Re-wiring
Re-wiring
I’m thinking about re-wiring my 1946 P2 12. The current wiring is a tangled mix of ancient and modern, some of it in poor condition. At the moment the car’s engine is out (partly rebuilt), the floor is up and the wings removed (pending much-delayed re-painting), so it seems like it might be a good opportunity to renew things. I understand wiring looms are available but that this is probably not something to be undertaken lightly. Does anyone have any advice, suggestions, tips etc.? Thanks
Re: Re-wiring
Dear John,
Rewiring is a straightforward process. If you can rewire a plug neatly and build an Airfix kit, you can rewire a car. One of my most recent rewiring jobs was on a 1946 Rover 14 last winter, virtually the same job as your 12 but just with a few extra inches in the front loom. The question is whether to buy a loom or make one. I've done both and also helped people who have bought a loom. If you want a car to potentially look as it did when new, buying a ready made loom is one option to achieve that. Assuming a supplier sends you a loom that is basically the right one for your car (yes, behind this cryptic phrase is a story - 3 days trying by the owner of a Morris 8, a night then with me ending up with me saying "the problem is it's not the loom for this car"), the three possibilities for the loom are :
1) It fits perfectly
2) It's too long or too short
3) It fits but has the wrong terminal connections on at least some of the ends.
Making a loom yourself can be a cost effective way of having your car running safely and well and it can also be turned into an "as built" result, without the risk of something being amiss. A loom that is too long can be a bit of bind if the makers have reduced their range so that one loom is sold as fitting several models with a similar layout and you have to hide excess wiring. I have about 2 feet of excess wire tucked under the rear of my 1933 Lanchester 10 for that reason.
A loom that has just been made that little bit net in length creates different problems such as neatly wiring the control box where 14 or so ends really want to fan neatly and not all have been cut to just the same length because, of course, the box has length and the layout needs to take account of where the terminals are. This can be a problem with just post war cars where the vehicle may have been originally fitted with an RF91 control box but subsequently fitted with an RF95 which has the same amount of wires but laid out in a different order.
There is also the question of any extras you may wish to have added to a loom, such as flashing indicators, a heater fan, accessory socket or the like.
I'm not going to say that one option will be trouble free and the other won't, just that both require a bit of forethought before you commit to either. A new loom will ideally incorporate everything you require in the right places and with the right pre fitted connections by the makers, otherwise why spend a considerable sum of money for it.
The question then becomes, if you end up doing quite a bit of research and working out yourself, why not go the whole way and do it all yourself for a total cost of in the region of £80 - £90 assuming you have some tools.
The best starting point, I've found, if you are doing the job yourself, is to first of all remove virtually all the wiring on the car. It is probably a mixture of the original, the patched, the added to. The wire can all be bought in its correct colours from Autosparks by the metre. You can also buy some of the colours cheaper elsewhere and, for example, 50 metres of thin wall black 16.5 amp on a roll would be a good start for earth wires.
You'll find you need comparatively small amounts of some colours but the thing to do is, with the help of a decently enlarged wiring diagram, work out what you need and think about where earth points either are or could be added to. Whether you're making it or buying it, fitting the loom to the dashboard really means taking the instrument panel out. This is a good opportunity to fix or paint anything connected with that area because you won't be wanting to do this again in a hurry. Take careful note and a few photos of how the instrument illumination bulbs are located. Things like instrument illumination wiring - in effect, an underdash "subloom" don't usually come with ready made looms so this is likely to be a do it yourself part if it is also tired. A 1 amp fuse in the supply to a working electric clock is a good idea.
The areas it would be a good idea to think carefully about before applying a pair of cutters are the trafficator wires and the roof light. It may be an option to just join in a new loom to the existing wiring at a suitable point. Making a job of these with new wiring can be a long process if you haven't a need to dismantle anything else in their area.
Just going back for a minute to the point I mentioned about connectors. This may seem very small but, to take two components as an example - the dynamo and the solenoid. Has your dynamo Lucar connections, rings or just bare ends into terminals ? Does the solenoid have a bare end connection for the wire from the push switch or a Lucar one ? The answers will depend on whether units like these are original or replacements. If you are having a loom made, it's a good idea to be able to tell the make what is fitted to each item where there is a choice as otherwise you'll end up doing what you would have been doing making a loom- fitting one yourself.
Finally (well, nearly!), the covering. I use cloth harness tape. I've found it to be surprisingly good in that the cloth cover does bear a reasonable resemblance to the original although without the original striping. I have thought of experimenting with a Sharpie pen to see if I could make a convincing yellow or red stripe but haven't got that far yet. Another option, particularly for the likes of the rear lights, would be to have some additional protection and that's really your choice, either an armoured covering or spiral of some material. Heat shrink is good for the ends of the cables to give a neat finish to terminals.
