Smiths Car Heater

While not specific to any particular vehicle, the information contained in the link below seems to cover the early V8 Bristols but may apply also to the 6 cyls. It is included so that members may get a better understanding of how things work, and we thank Per Blomquist for sending it in.



Chrysler 360 Rotomaster ignition

The Chrysler 360 Rotomaster turbocharged version fitted to about 30 Beaufighters and 25 Brigands apparently has a major flaw in engine control systems as originally configured and supplied by Bristol and Rotomaster. The flaw is with ignition timing which needs to be massively retarded under boost conditions, and the set up originally supplied by Bristol is very hit and miss. If the ignition is not retarded quickly enough by the distributor set up then you get massive detonation.

Any turbo charged car maintained by Bristols or where the owner has taken advice from them will have been fitted with a MSD Ignition system (part number MSD 6BTM) which is controlled by a MSD control knob (part number 6BTM 6462). The control knob allows the user to dial in the extent of retard under boost conditions from NIL to 3 degrees per pound of boost pressure. Once set up correctly the knob is best hidden, at least from a retard like me. You will of course appreciate why straightaway! The exact set up depends on fuel quality used and the set up of the turbo wastegate.

Below are copies of the instruction manuals. Please click the appropriate heading to download a copy.


408 miscelaneous parts suppliers


Bristol Part No Jaguar Part No Other Part No Part description Source
404-1-23049 N/A SKF 30304J2/Q Outer bearing -stub axle Bearing King
N721009 N/A SKF 32206J2/Q Inner bearing -stub axle Bearing King
907-1-23175 N/A MFC TC 1.750 2.750 0.375 1 Hub seal TOP Hinckley
407-1-23168 CAC9938X N/A Upper Ball Joint David Manners – CAC9938
907-1-23170 10821 Dunlop VBO 5138/L Brake pads(Dunlop calipers) David Manners – 10821
? 8522 N/A Handbrake pads (Dunlop) David Manners – 8522
407-1-23134 C29979 N/A Rebound stop David Manners – C17172
? 148876J N/A Voltage stabiliser for minor gauges David Manners – 148876J
907-1-63032 JLM9552 Lucas 35020 Flasher unit David Manners – JLM9552
907-1-68004 C24158 Lucas 33209B Ignition relay David Manners – C24158
907-1-68010 C26651 Lucas 33232A (6RA) Cooling Fan relay David Manners – C26651
908-1-68014 C26651 Lucas 33250A Heated Rear Window relay David Manners – C26651
907-1-63063 C26651 Lucas 33188B Horn relay David Manners – C26651
? N/A Lucas DLB102 Igniton coil Lucas DLB102 Auto Electrical Supplies Ltd,         Part No 060711
? N/A Lucas 060703 Ballast resistor 1.6 Ohms Auto Electrical Supplies Ltd, Part No 060703
907-1-63023 N/A Lucas 31788 Heater,Side/headlight switch OFF-ON-ON Holden – Part No 31837
N/A N/A Lucas 153601 Chromed sleeve Bezel for panel switch mounting Not currently available
907-1-63067 N/A Lucas 31800 Floor mounted Dip Switch Holden – 31800 (BMC J4 Van)
907-1-63024 N/A Lucas 31828A Petrol Reserve,Rooflight,Fog lamp switch, OFF-ON Holden – SPB200
908-1-68021 N/A Lucas 54330378 Fan Hold Pull Switch  OFF-ON Holden – 020.316
910-1-68045   Lucas 35633 Hazard warning switch Holden – 33888               Holden – 397511
  Holden Vintage & Classic Ltd, Linton Trading Estate,Bromyard, Herefordshire HR7 4QT.  T 01885 488488  Fax 01885 488889    Website – Order On-line Bearing King Unit 5 Stonerow Way Parkgate Rotherham S60 1SG Transmission of Power (TOP) Unit 37 Workshops Sketchley Meadows Industrial Estate, Hinckley  01455 616606/616538  Auto Electric Supplies Limited, Granville House, 11 Cross Street, Tenbury Wells, Worcestershire, WR15 8EF, UK T 01584 819552 Fax  01584 819355 email: David Manners Ltd          991Wolverhampton Road   Oldbury                  Birmingham B69 4RJ              T 0121544 4040                                   Fax  0121 544 5558



V8 ignition switch



 Recently, it was reported on various Bristol Forums, that owners of at least one model, the 411, were experiencing Ignition Switch failures. Initially, these parts were replaced, only to have a similar issue a short time later. Understandably, owners were less than pleased after the replacement failed again, and this article attempts to illustrate the reasons why, and to recommend a remedy, that is well proven.


