Robert_H

Is there a particular reason why the ground points are where they are?

More to the point actually, can ground points be added?

I am currently in the process of cleaning up the spare tire area on my car and I would like to move the wiring that currently goes to the ground point nearest the driver (at the front of the battery area) to near where the negative battery ground is.

What are the thoughts on this and has anyone ever added more ground points to their cars?

Rob

WallyP

There is no functional reason (electrically speaking) for having collected rather than individual ground points. Any good chassis or engine ground will serve.

Most American cars use individual grounds near the item being grounded. Porsche was apparently trying to make the car more serviceable by grouping the grounds.

Robert_H

Thanks Wally, that was what I wanted to hear.

Rob

zmandan

What would be the point of moving the Ground? To move ground wouldn't you have to run the ground wire across the spare tire well? Does not sound like "cleaning up" to me.

My philosophy has always been to leave original cars original. that way
you will not be a topic of a future thread ...." what !@#!!@ PO did this wire job ".....just my HO

dan z

jpitman2

Last point is quite valid - one day something will fail, new owner wont find ground where he expected it to be, wonders how it ever worked, until he finds the new ground elsewhere. Adding new grounds cant do any harm IMHO. Just make them obvious - eg a short black wire coming out of a light fitting bolted to chassis cant be mistaken for much else, I hope. I had what seemed like a poor ground in the engine bay once, so I used a 12" piece of terminated welding cable I had to run from a cam cover to cross member bolts.
jp 83 Euro S AT 47k

Robert_H

Dan,

You are correct, if I was going to do a hack job. Right now, the previous owner has all sorts of wires going to that particular ground point. I am going to get rid of all of the useless wiring and reroute the good stuff to a closer ground point.

The car will have it's radio and rear A/C deleted.

Ben Allison

The frames of these cars are galvanized. The surface of galvanized steel does not conduct electrical and therefore does not earth. Every ground point that is created must be done at a place that 1) it can electrically reach the other ground points in the car and 2) must have enough galvanization removed to have proper contact.

Unfortunately a break in a galvanized surface causes an area between two poles that is extremely prone to corrosion. This is why our car has so many electrical problems and why the ground points must be cleaned every so often.

More ground points = less likely that they all reach and more places for corrosion to build.

T_MaX

The frames of these cars are galvanized. The surface of galvanized steel does not conduct electrical and therefore does not earth.

Ben A. your the man of the hour in my book!

ViribusUnits

Ben, you sure?

IIRC, the coatings are made of Zinc. Zinc most deffently conducts electricty. However, IIRC, it forms a protective layer of zinc oxide that like aluminum prevents further corrosion. And that layer doesn't conduct electricty.

It would seem to me that the problem with the grounds is because of corrosion between the zinc, and the outer layer of the brass or galvanized connectors. Clean off the corrosion, and you have good contact again right?

Ben Allison

VU,

Sorry about the confusion in the post Yes, zinc is highly conductive. However, it corrodes quickly, even faster than aluminum (that's how galvanization works, it's rusts so that the steel doesn't). That's what I meant when I said that the surface does not conduct ...

Yes, you can clean the corrosion. However, it's astonishing how fast the corrosion comes back.

By limiting yourself to just a few ground points, you reduce the amount of total corrosion and the amount of cleaning required each year =)

Also, remember ground is a "bus". Various electrical systems assume that they all connect. Spreading the ground points out hurts you here also.

TimCo

Hello all,
I just bought an 83 928 and was troubleshooting a no start condition and found that there was only 9.5 v across the fuel pump. The pump wouldn't work with 12 ... but while I'm waiting for it, I'd like to locate the grounds and clean them up. I was trying to find them on the cd but have had no luck. I'd appreciate if someone could describe where they are.
Thanks,
Tim