If you want a home made loom to look really good, you can send your creation to Autosparks and have them bind what you have made.
Just thinking further, another wire you won't have in a new loom is the multicore cable for the horn and dipswitch. A length of the appropriate new multicore will solve that though. You may also wish to replace the main supply from the battery to the starter while doing the rest of it, the fitting or not of a master switch at the front being another variable. I don't know if your car still has a mechanical AC fuel pump at the front or has a replacement electric pump? My own 1947 12 is an export model with a front mounted SU pump but both 14s have been fitted with rear mounted SU pumps and these are all items that are best incorporated properly in a new loom with appropriate earth wiring if needed. Headlamp connections are now normally made with separate "pigtails" which connect to the main loom.
Should you decide to make a loom yourself and have a proper bullet crimper, I can recommend the bullet connectors Autosparks sell. They are better than the generic 1mm and 2mm ones you see on Ebay and elsewhere. They can work ok but only if the wire being used is very close to the 1mm or 2mm, which usually involved stripping back a bit further and turning over enough strands to make the wire the right diameter otherwise the bullets break. The Autosparks bullets actually fit the size of wire they are for and on that cheery note I'll stop and leave you to make up your own mind as to what the best thing to do is.
Rewiring is a straightforward process. If you can rewire a plug neatly and build an Airfix kit, you can rewire a car. One of my most recent rewiring jobs was on a 1946 Rover 14 last winter, virtually the same job as your 12 but just with a few extra inches in the front loom. The question is whether to buy a loom or make one. I've done both and also helped people who have bought a loom. If you want a car to potentially look as it did when new, buying a ready made loom is one option to achieve that. Assuming a supplier sends you a loom that is basically the right one for your car (yes, behind this cryptic phrase is a story - 3 days trying by the owner of a Morris 8, a night then with me ending up with me saying "the problem is it's not the loom for this car"), the three possibilities for the loom are :
1) It fits perfectly
2) It's too long or too short
3) It fits but has the wrong terminal connections on at least some of the ends.
Making a loom yourself can be a cost effective way of having your car running safely and well and it can also be turned into an "as built" result, without the risk of something being amiss. A loom that is too long can be a bit of bind if the makers have reduced their range so that one loom is sold as fitting several models with a similar layout and you have to hide excess wiring. I have about 2 feet of excess wire tucked under the rear of my 1933 Lanchester 10 for that reason.
A loom that has just been made that little bit net in length creates different problems such as neatly wiring the control box where 14 or so ends really want to fan neatly and not all have been cut to just the same length because, of course, the box has length and the layout needs to take account of where the terminals are. This can be a problem with just post war cars where the vehicle may have been originally fitted with an RF91 control box but subsequently fitted with an RF95 which has the same amount of wires but laid out in a different order.
There is also the question of any extras you may wish to have added to a loom, such as flashing indicators, a heater fan, accessory socket or the like.
I'm not going to say that one option will be trouble free and the other won't, just that both require a bit of forethought before you commit to either. A new loom will ideally incorporate everything you require in the right places and with the right pre fitted connections by the makers, otherwise why spend a considerable sum of money for it.
The question then becomes, if you end up doing quite a bit of research and working out yourself, why not go the whole way and do it all yourself for a total cost of in the region of £80 - £90 assuming you have some tools.
The best starting point, I've found, if you are doing the job yourself, is to first of all remove virtually all the wiring on the car. It is probably a mixture of the original, the patched, the added to. The wire can all be bought in its correct colours from Autosparks by the metre. You can also buy some of the colours cheaper elsewhere and, for example, 50 metres of thin wall black 16.5 amp on a roll would be a good start for earth wires.
You'll find you need comparatively small amounts of some colours but the thing to do is, with the help of a decently enlarged wiring diagram, work out what you need and think about where earth points either are or could be added to. Whether you're making it or buying it, fitting the loom to the dashboard really means taking the instrument panel out. This is a good opportunity to fix or paint anything connected with that area because you won't be wanting to do this again in a hurry. Take careful note and a few photos of how the instrument illumination bulbs are located. Things like instrument illumination wiring - in effect, an underdash "subloom" don't usually come with ready made looms so this is likely to be a do it yourself part if it is also tired. A 1 amp fuse in the supply to a working electric clock is a good idea.
