[6pack] Overdrive controller

[Terry Geiger]

Vance,

Volvo 240's used the J type overdrive.  The electrics consisted of a 
momentary contact switch, a lockout switch, and a relay.  It worked as you 
desribed. When you got the car in 4th gear, you would push the momentary 
contact switch in the center of the gearshift and ovedrive would engage. 
The lockout switch prevented the ovedrive from engaging in any gear but 4th. 
The relay was a "holding" relay that would hold the circuit as long as it 
was enegergized.  It worked great, anytime you shifted out of 4th the 
overdrive was disengaged and would stay that way until the car was in 4th 
gear and the momentary contact switch was pushed again. If you could pull 
the circuit diagrams for one of those cars it would probably give you some 
insight into circuit design save you some time.  Also, I see no reason the 
Volvo relay could not be used.  Coming up with a momentary action stalk 
switch would be the tricky part.

I'm going to look into as my wife's Herald progresses.  I have Spitfire 
engine and overdrive gearbox that is going into the Herald and I would like 
to wire it so that is not confusing for her to drive.

Terry Geiger
www.GeigerGarage.com



----- Original Message ----- 
From: "Navarrette, Vance" <vance.navarrette at intel.com>
To: <6pack at autox.team.net>
Sent: Monday, January 19, 2009 12:51 PM
Subject: [6pack] Overdrive controller


>    Folks:
>
>        Been thinking about a winter project for the TR6.
>
>        The thing that keeps rattling around in my brain is the fact that I
> always end up leaving the overdrive engaged when I want it disengaged 
> (like
> after coasting down an off ramp). When I pull away from the signal at the 
> end
> of the ramp, I invariably mutter a four letter word when I shift into 3rd 
> as
> the OD engages unexpectedly. You would think I would remember to flick the
> column switch but it seems that I never do, adding to my anxiety about 
> having
> Alzheimer's.
>        I was thinking about designing a black box that sees the inhibitor
> switch open when I down shift, and then locks out the OD until I toggle 
> the
> column stalk again. In other words, the OD disengages and stays disengaged
> until deliberately re-engaged.
>        Before I start sketching out a circuit, does something like this
> already exist? I don't want to reinvent the wheel. I am thinking that it 
> must
> plug into the existing wiring harness with no cutting or splicing, and be
> easily installed in a hidden location. Of course it must work for both A 
> and J
> type ODs too.
>        So, any pre-existing solutions out there? Please give me a 
> hyperlink
> if possible.
>
>        Thanks,