Phil,
Good idea. I intend relocating all my relays to the back of my passenger kickboard as per your suggestion.
Once I can tidy all my wiring around the battery (located in the footwell) the happier I'll be.
The kickboard is screwed down so there should be less vibration.
Trularin - yes most of mine are socketed types, but some have simply loosened (vibrated) from their mountings.
Access is my biggest issue in regard to such things - a bit of planning at build stage would have made all the difference
