T-Series Modern Electrics for a TD

[Sarastro]

The TD restoration continues. I've pretty much finished the mechanical part, and now I'm doing the electrics and the interior. I think that's almost as much work as the mechanical things.

I decided to modernize the electrical system quite a bit without making it obvious. I added a number of relays in the usual applications: headlights, switched power, brakes, and so on. I also duplicated the turn-signal relay cluster with modern relays and added more extensive fusing. It's not very different from what I did with my late bugeye, but now all the relays are in a single box and the fuses are on the outside, so they're accessible.

The whole story is at https://www.nonlintec.com/mgtd/electrics/#wiring, along with a circuit diagram for all you geeks out there, and some more pictures.

The relay and fuse box is mounted under the scuttle, behind the battery box. One of those two large connectors goes to the dash wiring and the other to the harness.



A British car with a working electrical system? What a concept!

 

[beachbumbarry]

I used a lot of relays on my TD also. I put 2 relays in each of the headlight containers. The relays work great and it's a good way to go. I have a 51 MG-TD/B that is a daily driver in the warmer months.

 

[PAUL161]

Steve I would like to install relays also in the TF, but I have a new original style harness and I don't want to cut into it. The brake switch will definitely be converted, but no cutting into the harness is needed there, the headlights should be relayed. Gotta figure that out without any cutting also. PJ

 

[JPSmit]

Steve I would like to install relays also in the TF, but I have a new original style harness and I don't want to cut into it. The brake switch will definitely be converted, but no cutting into the harness is needed there, the headlights should be relayed. Gotta figure that out without any cutting also. PJ

Fairly easy. Use the existing wire harness to power the "switch" side of the relay. In other words, where the wire would (for instance) power the lights - instead replace that circuit with the relay - wiring though terminals 85 & 86. Then make a new wire harness which starts at the battery, goes through the "power" side of the relay (87 &30) and then to the lights. You then have the circuit but it is completely reversible.

 

[Sarastro]

Yes, that's exactly it.

I decided to do my own harness, since I'd have to butcher a standard one to do things the way I'd planned. I'm away from home now, but I finished the harnesses before I left and tested it. It was fun to see it all working and all the lights lighting up the way they should. I just have to get a dashboard into it and all the electrical stuff on the dash, and then the electrics are pretty much finished. Just have to get an interior into it. Not looking forward to writing the checks for that....

 

[PAUL161]

Steve, I really haven't looked yet but, I would like the relays up behind the dash out of sight. I've done just about everything imaginable on restorations, but the newer systems with relays and heaven forbid computers, are not up my alley. Would there be a way to wire into a relay directly off the light switch with a short jumper wire and connect the wire harness to the relay instead of the switch? If it could be done that way, everything would be out of sight and no one would be the wiser. PJ

 

[drooartz]

I'm currently trying to think my way through this as well. I'll be adding relays for the headlights to my Bugeye (and making sure they're fused, can't remember if the lights are fused on a Bugeye) and want to keep the wiring as uncut as possible.

 

[JPSmit]

Yes of course. Jumper wire from switch to 85 in and then out through 86 through existing harness to ground (not headlights as it is now - you could even ground under the dash and leave the old wire unattached). Then new wire from battery to 87 and (probably new) wire from 30 to headlights to ground. You could use the previously unattached wire but it sort of defeats the purpose as the thinness of the wires themselves is often a factor in lack of light.

 

[drooartz]

JP - don't you have to account for the high beam/low beam circuits with a pair of relays? I was figuring:

light switch -> high/low switch -> high beam relay and low beam relay (2 wires) -> each relay to ground

With the power side of each relay running battery -> relay -> high (or low) beam.

This way the light switch and the high/low switch are just running on the low draw side. Am I amiss?

 

[JPSmit]

Yes, two relays one for each