I have made many a frame rail connection...
- For ultra critical "grounds" I scrape and wire brush the steel until it is bright
- Lugs to be stacked should look brand new bright
- I prefer to solder my lugs to copper cable wires
- Connection must remain tight and I mean very very tight
- So I use a bright bolt, nut, flatwasher and choice of nylock ring or stover distorted locknut
- Torque nut and bolt using torque wrench tension measurement
- Specs for each diameter are easy to find on Google
- At the last I spray both sides of frame rail with spray undercoating. A few coats.
Such protection can be submerged in salt water repeatedly and incur no damage. For decades.
Parts and hardware stores sell cylindrical shaped power wire brushes with 1/4" post and the steel wires of the brushes can be rope twisted. This makes cleaning a frame rail a snap. Rope twisted brush cups are aggressive. Take it easy around delicate stuff.
Properly applied undercoating or Wal-Mart truck bed undercoating is a forever fix. So I usually make a service loop of cable so the far end of the cable opposite the frame rail can be lopped off.
Overkill? Oh hell yes.
No worries, ever? Oh hell no. Absolutely bulletproof.
