I know fan belts are graded by their length, they have it printed on the outer edge in millimeters.

I have never really thought where this is measured, is it the length of the outer or the inner or the mean of the driven faces?

I measured mine at its smallest possible dimension at the outer face by wrapping masking tape around the pulleys, cutting it off and measuring - 825mm. I want to get the smallest belt possible as my alt will only adjust 38mm of belt length (did the same thing on maximum dimension)
Rescued attachment Masking Fan Belt.jpg

the lenght is the outside measurement but you also need to know what sort of v it is eg. spz or 52b there are meny different types.

take the crank pulley along, we bought a halfords hb 875a which should see you right

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Originally posted by boost
the lenght is the outside measurement but you also need to know what sort of v it is eg. spz or 52b there are meny different types.

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quote:

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Originally posted by macspeedy
take the crank pulley along, we bought a halfords hb 875a which should see you right

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I have been having the same fun recently mark trying to drive an alternator in a different position on a zetec.

You'll find that Halfords belts are mm then a letter a-f referring to the v spec. Other manufacturers use different codes.

From my experiments I found that all belt manufacturers (Gates, Bosch, Halfords etc ) belts are different lengths at a given size by +/- 10mm anyway.

Best bet is to pick the smallest as your doing and then exchange if not correct.

Cheers