Morris Minor Owners Club

I recently sanded and cleaned the nut and washers which make the battery earth terminal mount, while adding an extra earth bus bar. I note that the metal sheet is rather thin and the contact surface is not too large, although the spring washer fits snugly against it. It does seem that is a much less heavy duty connection than on the positive terminal despite taking the starter motor return current.

Was this always how they were from factory build?

As far as I know the earth wire to and from the battery was and always has been bolted to the side of the battery box.

Ah thanks. Still seems very weak but perhaps that's how they were all there back then.

That is how they were back then.

I added an additional strap from the battery negative to one of the engine to gearbox bolts , it seems to turn over fine.

kevin s wrote: ↑Mon Jul 26, 2021 12:03 pm I added an additional strap from the battery negative to one of the engine to gearbox bolts , it seems to turn over fine.

Was there an actual problem before you did that or was it just a random thing to do because you could?

There were 1.6 Million made all with the same battery connection......

The original engine earth strap was missing (I assume they had one somewhere) so this seemed the most sensible option.

kevin s wrote: ↑Mon Jul 26, 2021 2:55 pm The original engine earth strap was missing (I assume they had one somewhere) so this seemed the most sensible option.

SII onwards, it's on the underside of the gearbox.
It's mentioned in section FF 1 of the manual under 'gearbox removal'.

I believe on the MM it was in the engine bay from the top of the engine to the battery box area.

kevin s wrote: ↑Mon Jul 26, 2021 12:03 pm I added an additional strap from the battery negative to one of the engine to gearbox bolts , it seems to turn over fine.

This is the return path to the alternator isn't it? I'd worry that this would mean ever more current through that earthing point.

geoberni wrote: ↑Mon Jul 26, 2021 12:08 pm There were 1.6 Million made all with the same battery connection......

Was it always effectively sanded down by hand in the factory and then everything pushed in? Essentially, relying on the sanding to make the metal roughly match the shape of the spring washer?

There needs to be an earth return between chassis and battery for all the usual ancillaries, but also an earth path between the engine/gearbox and chassis 9or battery) for the starter motor (and the ignition system, theoretically).

I once operated the starter motor on a Ford Cortina or Anglia and the metal fuel pipe started glowing red. Likely no prop shaft fitted or that may have been enough to carry the current (still not a good idea to use gears/shafts (and possibly bearings) as an earth path.

oliver90owner wrote: ↑Mon Jul 26, 2021 10:18 pm I once operated the starter motor on a Ford Cortina or Anglia and the metal fuel pipe started glowing red. Likely no prop shaft fitted or that may have been enough to carry the current (still not a good idea to use gears/shafts (and possibly bearings) as an earth path.

That must be the reason why the original metal braided pump to carb hose on the later model Minor has the metal braid cut back and the rubber folded back over the end insulating the braid from the carb and pump.
https://www.morrisminorspares.com/fuel- ... ps-p830610
My dad managed to burn the throttle and choke cables once though, lesson learnt he never done it again.

Quite frankly, I don't understand what your concern is.

Your original post:

while adding an extra earth bus bar.

What?
The entire body is the earth return, why do you need a 'bus bar'?
It's a Morris Minor, not an aircraft.
I've not even seen an earth bus bar on my modern cars, just strategically placed earth bolts.

Look at the size of the contact area of the crimp lugs on the ends of the cables, to the earth point and the one onto the pull start/solenoid.
More than sufficient metal to metal contact for the current involved.

I'd worry that this would mean ever more current through that earthing point.

The current will take whatever is the shortest route, end of story.
It will go through the battery earth point no matter where the engine earth connection is connected to!

Was it always effectively sanded down by hand in the factory and then everything pushed in? Essentially, relying on the sanding to make the metal roughly match the shape of the spring washer?

What are you on about the Spring Washer for?
Pushed in where?
The Washer should be under the nut, not between the tag/lug and the metal surface!
I haven't even got a washer on my minor, but the nut is done up tight and the mating surfaces, crimp lug to body, are clean.
You're starting a Morris Minor, not a Chieftain Battle Tank.

Perhaps you have OCD, but please rest assured that as far as your original post goes, you are worrying about a non problem.