Relay for the overdrive?

[torehoi]

Hi everybody
I am trying to get my od working on my 66 3.4 S type. Is it correct there is no relay operating the solinoide?
The fuse is ok but no respons when I turn the switch on althou the od light turn on.
Regards from Norway.

Thanks for answer. I had to do the steering column with new brushes this weekend so the OD had to wait. Now its back in the car and working fine. Even the light for the OD lights up when I activate the OD handle when the gear is in 4. But there is no sound from the solenoid.
To be continued ...

New question: The warning light for the OD turns off when I turn on the headlight. Is this normal? Maybe to keep it dark in the coupe at night?

Hurra!! The OD is now OK. A bad contact inside the solonid was the problem. It was fixt on the kitchen table.

[340jag]

No relay as far as I know , you do know that it will only work when in 4th gear ?
If it's not working in gear , best thing to do is take the Overdrive solenoid off , and test it with 12v from a battery , see if it's working , if no give it a good clean , give it a good clean if it is !
If it's still not working you need to check the wires , may just be a lose connection !

You should hear it clicking in , with the ignition turned on and in 4th gear !!

On the same subject , Overdrives , I had a Triumph 2.5 PI , that had a Overdrive that worked in 3rd and 4th , has anyone tried that on a Jaguar gear box ?

[Tintin]

Many years ago I bypassed the gearbox switch on a 3.4 Mk 2 so the overdrive solenoid would act in all gears. The result was interesting but not entirely practical - why would you need an intermediate gear between 2nd and 3rd and 3rd and top? - and you had to engage/disengage on gear changes with attendant time lag. It was pretty useless in 1st and I had to remember never to use it in reverse! The drive train wasn't designed for the modification, so didn't use full power in the lower gears.

Robbie

[340jag]

On the Triumph the switch was at the top of the gear stick , the PI was around 150 bhp , when in 3rd in overdrive and you wanted to overtake or the like you flipped the switch the gear change down was instant , like the kick down on a Auto , no point in having it work in 1st or 2nd !

[Martec]

I replaced my knackered 4 speed moss box with a full synchromesh and over drive box many years ago and initially the the solenoid wire was falling off (resoldered on). The second fault was down to the switch on top of the gearbox, due to the power going through it, it went open circuit. I fitted a new switch and used it to operate a relay, after 10 -15 years it is still working fine.

I have used a few relays over the years when faults have occured.

Brian

[oldtimer]

Nobody has mentioned the fact that the overdrive operating solenoid comprises of two coils. When the overdrive is initially selected both coils are energized. Put an ammeter in the circuit at the solenoid and it will show up to a forty amp draw rate. This only lasts for a blink of the eye , why is this you might ask. Because on top of the solenoid iron core is an operating pin which shoots up and activates a switch beneath the rubber cover on the top. This disconnects the heavier pull in coil and leaves the economy/hold in coil to hold the solenoid in the correct position.

Taking the above into account it is essential to ensure that the range of movement is adjusted correctly to ensure the solenoid lifts sufficiently to operate and switch off the pull in coil. Failure to do this will mean that the forty amp draw rate will persist until the coil is burnt out.

Early overdrives with the selector shaft passing all the way through the overdrive have a short arm attached - the opposite side to the solenoid - this short arm has a 3/16 hole at the end ,this should line up with a 3/16 hole in the overdrive casing. Later overdrives referred to as compact overdrives and are associated with the all syncro gearbox have the same adjustment except that a rectangular plate cover the arm and adjustment

To test, select 4th gear ( with an assistant to turn on the ignition and select overdrive ) on your command switch on and insert 3/16inch drill through hole in arm described above and into hole a in casing and check for alignment. At the same time a positive clunk should be heard as the solenoid operates. It may be useful to have the Ammeter wired in to see what is happening. If on selection the Ammeter immediately drops back to 1-2 amps and the 3/16 drill slips into position all is correct

It is imperative to knock the power off immediately should the ammeter remain at forty amps as this will certainly burn out the coil.

I would suggest you remove the solenoid and check both coils for continuity . Pull the iron core out and ensure it is free to move . Examine the pin on the top of the core for integrity . Remove the band securing the rubber solenoid cover and cover. Manually slide the solenoid in and out ensuring that the cut out switch is working . Use a 12v battery and functionally test the solenoid.

The linear movement of the solenoid is remarkably small. It's function is to open an oil valve allowing accumulator oil pressure to operate two rams which engage the overdrive Ensure that the shaft is free to move.

By passing the Gearbox selector switch is not advised as the power output of the Jaguar engine is rather more than some other application.
Having tried in the dim and distant past the selection is with one huge thump

Come back if you need more - good luck - but let us know how you get on

[Martec]

Thanks Oldtimer I think I had better check mine ................ after the holiday.

Brian