J-type o/d wiring?

[Mj17]

Anyone able to help me with a run-down of the correct wiring for a J-type o/d unit?

Currently I've got a switch in the gear stick that I can flick to give me electric shocks through said gear stick.  While ...invigorating i'd prefer it to switch the overdrive in/out.

I've replaced the wires through the stick (though they didn't look too bad) and chased the origonals to the relay panel.  From here the PO seems to have added a wire to the solonoid and another from solonoid to earth (if the wire wasn't broken).

This seems to cut out the inhibitor switch completely but I couldn't find said inhibitor.

Anyone know the correct wiring for a J-type and also where the inhibitor switch is located (found reversing but couldn't find overdrive - or are they common on 2000, with o/d on all forward gears?).

[neilnaz]

I don't know whether this is of any use but it does show the wiring of  J-type on a Spitfire 1500. The relevant wiring is centre right on the diagram. The 'gearbox switch' is the inhibitor switch. If this is somehow different than a J-type on a 2000 then apologies but I would imagine that the principles should be the same.

http://www.triumphspitfire.com/images/wiring/76diagram.jpg

From what I have read, the inhibitor switch is just like the reverse light switch and the solenoid gets its juice from the reverse light 12v via the inhibitor switch and gear-knob switch. There is no need for a relay with a J-type O/D.

I hope it is helpful

Cheers, Neil

[Mj17]

I know what the wiring is like on a 1500 gearbox (and I'll never moan about having to remove the radio/carpet/tunnel cover to get at the gearbox again!).  The 2000 uses the big Triumph gearbox, not the Marina unit so things are in slightly different locations.

The inhibitor switch is (mechanically) the same as the reversing light switch but is triggered by the gear selectors for 1st/2nd in addition to reverse.  Never known the reason for not having 1st/2nd (too much torque for conical clutch?) but I do know that overdrive reverse is... very short lived (reverse isn't the uni-direction in the overdrives uni-directional clutch).

I'm not intending to flick the overdrive switch while in reverse - but nor do I want to rely on not flicking it!

[AlanChatterton]

don't know about Spitty wiring, but the 2000 J type should go......

Takes power from the positive feed side of the reversing light switch (nearside of the gearbox near the front on the side) to one side of the isolator (top of the gearbox, about 6 inches infront of the gearlever) from the other side of that up the stick to the switch, back down the switch to the solenoid (bottom rear of the box by the mounting crossmember) then to earth.

Hope this helps!

PS, infront of the 3/4 isolator is a large hex blanking nut. Remove, replace with another reversing light/isolator switch and wire in PARALELL with the 3/4 isolator (so that if either switch is engaged the o/d will work) and you know have o/d in 2nd, 3rd and 4th. Okay on a 2000 if you are not to harsh!

[Mj17]

Perfect - just what I needed to know.  At least when I'm groping around I know where to grope!

[Roger Keys]

The 2nd gear in overdrive mod was fantastic. I did this on my sprint, albeit after id beefed up the overdrive, came in with a bang. Used to spin the rear wheels going from 2nd to overdrive second when flat out. Not so clever in the outside lane of the A40 in the rain back in the day. Ahh memories!