Stillen U.D. pulleys help.

Elmo370z

I ordered stillen underdrive crank pulley and belt, after talking to my shop about the install they informed me that it would replace the damper which I didn't know was fluid filled to aid in engine vibration. Is the vibration that serve with the U.D.? Would NST pulley set work with the stillen U.D.? Or should I just try to sell them?

DEpointfive0

What fuckíng horseshit shop did you go to? Go somewhere else that doesn't shove their head up their own ásses for lunch...

Fluid filled, LOOOOOOL!!! Dampener, LOOOOOOOOL!!! It's a solid piece of cast iron, no fluid or dampener anywhere

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Chuck33079

Pretty much took the words out of my mouth.

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Elmo370z

SO they are fudging me around. They told me that I would have serve vibrations using the underdrive pulley, and since it is 20% underdrive my other pulley's couldn't keep up.

Masterbeatty

How you say......ra tards!

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BGTV8

You are going to get more vibration because you are removing the vibration damper .... you may not feel them because they are harmonics at higher rpm.

Whether it is a damper that is fluid filled or just a ring of cast iron, it is no longer present, so the damper effect is actually removed.

Whether this is going to affect your engine is the real issue. If you give the car a spanking every now and then, probably not, but drag it or track it with sustained hi-rpms, it might.

Many years ago, with a race engine based on a Traco-Olds 215, that was all internally balanced and with the crank damper deleted, we kept losing cranks and eventually solved the problem by using an ATL race damper, so I can confirm that revving the engine hard enough for long enough with cause failure.

DD road duties, it "should" last for as long as you own it ...

DEpointfive0

On THIS car, where is the dampener on the pulley?

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BGTV8

Refer page 1679 of workshop manual - is integral/internal to the pulley ... refer snips attached. Also here:
http://workshop-manuals.com/nissan/3...iew/page_1679/

If you reckon there is no damper, knock yourself out ... my workshop manual reckons it is internal to the OEM pulley and with 20K in parts to go into my race engine, I will be fitting a Ross damper.

Like I said to the OP, maybe not necessary on a DD but my bus lives at 6500-7500rpm on regular track days.

Tread your own path ....

Attached Images

	Z34 Damper Image 003.JPG (41.4 KB, 42 views)
	Z34 Damper Image 002.JPG (27.7 KB, 32 views)
	Z34 Damper Image 001.JPG (37.5 KB, 27 views)

DEpointfive0

STILLEN lightweight crank pulley

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Zoren 370

I have a stillen pulley no vibration no dampers no fluid all I know it was all fun fun...

Elmo370z

thank you all

DEpointfive0

May I pose the question of... (And I don't mean to be an ásshole)

Does an aftermarket flywheel damage the car? After all the flywheel is on the other end of the crank, and weighs MUCH more than the crank pulley, and is much bigger, so even the slightest vibration has gotta make a bigger difference, no?

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BGTV8

It is not vibration per se, it is the harmonics .. I'll find a reference for you and post it here later.

Reference 1: Wikpedia on harmonics: http://en.wikipedia.org/wiki/Engine_balance
Reference 2: Coming .....

In my post I used the word "vibration" but to be strictly accurate, I should have used the word "harmonic vibration".

It is harmonic vibration that destroys OEM oil pump gears in the VQ engine above 7500rpm - I cannot find the actual engine speed as my notes are in the orifice at work - but it is around 7600-7700.

The reason I have reservations about after-market pulley kits is that no-one knows what engine speed the critical harmonics are exhibited ... and these harmonic vibrations are engine killers ...

If you want to know more, take the time to speak to Jackson Stewart at Unitech Racing as I have done several times, or Clark Steppler at JWT and I am sure they can fill you in on the details.

A flywheel is an inertia storage device, not a damper.

The purpose of the damper on the nose of the crank is to either shift the rotational frequency (engine rpm) at which catastrophic harmonics become evident out of the engine operating range, or to damp them such that they are no longer destructive.

Mate, you can disagree with me, even tell me I am a d1ck-head full of sh1t, but 40 years of motorsport and the pain and disappointment of losing 3 cranks in one season taught me a hard lesson about harmonics, and that is knowledge that I respect.

Now, the OP was told by his shop the proceed with care, and all I am doing is echoing those words of advice.

I do not know what the implications for after-market pulleys actually are - they may be totally benign (and probably are) but if the OP wants to use his vehicle on the track or strip, I am simply saying buyer beware.

There is no need to continue this thread .. because we are each accountable to ourselves for our own actions - I am not dictating to the OP, merely providing fact-based information that may, or may not, be pertinent to his post.

He (and you) are always at liberty to ignore the statements and that is your right.

As I said, tread your own path ....

DEpointfive0

^I like you
Since I have been informed that you Aussie's don't drink Foster's in Australia... If you ever make your way to the states, Foster's on me! Lol

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1slow370

7500rpm with the factory balancer.

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