Bristol 403 Wiring Diagram

[Colin from Hull]

Hi
I was reading some old posts and a few years ago a member was modernising the 403 wiring diagram making coloured version did the pdf ever reach the forum.
If anyone has any advice putting new loom into the 403 please share your knowledge.

Cheers!

[HughMiller]

Here you go, Colin, as a .jpg.
I can convert it to .pdf if you need.
This is for a 401, so there will be some detail differences, and you'll want some add-ons for modern conveniences.

[pnaleahy]

My advice is firstly to obtain a new wiring harness made especially for the 403. It will have all the correct terminals on each wire termination and each wire will be tagged with connection details. Such harnesses are available from Vintage Wiring Harness in Australia, and are excellent. VINTAGE WIRING HARNESS
http://www.vinwire.com.au
1953-55 BRISTOL 401 & 403 (BR535)Price:$1,690.00 ex. GST $1,859.00 inc. GST
The next big item is getting the correctly fitting rubber grommets for the body holes and getting the stiff loom through them and in the correct location along its length so that the various 'arms' of the loom fall naturally through the correct parts of the body. Once the centrl part of the loom is in place, the rest is a matter of haveing a selection of the correct loom clips to keep it in place. Good luck. A wiring diagram is not particularly helpful or necessary, if you first have the correct loom which is made exactly for the car.

[pnaleahy]

Incidentally Bresco UK have the correct loom clips used in a Bristol sized according to the loom.

[Colin from Hull]

Hi
Thank you for your replies, while removing my old wiring harness I damaged one of my old 2.5volt lamp holders, I think there is three within the dashboard. The damaged one is for the foglight/ Headlight indication.
I didn't realise it had a built in coil on the back of it when trying to remove the holder from my dashboard which wasn't easy! And how do I remove the two next to each other at the drivers side ( I may just leave them in depending on the answer to my question)
So my question is are these still available if so, what are these holders called or could I modernise these with something simpler?

Also the dashboard top what was the original finish and colour? How is it removed?

Cheers!

[pnaleahy]

I think you'll find that the original Lucas part number for the lamp holder is P/N 318604, according to the original Lucas catalogue for the Bristol 403.

[peterg]

My dashboard top (below the windscreen) was painted Bristol red (same as the car) but had been over painted instrument (matt) black. That may have been done by Bristol. The shiny paint causes terrible reflections in the car.

My radiator grill was also Bristol red but had been over painted silver. I suspect that was also done by Bristol.

[mikebro]

Colin,

Firstly, Autosparks in the UK do a wiring loom for the 403. I have used one successfully. However, their loom ends up a bit thicker than the original, so I had to enlarge some of the holes through the bulkhead and use larger grommets. I had been told by someone else who had done an Aerodyne restoration that the main part of the loom had to be wired to the dashboard in situ in the car, with the windscreen not fitted. I decided to see if that was really necessary, as my windscreen was already fitted, and I was sure that wiring up on the bench would be infinitely preferable. I was able to remove the old loom complete with the dashboard without undoing any wires at the dashboard end. In which case I reckoned it would be possible to wire up the new (main part) loom to the dashboard on the bench. This I did, then reversed the sequence of pulling out the old loom and dashboard. Please don't ask me for detail on this! If your old loom is out already, I doubt you will be able to visualise how to thread the various bits of loom back in.

Regarding the 2.5v bulb and fitting - the bulb is a once very familiar standard hand torch bulb which draws 200mA. These are still available on (eg) Ebay, but be quick, as they are being rapidly replaced with LED torches. The Lucas bulb holders with the built in dropper resistor I don't think are still available and last time I did see replicas, they looked like the originals, but the dropper resistor was a dummy one. If you want to retain the 2.5v bulb, use a standard bulb holder but wire a dropper resistor in series. My calculation shows that about 50 Ohms at 2.5W should be about right to keep 200mA flowing through the bulb, but please get this checked as I did all this several years ago.

Regarding how to get the other two 2.5v bulbs and holders out, this is another good reason to get the dashboard out of the car. It's only a few 2BA screws and you'll be able to get at everything. Good Luck! Mike

[Raymond]

Colin. Mike is right about the replica bulb holders having a dummy resistor coil. By a strange coincidence I have just bought one of these thinking it was the same as the Lucas holder with a 2.5 volt bulb...but found that it is actually fitted with a 12 volt 3W bulb and a dummy coil that just looks like the original but actually does nothing.

????

The reason, I believe, for having a low voltage bulb and resistor coil in the first place was for reliability; a 2.5 V bulb with a resistor will last a lot longer than a 12 Volt one (without).

Another point to bear in mind is that if the light is left on for any length of time it will melt the plastic lens. I have a small light weight spring between the glass of the bulb and the lens to (hopefully) avoid this from happening .
.