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GT6 Tips and Hints on Rewiring GT6, Please

GT6_Mark

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The wiring was not replaced when my ’73 GT6 was “restored” by the previous owner a few years ago. I has always been something on my “to do” list, but poking around under the dash the past few days has convinced me this needs to be done sooner rather than later – too many brittle wires and some charred as well. Rewiring the car with a new loom is easily within my skill set. However, I wondered if anyone has advice to offer on how to go about this without entirely gutting the car? I do not really want to put the car out of commission for an extended period. It seems new main looms have a left and right side. Is there anyway to make this work to my advantage? Basically, any tip on things to do, and things to avoid, would be appreciated. Mark
 
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First, check with British Wiring and see if they have the proper loom. I have re-wired 2 TR6s without dismantling much. The trick is getting underneath the dash. Seems the GT6 is a little tighter fit, might consider removing one (or both) seat(s) so you can lay on your back to get your head under the dash. Again, the GT6 is foreign to me but it is Lucas. Not that complicated. Also, get a really accurate wiring diagram.
 
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GT6_Mark

GT6_Mark

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Thanks. British Wiring are on my list to call this week. I think you are right about the GT6 being a little more crowded that the TR6. I rewired a 13/60 convertible many years ago, and it was a breeze. Having a drop-top help with access. Mark
 

Bugeye58

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Mark, you'll have to remove the left seat, and pull the carpet back on that side. Both kick panels have to come off, as does the left rear trim panel. The rear wiring goes up inside the left quarter. You may have to drop the rear portion of the headliner to fish the interior light and heated glass wiring up and over.
Releasing the instument panel and pulling it back will make the under dash stuff a bit easier.
Mine is a Mk.I, and was a bare shell when I did it. If you have overdrive, the tunnel cover should come off. The OD harness is a separate item, incidentally.
It's been awhile since I did mine, but I'll try to answer specific questions if I can.
My harness(es) came from British Wiring, and were a perfect fit
Jeff
 
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Tinster

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Mark,

I can't help you with your car specific but I recently
rewired my TR6 and used bullets and bullet connectors.
Purchase the bullet crimper and bullet pliers. Page 15
of their catalog, I think. The folks at British Wiring
are very helpful.

Good luck and take your time.

dale
 

Bugeye58

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Dale, the B/W harness is plug and play. It comes with all the bullet connectors installed. I would recommend getting new connector sleeves, though. I made my own version of the bullet pliers, as they weren't offered when I did mine.
Jeff
 
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vagt6

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A quick and "easy" way to rewire what is possibly the most important part of your loom involves simply "cleaning up" and rewiring everything under the dash.

Refreshing the wiring under the dash is a great way to ensure that the important part of your wiring loom is safe and functional. It's a significant safety upgrade as well.

I've done this on a couple of GT6s, it really helps. Since the under dash wiring on practically all GT6s have been fiddled and fouled by DPOs (this is a prereqresite for all GT6s, I think!), it's usually a jumbled mess and really needs all the help it can get.

Rewiring the whole loom from stem to stern is very time-consuming. And if your electrics are working well, it may or may not be necessary.

Good luck, let us know how it goes! /bcforum/images/%%GRAEMLIN_URL%%/driving.gif
 
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Tinster

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And don't forget a dab of electric connector grease
on each and every bullet.
 

rotoflex

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Yours is a '73, a GT6 Mk3 like mine.

It is really not hard. This summer to look for a short I removed the engine wiring harness from the interior under the dash to the headlights, & since the problem wasn't there, re-wrapped & re-installed it.

It's a little slow, but just thread-the-needle. Take out the seats so you can have plenty of room. You will likely need to spray PB Blast or other rust penetrant on the seat bolts from above & below for 2 days before removing. Replace the seat bolts w/new stainless ones from the hardware store, & put plenty of anti-sieze on them. The seat bolts are pointed, so get them a bit long, run the right size nut or die on them, grind or file them to the same sort of point as the originals, then when you take the nut off it will straighten up the threads. Run the bolt on & off a few times to make the threads perform nicely. Many operations in the GT6 are best done with one seat or the other removed, which takes very little time (4 bolts per seat) if the fasteners are maintained.

I don't know what the replacement harness you'll be getting will be like, but the only thought-provoking area is the harness where it connects to the fusebox. The wires in the back of the ignition switch are blade connectors after removing the cap in the back.

The key to keeping all the electrics under control & not getting frustrated with future troubleshooting etc. is cable ties. The original harness even though wrapped in branches is still like a rat's nest when installed due to long free lines. Get a package of small cable ties, & when each harness is in place, gather the wires after the wrap ends as they continue in reducing groups to each individual gauge, switch, & light with a tie every couple of inches. You will be surprised how much better it looks, & how it then becomes as simple to look at as you'd think it would be when looking at the wiring diagram.

dashwiring.jpg


The harness which runs from the dash area to the rear of the car (taillights, gas gauge sender, etc.) goes down the left side I think, then turns around behind the rear panel, travels across, & terminates at the rear sidemarker on the other side. You will need to remove the seat on that side anyway to get at that, & you will need to remove the two vinyl/leathercloth upholstery panels on the sides in the rear to run the harness & get at the connections for the rear sidemarkers. Use one of those slotted spatula-like tools to pop out the upholstery panels, or the force of pulling the clips out will tear the cardboard-y backing of the panels that the clips attach to.

