If you look at the dimensions of the cable supplying the starter motor you will see that it is rather heavy, given the starter motor is the highest electrical load in the car... Logic would seem to hint that the earth lead to/from the engine to the chassis, would ideally be of similar dimensions as it has to carry the same amount of current for the starter motor to operate successfully..?
I would suggest to save you cash, that buying a crimping tool is rather costly, as you can buy ready made up earth leads from Halfords for less than the cost of a crimping tool...? Of course there may be even less costly earth options via the interweb..?
Before you fit the new lead, be sure to clean to bare metal either side of the earth lead connecting points on the engine /chassis you can paint or grease over the bolts/nuts/chassis engine both ends to reduce the risk of any bare metal exposed in the cleaning process from corrosion..?
Good luck in your choices
