New member/owner - issue with dim/dip

[mister bridger]

Hi all and thanks for accepting me on here. Recently bought a '47 9A Roadster which I'm delighted with, but still getting to know it. The dim/dip arrangement is puzzling me - the passenger side (left) is controlled by a solenoid which raises the reflector and works just fine. However the bulb on the drivers side goes out when on main beam. Is this right? Start as I mean to go on - asking questions!
Thanks in advance, Peter

[mikeyr]

That is the way it was supposed to work in the old day, now most people change it to have both lights on at same time.

[mister bridger]

Thanks, what a strange system! I guess it would be easy enough to run a feed from left to right so they both stay on.

[mister bridger]

Just to wind this up, it was a very simple job to bypass the contact breaker in the left headlamp so dipped beam on the right stays on when I go to main beam on the left. Sorted.

[jeans_old_man]

LED bulbs are recommended to reduce the load on the dynamo. Prolonged running at night with a full lighting load will overheat the dynamo which has limited cooling.

[Phillip]

That's very interesting!

I had a '47 Roadster (A-512-Q) and it had a foot operated dip switch on the floor and double filament bulbs in the headlamps. The car was an extremely original and low-mileage barn find. The headlamps were the same type as used on the early MG TC with the domed cat's eyes glasses, fixed reflectors and separate bulbs that could be adjusted for focus. I guess it is possible this was an export feature, as this car was shipped to Canada when new, but the wiring diagram in the owner's manual shows the same, I believe.

Here's a photo of the car and headlamps:

1947 A Series Original Headlamps_WEB.jpg (166.81 KiB) Viewed 1935 times

The 'dip and switch' system was certainly used pre-war and probably on the R-series Roadster of 1939/40. The kerb-side lamp (RHD) had a dipping reflector controlled by a solenoid. On main beam both lamps were on. When switched to 'dip', the road-side lamp went out so as not to dazzle on-coming drivers and the kerb-side lamp solenoid dipped the reflector down to illuminate the road.

All the R, A and 4A Roadsters were RHD even for export, but the parts books show various specification Lucas lamps were used for various markets to meet local laws.

[mister bridger]

LED bulbs is a good call, I'll look into that.

[Phillip]

Curiosity got the better of me!

I have a collection of Singer factory owner's manuals, so pulled out the earliest Roadster one I could find. I think this is the A Series one and it is very complete with some nice pull-out diagrams. Unfortunately there is no printing date in it. Singer were notorious for reusing stock photos in their manuals, but this one is well done. I bought it at Beaulieu many years ago and it is therefore for the domestic market I'd assume.

Here's the relevant wiring diagram:

Wiring Diagram_A Series_WEB.jpg (308.84 KiB) Viewed 1933 times

It clearly shows the 'dip and switch' system, so I guess this was still used in the UK in the early post-war years. The A Series Roadsters I know of here all have the 8 inch L-140-Q headlamps with double filament bulbs. The 4A's have the 7 inch L-700 lamps with fixed reflectors and removable pre-focus bulbs.

Anyway..a bit of Anorak musings...

[Phillip]

Just a little update regarding wiring on the A Series Roadster.

While digging out information for a local new Roadster owner, I came across this data sheet covering the specifications for the A - 1946 to 1949 - Export version:

It shows that, while the domestic product still seemed to use the old pre-war 'dip & switch', the export models were fitted with double dipping.