Welcome to our resource for MG Car Information.



TR parts and Triumph parts, TR bits, Triumph Car Spares and accessories are available for TR2, TR3, TR3A, TR4, TR4A, TR5, TR6, TR7, TR8, Spitfire and Stag and other TR models are available from British car spares and parts company LBCarCo.

Triumph TR3 - Revisit wiring loom

I'd like to revisit this wiring loom/harness question. Have any of you replaced one yourselves and what company supplied the product? Vinyl or fabric? What about the branch to headlights, brake switch, gas tank etc? Is there a product with all the right connections and color codes?
Lots are for sale, but which is better or worse? Please name names. I'd like to this just once.
Thanks, Steve
Steve Crosby

Yes I have done so - well, I haven't quite finished yet but muc of it is installed. I used the kit from Advance Auto Wire and would highly recommend it. Be aware it assume you will switch to an alternator witha built in regulator.
Dan Masters is the man behind it, and one of the best features of his kit is his support. If you want to customize to your needs (I did), he will accommodate you, and even draw your final schematic for you. The kit uses conventional British colour coded wiring but every wire is one gauge heavier than original. His manual has much information on the right tools to use, how to properly solder bullet connectors, etc.
This kit is NOT plug and play; it is meant for a hobbiest who is serious about upgrading the electrical system to the point where it will never cause you grief again, and so involves some work.

The manuals are online:

PS You get to wrap the harness yourself with whatever you prefer. I ordered grey non-sticky vinyl tape from British Wiring, and it looks good, in my opinion.
J. S. Wallace

I would recommend either pot-dip soldering the crimp-on solderless bullet connectors that are supplied by practically everybody, or using a LARGE sopldering gun to fill the bullet with solder. Usually the main harness does not include the pigtail harnesses for headlights, front turning signals, or overdrive. The sub harnesses usually are purchased separately.

As far as fabric insulation is concerned, this is ONLY for trailer queens, it doesn't hold up as well on ddriven cars.

In the overdrive harness (if you use one) I would put shrink tape over the conncectors to seal them.

Use dielectric grease on ALL conncections, then you put it together once, and never touch it again.

Al Christopher

A. R. Christopher

When you installed the wiring harness by advanceautowire what did you do for your ammmeter.

Was thinking about going that route but wanted to keep as much original equipment on the car as possible.

Would hate to change the look of a gague


I'm having my original wire harness re-loomed. I stripped all the black cotton weave off the wires and left all the original loops of tape there. I sent it to Rhode Island Wiring Inc. and they will fix 3 crispy wires by splicing new lengths to the good bits for those 3 cases and I've asked them to add 3 extra wires for my electric fan, for driving lights and for a back-up light if I ever feel I need to put one on. They will get it back to me in about 6 weeks for about 1/2 the price or less than a new one. I did the same last year for a TR3A that I restored for a fellow in Toronto. I looks great !
Don Elliott

Re: ammeter, I decided not to use one. I'm going with a voltmeter instead. Still workingon getting one together that suits cosmetically...
J. S. Wallace

More re: ammeter. If you want to go original, are you saying you want to stick with the generator? Going with the alternator means the ammeter has to be changed somehow as the alternator will be capable of charging more than 30 amps.
I have discovered that there are no aftermarket gauges that look like the originals on TR3s.
You could silkscreen a new face plate for it, and put a shunt resistor in parallel so that only half the current goes through the ammeter, but for me, it's more trouble than I care to go through.
In any case it is quite possible to run the charging current from the alternator through the firewall, through the ammeter, and back out the firewall to the solenoid.
J. S. Wallace

A new cloth harness was with all the parts I got along with my TR3B. It came to me in boxes and pieces for restoration and reassembly. I also got 2 old harnesses that I cannabalized for extra ground wires and to redo subharnesses for parking and headlights. I seem to recall that the main harness had a lead for the fuel guage to the the sender. though a short wire may have been necessary. It also had a lead to the brake switch. The old harnesses were useful for that type of thing though I was not always able to use the correct colored wire. I plan to drive it for quite awhile so the wrong color will only be my burden to remember. The cloth harness looks good and seems to be holding up. I try to keep after the car but I certainly have it to drive--admittedly not in rain if I can help it.
As an aside, to Jim in Lancaster, I live about 12 miles north. I'm interested in hearing more about your car.
GG Krafft

I got the quote from Rhode Island Wiring. They will charge me $330 US dollars to add the 3 new wires I asked for, to repair about 4 wires with new lengths and splices plus 2 new wires that need replacement. Then they will re-loom it all like new. A new wire harness for a TR3A is $650.00 US dollars.
Don Elliott

Thanks for the replies guys. I've been in touch with British Wiring, pvc at $254 and braid at $316, other short jumpers at minor extra cost. Has anyone used them? The website
tells a good story and the product list is impressive. I'm waiting for a final quote.
Steve Crosby

I recently did a ground up restoration and used a new Moss cloth bound wiring harness. My version was for a spaded voltage regulator and had nearly every bullet connection needed. All grounds had the eye clip. The set up was for a generator version. I paid $330 a few years back. I know the prices at Moss just went up about 30%. I am very happy with the product and have had no issues. I had spread out the original before the restoration, removed the cloth, cleaned the wires and retaped with black electrical tape. I checked out the connections and everything worked. How ever after spending many dollars on the rest of the restoration, I decided not to skimp on a very important part. I did reuse the pigtails for the lights, but wrapped them in shrink tubing. I put a fresh harness in the steering column for the horn and indicators. The old one is still good and I will hold on to it in case something goes wrong. For my accessory fog lights I used airplane wiring tubing. I threaded my wires through and then added the bullets. The reason for this, the tubing will protect the wires from stuff coming through the grill. It looks neat and tidy and adds that professional touch. The biggest issues or peave that I have is the spaghetti look of the connections for the lights and indicators and horn wires left and right side of the engine bay. Otherwise I am a happy puppy.

Gary - Glad to hear from another TR3 owner near the area - Send me an email, would be more than happy to chat.

Short story - My dad bought the car new in '60 was in a wreck in 78 and has sat garaged since. I started a total resto last year and its at the body shop now.


I have bought bits and pieces from British Wiring and have had great success. Highly recommended, from m experience - which was not with buying a harness though.
J. S. Wallace

Gee. Moss list for a TR-3A harness is $387.95 in lacquer, cheaper in vinyl. My price is less than that.

This thread was discussed between 26/02/2007 and 07/03/2007

Triumph TR3 index