Pulley problems!

[mike202]

Sorry to question your diagnosis, but I disagree with the cause of the failure. What is happening is that the pulley nut has effectively bottomed on the shoulder just below the threads on the alternator shaft. As a consequence what feels like a fully tightened pulley nut is in effect applying a much reduced pressure on the pulley itself. The photos clearly shows the cause is a loose pulley even though the pulley nut was tight but ineffective.
The argument about fitting a 'quality' pulley, better made, higher grade of steel / material, is by and large masking the problem for longer before it surfaces again. Unless you address the real cause it will eventually re-occur.
Peter Good

Peter, is the solution more shims between the nut and pulley wheel then? Is that what you mean by addressing the problem?


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[Peter Good]

Mike, on a stock set up, the solution is more often than not a lack of shims as you suggest. As a guide, if you check some of the period photos published by VW, the pulley nut is always at the end of the shaft with no threads visible. Conversely, if 2 or more threads are visible, it is a good and reliable indicator some shims are needed. I have seen some making statements that x number of shims are needed, (in total) I question the accuracy of this definition. Personally, I always ensure the nut end is in line with shaft end. However, the situation gets more complex with the many aftermarket pulleys and other belt arrangements.
Peter Good

 

[mike202]

Mike, on a stock set up, the solution is more often than not a lack of shims as you suggest. As a guide, if you check some of the period photos published by VW, the pulley nut is always at the end of the shaft with no threads visible. Conversely, if 2 or more threads are visible, it is a good and reliable indicator some shims are needed. I have seen some making statements that x number of shims are needed, (in total) I question the accuracy of this definition. Personally, I always ensure the nut end is in line with shaft end. However, the situation gets more complex with the many aftermarket pulleys and other belt arrangements.
Peter Good

Thanks for that advice I am going to check mine right now to make sure I have enough shims on there [emoji106]


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[alikat]

And genuine VW sadly no longer means quality either. A local importer had a heated conversation with the folks at Emden about pulleys not running true. They were not receptive! At least they had a cut out with one flat end and one 'D' shaped - the 'kafer' brand ones have 2 'D' ends, which is not as good at holding the 2 halves in place. I prefer the 2 tab ones (usually from Brazil back in the day) that work very well so long as the tabs haven't eaten into the other half when run loose.

 

[Peter Good]

Sorry, but I think you have still missed the point. If you are relying on 'flat ends' and 'D ends' once installed and operational then that is part of the evidence that it is not set up correctly. The pressure correctly applied by the pulley nut all but negates the need for any of the above.
Peter Good

 

[purpledog07]

I know this is an old thread but...
I agree Peter, maybe these cheapo pulleys are under-sized and thinner than stock? Some may not have had this issue yet especially if they fitted a new belt, but when their belt starts to stretch and they remove a shim or two...
That new one is the same as my SCAT pulley. The new billet pulley and huge cone shaped washer is a lot thicker and even though the nut is shouldered it will no longer bottom out, if anything you may be concerned with how few threads it goes on. Anyone running a 'KAFER' pulley might want to consider shimming by adding an extra thick washer under the nut. This would tide them over until they can get a decent replacement sorted.
Cheers
Dave

 

[K@rlos]

There is a multitude of things that cause this this, yes shit pulleys are a common culprit but as Pete said the nuts bottoming out is too but the amount of people that fit alternators or dynamos and don’t align the pulleys is amazing! :roll:

Generic repro pulleys are toffee and the spin tru’s aren’t as good as they used to be. You can’t beat a decent genuine VW pulley or the billet pulley CB performance offer. I have 1 on my stroker and it’s been flawless.

 

[subheatadey]

Sorry to question your diagnosis, but I disagree with the cause of the failure. What is happening is that the pulley nut has effectively bottomed on the shoulder just below the threads on the alternator shaft. As a consequence what feels like a fully tightened pulley nut is in effect applying a much reduced pressure on the pulley itself. The photos clearly shows the cause is a loose pulley even though the pulley nut was tight but ineffective.
The argument about fitting a 'quality' pulley, better made, higher grade of steel / material, is by and large masking the problem for longer before it surfaces again. Unless you address the real cause it will eventually re-occur.
Peter Good

Great advice, much appreciated.