The areas it would be a good idea to think carefully about before applying a pair of cutters are the trafficator wires and the roof light. It may be an option to just join in a new loom to the existing wiring at a suitable point. Making a job of these with new wiring can be a long process if you haven't a need to dismantle anything else in their area.
Just going back for a minute to the point I mentioned about connectors. This may seem very small but, to take two components as an example - the dynamo and the solenoid. Has your dynamo Lucar connections, rings or just bare ends into terminals ? Does the solenoid have a bare end connection for the wire from the push switch or a Lucar one ? The answers will depend on whether units like these are original or replacements. If you are having a loom made, it's a good idea to be able to tell the make what is fitted to each item where there is a choice as otherwise you'll end up doing what you would have been doing making a loom- fitting one yourself.
Finally (well, nearly!), the covering. I use cloth harness tape. I've found it to be surprisingly good in that the cloth cover does bear a reasonable resemblance to the original although without the original striping. I have thought of experimenting with a Sharpie pen to see if I could make a convincing yellow or red stripe but haven't got that far yet. Another option, particularly for the likes of the rear lights, would be to have some additional protection and that's really your choice, either an armoured covering or spiral of some material. Heat shrink is good for the ends of the cables to give a neat finish to terminals.
If you want a home made loom to look really good, you can send your creation to Autosparks and have them bind what you have made.
Just thinking further, another wire you won't have in a new loom is the multicore cable for the horn and dipswitch. A length of the appropriate new multicore will solve that though. You may also wish to replace the main supply from the battery to the starter while doing the rest of it, the fitting or not of a master switch at the front being another variable. I don't know if your car still has a mechanical AC fuel pump at the front or has a replacement electric pump? My own 1947 12 is an export model with a front mounted SU pump but both 14s have been fitted with rear mounted SU pumps and these are all items that are best incorporated properly in a new loom with appropriate earth wiring if needed. Headlamp connections are now normally made with separate "pigtails" which connect to the main loom.
Should you decide to make a loom yourself and have a proper bullet crimper, I can recommend the bullet connectors Autosparks sell. They are better than the generic 1mm and 2mm ones you see on Ebay and elsewhere. They can work ok but only if the wire being used is very close to the 1mm or 2mm, which usually involved stripping back a bit further and turning over enough strands to make the wire the right diameter otherwise the bullets break. The Autosparks bullets actually fit the size of wire they are for and on that cheery note I'll stop and leave you to make up your own mind as to what the best thing to do is.
Re: Re-wiring
Many thanks for your comprehensive guidance and tips on this issue. Certainly, now I feel a bit more confident about tackling the job, which had seemed a bit daunting, as I haven't done much electrical work in the past. I’d be inclined to buy a loom rather than do everything from scratch, though I must admit the latter option hadn’t occurred to me so I will give that some thought too.
Regards,
John
Regards,
John
Re: Re-wiring
Hi John,
I’ve rewired two cars now, a P1 and a P2. Having a professionally made loom is a great advantage and the end result is so much better than a DIY loom, which can so easily appear like a bodge job! AutoSparks can make you a loom in either plastic or cotton covered wires. They will also add in any additional bits like flashing indicators, electric fuel pump or an alternator. So the first thing to do is decide what you require. I fitted a Dynamator to my cars so the loom didn’t require wiring for a regulator box. I also changed to negative earth, which needs to be decided before buying an alternator or electric fuel pump.
When you order the loom you also need to buy new junction boxes and miscellaneous wiring bits like spade connectors and heat shrink sleeving. Personally, I don’t like crimp connectors and feel it’s best to solder wires and connectors.
Once you have the desired loom, lay it all out and identify each wire and mark what it is and where it goes, with reference to the wiring diagram, using paper masking tape. Then you can put it into the car with a fair idea of what goes where. It’s a long winded job getting everything connected but with good planning should be straight forward. Not a bad idea to leave the old wires in place at the lights, wiper motor, reg box etc and just cut them off short so you can swap for the new ones when you get to that bit. As suggested previously, it’s best to leave the old horn/dip wires and interior light and trafficator wiring for re-use if possible. That said, the wires through the steering column do wear and short out so replacing those is a good idea, if not already done, and the loom won’t include those.
You will need electrical solder, insulating tape, a soldering iron, wire strippers and a multi meter for testing. Stick to the wiring diagram and you can’t go far wrong. Wiring always seems a mystery but it’s just the right colour wire to the right place, one at a time!
Good luck and let us know how it goes.
Tony.
