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Serpentine Belt Pulley System

Serpentine Belt Pulley System

by Hairy Bus » Sun Nov 11, 2012 4:45 pm
Is it worth fitting one of these Serpentine Belt Pulley Systems?

What's the benefit over a standard pully system?

Is this one any good?

http://www.bmdpulleys.com/
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Re: Serpentine Belt Pulley System

by readyboy61 » Sun Nov 11, 2012 8:52 pm
Ask yourself why do you need it? Are you going to have a monster of an engine that your going to scream the nuts off at over 6000rpm which may throw a belt on the drag strip, if not its a waste of money and as soon as you have bought it you will have to throw away the tension pulley bearing and buy a decent one.

If millions of air cooled vw's have been going this long i think you will find vw knew what they were doing,
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Re: Serpentine Belt Pulley System

by e m p i » Sun Nov 11, 2012 11:23 pm
^^^ what he said. The fact that the bearings are cheap cr@p and wear out so quick gives me cause for concern about the rest of the kit. It looks the part but that don't mean sh!t if it doesn't do the job and last for more than 5 minutes. If the standard pulley and belt was good enough for VW then it's good enough for me. Unless you're looking to scream the nuts out of it on the M-way, in which case I'd go for a welded fan (berg?) and not much else or on the strip where I'd pull the belt anyway.

Shalom, Lee
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Re: Serpentine Belt Pulley System

by orb » Mon Nov 12, 2012 9:54 am
I've never known anyone not have an issue with them and I just can't see the point.
If everything is lined up properly then you shouldn't have a problem - mine spins to 7000rpm on a regular basis on stock stuff and has never thrown a belt on the road or at the track...

Stock set-up, properly aligned should be hassle free, also if something does go (bearing failure, shredded belt) whilst on holiday in europe then be prepared to be stranded for a couple of days (happened to 2 people I know) whilst you get parts sent over from the UK whereas if it's stock you'll get replacements anywhere and be back on the road that much faster.

Just my 2 penneth :wink:

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Re: Serpentine Belt Pulley System

by Hairy Bus » Mon Nov 12, 2012 1:16 pm
Thanks for the replies chaps, that's the question answered, I will stick with my standard stock set up and make sure it is properly maintained for a longer life.
And save myself the cash.....
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Re: Serpentine Belt Pulley System

by The Fordhams » Tue Nov 13, 2012 1:48 pm
There are a couple of points to consider re the serpentine system - I'm not advocating it just talking about them,

On a serpentine system the top pulley is sometimes a tad smaller and so it is possible that the fan spins slightly faster than you expect. This suggests more airflow / cooling which may be better in hot climates, it would suggest using a welded fan too. Potentially an amount of extra hp is required to spin the fan faster. But extra cooling is the point here.

There is an amount of slip (albeit small) on a stock V belt setup so it is possible the fan spins slightly slower than you expect / calculate. It is possible the slower fan is negated by the slipping friction heat on the belt.

It has been said serpentines are a little quieter / smoother / gentler on the pulleys.

I've used BMD pulleys and to me they're good quality, I have not used one of those cheaper serpentine systems. I carried a spare belt and concentrated to not over-tighten the tensioner.

For the climate in the UK I dont think it warrants them, but start to add camper weight, higher performance engines, and a European trip then I may consider it. But there are plenty of other things to optimise for engine cooling before having to resort to the smaller top pulley trick - which would be one of the bigger advantage of serpentine.
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Re: Serpentine Belt Pulley System

by scottish splitty » Tue Nov 13, 2012 3:18 pm
The Fordhams wrote:There are a couple of points to consider re the serpentine system - I'm not advocating it just talking about them,

On a serpentine system the top pulley is sometimes a tad smaller and so it is possible that the fan spins slightly faster than you expect. This suggests more airflow / cooling which may be better in hot climates, it would suggest using a welded fan too. Potentially an amount of extra hp is required to spin the fan faster. But extra cooling is the point here.

There is an amount of slip (albeit small) on a stock V belt setup so it is possible the fan spins slightly slower than you expect / calculate. It is possible the slower fan is negated by the slipping friction heat on the belt.

It has been said serpentines are a little quieter / smoother / gentler on the pulleys.

I've used BMD pulleys and to me they're good quality, I have not used one of those cheaper serpentine systems. I carried a spare belt and concentrated to not over-tighten the tensioner.

For the climate in the UK I dont think it warrants them, but start to add camper weight, higher performance engines, and a European trip then I may consider it. But there are plenty of other things to optimise for engine cooling before having to resort to the smaller top pulley trick - which would be one of the bigger advantage of serpentine.



as above i agree
also when vw made these engines they didnt have serpentine belts,tensioners etc,thats why they didnt use them
im sure if the engine was designed today a lot of things would be diffrent.
electronic ignition ,fuel injection ,vairable geometry turbo,etc,etc
just because V.W didnt use it in the 40s when they designed the engine doesnt mean its no good.
another point to note is most mild performance vw engines make about double the power they were designed to make as standard.
anything to help keep it cool is good in my book 8)
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Re: Serpentine Belt Pulley System

by GreenPanel » Wed Nov 14, 2012 8:16 pm
Had two sets of tensioner bearings fail on a bmd one and don't recon I had over tightened it, also had couple of other issues which had no bother with before or since changing back to stock style. Never again, they look nice but thats about it.
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