Hi, was wondering if anyone had any ideas as to why my 120y coupe is reading slower than what I'm actually going. It reads 80km/h when the gps tells me I'm doing about 100 km/h. Was thinking it could maybe be a seepdo cable issue. It has a A14 with 56a 4speed in it.
Thanks Geoff.

What size rims and what profile tyres are you running.
That can also have an effect on speedo reading.

Stock 12 inch standard profile tyres.
Thanks

does the needle move smoothly from slow all the way to fast or does it 'flick' around?

if it flicks a bit it's likely the cable. If it's smooth, its likely the guage.

The needle is smooth in motion, just doestn't read correctly. Is about 20km/h out gets further out the faster you go.

The gearbox probably was originally in a 13" tyre vehicle.

You just need to get a different gear for the end of the speedo cable thing that goes into the gearbox.

Thanks mate, I was thinking it would be something like that.

the original calibration would have been for 12" cross ply tyres which are bigger in diameter then the modern 12" radials ... a set of 13's with like 70 profile tyres will fix it all up

Man a 120y can never go too fast :P....

Yes, no 120Y has ever gone too fast.


Here's my 1200 speedometer:


Reads: 35
Actual: 29