Clocks over-reading

[mintyfresh]

Sorted now!

Recently fitted some clocks with rev counter, but i suddenly found myself driving 50mph everywhere.. it didnt feel like 50 at all so me and a mate decided to do a rough speed check on the dual carriageway with his car in front, the results were:

at 30mph my clock was reading ~ 35mph

at 40mph my clocks were reading ~ 50mph

at 50mph my clocks were reading ~ 60mph

and at 70mph my clocks were reading ~ 80mph

now these are just rough figures but i want to know how i can fix this, preferably by making the clocks read right, not just by putting markers on my clocks

cheers

 

[Alienfish360]

What wheels do you have? they will affect it.

 

[mintyfresh]

I've only got 14" steelies at the moment, (165/65/R14) and according to a tyre size calculator (which is very useful btw) my clocks should under-read so that when they say im travelling at 70 i'll actually be doing 72.93mph which is the opposite of what my clocks are doing anyways

 

[Alienfish360]

most clocks are designed to over-read anyway. All clocks are made to within a tolerence, so the speeds may vary.

 

[mintyfresh]

but still, over reading 10mph isnt normal, most clocks are only out by a little

forgot to mention, ive got a 1.0L and i think the clocks are from a 1.3, when i swapped the clocks over i used the innards from my old clocks (wanted to keep my milage) with the front of the new clocks basically i only swapped the front of the dials and the speedo unit is the original from my car, dont know if this makes any difference?

Yet another edit.. realised that the dials for the 1.3 have a higher top speed sooo the other speed markings are in different places. i'd put the old 1.0L clock face in the new clock unit but i want to keep the trip meter so is it possible to get a 1.0L speedo front with the cutouts for the trip meter from Nissan?