JoelP
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| posted on 19/9/03 at 09:45 AM |
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Chassis Earths
What are people doing for earths? Just welding a bolt on? Are there ant bolts to be avoided (ie poor conductivity...)?
Thanks in advance...
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David Jenkins
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| posted on 19/9/03 at 09:59 AM |
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For the main 'system earth' I welded in a slab of metal with an 8mm hole tapped into it. All the main stuff gets a soldered
'eye' which is held down into this with a bolt.
There are some local earths where the current would be high (e.g. next to the headlight connectors).
David
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stephen_gusterson
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| posted on 19/9/03 at 11:27 AM |
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bolts are OK. Better than rivets.
Important thing is surface area. Make sure the bolt is well in contact with the metal.
I used two main earth 'studs' under the dash - bolts welded to the chassis - four or so at the rear for lamps, same for front.
REALLY IMPORTANT is that you have a good earth to the engine and another to the gearbox. if you dont, the starter motor current will go places it
shouldnt - like throttle and clutch cables - and you will get a fire!
atb
steve
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JoelP
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| posted on 20/9/03 at 03:53 PM |
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thanks chaps, i lost the thread for a min and only just found it again! doh...
so any old bolts ok? just though maybe stainless or galv etc might not be ok...
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stephen_gusterson
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| posted on 20/9/03 at 08:44 PM |
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as long as it welds (if thats how you moun them) it will be fine.
atb
steve
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MB
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| posted on 21/9/03 at 08:53 PM |
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I certainly echo the bit about making sure you get a good earth to the engine as well as the chassis.
The most stupid thing I have managed in my build so far was to hand tighten up my earth bolts. In my eargerness to start up the engine I forgot to
tighten them properly... the last thing I expected was to see the clutch cable glow red and start smoking - doh!
Learned that the hard way!
Top tip: make sure you can disconnect the battery quick, standard battery clamps take far to long!
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JoelP
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| posted on 21/9/03 at 08:59 PM |
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i reckon im gonna drill a hole thru both sides of a tube and get a bolt about 40 or 50mm. put it all the way thru and weld the head, then it'll
just be a nice clean thread coming out of a tube. and use big washers soldered onto the wires. Should be ok.
in thinking a big one for the battery and engine earth, another for the g box, 2 for the dash area, 4 front and 4 back. the horn earths thru its
housing n'est pas?!
anyone remembered any others?
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GO
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| posted on 22/9/03 at 11:12 AM |
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Having a powder coated chassis and absolutely no welding ability whatsoever, I've been pondering the earth question.
I'm thinking of using an 8mm brass rivnut with a bolt to secure, probably using soldered washers as above. Would that make a good enough
connection?
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darren(SA)
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| posted on 22/9/03 at 07:14 PM |
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I ran the earth cable from my battery, to one of the g/box bolts, from a g/box bolt on the other side to the bolt holding my engine mount. worked very
well while being very neat at the same time!
cheers
darren
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stephen_gusterson
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| posted on 23/9/03 at 09:47 PM |
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the earth connection to the engine needs to be REALLY GOOD.
no soldering to washers or rivnuts.
You need to get a good large area between the chassis and the earth tag. Just a bit of resistance at 300 odd amps will cause a voltage drop that will
make your starter run on low volts and the joint get hot.
A rivnut would need to be tight as it joins the steel, and you would need to clamp the tag against a nice 'tag sized' area of clean bare
metal.
Dont spend money on earth braids and power cables. Scrap yards are full of em and they can be cleaned up to look like new.
atb
steve
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JoelP
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| posted on 23/9/03 at 10:00 PM |
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got the original wires from the donor, a polish and that should suffice?
would the engine earth rather go straight to the battery, or does it want to go to the chassis anyway? thinking about it, i suppose its the altenator
it should head for?
gonna wire to the chassis anyway with the battery on the same bolt, so its just a matter of interest.
since the altenator effectivly goes from the live to earth its easy to forget that the current actually goes backward thru it, charging the battery.
so is everything, including the battery, really earthed on the alternator?
that might actually be a confusing way to word it....
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