harmonic balance pulley, necessary?

[shwartzbewithyou]

From the 1.6TD SAE paper,

4- and 5-cylinder turbocharged Diesel engines are provided with a torsional vibration damper. The main goal was to dampen the critical 6th order at 4800 rpm. All other orders were less than +/- O.16 degrees crankangle. The problem was solved by design modifications and the proper damper material selection.

Generally when engineering types refer to a harmonic as "critical" it means that the oscillation will not self-damp to any non-destructive level, meaning that if the engine is operated continuously at the speeds and loads neccessary to induce the oscillation, the torsional vibration will deflect the crankshaft beyond its elastic limit. This will eventually lead to fatigue and ultimately to crankshaft breakage.

Have you ever seen that video clip of Diana Ross breaking that wine glass by singing into the microphone and placing the speaker beside the galss?  That's the same issue as what were dealing with here.  The crank is "resonating" at the 6th order harmonic (it's a frequency) when running at exactly 4800rpm (apparantly that's where that harmonic would resonate at it's purest form), and if the crank would resonate at that frequency long enough and loud enough it would eventually shatter (really the shattering would stop as soon as the first crack developed and thus changed the frequency at which the crank would resonate at) and thus break apart.

So yes or no on keeping it...  I don't think it's going to kill it to take it off but it may shorten the life of it slightly.

[macsdub]

i hear ya,,especially your last line(may shorten life)
but then,what should a "stock " engine last,lets say 300k,so you shortened its life by  one third lets say,thats still 200k

[vwmike]

I just took apart a 1.6TD that had A/C and the crank sprocket key was cracked and badly destorted. It had compressed about half a millimeter so the fit was very sloppy. Those harmonic balancers are only on there when the car has A/C and often the crank/sprocket is damaged because of it. This problem isn't just with 1.9's so I'm going to avoid any additional rotating mass on the front of the engine as it seems the cause of the key problem is due to the inertia of the crank pulley in addition to any loads put on the crankshaft and the sudden change in direction associated with accel/decel conditions. I'd probably break the crankshaft key long before I'd break the crankshaft.

[shwartzbewithyou]

If you don't care then it doesn't seem like alot because it's still more than the life of an average car, HOWEVER if you're a diesel Vdub diehard, then one third of the life is a lot to sacrifice.

So you need to ask yourself just one question....

Do you care?

[935racer]

Yep the more weight you put on there the more stress you put on the key way, ever seen what happens to early 1.5 and 1.6 cranks when they are retrofitted with ac? Its not good, mind you they have the lamest key way ever made but it means something. Also 1.6's are not known to have crank failure issues, when vw went with the aaz engine they kept the same crank sprocket they had been using on the 1.6's, now with the aaz's they are falling apart like mad, I have done 5 1.9 rebuilds this year already all from the crank failure issue. 1.9's have a serpentine setup and a heavy harmonic balancer, and many also have AC, the combo off all these things is disaster for for the aaz engine. IF I for some reason got the notion to put ac, a serpentine belt or a heavy harmonic balancer on a 1.6 I would be cutting the crank nose to accept the tdi sprocket for insurance.
Luckily though all I even run on my cars is the alternator.   Ps, ac, serp, harmonic balancer etc is just all extra rotating mass and just weight in general

[subsonic]

Just finished reading the thread.  I am going to have my rotating assembly balanced.  This is for my franken build up.  I will not have A/C or PS or a serp setup.  
Did I read correctly that if the car did not come with A/C then there is no vibration damper / harmonic balancer?

I was looking through my parts box from what I pulled off the engine.  I don't think I see one :?   If there is one, what the hell do the look like?

Did I also read that the crank bolt was a one time use item?

[smutts]

The European SB motor on both my GTD's has one, neither has AC. There is a 1/4" ring of black rubber (usually perished & falling to bits) on the crank pulley, and it has a heavy weighted rim.

[jimfoo]

Did I also read that the crank bolt was a one time use item?

YES!!! anything with x ft/lbs then y degrees is a stretch bolt and should be replaced.

[subsonic]

So how the hell do I get it balanced with this bolt?  Just not torque it on so tight?

[jimfoo]

It doesn't have to be torqued to spec for balancing as there's no load on any pulleys. Just tight enough. I would think 30 ft/lbs would be plenty tight for a quick balance. Or just use your old bolt for the balancing, then put your new one in for assembly. That's what I did.

[hillfolk'r]

So how the hell do I get it balanced with this bolt?  Just not torque it on so tight?

tighten it to "torque",just dont "turn" it
only do 1/2 of the bolt tightening sequence,or yea,use yer old bolt+crank it down