Q: What is the minimum thickness before this belt needs replacing? 1983 Argo TB 8X8. Thanks.
A: Belt replacement is rated by any cracking between the cogs and how far it's dropping down in the secondary clutch when in neutral and at a stop. The clutch should be flush with the top of the clutch sheaves or 1 - 2 mm above. If it's sitting down in the clutch or you have cracking in between the rubber cogs its time to replace it.
Belt rubber can also lose its efficiency from dry rot over the years and we recommend replacing a belt on an older vehicle that has been stored over the years.