Having been employed at a leading company in the Motor Industry in Coventry for over thirty years, reliability testing was a major part of my engineering activities. This involved the logging of prototype vehicle test data to prove out the various electrical components. The information thus gathered then gave an indication of the vehicle lifetime expectancy of each item, and this could be used for warranty investigations later on, if required.

Major electrical loads were monitored during the tests, including air conditioning, cooling fans, external lighting, heated rear screen, heated front screen, electric windows, seat heaters, and in-car entertainment ( radio/ amplifiers, TV etc.). Data from component suppliers was also analysed, to ensure that, for example, the ignition switch, was being operated under electrical load conditions appropriate to the supply company’s recommendations. Also, back emf (the spark that appears across the contacts) at switch-off, did not exceed the limit outlined in DIN57-879. This Europe-wide specification relates to radio frequency interference by induced transients from inductors, ie, motors and solenoids, and requires sufficient suppression to be fitted to eliminate the effect.

The table below, illustrates some of the issues involved, with measurements taken before and after suppression components had been added, clearly demonstrating an improvement and compliance with the DIN regulation, (36V max @ 1mS duration).



Transient  at switch-off  before suppression

Transient  at switch-off  with suppression

Seat motor

– 232v @ 1 mS duration

– 31v @ 0.5 mS duration

Cooling fan

-183v @  0.5 mS duration

– 32v @ 0.4 mS duration

Air Con fan (interior)

– 247v @ 0.4 mS duration

– 34v @ 0.35mS duration

mS = mille-second

Over time, the energy generated across relay contacts at switch-off from unsuppressed components, will burn away the contact faces, and lead to switch/relay failure. Adding the suppression improved the reliability of the circuit components, and thus reduced failures to a minimum. Good for customer satisfaction.

A similar approach was taken with external lighting, where values obtained for the switch-on current of filament lamps were also measured. These included sidelights, head and fog lamps. The following table gives some of the results that could be applied to the wiring systems of Bristol cars:



In-rush current at switch     ON – AMPS

Illuminated/rated current – AMPS

H4 – Dip beam 55 watts

45 peak @ 10mS

4.58 @12v nominal

H4 – Main beam 60 watts

50 peak @  10mS

5.00 @ 12v nominal

Indicator 21 watts

17.5 peak @  10mS

1.75 @ 12v nominal

Sidelight 5 watts

  4.1 peak @ 10mS

0.41 @ 12v nominal

Also, the value of current that could be reliably passed by the ignition key switch was determined to be approximately 20 amperes. To switch more than this limit, several load relays were introduced to power up the various vehicle systems controlled by “Ignition ON “. These included headlamp flash, headlamps, fog lamps, heated rear/front screens, air conditioning, seat motors, In-Car entertainment systems, and fuel injection/engine management.  The circuitry included fusing for each relay controlled load, and reduced the amount of current directly switched by the ignition key. This reduced the probability of electrical failure of the ignition switch by a considerable margin. Also, the impact of Vehicle Construction and Use Regulations, and Federal (USA) NHTSA legislation, led to circuit evaluation for compliance. For example, all cigar lighters at that time, were required to be switched by the ignition key, and driving/ fog lamps if fitted, were to be switched in pairs, and not individually. These legislative requirements were subsequently incorporated into the circuitry.


Ignition switch

This is sourced from a Range Rover application amongst others for the 411 model, but the following set of conditions leading to failure, would apply to most other vehicles produced by Bristol with similar wiring/circuitry. Excessive loading leading to early contact failure, especially with the cigar lighter sockets being used to power up various items such as games and DVD players for the rear seat passengers, combined with heated rear window current, plus the usual driving aids such as demisters, windscreen wipers, and cooling fans, will cause the ignition switch contacts to fail after a short time. This is exactly what happened previously.

The following re-routing of the circuits is applicable to most of the later cars from 408 onwards, as the wiring is terminated in the right hand wing locker, and the circuit colours can easily be identified and modified. Of course, when designing circuitry for a new vehicle, one relay would supply two or three additional loads, however, when modifying existing wiring, individual load relays are easier to include without a major strip out of the wiring looms.

See Appendix 1 for the wire colour designations, these follow the old Lucas wiring colours, but for some applications, owners should consult the vehicle handbook/workshop manual for specifics.

