For historic road rallies in this country you need a trip meter with large read-out, a twin display and the ability to calibrate it to around 0.5%.
That's why Brantz are popular as they are not expensive and work really well. They are easy to fit and easy to calibrate.
Highly recommended.
Yeah, for sure, I don't think I'd personally bother trying to 'make' a mechanical unit these days, something like the Brantz would be wise. We had a TerraTrip (I think, was a while back!) in the Rally Car, very
Awesome cheers guys! How do they fit? Guessing you have to connect them to the speedo drive somehow?
There are many ways the Electronic jobbies can sense & count the wheels turning, I tend to think the simplest is to fit an pulse sender to the speedo drive, these are what you'd fit if you were fitting an electronic speedo, there are 'through' versions available, the sending basically going 'in-line' (usually at the gearbox end of the cable) if you wanted to retain a mechanical speedo. However, while easy to fit up, these do have a disadvantage of not accounting for wheel slip / spin.
Some units (possibly the Brantz, I haven't looked) can take up to 4 inputs and will generally take a calculated average to work from, and even in these there are more up market ones that will automatically exclude a wheel sensor if say 3 are reading 60 and 1 is reading 0, clearly that one is faulty and so will then only work from the remaining 3. Very clever.
Probably the most accurate pick up would be a rear wheel mounted inductive pick up for a Mini.