Loom replacement in assembled car

[iani]

My car is a '69 CP PI, however, when it was rebuilt, a number of changes were made. The car is fitted with a steering lock so the ignition has been moved from the switch plinth, I also see a thick brown/white wire that has been cut off by the steering column and another end of it is loose near behind the dash, the car still has an ammeter which works. Given that I'm now having some "fun" with something shorting out and blowing fuse one (14v on a solid state voltage regulator before it started smoking) I appear to have cocked something up with the wiring. The wiring isn't in the best of health, I'm prepared to buy a new loom but how realistic is it to fit one an a car that is assembled? Obviously I'll remove the seats & gearbox tunnel for access, should I be able to swap everything over in a standard garage?

Ian

[Waldi]

Hi Ian,

I could first try to see which wiring is damaged. Maybe some bypasses can solve the issue at little effort and cost.That’s the quickest /cheapest option.

Fitting a new loom in a complete car is quite a bit of work and money, but not undoable. You may be tempted to increase the scope, like heater hoses, checking all switches, refurbing the heater and do some sensible upgrades to the electrical system. 

Waldi

[PodOne]

Not wanting to highjack this thread Ian but mine is also a 69 CP and currently stripped to a shell.

I've salvaged what I can in terms of switches and replaced where required. The harness is an unknown commodity and I'm torn between trying to salvage it or simply buying a new loom form AutoSparkes but with mods for electric fan, radio and fuel pump etc its going to be touching £400 which seems expensive. So I'm pondering salvaging the current loom and incorporating the mods, cutting off all the bullet connectors and replacing with resin impregnated spades, rewrapping and replacing and cutting the loom so that the dash will simply lift out after "unplugging it" along with a few extra fuses.

Think its going to depend on the quality of the copper wire itself in terms of how oxidised it is at the ends if its blackened it could be toast as there is no way of knowing how far this will extend down the affected wires and a fire risk.

Anyone done anything similar? 

Andy

  

[Nigel Triumph]

If I was rebuilding a 50+ year old car from a bare shell, I would fit a new loom. Autosparks have a good reputation.

In Ian's case, I would follow Waldi's advice and try to trace and repair any damaged wires. It will be quicker and cheaper than a complete rewire.

Nigel

[Mike C]

I'm interested in Andy's ideas- get rid of the troublesome bullet connectors and bring all the dashboard wiring to one central plug to allow easy removal- and avoid having to connect wires directly to the back of the instrumentation  gauges.

[harrytr5]

4 hours ago, iani said:

My car is a '69 CP PI, however, when it was rebuilt, a number of changes were made. The car is fitted with a steering lock so the ignition has been moved from the switch plinth, I also see a thick brown/white wire that has been cut off by the steering column and another end of it is loose near behind the dash, the car still has an ammeter which works. Given that I'm now having some "fun" with something shorting out and blowing fuse one (14v on a solid state voltage regulator before it started smoking) I appear to have cocked something up with the wiring. The wiring isn't in the best of health, I'm prepared to buy a new loom but how realistic is it to fit one an a car that is assembled? Obviously I'll remove the seats & gearbox tunnel for access, should I be able to swap everything over in a standard garage?

Ian

It is all doable Ian. Just make sure you have a coloured wiring diagram (I laminate mine).

Regards Harry TR5 Nutter

[JochemsTR]

16 hours ago, iani said:

The wiring isn't in the best of health, I'm prepared to buy a new loom but how realistic is it to fit one an a car that is assembled?

If you think there may be more wiring affected, replacing just one of them is not going to help you. Since you cannot be sure about the quality which is hidden behind the wrapping.

You did such a great job with the EFI, why stop there? If you are not sure, replace the loom. Add some mods such as additional relais and replace the original fuse box with a modern fuse box. I spent about 120 hours on my loom, but I added three additional relais/fuse boxes, and replaced a few connectors. I have no worries anything electrical happening.....that is a good feeling driving around.....

Jochem

Edited March 2, 2020 by JochemsTR

[Pogo]

Hi Ian

I wouldn't take any chances - I'd replace the complete loom with the upgrades you need.

I did mine last year as I has some suspect smoke coming from under the dash. I bought mine from Autosparks and I'm very happy with it.

It wasn't too difficult and to be honest I quite enjoyed the challenge. My car was completely assembled when I did it.

Take your time. Cut off all the existing wires so it's easy to identify what goes where. I also had a laminated wiring diagram and double checked all the wires went where I expected them to go. I had additional relays put in and added wiring for electric fan (just in case I decide to do add one in the future), spot lights, Bosch fuel pump in the boot, additional socket under the dash and radio. I also changed my ammeter for a voltmeter (with all the relevant wiring) after recommendations from some TR Gurus!

I don't actually think it was the loom that was smoking now, but I'm glad I did the loom. Your car is 50+ years old and that wiring is probably past its best now.

