Mark G
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| posted on 23/7/08 at 05:06 PM |
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Making a decent earth?
At the risk of sounding stupid will a rivnut be any good for making an earth on the chassis?
If not are there any decent ways other than welding bolts on?
Thanks,
Mark
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Paul (Notts)
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| posted on 23/7/08 at 05:14 PM |
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Rivnut works fine for me + cleaned a small area around it for a locking washer.
Paul
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tomblyth
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| posted on 23/7/08 at 05:17 PM |
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I've been told it takes six days to make the earth , then you can have a day off! but I hav'nt seen this proved yet!
[Edited on 23/7/08 by tomblyth]
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Mix
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| posted on 23/7/08 at 05:24 PM |
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Hi
I would not personally use a rivnut, they do not allow sufficient torque to be applied in my opinion. I would pick an area of the chassis consisting
of a 3mm+ plate and drill an 8mm hole in that. Thouroughly clean the area around the hole both sides and install a spotlessly clean 8mm bolt and two
nuts, torque the first nut and use the second to lock it. Then protect all surfaces except the outside face of the second nut and exposed thread with
paint, silicon etc. If you have a multimeter you can check the resistance from the bolt shank to another clean area of the chassis and it should be
very low, about 50 milliohms. For convenience I would suggest installing two or three earth posts at convenient locations.
Regards Mick
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turbodisplay
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| posted on 23/7/08 at 05:30 PM |
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You could run a seperate earth wire. I used car amp power cable running from the batery, front and rear.
Darren
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NOTE:This user is registered as a LocostBuilders trader and may offer commercial services to other users
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philw
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| posted on 23/7/08 at 05:55 PM |
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quote:
Originally posted by Paul (Notts)
Rivnut works fine for me + cleaned a small area around it for a locking washer.
Paul
+1
Must try harder
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Paul TigerB6
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| posted on 23/7/08 at 05:59 PM |
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quote:
Originally posted by tomblyth
I've been told it takes six days to make the earth , then you can have a day off! but I hav'nt seen this proved yet!
[Edited on 23/7/08 by tomblyth]
Question needs answering also - can it be done for £250??? 
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David Jenkins
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| posted on 23/7/08 at 06:30 PM |
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I welded a bolt into a small metal plate, then welded the plate to the chassis. This is located on a cross-piece between the engine and battery.
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wilkingj
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| posted on 23/7/08 at 08:22 PM |
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Ive used several methods.
The Main Battery earth is a small welded plate with a bolt welded to it.
The headlight earths are a hole in a bracket with a bolt through.
The rear lights are a Rivnut.
All working OK after 3 years and 4000 miles.
All earth points were rubbed back to bare metal, then smeared with grease to prevent rusting on the bare metal parts.
1. The point of a journey is not to arrive.
2. Never take life seriously. Nobody gets out alive anyway.
Best Regards
Geoff
http://www.v8viento.co.uk
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britishtrident
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| posted on 23/7/08 at 08:31 PM |
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Allow 6 working days + 1 day of rest for the job.
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BenB
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| posted on 23/7/08 at 09:12 PM |
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I wouldn't. Aren't riv-nuts made from ali? Is it a good conductor of electrikity??? I know it conducts heat nicely but not sure about
electrons... I'd also worry the contact area isn't huge....
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BenB
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| posted on 23/7/08 at 09:14 PM |
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Just looked it up. Ali has 3.9x the resistance of steel per metre (for a given diameter)....
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bassett
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| posted on 23/7/08 at 09:17 PM |
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Talking about the grease on the earth point would it be better to use copper grease to make a better connection
My MNR Blog Updated Jan 2010 - Track Day Prep Begins!
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BenB
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| posted on 23/7/08 at 09:23 PM |
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I wouldn't put copper grease (or any other grease) between the bolts / washer or whatever is making the contact. Copper slip has copper in it
but only as a lubricant. It will still act as an insulator. Normally you just do plain steel/steel but liberally apply the grease over the top to
prevent moisture getting in. It won't make any difference if its copper slip or not...
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Mark G
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| posted on 23/7/08 at 10:04 PM |
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ok, thanks all. I'll try to nut n bolt if poss.
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907
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| posted on 24/7/08 at 12:16 AM |
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Tee He
I just can't see the problem. 
Paul G
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matt_gsxr
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| posted on 24/7/08 at 07:08 AM |
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ALUMINIUM IS A GOOD CONDUCTOR
Aluminium is a good conductor,
Aluminum is a silvery-white metal with many valuable properties. It is light (density 2.70 g/cm3), non-toxic, and can be easily machined or cast. With
an electrical conductivity 60% that of copper and a much lower density, it is used extensively for electrical transmission lines.
Or from wikipedia (if you like that one)
Aluminium Electrical resistivity (20 °C) 26.50 nOhm·m
Iron Electrical resistivity (20 °C) 96.1 nOhm·m
The ratios are 1:3.9 but the aluminium is more conductive (lower resistance). Conductivity and resistivity often confused.
Matt
[Edited on 24/7/08 by matt_gsxr]
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BenB
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| posted on 24/7/08 at 02:48 PM |
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Bizarre! The website I looked at had it per metre and it was the other way round
Oh well I live and learn!!!
Then again.... wikepedia 
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