Currently in the process of electrics. I have welded an M8 bolt through one of the chassis tubes near to the battery shelf for the main earth. I intend to weld short lengths of M6 stud into the chassis at various points around the car for the other earth points.

I intend to put them:

1. one each side of the nosecone, close to where the headlights indicators horn are.

2. one each side at the rear of the car close to the rear lights and fuel pump.

3. one under the dash somewhere for instruments etc.

Interested how other people have done this.

Hi,
Yes, likewise.
From bat to bolt, then from bolt to starter motor mounting bolt (bell housing) with welding cable.
Will TIG on M4's in other places.
With a s/s chassis I'v used s/s bolts with
brass nuts, but only because I had some.

Paul G

handbrake might need an earth too depending on how you wire it all.

actually ignore that... probably goes thru the mounting...

[Edited on 21/3/04 by JoelP]

We've put earthings: two at front (either side) for lights, indicators. One near drivers bulkhead for switch and dashboard earths and one in passeger bulkhead for relay earths. One also at rear for rear lights, fog and indicators.

The handbrake on ours is from a Sierra and it does earth through the mount so we made sure the mounting points were cleaned up and then copperslipped to aid conduction and resist corrosion.

Better to weld a fillet plate across the junction of 2 tubes for the main earth point, if you put a bolt through a tube the tube will crush when you try and tigthen the bolt.

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Originally posted by britishtrident
Better to weld a fillet plate across the junction of 2 tubes for the main earth point, if you put a bolt through a tube the tube will crush when you try and tigthen the bolt.

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Originally posted by Staple balls
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good idea for a rollbar or whatever, but it's a bit pointless for an earth, you're going for a good contact not a silly tight bolt

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Originally posted by Hellfire
the mounting points were cleaned up and then copperslipped to aid conduction and resist corrosion.

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Mmm, we just got our engine running, not sure what the difference was between when it was't firing properly on all cylinders and when it was: only things it might have been were taking injector electrical connectors off and putting them back on (unlikely), and taking the plugs out and cleaning the threads and holes. I had previously put a bit of coppaslip on them.. but they were oily too.

Not sure, not very good evidence I know. I am a little more wary of coppaslip now though.

thanks

been thinking about this I think now that M6 studs may be a little too large for earth points at the front and rear etc. Will probably use M4 or M5 like Type 907 says.

As far as the crush tube stuff goes, could you not just use a copper crush washer between the chassis tube and the nut ? Exactly how much torque do you really need on and earth point ?

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Er, copperslip is NOT conuctive.

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maybe with jump leads it might spark, however it would be good to know how resistive an inch line of it was, for future reference. it cant be 'totally' conductive cos only part of the compound is metal!

Hi again,

Just to clarify a point..... I welded the head of the bolt to the outside of the box section; no need to drill a hole. Can be tightened as much as you like.

Paul G

for info, in the aircraft industry a zinc compound is used between the bolt assy and structure to limit dissimilar metal corrosion (bolt may be steel and structure may be alluminium), then on some aircraft after the earth point has been connected to and complete the whole thing is painted to limit water ingress (called chemical corrosion).
this is a little ott for a car but its your car!!!
the bolts dont need to be super tight, remember you are only using m4/m6 tags, the big earths need to be tight like the main earth but they are bigger cables /tags.

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Originally posted by Northy
Er, copperslip is NOT conuctive.

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I posted last year in another thread about the nonconductive properties of copaslip. It was in a thread about spark plugs. I had a friend who copaslipped his battery terminals and effectively stopped them working (very generous coating) so I knew it was not a good idea. If you want to use it put it on the connection after it is joined up to seal it from corrosion