[T3] Fan replacement for a 1967 TYPE 3

[Jim Adney]

On 25 Jul 2025 at 17:43, bobsnotch at aol.com wrote:

>  I always thought the large cooling fan was a harmonic dampener. And you
>  want the rubber intact between the fan and the hub. I would think that it
>  being welded would cause a vibration problem, unless it's welded and
>  balanced before the crankshaft and it's components are balanced (you'd
>  want the entire rotating assembly balanced together).

I agree, and I believe Berg always does this as part of a complete crankshaft 
balancing. He has a writeup on this, which describes their balancing 
process, where they first balance the crank by itself, then add parts 
(flywheel, pressure plate, fan, pulley) one at a time, balancing each one as it 
is added.  

It took me a long time to understand why this is done, but it's because 
dynamic balancing is, by necessity, a two plane operation, meaning that you 
can only choose two planes at a time to balance. So you do the best balance 
you can with the crank, then add other parts one at a time, choosing that 
part's location as the next plane.

Still, it would be nice to be able to preserve the damping feature of the fan, 
but I don't know anyone who has done that.

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Jim Adney, jadney at vwtype3.org
Madison, Wisconsin, USA
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