speedo reading wrong, but wheels tyres normal. (Read 67 times)

[chrisdevon]

I have just bought a 1988 bluebird. drove it home seems ok ish.

However speedo seemed out so got my dad to check against his speedo, following me.
Im getting 70mph when really doing 60
getting 60 when doing 50
getting 40 when doing 33
So its quite a bit out, the wheels are normal 165/r14 or something similar.

any ideas ?

thanks
Chris.

[dirtynails]

Speedometers are allowed by law in manufacture to read up to 14% too much & 0% too little according to one vehicle importer. This is to allow fitment of bigger wheels without reading less speed than you are actually doing.If it's outside spec & the car is original -diff not changed etc,the problem is a weak hairspring in the speedo head.Afraid new clock is the only cure.
Hope this points you the right direction.