Anything and everything GT6.

I've just installed a GT6 engine and D type overdrive to my 1500 spitfire. Following the overdrive circuit for the later models in the Haynes Manual I made up a wiring loom, but I am now unsure as to the supply to the relay terminals W1 and C1. The manual states W1 as no2 ignition switch and C1 as no1 ignition switch. But this changes in different diagrams that i look at. Can anyone help me with what supplies these terminals, where i can pick up the supply and what gauge wire i need ?
Thanks, Paul Lee

Paul,
W1 should be connected to terminal 3 (this has 4 white cables coming from it).
C1 should be connected to terminal 2 (this has a brown cable connected to it coming from the starter solenoid and is live!)
Use the same gauge cables (28/003") as used on the headlights (28Amp)
Triumph actually used 'piggy-back' Lucar connectors to make these connections at the ignition switch, so there is no reason why you should not either!

Hi Lindsay,
I've just looked at the ignition terminals which are:
Terminal 1 White and Red heavy duty
Terminal 2 Brown heavy duty
Terminal 3 White
Terminal 4 White and Pink.
The loom is 79 spitfire. Do I just pick up the feed as you said W1 from terminal 3 and C1 terminal 2.
When you say 'piggy back' are these the ones that just clap onto the original wire???
Thanks Paul

Hello Paul.

Yes, those colours/terminals are correct. 2 = brown, 3 = white. To add the new wiring use piggy-back connectors like the photo. You have to remember that a '79 spitfire had J type overdrive and did not require a relay, so do not let the later wiring diagrams confuse you. If in doubt refer to Mk4 Spitfire and GT6 Mk3 diagrams. Do remember to disconnect the battery BEFORE working on the wiring.
Good Luck!

Hi Lindsay,
I'm OK with terminals on the ignition! But still unsure about the 'piggy back' connectors. The ignition doesn't have any spade connectors to piggy back from. Do you mean that i have to pick the feed up from somewhere else? ie coil/solenoid.
Also when i've got round to connecting up the relay. How will i know if the overdrive is working, as the car is not on the road yet. Will the solenoid click?
It may sound a silly thing to ask but i've never used an overdrive before.
Thank you for all the advice.
Paul

Paul,
Yes you can wire the brown (No2) from the solenoid direct to the C1 terminal on the relay. If you are mounting the 6RA in the correct place on the bulkhead it's a simple operation. You might want to put an in-line 30A fuse in here as it is live! You can take a feed from any ignition controlled circuit on No3 (white wire) to W1. Do not use the Spitfire coil connection IF you are still on the 6volt coil and ballast resistor wire which was standard on the late Spitfires. The coil will have a salmon coloured wire if you do. Your existing loom should have a spare bullet terminal on the green coloured reverse light feed to the left of the solenoid/coil position going onto the gearbox that you can take the supply from. This was where the J type overdrive took its supply from, is ignition controlled and fused, so it should be there! The beauty of doing it this way is that you do not have alter the existing wiring and you can keep the new wiring short and under the bonnet.
When you have connect these two wires up you will still need the switch circuit from W2 connected through the gearbox switch which is only 'on' when in 3rd or 4th gear and then to the switch mounted on the gearknob. However, to simply 'test' the circuit just earth W2 and the relay will click. If you connect a bulb to C2 and earth it will light when you energise the relay. If you have the D type connected to C2 the overdrive solenoid should also be heard to operate.

Hi Lindsay,
Just to confirm before i do anything. For the C1 terminal I can take a feed from the solenoid. This would be from the centre of the solenoid where the live comes in from the battery. Or is it one of the terminals on the side? For the W1 can I use a double bullet connector on the green reverse feed and take a spare feed to the W1???
Thanks Paul.

Paul, the answer is yes to both your questions. Connect to the solenoid with a ring connector (pictured) and ensure the insulator boot covers the connections on the solenoid threaded terminal properly. For extra safety though, I suggest putting an in-line fuse between the starter solenoid and C1 as it is, as you have pointed out, live and NOT ignition controlled.

Hi Lindsay,
A BIG thank you for your advice and support.
I'll give it a shot this coming Friday and will let you know of the outcome

Paul

Ureka we have power.
Thanks again.
Paul

Section : Overdrive

D type overdrive relay terminals

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