the floor, Wham! you're in overdrive, which
> effectively kills your acceleration, not to mention being hard on the OD
> unit. THAT's the point of having a light to remind you the OD switch is on
> (especially when you've just added OD to a car you're otherwise used to).

   Wouldn't it be nice to have a 10 second, or so, timer that would flash
a light telling you that the OD was GOING to engage then go solid once
it DOES engage; A delayed activation, of sorts.  That could work either
on the highway cruising or when you're pounding the throttle in a pass --
assuming you take less than 10 seconds to pass.
   Another option might be a throttle activated switch (like BMWs use to
change the shift profile).  At WOT, the system would respond differently
than at part throttle.
   Just thinking out loud...  Then again, there's the principle of Occum's Razor
that says, paraphrasing, that "...the simplest solution is the most likely (and
probably best) solution."

   The reason that I am curious about this issue is not because of OD
but because I am planning to add A/C to my B-GT.  I intend to install a
throttle activated switch that will turn OFF the A/C compressor <clutch>
when at WOT (as the B doesn't need anything else robbing power when
I need it most).  To avoid excessive OFF-ON-OFF switching, a delay circuit
will be incorporated that will instantly disconnect the A/C when the throttle
hits WOT and not turn it back on until 8-10 seconds AFTER the switch is
released (driver lifts).   Many low power economy cars incorporate such
a design.

Rick Lindsay
Diamond Geoscience Research
5727 S. Lewis Ave., Tulsa, OK
Voice: +1 918-747-3456
Fax: +1 918-747-8599

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