From the Unorthodox web site. Talks about difference between torsional damping and harmonic damping. Well, read on...
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The factory pulleys on today's late model cars (from 1986 to Present and sometimes even earlier depending on the vehicle) serve two functions. First and most importantly they are designed to reduce or eliminate the audible noises herd in the cabin of the car that the accessories (alternator, air conditioning, power steering, and air pump) make when the engine is running. This fact exhibits the factory fanaticism about making the car quiet for the occupants (i.e. the use of resonators in the intake to quiet intake noise, all aftermarket intakes eliminate these resonators). It has nothing to do with engine function or longevity.

The second function of late model crank pulleys is torsional damping. Torsional damping is necessary due to the excessive diameter and weight of the factory crank pulleys. The design of our underdrive crank pulleys eliminates the need for any torsional damping for two reasons. One, the diameter of our crank pulleys is smaller than the original designs, in almost all cases smaller even than the rubber torsional ring, therefore effectively reducing the force the accessories have on the crankshaft. Second and most importantly is that our pulleys are significantly lighter than their OEM counterparts (anywhere from 3 to 11 lbs.). This weight loss dramatically reduces the stress exerted upon the rotating assembly by the excessively heavy factory crank pulley.

Our pulleys are so well balanced that when owners call us about how happy they are with the product they always mention their motor feeling smoother. Lastly is the misconception that the crank pulleys on these vehicles are harmonic dampers. A harmonic damper is a unit bolted to the crankshaft snout that is completely separate from the belt drive system. An engine that uses a harmonic damper has the accessory drive crank pulley bolted to it, they are separate pieces that are attached to each other. Balance shafts, which are used by several manufacturers, are specifically designed to eliminate harmonic vibrations. None of the vehicles we manufacture pulleys for have harmonic dampers in the traditional sense.

Owners who have engines that use balance shafts must understand that if they eliminate their balance shafts their engines must be balanced to 0 grams if they expect to have no long-term engine problems with or without the use of our crank pulleys. Our pulleys are made with 6061-T6 aluminum billet which is a very consistent material and the CNC machining process ensures that all our pulleys are perfectly true. This balance shaft elimination is rare and only happens on a few models that are modified for racing only (Eclipse/Talon/Laser/Galant VR4/Conquest TSI/Starion just to name a few).

 

Good research!!! sounds very intelligent, but I have no idea what you just said
hehe... anyways, If I change my pulley my max will die.
Vic

 

I used to work for the Government, and we had a saying - "My job is so damn top secret, even I don't know what the hell I'm doing!"

You have a S/C - you don't NEED a pulley!!! It would underdrive the S/C and give you LESS boost.

That is a mighty cool pic in your sig. Damn, the photographer was good!

Greg

 

of my post in http://forums.maxima.org/showthread....threadid=16458

Interesting dialogue between GregP and Dave B. I must say I respect both of your opinions and the contributions you have made here. But it appears to me that Unorthodox Racing has a vested interest in discounting the pulley's function as a damper whereas neither Nissan nor Chilton has any such interest. If Nissan and Chilton both call the pulley a damper, I'm inclined to believe them. I'm also persuaded by Chilton's caveat not to damage or scar the rubber isolation ring within the damper because the harmonics of the crank could be altered.

I suppose if I have to make a choice on something as critical as the proper functioning of my engine, I'd rather make it on the side of conservatism. So . . .

No UDP for my Max!

 

I'm suprised the photographer's hand wasn't shaking from the cold! hehe..thanks greg.
Vic

That is a mighty cool pic in your sig. Damn, the photographer was good!

Greg
[/I][/QUOTE]

 

The pulley debate has been a long-going discussion on the 300ZX forum (2+ years). It's gotten to the point where I don't jumping in because all that is being tossed around is opinions and very little fact. I'll let the others argue .

No lighter underdrive pulleys on my car!

 

I just went out and popped the hood on my Max to take a look at the pulley. Since I'm a genius, I thought I would pass along the wisdom of what I found...
Damn... my car needs to be washed!

 

Greg-

Remember, you are reading information from a vendor website.

The Maxima crank damper/pulley looks exactly like the one on my old 94 Z28. The damper/pulley on the Z28 had the same exact rubber ring (isolator) as the Maxima damper and it was clearly stated both in the service manual, Chiltons, and Haynes manual as being a harmonic balancer. March Pullies also noted this and said it was a hightech and effective approach to not having to run a seperate piggyback balancer. If you don't believe me, I suggest you go to camaroz28.com and research what you want.

There has yet to be a verified problem with the UDP on the VQ, but the fact that it is getting rid of something that Nissan enginners sought fit to install on probably the most important part of the motor makes me not want to remove it. UDP crank failures on other cars only makes me more nervous.


Dave

 

I wanna know something. Does Unorthodox Racing warranty thier pullies not to cause motor failures if installed correctly?

Dave

 

Of course they don't. The reason is because any number of factors could be responsible for a motor failure. That's one of the reasons why people won't necessarily lay responsibility for a motor failure on a UDP even if the UDP is the likely culprit.

I honestly don't think that either side of this argument is winnable, Dave. It's all a matter of how each of us interprets the risk and the amount of risk we're then willing to assume.

[Edited by y2kse on 01-01-2001 at 10:08 PM]

 

I had a long talk with Jim Wolf about this subject and he feels that we shouldn't fool with the factory crankshaft balancing, ie, he said the oem UDP also functions as an harmonic balancer, period. I removed mine the following week. Do what you have to do.

 

I just ordored a UDP for my I30 right before this topic came to life argh I wish I knew there was such a contraversy on this subject because I would have re thought purchasing it.Now I don't no what to do.

 

I agree. It's all in what you are willing to risk.


Dave

 

Follow your instincts!

 

Hi Dave,

Call me crazy, but if the "rubber ring" people are talking about is NOT the crank pulley seal, then I honestly don't know what they are talking about. My stock crank pulley is ONE single solid piece of steel, and there is no rubber ring anywhere.

Maybe this is why I am wondering what you guys are talking about.

Still, I have had no problems whatsoever with my pulley and the engine runs smooth as silk. I certainly don't advocate doing any mod that a person is uncomfortable with though. My opinion is that there are other mods (valve body, S/C, NOS) that are FAR more potentially damaging to the engine than the UDP, which I don't see any risk in at all.

If I do blow my engine however, and it can be atributed to the UDP, I will be the first on this forum to log in and eat crow!

GP

 

Hi Murphy,

I see what you are talking about, but the crank pulley is all one piece. When I go home I will take a better digital picture to illustrate.

-GP