I’ve rewired two cars now, a P1 and a P2. Having a professionally made loom is a great advantage and the end result is so much better than a DIY loom, which can so easily appear like a bodge job! AutoSparks can make you a loom in either plastic or cotton covered wires. They will also add in any additional bits like flashing indicators, electric fuel pump or an alternator. So the first thing to do is decide what you require. I fitted a Dynamator to my cars so the loom didn’t require wiring for a regulator box. I also changed to negative earth, which needs to be decided before buying an alternator or electric fuel pump.
When you order the loom you also need to buy new junction boxes and miscellaneous wiring bits like spade connectors and heat shrink sleeving. Personally, I don’t like crimp connectors and feel it’s best to solder wires and connectors.
Once you have the desired loom, lay it all out and identify each wire and mark what it is and where it goes, with reference to the wiring diagram, using paper masking tape. Then you can put it into the car with a fair idea of what goes where. It’s a long winded job getting everything connected but with good planning should be straight forward. Not a bad idea to leave the old wires in place at the lights, wiper motor, reg box etc and just cut them off short so you can swap for the new ones when you get to that bit. As suggested previously, it’s best to leave the old horn/dip wires and interior light and trafficator wiring for re-use if possible. That said, the wires through the steering column do wear and short out so replacing those is a good idea, if not already done, and the loom won’t include those.
You will need electrical solder, insulating tape, a soldering iron, wire strippers and a multi meter for testing. Stick to the wiring diagram and you can’t go far wrong. Wiring always seems a mystery but it’s just the right colour wire to the right place, one at a time!
Good luck and let us know how it goes.
Tony.
Tony Gilbert
P1 12 Tourer
P2 12 6 Light Saloon
Discovery 3
Discovery Sport
P1 12 Tourer
P2 12 6 Light Saloon
Discovery 3
Discovery Sport
Re: Re-wiring
My advice, and I think it is important, is to remove the instrument fascia from the car and do (most) of the wiring on the working table, then to test it there and only when tested to introduce it back to car. It really makes the whole procedure easier and safer. See some examples here:
https://lulis.org/2012/07/20/26-453-%d7 ... %95%d7%97/
https://lulis.org/2012/08/28/26-453-%d7 ... -%d7%94-2/
https://lulis.org/2012/07/20/26-453-%d7 ... %95%d7%97/
https://lulis.org/2017/10/30/wiring-tourer/
https://lulis.org/2018/10/19/51-%d7%92% ... %a1%d7%99/
-
https://lulis.org/2012/07/20/26-453-%d7 ... %95%d7%97/
https://lulis.org/2012/08/28/26-453-%d7 ... -%d7%94-2/
https://lulis.org/2012/07/20/26-453-%d7 ... %95%d7%97/
https://lulis.org/2017/10/30/wiring-tourer/
https://lulis.org/2018/10/19/51-%d7%92% ... %a1%d7%99/
-
Re: Re-wiring
Hello Tony and Luli,
Thank you for your advice and insights, and for sharing the benefit of your collective experience . Very much appreciated. I think I've got a sense now of what this will entail.
Regards,
John
Thank you for your advice and insights, and for sharing the benefit of your collective experience . Very much appreciated. I think I've got a sense now of what this will entail.
Regards,
John
Re: Re-wiring
John,
Having suffered from some "original Lucas smoke" (Apparently available in cans in the USA.....) from the dash I set about checking the wiring from the regulator to the dashboard. I discovered that where the loom went through the scuttle on the nearside there was evidence of damage. It did not look good so I took a deep breath and slit the original loon covering. In the loom were some 20 wires, and at least 10 of them showed evidence of insulation failure...cracked, worn away or in some cases non-existent! Clearly all that was keeping the wires from shorting out was the fact that none were actually touching, and being tightly held together, were not able to chafe against each other....The Dynamo & starter solenoid cables were also tackled
Replacing was easier than I feared. The wiring diagram is your new best friend !
I had bought replacement cotton covered (over modern flexible insulation) cable from SVC (Also trade as Vintage & Classic Spares / was Complete Automobilist etc) and was able to source almost all the original colour combinations from stock. The old loom looked as if it was from an old fashioned ladies' hairdresser salon - with paper identifiers on every wire! Re wiring was straightforward...ONE WIRE AT A TIME. Check the Diagram, check continuity, check the length. It was a good opportunity to get rid of a number of (later) additional bits of wiring....the wiper was a particular challenge! and to add the supplementary temperature gauge. It took two of us a full day, but by the end I believe I have a much safer car! Properly fitted bullet and ring connectors and a tidy loom...mostly in the original colours!