I don't think you'll need to remove the black cardboard interior panel at the very back underneath the hatch, as the wiring in that area is accessed from under the spare tire & gas tank covers. Don't fool with that black panel ever if possible, it is VERY prone to disintegration & tearing. Nothing to see under there, move along.

More typical than problems with the wire itself are problems at the connections & with the units themselves like the taillight bulb holders, etc. You can clean up connectors with a small piece cut from a Scotchbrite pad, or with little wire wheels on a Dremel tool. There is one wire "wheel" that is like a Q-Tip & works very well for getting inside the metal loops where the ground wire 'bullets' connect.

On the taillight bulb holders, often there is discontinuity in the unit on the ground side of the holder. It's a difficult problem if you identify it, as the solution is either a big glob of solder applied with a soldering gun in a good location & lots of luck, or just replacing the holder with a new one.

To get to the wires going to the door switches, it will be neccessary to peel away the carpeting on the sides of the door jamb before the footwell. I cannot remember where the wire to the dome light runs. I'd say just leave that run if nothing's wrong with it.

When I removed & unwrapped the engine harness last summer, I was surprised that the wiring was in such good condition. The short wasn't in the harness, so I re-installed it after I re-wrapped it with the same-width wiring harness wrap tape from ebay (wiring harness wrap tape is not electrical tape, it does not have adhesive but it does cling to itself). Yours may be different, if a previous owner has added aftermarket stereos, aircraft landing lights, etc. with lots of evil Scotchlok tap doodads here & there.

Edit:
Where the wires pass through the sheetmetal there are grommets of course, some are orignally of sort of strange design (solid with pierced center, etc.) I'd suggest being sure you've got all-new grommets on hand before starting.
 

Geo Hahn

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I had a lot of time to prepare for the re-wire of the TR3A when it went in for a 4-week paint job that took a year and 4 months.

Just because I had the time I did a rather methodical approach... laid the harness out just as it would lay in the car, made a large literal wiring diagram of the harness, compared that to the wiring diagrams in various manuals, verified every connector & tinned all ends that remained bare wire.

I then made a cardboard mockup of the dashboard with gauges and switches drawn in position (rear view) with holes for the connectors. I then wired it up making the ground harness and other bits that would be needed.

When the car finally came back I installed the harness in an afternoon and everything worked first time.

Not your situation I realize (and a GT6 loom is way more complex than a TR3A) but since you want to minimize downtime might give you some ideas on how to work ahead and encounter problems on paper before you tear into the car.
 
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rotoflex said:
Edit:
Where the wires pass through the sheetmetal there are grommets of course, some are orignally of sort of strange design (solid with pierced center, etc.) I'd suggest being sure you've got all-new grommets on hand before starting.


All the harnesses that I ever got from British Wiring had the grommets pre-installed in the proper places.
 

tomgt6

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Well, I just did a 63 spitfire. I found that the harness had been redone with 3 foot pieces of wire put together. So I did the cardinal sin, I bought a new general after market harness with more fuses and rewired the entire car. To make this easy you will want the left seat out. and the left rear side panel. The rest can be gotten from under the dash or by taking the dash out. I would do this in steps. If I remember there is a harness for the front headlights. Then a harness for the front engine and connects to the headlight area and then and the rear.

I would say if you had a good long weekend you could rewire the hole thing. If you get a new set of harnesses you will be able to breeze through parts of this. It seems like the connectors to the lighting was the biggest issue in my older car. The new 73 may be better. Good luck. Tom
 

rotoflex

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I added a photo of cable-tied wiring to the post above, taken last summer. The same approach should be undertaken behind the instruments in the section of dash over the steering wheel, going to outside sidemarkers & turn signals, the little buzzer behind the dash on the left, etc.

You will need to remove both seats if you intend to completely re-wire the car. The wiring for passenger seat pressure switch & the switches in both seatbelt latches runs under the seats.

tomgt6 said:
Well, I just did a 63 spitfire. I found that the harness had been redone with 3 foot pieces of wire put together.

After I bought the XK140 I had years ago, I found on the day when I finally undertook to remove the center of the dash to chase the electrical problems that the previous owner had completely rewired, all with zip cord. Light switch to lights, brown; windshield wiper switch to wiper motor, brown; fuses to switches, brown; everything else, brown. Simplified color code.
 

tomgt6

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That sounds like what I had to do. I would have 3 feet of white, tied to 3 feet of blue\green to 3 feet of black. What a mess. What was funny was that 90 of the electrical worked in this condition. But that was in the garage and it was dry. What do you think it would be like when it got wet?
 

Bugeye58

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Ah, yes. Lamp cord and speaker wire! /bcforum/images/%%GRAEMLIN_URL%%/grin.gif
Mine wasn't like that at all, but I've had 'em that were.
Jeff
 

TR3driver

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tomgt6 said:
I would have 3 feet of white, tied to 3 feet of blue\green to 3 feet of black. What a mess. What was funny was that 90 of the electrical worked in this condition.
Dang ! Those electrons must be color-blind !
/bcforum/images/%%GRAEMLIN_URL%%/jester.gif
 
OP
GT6_Mark

GT6_Mark

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These are great posts. Thanks. I have my tube of dielectric grease and dremel ready. A bit more digging around confirms dash and forward definitely needs redoing. Unwinding some of the harness tape shows too many examples where the wire sheathings have welded together, presumably due to heat from too much current draw. The harness looks to be on a six to eight week backorder, so I will have plenty of time to prepare. I'll take pictures and post back with progress. Mark
 
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GT6_Mark

GT6_Mark

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Jeff, Thanks. I know where to como for help. Mark
 
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