drilling holes for new ground and more - rust?

[skipdup]

I'm rewiring my headlights, horn, fogs, etc and decided the existing ground (by the battery) is too cluttered. So, I think I'm going to drill a hole and add another stud for a ground on the passenger side. The bumper is already off, so I can reach both sides for attaching.

I also want to drill two more holes, to mount a circuit breaker panel, above the windshield washer pump.

Will I invite rust at the new holes? Any "finishing" or protection I should do to prevent rust?

And for the ground, anything special I should do? Does the bolt and nut material matter (i.e. stainless, zinc coated, etc)? I plan on putting a bolt through, holding in place with a nut, then secure wires with another nut. Also plan on removing paint on the inside for conductivity.

Is this a bad idea? The idea of drilling into the car FREAKS me out, so I'm hesitant.

Many thanks,
Skip

[Cipotifoso]

I had an underbelly airconditioning condenser installed on my car as part of an overall upgrade. In the process, there were many holes drilled for the condenser and associated lines without any concern by the installer. I had the same thoughts over corrosion that you have and as a result I'll keep an eye on these areas, but being in Southern California it most likely won't be a problem.
There are two things to think about: Rust from moisture and galvanic corrosion. Since you'll be drilling through galvanized steel (Anodic Index = 1.20V), I would use zinc-plated fasteners (Anodic Index = 1.25V), which would give you a differential of 0.05. If you use a chromium steel (stainless steel), this has a Anodic Index of 0.50V - 0.60V, which would give you a differential of 0.60V - 0.70V. You should stay below 0.15 for harsh environments.
You obviously need to have bare metal for a good ground, but once everything is assembled and tightened up, you could coat the whole area with a sealant to prevent future corrosion.

[Joeaksa]

Might get some POR15 and coat the areas after you are done. Lots of people forget about this and it can lead to rust, especially if its in an area where water is splashed.

Joe

[Bobboloo]

Any exposed metal "will" rust. How far it travels depends on other factors.

The real rust issues that damage chassis occur from trapped moisture. Places like inside the wheel wells where mud collects and traps moisture or at the corners of the windshield when the gasket leaves a gap for water to enter and get trapped behind the seal.

Just dab a little paint on the holes after you drill and you'll be fine.

For the ground pick a spot the stays relatively dry. You can always paint over the bolt and nut after you attach the ground wire if you're worried about it.

[skipdup]

You guys are great. Thanks a ton!

- Skip