I should add that the car started first time and that EVERYTHING worked. No Smoke. Very satisfying The dash is now back in place and the trim will go back next
Having suffered from some "original Lucas smoke" (Apparently available in cans in the USA.....) from the dash I set about checking the wiring from the regulator to the dashboard. I discovered that where the loom went through the scuttle on the nearside there was evidence of damage. It did not look good so I took a deep breath and slit the original loon covering. In the loom were some 20 wires, and at least 10 of them showed evidence of insulation failure...cracked, worn away or in some cases non-existent! Clearly all that was keeping the wires from shorting out was the fact that none were actually touching, and being tightly held together, were not able to chafe against each other....The Dynamo & starter solenoid cables were also tackled
Replacing was easier than I feared. The wiring diagram is your new best friend !
I had bought replacement cotton covered (over modern flexible insulation) cable from SVC (Also trade as Vintage & Classic Spares / was Complete Automobilist etc) and was able to source almost all the original colour combinations from stock. The old loom looked as if it was from an old fashioned ladies' hairdresser salon - with paper identifiers on every wire! Re wiring was straightforward...ONE WIRE AT A TIME. Check the Diagram, check continuity, check the length. It was a good opportunity to get rid of a number of (later) additional bits of wiring....the wiper was a particular challenge! and to add the supplementary temperature gauge. It took two of us a full day, but by the end I believe I have a much safer car! Properly fitted bullet and ring connectors and a tidy loom...mostly in the original colours!
I should add that the car started first time and that EVERYTHING worked. No Smoke. Very satisfying The dash is now back in place and the trim will go back next
Re: Re-wiring
Hello David,
Thanks very much for your comments and tips. Further encouragement to tackle the job. And particularly good to know that in theory a couple of people can do it in a day.
Regards,
John
Thanks very much for your comments and tips. Further encouragement to tackle the job. And particularly good to know that in theory a couple of people can do it in a day.
Regards,
John
-
RobHomewood
- Posts: 320
- Joined: Tue Oct 22, 2013 8:04 pm
Re: Re-wiring
Hi David
I have to say that my rewiring took a lot more than one day! Admittedly I did not dismantle the car at all except for removing the dash, I was single-handed and a novice but it took me any number of days (OK not full days). I had certainly spent many more days drawing up diagrams of the wiring looms, colours & lengths etc. My aim was to eliminate any intermediate joints in the wiring as that was where I had had a lot if issues. I didn't buy a ready-made loom because there seemed to be a lot of differences to the basic. I made up part looms prior to installation by fixing the different coloured wires on the inside of the garage door, pulled them together down the garage, cut them off at the required lengths and fitting the sleeve - in sections as each branch came off. The only part I didn't do yet was the trafficators where the re-wiring will require the destructive removal of leather upholstery around the rear seats (the flashing indicators to front and rear and twin flasher units were done OK).
As well as trying to get the correct wiring colours I did get a heavier wire where available to reduce 'electrical stress'. I am very happy that I did rewire because the state of the 80 year old wiring was an on-going fire hazard apart from the source of untraceable failures.
One point which I am sure you wont forget is to leave a pull wire down the steering shaft- my new loom was a very tight fit partly because of heavier gauge wires but also there was an extra wire due to changing the headlamp/passlight system of dipping to dipping headlights and separate foglamp. I couldnt have managed without a strong pull wire.
Best of luck
Rob
I have to say that my rewiring took a lot more than one day! Admittedly I did not dismantle the car at all except for removing the dash, I was single-handed and a novice but it took me any number of days (OK not full days). I had certainly spent many more days drawing up diagrams of the wiring looms, colours & lengths etc. My aim was to eliminate any intermediate joints in the wiring as that was where I had had a lot if issues. I didn't buy a ready-made loom because there seemed to be a lot of differences to the basic. I made up part looms prior to installation by fixing the different coloured wires on the inside of the garage door, pulled them together down the garage, cut them off at the required lengths and fitting the sleeve - in sections as each branch came off. The only part I didn't do yet was the trafficators where the re-wiring will require the destructive removal of leather upholstery around the rear seats (the flashing indicators to front and rear and twin flasher units were done OK).
As well as trying to get the correct wiring colours I did get a heavier wire where available to reduce 'electrical stress'. I am very happy that I did rewire because the state of the 80 year old wiring was an on-going fire hazard apart from the source of untraceable failures.
One point which I am sure you wont forget is to leave a pull wire down the steering shaft- my new loom was a very tight fit partly because of heavier gauge wires but also there was an extra wire due to changing the headlamp/passlight system of dipping to dipping headlights and separate foglamp. I couldnt have managed without a strong pull wire.
Best of luck
Rob