chrsgrain
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| posted on 10/5/06 at 12:45 PM |
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Earthing stuff - very basic question!
Hi all...
Approaching trying to start it all up... think we have all the bits we need - but have really no idea about where to put earthing straps and the
like...
My guess at the moment is;
Battery negative to chassis
Earth strap from block to chassis
Earth from all the bits - lights etc etc to multiple points on chassis
Right / wrong or somewhere in between?? I feel I should know this somehow, or at least be able to find it out - but its apparently too obvious to be
in any of the books I have!
Chris
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mackei23b
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| posted on 10/5/06 at 12:49 PM |
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Yes, thats the one!
Cheers
Ian
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David Jenkins
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| posted on 10/5/06 at 12:55 PM |
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That sounds about right.
If you can fix the battery negative strap to the same point as the engine earth strap then that would be ideal (i.e. both under the same nut/bolt).
Don't underestimate the size of the engine-chassis earth strap - the bigger the better, within reason, and use a proper braided strap from any
of the reputable electrical dealers.
David
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smart51
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| posted on 10/5/06 at 01:02 PM |
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I found that the engine mounting bolts gave me a good earth even before I connected the bike loom which has a thick wire from the block to the battery
-ve terminal. I haven't used rubber engine mounts though.
As for earthing rear lights, why not just run a length of wire to the battery? For the cost and weight of wire, it seems better than relying on the
chassis for earth.
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muzchap
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| posted on 10/5/06 at 01:13 PM |
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Smart51,
Well my recommendation would be to do both! Earth to the chassis and back to the battery.
I really, really don't want to have to unravel all that loom tape again :p
------------------------------------
If you believe you're not crazy, whilst everybody is telling you, you are - then they are definitely wrong!
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nitram38
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| posted on 10/5/06 at 01:28 PM |
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quote:
Originally posted by smart51
I found that the engine mounting bolts gave me a good earth even before I connected the bike loom which has a thick wire from the block to the battery
-ve terminal. I haven't used rubber engine mounts though.
As for earthing rear lights, why not just run a length of wire to the battery? For the cost and weight of wire, it seems better than relying on the
chassis for earth.
Because you would have to run about 20 wires in the loom. Apart from the cost there you would double the loom thickness plus it is just more
un-necessary work!
K.I.S.S= Keep It Simple Stupid!
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02GF74
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| posted on 10/5/06 at 01:43 PM |
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quote:
Originally posted by David Jenkins
That sounds about right.
If you can fix the battery negative strap to the same point as the engine earth strap then that would be ideal (i.e. both under the same nut/bolt).
Don't underestimate the size of the engine-chassis earth strap - the bigger the better, within reason, and use a proper braided strap from any
of the reputable electrical dealers.
David
sounds right but isn't quite there - ideally you want -ve from battery connected to the gearbox/engine as this lead will take the heavy
starting current.
then as said, strap to chassis for earthing lamps and stuff.
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David Jenkins
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| posted on 10/5/06 at 01:57 PM |
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Think of the chassis as a readily available and very big wire that goes all round the car! This means that you only have to run one long wire to each
load, with just a short return to a local chassis earth.
The reason for using a braided strap between the engine and chassis instead of ordinary starter cable is due to the engine vibration - an ordinary
cable would soon fracture.
David
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smart51
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| posted on 10/5/06 at 02:19 PM |
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quote:
Originally posted by nitram38
quote:
Originally posted by smart51
As for earthing rear lights, why not just run a length of wire to the battery?
Because you would have to run about 20 wires in the loom. Apart from the cost there you would double the loom thickness plus it is just more
un-necessary work!
K.I.S.S= Keep It Simple Stupid!
No you wouldn't. 1 wire is all that is needed for an earth all the way from the point where your chassis earth would have been all the way to
the battery. You don't have to have a separate earth for each light!
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nitram38
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| posted on 10/5/06 at 02:26 PM |
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quote:
Originally posted by smart51
quote:
Originally posted by nitram38
quote:
Originally posted by smart51
As for earthing rear lights, why not just run a length of wire to the battery?
Because you would have to run about 20 wires in the loom. Apart from the cost there you would double the loom thickness plus it is just more
un-necessary work!
K.I.S.S= Keep It Simple Stupid!
No you wouldn't. 1 wire is all that is needed for an earth all the way from the point where your chassis earth would have been all the way to
the battery. You don't have to have a separate earth for each light!
That is a possible answer, but the cable would have to be bigger to handle the combined currents. Then you still have the problem of creating
terminals for the bigger cable and branching off to the accessories as they have small terminals.
Again you have the possibility of another break point like you would have had just using the chassis.
The chassis is a solid conductor so why not use it?
Cars always use this for a reason and that is one of cost and simplicity.
Like I said, Keep it simple............
