I'm a big believer in electrical ground wires. My 1981 R65 carries the OE negative battery cable. It looks it, too. OK, another project.
Solid copper lugs for #4-6 cable with .187" holes were $2.99 at the 'Zone. A pre-made #4 battery cable with copper wire ran me $3.99 and I'm out the door.
Back in the shop, first order of business is to cut off the stamped steel terminal lug and swage on a new copper lug. Smooth off some sharp edges, couple layers of shrink tubing and we can test fit to the upper battery terminal.
Run the loose end down to the ground location near the speedometer drive and mark it for length. Finish the cable as the other end. Bolt that rascal up.
Tested the old cable on the DVOM and found a little bit of resistance. My eight buck cable compares to BMWs asking price of $28.33.
The original cable is a metric size that specs out to 5 gauge. You're not likely going to find that wire size at NAPA! Step up to 4 ga - it's a bit heavier and a tad more difficult to shape - rather than the smaller 6 ga. It's worth the effort.
Here's my aircraft cable swaging tool at work. Stone axe simple and FAA approved. The swaging tool is available through Aircraft Spruce and Supply, Wicks Aircraft and several other sources.
Finished cable with two layers of shrink tubing. This end is ready to install.
