Calibrating speedo ?

[M 80NGO]

Standard wheels n tyres are 15" with 215 65 15 tyres giving a rolling radius of 207.50 cm, My 18's have 245 40 tyres on with a rolling radius of 205.21cm which according to the tyre calculator site should put my speedo out by 1.1%, so when my speedo reads 60mph i'm actually doing 59.3 mph.

If the above was true then i'd be quite happy with that but my speedo is 10% out, at 33 mph i'm doing 30, at 55mph i'm actually doing 50mph, 66mph i'm doing 60 etc so what is the problem and how do i solve it ?

I'm soon gonna need new tyres and 225 45 18's have a R/R of 207.25cm just .25cm off of the manafactures R/R.

Thanx Pete.

[Northern Bongolow]

fit a GA5R speedo out of a 626 it has it on the dial, and no face plates or chips needed with 195 70 15's on or 215 65's on its spot on.

[M 80NGO]

fit a GA5R speedo out of a 626 it has it on the dial, and no face plates or chips needed with 195 70 15's on or 215 65's on its spot on.

Thats great thanx, what year 626 do i need to get the speedo out of and also L'oreal is wearing 18's not 15's or 16's

[Northern Bongolow]

225 45 18's are within 1% of 195 70 15's . 0.92. and 6mm circumference bigger. so to all but the pure are the same size.

early to mid 626 ------- pre digital dash/odmeter, fits straight in mate.

[winchman]

I drove on a straight road at 30mph
Pulled needle off and re positioned it after 3 or 4 attempts its now very good at 30, 50 and 70, cost nothing took 30 mins
I did try changing the speedo but coulnt find one

[llitvack]

Hi folks.
Does anyone know of a Mazda auto dismantler (perhaps in England) who might have a GA5R speedometer?
Many thanks!

[Northern Bongolow]

lots of the scrappies are linked to the parts finder system leon, try that route.

just type in google. mazda 626 speedo breakers.

[Jim the Box]

I drove on a straight road at 30mph
Pulled needle off and re positioned it after 3 or 4 attempts its now very good at 30, 50 and 70, cost nothing took 30 mins
I did try changing the speedo but coulnt find one

How easy is it to get to the speedometer (to pull the needle, mine's about 8mph out at 60) I hope to get the correct speed from my sat nav and get my wife to push the needle back on at the correct speed whilst I am driving, hope it's easy to get to as don't know much about bongos yet.

[winchman]

From memory, few screws to remove the surrond, glass clips off, needle pulls off, some people lever it off with twop small spoons, ideal if its tight, whatch out incase the weights fall out of the needle round bit.
Its easy really