Bristol 400 - access to rear of ignition swx

[Marcus]

A loose contact / bad connection has arisen in the ignition switch and from time to time I lose all electrical contact, normally regained after 'fiddling' with the ignition key in the switch. I really need to examine the rear of the switch unit to either reconnect the wires more securely or effect some other remedy.

So Gentlemen - question - how do I access the rear of the switch? I have removed the two front chrome bezels but the switch 'unit' is held within a metal cradle which seems to be soldered to the metal base plate and clearly was positioned in 1949 and has not moved since! Before I remove the radio - original kit - and try to locate the rear of the switch from below and behind, is there any other simpler means to get at the back of the switch?

Thankyou

[Geoff Dowdle]

Marcus ,
I had a similar problem many years ago , just after the first restoration of my 400 . I fitted a new wiring loom and later found that all the screws at the back of the ignition switch needed retightening.
In the past 25 years I have not had a further problem except that when I have the head lights on the ignition key gets warm , probably caused by worn contacts within the switch. I suggest 400 owners fit relays to both the high & low beam circuits and the main power will then not go through the light switch.
I'm about to fit a new loom to my other 400 and will solder the ends of the wires before fitting them to the ignition/light switch, this should give a better contact .

I doubt that you would achieve much by pulling the switch apart except cleaning the contacts , I think your problem is loose wires .

The switch bracket is held onto the steel dash frame with a few screws , the central wooden dash panel must be removed to access them .
depending on the length of wire available behind the switch its possible to draw the switch away from the frame and tighten the grub screws that are fixing the wires to the back of the switch. But more than likely there will not be enough length in those wires , so I suggest you drop the radio and you then have reasonable access but poor visibility.

I have never pulled one of this switches apart but have a spare which is probably no better than yours .

Good luck
Geoff

[Geoff Dowdle]

Marcus ,
I have just disassembled a Ignition/headlight switch from a 400 (same as 401 but uses a different key blank) .
As you can see from the photos , the grub screws that hold the wires to the rear of the switch .
The internal contacts shown are for the light switch which had a build up if dirt/dust and some oil and would not have allowed a proper contact .

To remove the key barrel assembly and expose ignition switch contacts the central lock nut would have to have its solder removed .
Unless the ignition switch was not working I would not touch that .

I hope this helps
Geoff

[Marcus]

Wow Geoff how generous you are with your time and effort and a detailed explanation complete with pics...! Thankyou so much.

I had assumed the radio would have to come out as I could not get any where near releasing the fine screw heads that hold the cradle to the metal back plate and perhaps it is just as well as the next step would have been an impact driver or something similar... It is clear these have never been removed.

I am hopeful that the final remedy will be reseating the various wires securely at the rear of the switch as this intermittent electrical 'blackout' has all the hallmarks of being a bad/loose connection.

Again thankyou so much for your help and I will get on with dropping the radio though my post had hoped that there would have been some quick and easy way to access the rear of the switch in a manner I had not considered. Ah well!