The following Key-In Ignition ON loads supplied directly from the ignition switch should be removed, and powered up via an additional relay

1)     Heated rear window;

2)     Electric windows;

3)     Air conditioning(where fitted);

4)     Cooling fans

5)     Cigar lighters (where applicable)


This then leaves the ignition circuits, wiper motor plus the radio, (without external/ additional amplifiers) at about 12 – 14 amps, that is well within the load capability of the key switch.  .




This is a function of the indicator switch stalk. However, the contact rating is about 10 amps on my car (a 408 MkII), and looking at the current in-rush values for the main beam filaments in Table B, it can be seen that flashing four headlights results in a combined in-rush current of 190 amps for 10mS duration, after which the steady current is 19 amps, almost twice the rating of the switch. Also, the voltage at the lamps is reduced, and hence the light output, because the cross sectional area of the wiring to the flasher switch is too small. This is another circuit that requires a relay to switch the filament load.


The supply to this circuit should be removed from the ignition switch as previously discussed, and the following additional modification ought to be carried out. The cooling fan circuit utilises a thermal switch manufactured by Otter, situated in the radiator header tank. This switch controls the fan relay, and will fail if the relay coil is not suppressed. The back emf (spark), generated at switch off on an unsuppressed relay, is typically as high as 92 volts for 2mS duration. This appears across the thermal switch contacts that open relatively slowly when compared to similar relay contacts. The slow opening speed draws an arc across the air gap as the contacts move apart, and erodes the mating faces. Eventually, with carbon build up, the contacts when made will be of a high resistance, and the relay will fail to operate because of it. Therefore, a 0.1 microfarad capacitor should be wired in parallel with the relay windings to eliminate the issue. These suppressors are readily available from accessory suppliers



The only modifications that I have carried out to my own vehicle, a 408 MkII, are the suppressor modification on the cooling fan relay, a headlamp flash relay with a fuse in the power feed, fog lamps paired up with their own relay, and changed the starter relay for a plug-in type, as the original had burnt contacts. Additional fuses have been fitted in the headlamp circuit, the front fog lamp pair, and the rear fog lamp pair. As my vehicle is without a heated rear screen, the cooling fans remain wired through the key-switch as is, the load current is about 10 amperes. All of the applications discussed previously, can use relays sourced from Jaguar parts suppliers, See Appendix 2.( NB The cigar lighters on my vehicle are powered directly via a fuse from the battery, and therefore are not controlled by Ign-ON.)

When attempting to modify the circuitry, it is recommended that the cheaper alloy type of lucar spade terminations are not used, as electrolytic corrosion will ensue in damp conditions, owing to two dissimilar metals being brought together in the cable crimp, ie copper and aluminium. Always use either brass or tinned brass for these crimped terminations. Again, these are available from companies that advertise in classic car publications and the Internet.

Regarding the 411 ignition switch failures. These occur because the original circuit design did not take into account the maximum current that could be reliably switched by the contacts. Having the air conditioning on, with the wipers and demisters running, plus the heated rear screen and other accessories being powered from the cigar lighter socket(s), would probably produce a back emf at switch-off, that would easily erode the contact faces of the switch element in a relatively short time. Changing the switch again is only a short term solution, and the only effective method to eliminate premature failure, is to apply the circuit changes discussed in this article.


APPENDIX 1 – Wire colours


Many British designed vehicles use colour coded cables to assist in identifying the various circuits in use. This is an extract from BS-AU7a 1983 Colour Code for Vehicle Wiring, from the British Standards Institution, 2 Park St., London W1A 2BS.

(Note that these colour codes may not apply directly to older cars. For example, the wipers on cars up to 1980 (at least) are not on a separate fuse circuit, so they are not orange, but green. Check the schematic for your car to be certain.)


Black   All earth connections
Black Purple Temperature switch to warning light
Black Green Relay to radiator fan motor
Black White Brake fluid level warning light to switch and handbrake switch, or radio to speakers
Black Orange Radiator fan motor to thermal switch


Blue   Lighting switch (head) to dip switch
Blue Brown Headlamp relay to headlamp fuse
Blue Red Dip switch to headlamp dip beam fuse
    Fuse to right-hand dip headlamp
Blue Light green Headlamp wiper motor to headlamp wash pump motor
Blue White a) Dip switch to headlamp main beam fuse
    b)Headlamp flasher to main beam fuse
    c)Dip switch main beam warning light
    d)Dip switch to long-range driving light switch
Blue Yellow Long-range driving light switch to lamp
Blue Black Fuse to right-hand main headlamp
Blue Pink Fuse to left-hand dip headlamp
Blue Slate Headlamp main beam fuse to left-hand headlamp or inboard headlamps when independently fused
Blue Orange Fuse to right-hand dip headlamp


