- My model of MX-5 is: MK1 Eunos 1992
- I’m based near: Hounslow
- I’m looking for technical help or recommendations on: Replacing my rusted/seized battery terminals (particularly the negative terminal).
The car recently completely cut off when driving after a going over a small ditch. It turned out after playing around with the negative terminal wire it started again.
This obviously is loose and rusted.
I would like to replace the wire and add two new terminals, what would you recommend?
Where should I source these parts from?
Would it just benefit from taking apart clean up and reconnect?
Giving how rusted and seized they are I would rather replace atleast the terminals.
Probably wouldn’t do any harm to try rust remover.
Personally I’d just remove the battery and then dangle the cable into a cup of rust remover (not converter) since they don’t look that rusty really, for one thing you can still see the threads and the bolt (and indeed the rest of the metal shown) doesn’t appear to be expanded from the rust in any way.
And if it didn’t work as well as it should, you’d still have the remaining rust remover for other jobs that required it 
Hmm, seeing how the bolt has fully closed the jaws of the clamp ring, it looks like the clamp ring is a fraction too big to grip securely to the post on that isolator switch.
Fortunately, there is a cheap quick-fix. Wrap a 1mm thick copper shim around the post, open the clamp to fit over it and that should guarantee a decent grip and contact. Once done smear it all with silicone grease to keep out the rot.
Wire wool is your friend for cleaning up ALL the contact surfaces before reassembly, but use a wire brush for the bolt and nut.
Where do I find a 1mm copper shim?
If you happen to have some old copper water pipe lying around, say 3/4" or 22mm, there’s your shim.
Use wire wool to clean one end of the pipe back to bright copper inside and out.
Then cut into the nice new shiny bit a lengthways slot as long as that clamp.
Then cut that slotted bit off the pipe.
Then adjust it as necessary to slide easily over the post, the shim will probably need a trim for a snug fit with a small slot still visible when fully tight.
Have fun and be safe.
