Amp Grounding Question

Had a noise problem and figured it down to the ground on the amp. So, I changed the ground and the noise went away.

Unfortunately, it came back after two weeks. Switched screws and added a lock washer. Went away...

Big surprise, three more weeks later and it's back (rough estimate of time)...

So, my questions:

Where is the best grounding point in a passenger car trunk that seems to have no support beams?

What is the best grounding hardware to use, screws, type, etc..?

Any other useful suggestions?

Before I got this car, I had a minivan, and boy, that thing had more steel grounding points than I would ever had needed....This car, it has nothing useful....

Thanks for the help.
-Steve

You could always run a longer wire (proper gauge!) to a more suitable ground point.

There's also nothing wrong with drilling your own ground point, remember. Just don't drill an outer panel that goes through to the outside of the car, and if it's a point that's going to get wet (such as inside a wheel well) you'll need to protect it with RTV silicone.

Best would be a through-metal bolt of some kind, so that you can cinch both sides of the connection with lock washers.

In looking closer at my grounding point, it seems it did make it to the outside of the car, so that is definitely an issue. I'll see if there is another point that is not an outer panel and try that....

When I said not to make it go outside, I meant not to make it poke through the visible, painted part of the car.

If you have a good connection point which happens to poke through into a wheel well or something, and you can reach it from the outside, then that's fine. Make it a full-on two-part bolt with a big old bolt head. (Head of bolt on outside of vehicle, thread and nut inside vehicle.) Scrape all the rust away, drill the hole to the proper size, and bolt away. Have a friend hold the outside wrench if necessary. When you're done, RTV-silicone the outside portion really good so it doesn't rust.