# Harmonic Balancer or Crank pulley? Difference?



## SimonH (May 28, 2000)

I notice that my '89 Jetta has what I would call a harmonic balancer (Stock), while the other Mk2's have regular crank pullies. 
What does the harmonic balancer do, which will also answer which of the two is preferable?
Thanks in advance.


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## citti2004 (May 21, 2011)

*harmonic balancer*



SimonH said:


> I notice that my '89 Jetta has what I would call a harmonic balancer (Stock), while the other Mk2's have regular crank pullies.
> What does the harmonic balancer do, which will also answer which of the two is preferable?
> Thanks in advance.


It dampens crankshaft vibrations on your main drive pully for the serpentine belt. It's an inner steel wheel bolted to the crankshaft, with a rubber bushing, then the actual crankshaft drive pully on the outside of that. Without it you would likely loose your belt, or wear it out prematurely.The vibrations give off a harmonic frequency and the harmonic balancer, made of both rubber and metal, is tuned to cancel out those frequencies, specifically. Since the crankshaft has to twist every time it rotates, its gives off a harmonic frequency, and the harmonic balancer helps to control that twist and the vibration. The harmonic balancer serves a second purpose, as well. It helps the engine by adding weight to the front of the engine, which allows it to runner smoother.


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## Glegor (Mar 31, 2008)

citti2004 said:


> It dampens crankshaft vibrations on your main drive pully for the serpentine belt. It's an inner steel wheel bolted to the crankshaft, with a rubber bushing, then the actual crankshaft drive pully on the outside of that. Without it you would likely loose your belt, or wear it out prematurely.The vibrations give off a harmonic frequency and the harmonic balancer, made of both rubber and metal, is tuned to cancel out those frequencies, specifically. Since the crankshaft has to twist every time it rotates, its gives off a harmonic frequency, and the harmonic balancer helps to control that twist and the vibration. The harmonic balancer serves a second purpose, as well. It helps the engine by adding weight to the front of the engine, which allows it to runner smoother.


most older VWs dont have a harmonic balancer, FWIW.. just a crank pulley. so they must not have been that important..


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## chois (May 12, 2000)

My 86 came without one.

The engine builder suggested using one, so I took a 16v harmonic pulley, removed some of the mass, and used it on the fresh motor.


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## Glegor (Mar 31, 2008)

chois said:


> My 86 came without one.
> 
> The engine builder suggested using one, so I took a 16v harmonic pulley, removed some of the mass, and used it on the fresh motor.


that shouldnt even work, the 16v pullies and 8v pullies have different offsets..


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## chois (May 12, 2000)

Glegor said:


> that shouldnt even work, the 16v pullies and 8v pullies have different offsets..


I just used the 16v harmonic balancer, and knocked off the V groove section, along with some of the OD on a lathe.

I made my own AL under drive pulley set, so the offset issue was easily corrected.

There are a number of different H2O pump pulley offsets out there, and the alternator has some flexibility in mounting, as well as a few different pulleys. You can also space stock pulleys a bit in a pinch.

IIRCC the later 8v motors came with a harmonic balancer, so there may be an easy solution out there that I didn't use...


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## Glegor (Mar 31, 2008)

chois said:


> I just used the 16v harmonic balancer, and knocked off the V groove section, along with some of the OD on a lathe.
> 
> I made my own AL under drive pulley set, so the offset issue was easily corrected.
> 
> ...


the later 8v motors did INDEED come with a harmonic balancer, but it was a serpentine setup..


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## draculia (Feb 27, 2002)

citti2004 said:


> It dampens crankshaft vibrations on your main drive pully for the serpentine belt. It's an inner steel wheel bolted to the crankshaft, with a rubber bushing, then the actual crankshaft drive pully on the outside of that. Without it you would likely loose your belt, or wear it out prematurely.The vibrations give off a harmonic frequency and the harmonic balancer, made of both rubber and metal, is tuned to cancel out those frequencies, specifically. Since the crankshaft has to twist every time it rotates, its gives off a harmonic frequency, and the harmonic balancer helps to control that twist and the vibration. The harmonic balancer serves a second purpose, as well. It helps the engine by adding weight to the front of the engine, which allows it to runner smoother.


WTF? and yes...

The purpose of a damper is to keep the crankshaft from destroying itself. While every combustion event causes the crankshaft to twist a bit this is relatively a non issue. The damper is designed to help soften the possible damage from that twist, but ultimately what you don't want is to reach the resonant frequency of the crank and have a catastrophic failure. 

That being said, dampers are designed for the specifics of the engine it's going on. If you start changing things, making more power, new pistons and rods, etc, that damper designed for the stock engine is no longer as effective. 

Does it matter to us and our 100hp engines? Not really. If you're building a race engine, or a very hot street engine with a nice high redline, then it's absolutely a good idea


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