I've got the TVR back looking like a car again now, so it's time to sort out the wiring.
I drew a schematic of the grounding so I knew what went where, and it turns out that this could easily be written into Rob's guide in the "don't do it like this" section. (I will post the picture when I'm at home)
The battery is connected via ONE wire and a bolt to a point on the chassis. (This bolt is one of the main bolts that holds the car together and therefore passes through the fibreglass body).
The engine is grounded to the chassis, about 2 metres (as the electron travels) from the battery connection by ONE braided strap. It's quite thick, so will pass a fair bit of current.
There is a fairly thin ground wire on the gearbox that bolts to one of the gearbox mounting points.
The original ECU earthed itself to a number of ground points, including the chassis/battery point and the back of the engine, as far away from the braided strap as possible.
Most electrical things that required a ground had wires & a ring terminal taken to the nearest bolt on the chassis. This is OK until you see that the headlamps used something not much better than doorbell wire!
However some things risked causing nasties with ground loops, and a lot of the grounds were in the engine bay under the radiator where the chassis is prone to corrosion and the connection gets a high resistance so the ground becomes bad and generates lots of noise.
Stupidly, I used some of these for VEMS and found signal noise was dreadful. I sorted them out and used only the ones that went to the engine and it was better, but now I know why I could never get it perfect.
I didn't know how bad the grounding design was until I stripped the car for the refurb work. I'm going to put it back together in a slightly different way and actually have a decent engine earth for one thing.
