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Stop / Tail Lights


As I get closer to the painting of my 30C I am doing some of the fiddly bits I want to do to the tractor while I wait for the weather to be in my favour. One thing I am doing is fitting rear lights and these ones although not David Brown lights are what I wanted, a stop/tail light which is a low profile. So in my search of lights I found some MF lights that filled my requirements so I bought them. they came from Sparex and I have had them stored for well over a year now and today I mounted both guards on a bench and fitted them up. It was not until I took them apart I realised that they are made with-out and earth at all. SO I had to solder an earth wire to the mounting bracket to get them to work.
There is nothing so annoying as having to repair a brand new part. Sparex Crap!


I like oldstuff

Last Subscription Date
Same junk here. They rely on earthing through the mounting stud which gets rusty and oxidises within a month. Another trick is to grease the bulb base and sides as they also develop resistance. Then I seal the lens to the body with RTV silicone to keep water out.

I wire the trailer with an insulated 3 conductor extension cord to each light. These terminate in a junction box with one cord going to the vehicle. I'll buy a 75 foot cord for around $15 and just cut it up to suit. It's been about 5 years and all the lights work well.


The outer housing attaches the complete assembly but does not earth anything as the outer housing sits on the rubber grommet and nothing else. The rivet head that holds the mounting bracket of the globe holder is the only possible way an earth could be found but surely replying on that to make an earth through paint ot ground is near impossible.
This time when I re-wire the complete tractor I am doing it based on marine basis and that is everything will have a dedicated earth wire run to it and to a very good earth and not relying on the tinware to be the ground.

eddie bedwell

Hi Team,
from memory from way back in my youth I recall lights with a single filament bulb and the bulb had 2 contacts--one for power and the other for earth return--maybe some one has confused this what appears to be single filament unit for a two filament one which, as you found, would not work without earthing the bulb mount as you have had to do--needs three wires to operate.
I stand to be corrected.
Eddie B.


Hi Eddie, your stands up pretty strong. All they would have to do is swap the globes over and away you go.
At least I now will have a working stop/tail light when it all goes back together.


The standard 'stop-tail' light 2-filament globes used to have offset bayonet lugs so that they could supposedly only be put in the right way around, important because each light is supposed to be a different watts / brightness.

how about a check of the both the globe and more importantly the housing, to see if they both have the offset lugs / lug slots, and tell us what you find.
if the slots are not offset, but at the same 'level' then it could well be for a double contact single filament globe as previously suggested.
you said you bought these lights as stop-tail lights, but what did the box label / fine print specify the light as?

at current face value, it seems this light fitting is designed for the
"if it aint got chrome - go home" segment of the market,
as it should work on chrome bumpers with their permanent non-rusting metal surface. cheers Rod.


No offset in the globe holder at all. No description other than rear light on the box and the part number still exists for Sparex and says similar to rear facing light or similar.
The globe supplied is a proper stop tail light globe with 5w/20w dual filaments so they are correct for what I asked for.
There is an idea of them being just a rear facing clearance light using a double contact single filament globe and this is what I think the light assembly was built as but then if you ask for what I did they swap over the globe but not supply an earth.
It is crazy but at least I can use what I have and it will work fine too. Next step after painting is to mount the brake light switch and there is a place to that already under the foot plate.


In Memory Of
Last Subscription Date
My guess is that the lights are adaptions of an existing design that had a stamped metal base. They just replaced base with hunk of plastic, giving no (or little) thought to electrics. Could maybe have supplied a "spot" ground with a lump of solder on bottom side of the rivet that bonds socket to base.

Andrew Mackey

Last Subscription Date
If the lug mounts on your base are not offset, then you should have a single filament bulb base. A dual filament bulb should not fit in that mount. A single filament bulb does not have a grounded (earth) base, the ground is a second wire out of the base, usually green in color. On dual filament bulbs, one side of the filaments is grounded to the bulb base, thus the need for a grounded mount. Both wires to the bulb get power, depending on wether you want running light or brake lite.

Frank DeWitt

Last Subscription Date
Years ago I got so frustrated with trailer lights not working after sitting for a while that I took a 2X 6 and mount tail lights, clearence lights, and a license light and the license plate on it. In use, this board clamps to the trailer. When not in use it hangs on a hook in the garage. Works fine. A side benefit is that I can fasten it to any utility trailer I want and it is registered and reDy to go. Grin


Thanks for the ongoing replies. I should take a photo of the globe holder with the globe out. It has 2 contacts for a double contact globe. Now this is where it gets really curly, you can buy a single filament globe with double contacts and in this case would work perfectly as a clearance light. But since Australia dropped it's standards just about on everything importers send anything they like and don't always have to conform to our ADR (Australian Design Rules) and get away with using or selling the same product for a dual purpose as is this case.
It was a very simple fix but having the need to repair a brand new product to make it work to do a job it was specifically ordered for is crazy, but I'm mad enough to go along with what we are sent.
As for LED lights, I love them on my trailer and on the caravan where they can be retro fitted, but here again some lights cannot be replaced with LED as the size of the old style don't match up with the new. LED are very much trouble free so far, but not on a Vintage tractor thanks.