[Healeys] Odd Overdrive Electrics

[Bob Haskell]

Patrick,

Thinking out loud here.  The hydraulic pump in the overdrive is always 
supplying pressure.  When you turn the OD switch to Overdrive the 
solenoid moves a linkage in the overdrive to open the hydraulic valve.  
When you flip the OD switch to Normal, the throttle switch keeps the 
solenoid energized so the hydraulic valve is still open.  When you press 
on the accelerator pedal, the solenoid de-energizes, the hydraulic valve 
closes and the OD goes to direct.

It seems like the hydraulic valve is moving since the OD goes to direct 
when you press on the throttle.  So, the solenoid would have to be 
energized to move the valve again.

When you first start out, with the OD in Normal, it doesn't attempt to 
go into Overdrive, right?

When I am coming to a stop with the car in Overdrive, I flip the switch 
to Normal, put the gearbox in neutral, and blip the throttle. I then 
move the gear shift lever left and right.  If I hear the solenoid 
engaging when I'm next to 3rd/4th and disengaging next to 1st/2nd, I 
know the OD solenoid circuit is still energized and blip the throttle 
again.

If you put the gearbox in neutral, do you hear the solenoid when you 
move the gear shift lever left/right?

Cheers,

Bob Haskell
Austin-Healey 3000 roadster registrar

On 8/24/25 05:27, Patrick and Caroline Quinn wrote:
>
> G’day
>
> Thank you to those who responded concerning how best to adjust the 
> overdrive throttle switch.
>
> Well I did what was suggested and have the overdrive cutting out when 
> the accelerator is pressed about a fifth of the throttle opening.
>
> I wish that was as simple as that, because what’s happening next is 
> confusing.
>
> What’s happening is that I could be driving along in top overdrive. 
> Flick the switch to “Normal” and it behaves as it should, staying in 
> overdrive. Press down on the accelerator and it changes down to direct 
> top. So far so good.
>
> Ease up on the accelerator and does it stay in direct top? No, it goes 
> back into overdrive even though the dash switch is still on “Normal”.
>
> Any ideas?
>
> Hoo Roo
>
> Patrick Quinn
>
> Blue Mountains, Australia
>
>
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