Why is using only OEM or OEM-equivalent timing belts important?

A car engine timing belt with coloured arrows showing the various parts

This image shows some details of how a new, OEM or OEM-equivalent timing belt is required to fit on a driven sprocket. Let us look at what the arrows mean in this picture-

Red arrows

These indicate the required clearance between the bottom of the timing belt’s teeth and the deepest part of the valley between the teeth on the sprocket. This clearance is required to ensure that the sprocket’s teeth engage the teeth on the belt at the points indicated by the-

Blue arrows

The points indicated by the blue arrows are where the structure of the car timing belt is the strongest. This reduces wear on both the timing belt and the sprocket, thereby largely preventing premature timing belt failure.

Yellow arrow

This arrow indicates the braided reinforcing threads that give the belt its structural strength. In OEM and OEM-equivalent timing belts, this layer of threads will be visible along the entire length of the timing belt. This can be taken as proof that the reinforcing threads are exactly aligned along the timing belt’s direction of rotation.

If this layer is not visible over the entire length of the timing belt, the reinforcing layer is not aligned along the timing belt’s direction of rotation. In practice, this places unequal loads on the timing belt, which causes premature belt failure.

Note that an angled reinforcing layer is a common feature of substandard, low-quality timing belts. Such timing belts should, therefore, be avoided at all costs. Other signs of low-quality timing belts are-

  • that the bottom of some, or all of the belt’s teeth touch the bottom of the valleys between the sprockets’ teeth
  • that printed identifying marks or information on the belt are smudged, misspelled, or missing
  • their unusually low price

The best way to avoid buying low quality timing belts is to deal with professional mechanics and workshops near you that can advise you on the best timing belt brands for your particular vehicle.

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