mk3 brake/ rear lamp

[Horace]

Having a bit of a ding dong with an ebay seller at the moment re a combined rear lamp/brake lamp on a mk3 spit.  Basically he said it was new old stock but completely different internals to my original 1970 lamp (later admitted that he'd got them 20 years ago from someone who'd recast them from an original casting) It worked fine when not screwed to the body but as soon as it was the brake lights didn't work and the cables got hot. It seems it was earthing through the body rather than the earth cable and effectively shorting out before lighting the brake filament of the lamp.  The other lamp definitely does not earth through the body and there seems to be insulating bits of plastic in the original and not in the replacement that ensure this does not happen.  It does work as a rear lamp, its just the brake circuit that shorts out as soon as attached to the body (the screws effectively earth it).  I'd welcome anyone who's had similar experiences and also just let others know there is another on ebay at the moment!

Bob

[Rallyspit]

Both the brake and side light arrangement on the Mk1-3 Spit and Mk1-2 GT6 leave something to be desired with their rivetted construction and bits of crusty plastic insulation.

I modified mine by chucking all the internals away, cutting out the inside of the monkey metal frame and adapting a Mk4 Spit lampholder and reflector to fit. I also removed the silver tape behind the reflector on the lens. I've now got one dual filament 21/5W bulb and one single filament 10W bulb. How you wire them is up to you but I use mine as a 10W + 5W sidelight, and a 21W brakelight. If you utilised two dual filament lampholders, you could also incorporate rear foglights, but I didn't as I was concerned about the heat generated perhaps warping or even melting the plastic lens if left on for long periods - as a fog light could be. Intermittent use of 21W of brakelight is not likely to cause any problems. It's still not as bright as a modern, but much better (and safer) than the original.

[GT6chris]

My Modification was a little more agricultural. I refitted the lamp holder to the back plate with some small bolts. I removed the broken brass lamp contacts. I hacksawed through the bulb holder and used an appropriate sized jubilee clip around the holder to clamp the bulb in place. I soldered fly leads onto the two bulb connectors and connected these straight to the the wiring loom with bullet connectors. I polished the original reflector and the whole thing is 100% reliable. I modified a couple of spare bulbs to keep in my spares kit.