Brown   Main battery lead
Brow Blue Control box (compensated voltage control only) to ignition switch and lighting switch (feed)
Brown Red Compression ignition starting aid to switch
    Main battery feed to double pole ignition switch
Brown Purple Alternator regulator feed
Brown Green Dynamo ‘F’ to control box ‘F’
Brown White Ammeter to control box
    Ammeter to main alternator terminal
Brown Yellow Alternator to ‘no charge’ warning light
Brown Black Alternator battery sensing lead
Brown Slate Starter relay contact to starter solenoid


Green   Accessories fused via ignition switch
Green Brown Switch to reverse lamp
Green Red Direction indicator switch to left-hand flasher lamps
Green Purple Stop lamp switch to stop lamps, or stop lamp switch to lamp failure unit
Green Light green Hazard flasher unit to hazard pilot lamp or lamp failure unit to stop lamp bulbs
Green White Direction indicator switch to right hand flasher lamps
Green Yellow Heater motor to switch single speed (or to ‘slow’ on tow- or three-speed motor)
Green Black Fuel gauge to fuel tank unit or changeover switch or voltage stabilizer to tank units
Green Pink Fuse to flasher unit
Green Slate a)Heater motor to switch (‘fast’ on two- or three-speed motor)
    b)Coolant level unit to warning light
Green Orange Low fuel level switch to warning light


Light green   Instrument voltage stabilizer to instruments
Light green Brown Flasher switch to flasher unit
Light green Blue a)Flasher switch to left-hand flasher warning light
    b)Coolant level sensor to control unit
    c)Test switch to coolant level control unit
Light green Purple Flasher unit to flasher warning light
Light green Green Start inhibitor relay to change speed switch; or switch to heater blower motor second speed on three-speed unit
Light green Yellow Flasher switch to right-hand warning light
Light green Black Front screen jet switch to screen jet motor


Orange   Wiper circuits fused via ignition switch
Orange Black Switch to front screen wiper motor parking circuit
Orange White Timer or intermittent unit to motor parking circuit
Pink white Ballast terminal to ignition distributor


Purple   Accessories fed direct from battery via fuse
Purple Brown Horn fuse to horn relay when horn is fused separately
Purple Blue Fuse to heated rear window relay or switch and warning light
Purple Red Switches to map light, under bonnet light, glove box light and boot lamp when fed direct from battery fuse
Purple Green Fuse to hazard flasher
Purple Light green Fuse to relay for screen demist
Purple White Interior lights to switch (subsidiary circuit door safety lights to switch)
Purple Yellow Horn to horn relay
Purple Black Horn to horn relay to horn push
Purple Pink Rear heated window to switch or relay
Red   Main feed to all circuits mastered by side lamp switch
Red Brown Rear fog guard switch to lamps
Red Blue Front fog lamp fuse to fog lamp switch
Red Purple Switches to map light, under bonnet light, glove box light and boot lamp when side lamp circuit fed
Red White a)Side lamp fuse to right-hand side and rear lamps
    b)Side lamp fuse to panel light rheostat
    c)Fuse to panel light switch or rheostat
Red Yellow Fog lamp switch to fog lamp or front fog fuse to fog lamps
Red Black Left-hand, side lamp fuse to side and tail lamps and number plate illumination
Red Pink Side lamp fuse to lighting relay
Red Orange Fuse box to rear fog guard switch
Slate   Window lift main lead
White   Ignition switch or starter solenoid to ballast resistor
White Brown Oil pressure switch to warning light or gauge, or starter relay to oil pressure switch
White Blue Choke switch to choke solenoid (un-fused) and/or choke to switch to warning light, or electronic ignition distributor to drive resistor
White Red Starter switch to starter solenoid or inhibitor switch or starter relay or ignition (start position) to bulb failure unit
White Light green Start switch to starter interlock or oil pressure switch to fuel pump or start inhibitor switch to starter relay or solenoid
White Yellow Ballast resistor to coil or starter solenoid to coil
White Pink Ignition switch to radio fuse
White Slate Current tachometer to ignition coil
White Orange Hazard warning lead to switch
Yellow   a)Overdrive
    b)Door locks
    c)Gear selector switch to start


V8 column stalk

Courtesy of John Lawley
Greg Lowe started off a useful investigation regarding a steering column indicator stalk switch for his 410, asking if BODA could establish which volume produced cars these switches were fitted to. The first action was to talk to Bristol Cars who stated that they haven’t had any switches for 407-410 models for some time and have been modifying 411 switches.

