givemethebighammer
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| posted on 21/3/04 at 08:59 PM |
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Chassis earth points
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.
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type 907
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| posted on 21/3/04 at 09:21 PM |
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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
Too much is just enough
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JoelP
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| posted on 21/3/04 at 11:25 PM |
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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]
Beware! Bourettes is binfectious.
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Hellfire
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| posted on 22/3/04 at 01:01 AM |
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Earthing
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.
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britishtrident
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| posted on 22/3/04 at 06:24 AM |
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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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Staple balls
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| posted on 22/3/04 at 08:52 AM |
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quote:
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.
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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britishtrident
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| posted on 22/3/04 at 05:16 PM |
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quote:
Originally posted by Staple balls
[
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
A main earth has got to be tight 1.6mm RHS has no resisstance to crush at all if you put a bolt through it needs a spacer inserted through the
centre or you can't tighten the bolt enough and you damange the tube.
In these days of electronic control earths have got to be 100% spot on or the ECU can throw a wobbly -- just ask anyone who works on Rovers, the
200/400 are infamous for ECU earth faults caused by the earthing point of ECU being badly designed.
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Northy
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| posted on 22/3/04 at 06:30 PM |
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quote:
Originally posted by Hellfire
the mounting points were cleaned up and then copperslipped to aid conduction and resist corrosion.
Er, copperslip is NOT conuctive. 
Test it with a multimeter! 
Graham
Website under construction. Help greatfully received as I don't really know what I'm doing!
"If a man says something in the woods and there are no women there, is he still wrong?"
Built 2L 8 Valve Vx Powered Avon
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blueshift
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| posted on 22/3/04 at 07:41 PM |
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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.
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givemethebighammer
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| posted on 22/3/04 at 10:33 PM |
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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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Hellfire
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| posted on 22/3/04 at 10:39 PM |
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copperslip conductor
quote:
Er, copperslip is NOT conuctive.
Northy
Just put the jump leads positive and negative in the pot - switched on - BANG!
WOULD YOU LIKE TO RETRACT YOUR STATEMENT?
Just joking - I thought the grease would crush up with the molybdenum (which is!) and the copper (which is) and squeeze out... maybe I'm
wrong... but it seems to be earthing very well as it is... am I just lucky (FOR ONCE!) if so I'll take it all off!
Thanks for the info. !
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JoelP
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| posted on 22/3/04 at 11:06 PM |
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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!
Beware! Bourettes is binfectious.
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type 907
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| posted on 23/3/04 at 12:23 AM |
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Earth bolts
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
Too much is just enough
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elitewiring
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| posted on 23/3/04 at 03:20 PM |
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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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Hellfire
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| posted on 24/3/04 at 02:09 AM |
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Copperslip
quote:
Originally posted by Northy
Er, copperslip is NOT conuctive.
Just checked your statement and you're right... shows open circuit. Also, tested with 9V no conductivity. However, under load it compresses and
shows almost identical resistance to the probes contacting - ie 0 Ohms.
Perhaps that's why they recommend it for Battery Terminals, Posts and Cables. Does exactly what it says on the tube! 
I'll stick to manufacturer advice!!!
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Peteff
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| posted on 24/3/04 at 10:07 AM |
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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
yours, Pete
I went into the RSPCA office the other day. It was so small you could hardly swing a cat in there.
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