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Engine Specific Info and Questions => IDI Engine => Topic started by: RabbitJockey on May 09, 2006, 06:31:52 pm
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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?
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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
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that's what i figured
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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.... :?:
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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.
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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???
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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.
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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:
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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
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but they only use them on cars with ac,whats up with that??a 4 cylinder doesnt really need one
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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
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AFAIK, all 1.6lTDs came with a factory harmonic balancer pulley.
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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.
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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...
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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.
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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.
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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
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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.
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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?
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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 :P
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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?
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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.
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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.
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So how the hell do I get it balanced with this bolt? Just not torque it on so tight?
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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.
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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