Chassis earth points before bodyshell is fitted

[jono]

I am busily trying to cover all sensible chassis jobs before my restored shell is delivered (imminent).

It is a Spyder chassis and I would be grateful for advice on where to fix the various earthing points which cannot be left until the body has been re fitted (or which would be very difficult to do then).

Also is there a good technique to ensure perfect continuity where chassis straps etc are fixed? Paranoid about bad earths.

I have fitted earth straps between the chassis and engine (2 for good measure, one on each side), cross bonded the steering joint and earthed the steering rack. I think that is probably all I can do up front at this stage and the rest can be done along with the re wire once the body is fitted.

It's the back where I could probably do with some advice - diff, battery ground, petrol tank etc., - where do these go and what sort of wires/straps are needed? Photos would be great if anyone has some

...as I bought the car as a stalled resto in boxes of bits (never again!) I don't have the benefit of photos taken during the strip down.

Thanks, as ever.

Jon

[gerrym]

Jono, the rear earthing point is the critical earth (battery to chassis) as without a good one here, everything else will give you grief.

Graham Lund ran a separate earth wire from the rear of the car up to the front.

I figured that the chassis is actually the lowest resistance conduit front to rear that can ever be had, but is all depends on a good electrical connection at the battery end. My solution was/is to weld a screwed pin (AKA threaded screw with a tapered end) to the chassis and have this penetrate up inside the relatively dry bootspace where the actual mechanical connection can be made. This can use a toothed washer etc. The problem with having the mechanical connection under the car as per the original Lotus design is that inevitably it will become corroded and provide significant resistance. A welded connection is inherently low resistance.

Regards
Gerry

[dougweall]

Jon,

Just for good measure (as GerryM has said) about running a wire from all earth points to the rear, I did this on advice from a wily old electrician where I worked.

I asked what do I do about being sure of a good earth on a fibreglass car. His answer was start at the front O/S link a wire to N/S front, then to the point under the dash and so back to the rear point near the petrol tank.
Admittedly I had new looms all round, but this gave me extra piece of mind, and 5 years down the line, touching wood, shaking a lambs tail, not walking under ladders etc etc so far I have not had any problems.

Hope this helps you overcome your nerves a little.

Doug.

By the way if you use black covered wire it blends in nicely, and no one seems to notice. (i.e. purists, of which I am not)

[bob_rich]

Hi Jon

Welding in a bolt is a good idea if you want to go down that route. At the rear I have cleaned up and use the original earthing system using the two rear bobbin with the bodies and the bolts throughly cleaned for metal to metal contact. I have used large washer with the bolts and cleaned off the chassis paint so they make metal to metal contact and have a tinned copper strap across the bobbins on the inside of the boot. On this strap I have fitted some soldered on Lucar (1/4') connectors to take the variuos rear earths. the whole assembly then given a liberal dose of waxoil.

I have also added a 25sq.mm conductor from this assembly to the front mounting earth.

For the dash I intend to run a large conductor 10sq.mm to the rear of the dash from the front earth point as well. then all earth will not only go via the chassis but will also have thick copper conductors a back up. On strip down prior to the rebuild I found the dash earth via the one bobbin bolt that also secures the dash lower bracket to be a bit iffy.

hope this helps best of luck

Bob