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Supratruck Pilot
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882 Posts
Discussion Starter #1
I did some searching and found plenty of bad things said about the Unorthodox pulley on the 2JZ but nothing on the 7M. Do the problems with the pulley on the 2JZ also apply to the 7M? The new engine I bought came with a new one installed and I am debating on whether to use it or not. Anyone have one on their 7M, and if so, what are your impressions of it?
 

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MKIV SUPRA FREAK
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i got one on mine..it's been eating alot of belts...i'm thinking about changing it back to stock..
 

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Super Moderator
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The stock 12 lb crank pulley acts as a harmonic dampener to absorb any vibrations in the crankshaft to avoid bottom end damage. You can run one but there's an increased risk of killing a main bearing. If you're running a fully balanced/blueprinted motor there's less vibration so its less of a risk. But on a street car especially with a stock bottom end it's generally considered a bad idea, 7M or 2JZ.
 

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Just some guy
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I'm working on a possible aluminum underdrive pulley w/ built in harmonic dampner for less than the unorthodox one. I'll post something about it when I have more info.

Christian
 

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hmm

I wonder if this hold true for the pulley.

Reason is that pulley has a lot of rubber to absor vibes. The vrank bearings don't. So that would mean that the bearing would go before the Pulley makes it go.
 

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Banned
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I would not put one on any car. I had those exact pulleys. I have a stand alone in my car TECII and one day the guy that made my trigger wheel fell off the back of the pulley. Long story short it din't hurt my motor (thanks GOD!) and I then notived that when we pulled off the pulley it has been wobbling slightly and had worn a pattern in it. Now I have the stock OEM pulley back on with! Get this!! > A trigger wheel built in my pulley. So no more falling off since there are no attachments :D

Underdrive pulleys are a no for me.

My .02

Duane
 

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...heading for 500+ RWHP
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No dampner = (eventual) bad motor

A pulley with out a dampner on anything but a full balanced race engine is a no no. If you could get one with a dampner like the one that racefiend was thinking about making that would be good. I heard that a performance company was tinkering with the idea of producing an underdrive pulley w/bulit in dampner for many applications...lets hope they do!
 

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MK3_300

what EXACTLY is the pulley going to dampen? Again. If there is that much play that the pulley has to dampen something. The crank bearing will NOT survive that. Period. Dampened pulley or NOT. On the other hand if you mean sound ISOLATION. then that is a totally different story.
 
H

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The Damper is tuned to the motor to absorb the harsh frequencies that are produced when the motor fires one, some, or all of the cylinders. In Toyota's case, it is tuned to absorb or cancel out the harmful frequencies that are produced when the #1 cylinder fires. I can't seem to find it, but there is a toyota tech article that explains it. Also included is a diagram of the frequencies produced during the motor's cycle. The Firing of #1 is the harshest, and lessen as the other cylinders are fired. The damper has nothing to do with motor balancing, it's like trying to stick a piece of rubber on a long unbalanced stick, it's not going to make a difference. Maybe a reason why the damper is referred to as a "Hamonic Balancer," to balance out the harmful harmonics that are produced by the motor, Aye? Mostly required on inline motors than V-Motors and some 4 cylinders.
 

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2/3 HP to the Paws
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They're a bad idea on any engine. Harmonic dampers exist for a reason.

Read Reg's writeup here and here.
 

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ok now here is the other mind excersise.

If the pulley does in fact dampen a harmonic at a certain frequency. That harmonic still has to travel through the main bearing. The dampner has to somehow dampen freq X and all it's resonant frequencies. That alot of dampening going on for a 20 lbs pulley to take care off.
 

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when this baby hits 88mph
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2,198 Posts
i like the pulley set otherwise tho. for the cost i dont know how much benefit you would get out of them tho. i guess it would pretty up the engine bay. other than that prob not much.
duane- dave moskowitz saw the same prob when he pulled his off too.

dave

edit: i thought i would check to see what the set sold for these days- $297. if i could buy the set w/o the crank pulley i would prob go for it. cant tho. i suppose you could sell the crank pulley on ebay but i would feel bad selling that to someone. maybe i could use as a paperweight or somethin ;)
 
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