[Edited on 10/5/2006 by nitram38]
[Edited on 10/5/2006 by nitram38]
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chrsgrain
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| posted on 10/5/06 at 02:32 PM |
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Thanks for the help - I'm pretty clear on what the next step is.... how would you guys suggest securing the earth points onto the (powder
coated) chassis. I guess the best way would have been to weld a threaded insert into the chassis then bolt to that - but too late!
How about a tapped hole and bolt with the terminated cables under the bolt?
Chris
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nitram38
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| posted on 10/5/06 at 02:43 PM |
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You could use a rivnut?
Use a top hat type for good measure. That way you can expose a little more chassis just under the top hat area.
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robertst
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| posted on 10/5/06 at 03:16 PM |
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i read somewhere the best way of making an earth contact with the chassis is welding a bolt to it to then connect the earthing wire to it.
should i then weld a couple of these all along the chassis? about two at the front (headlights, indicators..) two in the middle (scuttle instruments
and whatnot) and two in the back (rear lights, fuel tank, and whatnot) would that be enough?
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nitram38
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| posted on 10/5/06 at 03:20 PM |
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You can weld them, but you will destroy your powdercoating!
Another option is to use a spot welder with weld on studs. You just hold the stud onto the chassis (bare) and they spot weld themselves. This would
minimise your heat and damage.
I ran my cables first and left the earths untill last and then I used 4mm rivnuts in the chassis for the small cables. For my main earth, I welded my
battery tray to the chassis (from a rover 214) which had a threaded earth point for the main earth lead.
[Edited on 10/5/2006 by nitram38]
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omega 24 v6
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| posted on 10/5/06 at 04:47 PM |
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Remember to grease (petroleum jelly you know the stuff ) the earthing points to keep them nice and corrosion free.
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RazMan
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| posted on 10/5/06 at 07:51 PM |
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quote:
Originally posted by omega 24 v6
Remember to grease (petroleum jelly you know the stuff) the earthing points to keep them nice and corrosion free.
Copperslip is even better as it is conductive
Best to have about three or four separate earth points on the chassis, then common the different groups of components (front lights, rear lights, dash
instruments etc) and run all the earths to one of these.
Cheers,
Raz
When thinking outside the box doesn't work any more, it's time to build a new box
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bigrich
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| posted on 10/5/06 at 10:33 PM |
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rivnuts work really well as earth points no probs with mine so far
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Peteff
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| posted on 10/5/06 at 11:26 PM |
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Copperslip is even better as it is conductive.
I know a mechanic who wil tell you different . Cover them after you bolt them up by all means but don't rely on the copaslip to aid
conductivity.
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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RazMan
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| posted on 11/5/06 at 07:12 AM |
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quote:
Originally posted by Peteff
I know a mechanic who wil tell you different . Cover them after you bolt them up by all means but don't rely on the copaslip to aid
conductivity.
Just stick the probes of your multimeter into a pot of Copperslip and you will see what I mean. I am not suggesting that you rely on copper grease to
provide an earth - just to lubricate the earth stud and help with prevention of corrosion. A loose connection with vaseline in between can be
insulated and the copper particles just encourage a good connection.
Cheers,
Raz
When thinking outside the box doesn't work any more, it's time to build a new box
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David Jenkins
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| posted on 11/5/06 at 07:16 AM |
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I believe that there are 2 kinds of copper grease in this world - the copperslip type, the sole aim of which is to leave a trace of copper behind once
the grease has dried. This copper allows the nut or whatever to be undone.
The other type is conductive, but I've only ever heard of that used in a military context. I've never seen it in real life.
David
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NS Dev
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| posted on 11/5/06 at 07:35 AM |
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quote:
Originally posted by chrsgrain
Thanks for the help - I'm pretty clear on what the next step is.... how would you guys suggest securing the earth points onto the (powder
coated) chassis. I guess the best way would have been to weld a threaded insert into the chassis then bolt to that - but too late!
How about a tapped hole and bolt with the terminated cables under the bolt?
Chris
If you can live with touching up the powdercoat in a few places (which I've had to do anyway after making lots of mods!) then as somebody else
mentioned, the best way is to weld some M6 bolts (machine screws to be technical I suppose!) to the chassis in a few useful locations, and earth to
these with ring crimps.
That's what I'll be doing on mine.
Another way if you want something to be easier to remove and it's a small load like taillights etc, is to buy some rivet-on 6.3mm blade
terminals like these:
or these:
Retro RWD is the way forward...........automotive fabrication, car restoration, sheetmetal work, engine conversion
retro car restoration and tuning
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ned
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| posted on 11/5/06 at 07:44 AM |
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I welded a bolt to my chassis for the main earth which was taped up when it was powder coated. I've also used rivnuts for smaller earths in
places.
I earthed my xe from the rear most exhaust stud and from one of the bolts that holds the dipstick pipe on - both m8 and go directly to the chassis
earth and the chassis earth top battery negative.
might be some pics in my archive under april/may build folders.
Ned.
beware, I've got yellow skin
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