Rog

[Fireman049]

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Edited April 15, 2020 by Fireman049

[iani]

Thanks chaps, an interesting array of opinions, my loom is a rats nest of PO added wiring, further complicated by my adding the EFI wires. I think I’m best off replacing the lot of it.

Ian

[Keith66]

Hi

Andy and Ian

Here’s my two peneth.

Firstly Andy you say that the original harness is an unknown quantity. Assume by that either you bought the car non-working or it’s been sat for ages.

Pretty similar to mine. My car had been off the road for over a decade and was undergoing a complete strip down so I made the decision to buy new. Unless you can thoughouly test the old harness you might be refitting existing faults or something about to fail and its 50 years old anyway so manhandling it might not do it any good. So given similar circumstances and a car in bits I paid the money and bought an Autosparks.

But I made a mistake as I went standard apart from an electric fan option. Now I would add a direct feed for the fuel pump via a relay. I’m still going to do that but simpler if they do it.

Similar one for you Ian, How’s the existing harness? If any probs I’d replace but it’s a big job (I would imagine) on a complete car as its going to be fiddly and a pain, esp. wiring the dash with things in place. Removing lots of stuff is a job in itself.

Can you do it in a domestic garage? Well yes cuz my complete restoration has been done in single garages, but again it can be a pain, but like me if you don’t have a double garage or workshop you’ve got little choice other than to just got to struggle on.

Cheers   Keith

 

Not as easy with everything in place

Edited March 2, 2020 by Keith66

[Pogo]

20 hours ago, iani said:

should I be able to swap everything over in a standard garage?

I would have thought it possible, but I moved mine onto the drive so I could open the doors and work without restrictions. I did take the dash out - refurbished that whilst I had the opportunity. I suppose a lot depends on how bendy you are! I'm not any more so it was easier on the drive. It was fiddly but OK having the car complete rather than doing it on a stripped down car.

[PodOne]

8 hours ago, Keith66 said:

Firstly Andy you say that the original harness is an unknown quantity. Assume by that either you bought the car non-working or it’s been sat for ages.

Pretty similar to mine. My car had been off the road for over a decade and was undergoing a complete strip down so I made the decision to buy new. Unless you can thoughouly test the old harness you might be refitting existing faults or something about to fail and its 50 years old anyway so manhandling it might not do it any good. So given similar circumstances and a car in bits I paid the money and bought an Autosparks.

But I made a mistake as I went standard apart from an electric fan option. Now I would add a direct feed for the fuel pump via a relay. I’m still going to do that but simpler if they do it.

Hi Keith

Bought mostly stripped and in boxes so nothing working and I've no idea how log its been off the road. Your probably right I could be simply refitting problems and I'd rather be driving her than tracking niggling electrical gremlins. Take your point re fuel pump feed which is a good idea if I ever get the itch to go down the EFI root.

Andy

[Keith66]

Hi Andy

On the direct feed fo the fuel pump I was actuality thinking of a Pi car esp one still fitted with a Lucas fuel pump as they tend to be less tolerant of voltage drop, even a small one, that can sometimes be present in a harness, though less common in a new harness one would hope. Not sure if the same is true of a Bosch type pump.

Cheers  Keith

[mhossack]

Hi Iani I purchased an ex USA rebuilt and rewired very badly to RHD in the UK. 

 

First in a single garage, if you can get the doors fully open yes but more difficult.

I did mine in a large single garage but was always able to roll it out into the open to work on. I did mine with the hardtop fitted.

If you think you are capable of doing the work I consider it quite an easy job.

Like me I am sure you will come across a few unknowns, mine mainly due to the difference between US and UK cars.

 

I purchased both front and rear UK 1975 looms from AutoSparkes which I thought were very good value for money.

I worked off the correct 1975 wiring diagram and did not cut of the old loom ends, but I think that is a very good idea.

I completely stripped the old wiring loom and kept it for any changes in the correct coloured wires.

 

To show how eccentric I am I even used the correct colour wire about 75mm to get the rear side indicators working, both sides had different colour wires, my original US car came with red rear side lights.     

[Pogo]

43 minutes ago, mhossack said:

To show how eccentric I am I even used the correct colour wire about 75mm to get the rear side indicators working, both sides had different colour wires, my original US car came with red rear side lights.     

Yep - me too! 

[PodOne]

21 hours ago, Keith66 said:

Hi Andy

On the direct feed fo the fuel pump I was actuality thinking of a Pi car esp one still fitted with a Lucas fuel pump as they tend to be less tolerant of voltage drop, even a small one, that can sometimes be present in a harness, though less common in a new harness one would hope. Not sure if the same is true of a Bosch type pump.

Cheers  Keith

Hi Keith

Planning on running the original Lucas PI system which has all been reconditioned including the Lucas pump. A separate feed was on the list but I suspect any fuel pump will benefit from a separate feed direct from the battery.

Andy