harmonic balance pulley, necessary?

[RabbitJockey]

i did the td swap on my jetta, when i switched it over, i put all the pulleys and  accessories from my old na motor onto the turbo diesel because the turbo diesel had air conditioning.  i'm wondering if i should switch to the harmonic balance pulley, and keep it with the turbo diesel engine, which is where it came from, or should i not worry about it?

[hillfolk'r]

i threw mine into my backyard as far as i could,,so i wouldnt hit it with the lawnmower :shock: just run a stamped steel pulley,less weight,the only time ive seen the balancers is if it has ac

[RabbitJockey]

that's what i figured

[hillfolk'r]

i never weighed it though,,got any idea in difference between a stamped pulley,and a big chunko??its gotta be 4 pounds or so.... :?:

[RabbitJockey]

well, me and my dad are trying to decide whether or not to put it on.  i don't want to put it on and my dad does,  i think it's an ugly piece of metal, and he's not sure,  but he parts guy at the dealership says it helps eliminate vibration, which i could care less about.  i'm jsut seeing what other people have done.

[hillfolk'r]

you dont need it,um,im trying to think of a "techy" reason you can tell them  in favor of not running one......iknow and you know,,gotta convince them,,,the older ones didnt have them,,non ac applications dont have one,i dunno, um,theyre ugly+heavy???anyone???

[fspGTD]

I run one.  The 1.6lTD SAE paper explains why they are helpful... to reduce a critical harmonic frequency of the crankshaft of the engine at a very specific, pretty high RPM (I'm going to say it's somewhere around 5000, IIRC.)

Crankshaft vibrations have been shown in dyno tests on other motors (like drag racing V8s) to rob power and torque.  These dampers and other style of harmonic balancer dampers, despite their added rotational mass, have been demonstrated to add power and acceleration that outweighs the added crankshaft rotating mass.  They do this by reducing deflection of the crankshaft.  This explains why you often find these harmonic balancers on all-out racing motors (among other applications.)

The amount of crankshaft deflection and needs of the balancer do vary on an engine-by-engine basis and I have not seen any testing on a VW 1.6, so if someone were to dyno with the TD harmonic balancer pulley and with stock pulley, it would be interesting to see the findings.

[hillfolk'r]

if i was gonna use one at all it would have tobe a fluiddamper design,,the rubber  ones only control a small range of the harmonics,and they dont even know if its really tuned to your application after more power is added, the fluid ones are more forgiving,,,how long are the revs up past 5k any ways,and the gassers dont have them either,,i think the weight loss,in the real world outweighs any torsional /defelection problems,just my opinion,,i have never broken a crank anyways,but i think the weight loss is a better thing :wink:

[dieselweasel]

I wouldn't even consider not running a dampener due to the crankshaft torsional vibrations...can cause crank to crack and or break although hillfolk has had good luck

[hillfolk'r]

but they only use them on cars with ac,whats up with that??a 4 cylinder doesnt really  need one

[RabbitJockey]

maybe vw just put it on to make the cars more drivable to the consumer, so that it would vibrate less when the a/c is on, even though the one thing is supposed to bring the revs up

[fspGTD]

AFAIK, all 1.6lTDs came with a factory harmonic balancer pulley.

[tylernt]

My understanding is that the A/C puts a pulsating load on the accesory pulleys. The extra mass and design of the harmonic balancer is supposedly designed to smooth and cancel them out.

I'm not agreeing or disagreeing with the other theories -- I don't know anything about it. Just passing along what I've read.

[QuickTD]

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. That said, it would take considerable skill with the throttle to keep the engine within the very narrow "critical" band of rpm and load for long. Most of us here have lightened flywheels and other modifications that probably render the stock damper useless anyway, so do whatever makes you feel good I guess...

[Black Smokin' Diesel]

AFAIK, all 1.6lTDs came with a factory harmonic balancer pulley.

The one I got from the junker didn't have one. It had the "dual pulley" for the alt and PS but it's all metal.

If you don't have AC, I don't think it's all that necessary.