Fan Belt, 1200-1600cc, Dynamo or Alternator, 11.3x912, T1 engine (Optibelt)
We always recommend using the wider 11.3mm fan belt on all T1 engines, irrespective of Dynamo / Alternator / model year. Back in the 1970's more and more demands were put onto the fan belt, with the introduction of the larger twin port fan, and also larger output alternators. This resulted in the earlier 9.5mm fan belts failing, due to the extra demand. VW addressed the problem in 1973, by introducing this stronger 11.3mm belt which can also be used on earlier vehicles.