Originally Posted by Reiver
I thought the battery earth to chassis braided strap looked a bit puny but then I'm used to bigger and more modern battery setups. The chassis stud the earth connected to was pretty corroded and I don't think it would survive an attempt to undo it. It worked well enough for the test I did.

I couldn't get under the car to comment on the gearbox earth. I couldn't see any earth strap around the starter motor area but the advice to run an earth from the upper starter mounting bolt to the chassis seemed a good idea.

Of course I forgot to check the size of the bolts - 17mm ?

Getting ready made cables seems somewhat difficult so I thought I'd invest in a crimping tool (Draper 64335 Crimping Tool) and make my own.

What size cable would you suggest? 16 or 25mm ? Since this is an additional earth I thought the 16 would be sufficient.

I intend to put a longer (M10?) bolt through the starter/bellhousing and connect a right-angle ring terminal onto the end with a locknut to secure it. The other end would be an M8 ring terminal secured to the chassis brace below the bulkhead.


At least 25mm2, better 35. You will always gain to some degree (however small) with the larger cross section. The tiniest resistance magnifies the power (i2r) loss by the square of the current it carries remember. Consider the equivalent cross section flat braid for earth connections between components that move or vibrate with respect to each other.


Richard

2018 Roadster 3.7
1966 Land Rover S2a 88
2024 Royal Enfield Guerrilla 450
1945 Guzzi Airone