They do, out of interest, have two that they have converted at £141.35 each but would haggle on price. What I did establish was that it is a Lucas switch. On looking at our database, there were two indicator switches that show they were fitted to Bristols. These were Lucas 37SA and Lucas 119SA. It seems 407-410 were fitted with versions of 37SA of which we have found 8 types so far. We found that we could break these down into two categories; those with horn pushes and those without. On close examination of datasheets, the internals of all versions seem to carry the same Lucas part numbers so may be interchangeable if you get desperate.

Model 37SA Version 31885 (no horn push) fitted to:- Austin A60 1964-67; Bedford Beagle and 8cwt van 1966-69; Morris Oxford 1966-71; Riley 4/72 1966-69; Wolseley 16/60 1966-71. Version 31883 (with horn push) fitted to:- Austin Morris 5/6cwt van 1967-71; Morris Minor 1964-71 (not 68). Bristol Car Services believe they fitted Version 34385 – we cannot find this called up anywhere.

Model 119SA Version 33480 was fitted to:- Bristol 411; Reliant Scimitar; Hillman Hunter. Also rumoured that Sherpa vans and pickups were fitted a version. Having received the results of the database search, Greg came back, within a couple of days, saying that he had found a replacement switch for £35. So a minor success stemming from all BODA’s hard work on the data collection. Greg also reported that the main difference in the models appeared to be the harness connections; one being the bullet type and the other Lucas spade connectors. This will be finalised later and I will ask Greg to confirm which version he obtained and if there were any issues worth considering when fitting. So, many thanks Greg for raising what turned out to be a useful exercise.







412 Lighting

The following information was supplied by Adrian Berry, who owned a 412 for 12 years and provided reference numbers based on the boxes of the lights he used, and from direct contact with Bosch.

They were originally fitted to German Opel Commodore and Viceroy cars between 1972 and 1978

The single headlights for the 412 (as opposed to the double units on the Beaufighter) were:-

Complete unit Left (nearside) 0 301 054 600 – Right (offside) 0 301 054 601

Lens left 1 305 620 141 – Lens right 1 305 620 142

Reflector left 1 305 320 968 – Reflector right 1 305 320 969

Indicator left 1 305 320 191 – Indicator right 1 305 320 192

V8 shock absorbers and suspension

One set of data produced by Geoff Dowdle in Australia is currently being checked out in the UK for possible local supply.  The 407 listing  does not appear in the current Koni online catalogue, although the numbers are valid.  The SPAX numbers are also being checked out.

 407 shock absorbers

Model Setting Compression Rebound Possible Replacement
407 Front ——– ——– ——– Koni 82.1328 OR SPAX 210-S or G712
For Armstrong see below
407 Rear ——– ——– ——– Koni 82.1059 OR SPAX G211 or G713
For Armstrong see below

Armstrong Shock Absorbers


408 Suspension

Front Upper Wishbone bump stops – 4off – Jaguar Part No. C29979 (NOTE: the hole size in the wishbone has to be enlarged to 5/16ths (appox 8mm) to accommodate the stud on the bump stop fixing plate.)

Upper ball joint front suspension – Jaguar Part No. CAC9938X (NOTE: the fixing nut is larger than the original part. However, there is sufficient space to tighten up with a shallow socket, the taper identical to original but it is advisable to pull taper into its locked position on the forging with a bare nut and washer. Then once locked up, replace with the Nyloc nut provided.

General V8 suspension

Front upper wishbone bump stops (4 off) – Jaguar Part No. C29979. Source: British Parts UK Tel: 01438 – 354816 Cost (Oct 07) £2.45 each + VAT + post NB. The hole size in the wishbone has to be enlarged to 5/16th to accommodate the stud on the bump stop fixing plate. Upper Ball Joint – Jaguar Part No. CAC9938X Source: British Parts UK Tel: 01438 – 354816 Cost (Oct 07) £9.99 + VAT + post.

NB. The fixing nut is larger than the original part. However, there is still sufficient space to tighten up with a shallow socket. Taper is identical to original but it is advisable to pull the taper into its locked position on the casting with a sacrificial bare nut and washer and then remove the nut before attempting to put on the nyloc nut.