Belt Tension

[Guest]

I've been looking into replacing my fan belts. It looks as if they are tensioned by the use of shims on the shafts. Is this right? I can't see how this can tension the belts without inducing lateral force on them, causing them to wear on the edges.
What have I misunderstood?
http://p-car.com/diy/vbelt/

Cheers

 

[Dave Wilkinson]

Andy,

You're right that they ARE tensioned via the use of shims. The sides of the belt (and, indeed, the pulleys) are "V" shaped and, as shims are removed between the pulley halves, the sides get closer together and the belt is forced to ride higher in the "V" - hence increasing the effective pulley diameter and elongating the total path traversed. A longer path for a belt of a fixed length means a higher tension. The reverse is true when shims are added.

Hope that makes it clearer.

Regards

Dave

 

[Guest]

Ah! It all becomes clear. Thank you for that very good explanation.
I've ordered the "special" tool to stop the alternator shaft rotating, £11+vat which I didn't think was bad from Porsche!

Cheers and Merry Christmas []

 

[Richard_Hamilton]

There should be (from memory) 6 shims in the set. Make sure that any you remove from between the pulley halves go back against the outer face of the outer pulley (and vice-versa). Some people put them in their toolbox for future use, or worse still discard them, and it screws up the next person when they haven't got enough shims. Shims are item 16 in the picture.