Grounding Question
 

Hi Guys and Gals!

I know there is a heap of info on Grounding (i have read quite a bit of good info from the archived posts), but i havent yet seen any info clarifying what im about to ask (or maybe i dont understand auto grounding well - might be the case :))

Between the ring-terminals on most stock-fitted chassis grounds and the actual metal car frame, there is a thick layer of engine-bay paint (so i am assuming that the ground link between the ring-terminal of the stock ground wires and the car-frame is via the chassis-bolt thread).

When fitting new grounds is it recommended practice to chip away the paint in the engine bay around the chassis-ground bolt holes to allow a direct connection between the car-frame metal and the ring-terminals you have on your new grouding wires (or is this not really necessary?)

Just spending a bit of time doing it, so i want to make sure it is done right.

Cheers;
Sco

I do usually remove the paint VERY carefully with a wire wheel bit in a Dremel rotary tool. Put the ring terminal on, then use dielectric grease to coat it to prevent corrosion.

Dale

Screw dat. :)I bought star washers that go between the terminal ring and body. The star teeth bite into both sides.

Dave

Once again thanks for the good info Dale and Dave - I really appreciate you getting a quick response off to me bout this, gunna get on to this puppy tonight!

The teeth from a star washer is going to give you almost no surface area, even if it bites in.

I used a dremel as well to get to bare metal. Not so carefully though. :D

Blake

If I am grounding to any existing bolt hole, I often run a tap through the hole to clean the threads of any paint and debris that may insulate the bolt, and also clean the bolt with some brake parts cleaner and a wire brush. Ensure the area around the bolt head is free from paint, etc.

Thanks for the additional info Blake and Broken, good advice i will definately take on board!

The teeth are indeed not as large as the wire, but the resistance across the junction is negligibly low, I assure you. I checked with my multimeter.

Perhaps you're not aware, but pressing a smooth metal face onto metal face is the poorest form of electrical connection, especially with steel. Connector engineers will often assume less than 10% effective contact area in these cases. The steel creates an oxide layer that clamping pressure will alleviate, but not eliminate. A star washer will cut thru both paint and iron oxide and create metal/metal interface because of the sharp edges and wiping action. Since this doesn't happen until the very end of the tightening, the oxygen cannot get in and cause oxidation.

Just wanted to make clear that both methods work and are ample for our needs.

Dave

I'm sure your multimeter would also read zero ohms across a 200 mA fuse.

A multimeter is a better check than no check at all.

Dave

I agree... :)

Thanks for the extra explaination Dave, never though of taking oxidation into account like that (and i have sort of an electonics background... Hmm... someone needs to do some more reading :) ). It makes alot of sense though and i could see how both methods definately have their merits.