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The mkiv Supra Owners Club

solid crank pulley


little num

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as above, ive been reading about how the harmonic pulley stops the crank from cracking and failing, but has anybody on here fitted a solid pulley and never had a problem.

Toyota want £220 with vat for the original 1 but ebay do a light alloy CNC machined 1 thats £50 but with no damper.

Will this be a bad idea to buy 1 and fit it.

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What discount are Westlands offering you James?

 

They normally do me 28% but they guy who i see (gary) is away today so need to wait for himto price me, i will contact some traders on here to see what price's i get.

i have ordered the alloy set that come's with power steering - alternator - water pump in alloy as they are solid anyway.

Think im going to do the tipex trick and see how if its work out.

Simons is wobbling so i thought id change mine as well.

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I take it the harmonic balancer is to remove the effect of the forces out of balance on the crank. Would that make it possible to use a solid pulley if it was dynamically balanced or would it require the balancing of the crank and pulley as a set?

 

No. It's got nothing to do with rotational balance at all.

 

Here's a link to a document that explains it all: "Torsional vibration damper"

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Cheers for that, basically from what i can gather if you do a full engine rebuild and can get the flywheel, crank and pulley balanced dynamically as a set then you could do without the harmonic dampening, but if you ever need to replace either the flywheel or the pulley you would have to resume the use of a harmonic balancer.

So basically its safe to replace the other pulleys but leave the harmonic dampened pulley alone :D

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No, if you read the link then I'm afraid you misunderstood it. As I said before, the function of the crank pulley damper has absolutely nothing to do with rotational balance - or in fact balance of any other sort.

 

 

Some people call these items "harmonic balancers" but that is a really misleading term.

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Looked a bit more into this today (was very slow at work). Finally got the idea to gel, its not forces OOB that cause the torsional vibs its the energy imparted at an angle onto the crank that induces it (in a nutshell).

However something i have been thinking about is the harmonic balancers are manufactured to work at a particular resonance and absorb the vibrations within a certain band. So when you go BPU or even further you change the torque curves and inputs on the crank which would have an effect on the point torsional resonance will occur. Assuming that resonance does occur at a different point when you change the torque loadings the harmonic balancer on the front of the crank is now useless as it resonates at a different time to when the crank does. I would think there would be some small benefit but the main reason the harmonic balancer is there would be lost.

Also assuming that is correct then the aftermarket balancers (Titan on mine i think) would have to be manufactured to work at the right frequencies too.

Admittedly this is conjecture from some reading etc i did today and when i talked to the guys who do dynamic balancing and said torsional vibration they looked at me as if i had told them i took a dump in their lunch boxes, so i can't get any input atm from our guys who do this kind of thing on the gas turbines.

Would be interested if anyone has anymore information.

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