I think those guys are clueless to how much a flywheel should be lightened. There is a point for a weighted and relatively thick flywheel. My first argument would be how do you guard against warpage? Flywheels are under extreme heat because they are the device that meshes with the clutch. My second arguement would be driveability in terms of shifting and launching the car. Light flywheels are horrible for drag racing since they cause cars to bog and as all dragracers know, the first 100' of the race is the most important. Light flywheels are great for road course racing where the motor spends it's time in upper rpms and the driver is good at rev matching (as the author of 350Z post says).

 

I've enclosed a shot of JDKmans pulley that may show where the inner hub and outer inertia ring join. Don't know if the outer ring is pressed on or molded together with rubber to the inner hub?

 

How far the rubber goes is only a tangent but you can convince yourself of anything you want.

No you won't. Your initial assertion was that UR pullies do not damage the engine. Cutting open a damping pully only settles a pissing match of a tangential subject.

You are in no position to make such a technical judgment. And your first reaction will be "but neither are you!" And my response is yes I am, I have performed shock and vibration testing/analysis/qualification on several components over the years and have a good understanding of the subject. This comes through first hand experience.

So what do you know about vibration damping the Nissan engineers do not? What is your background in shock or vibration analysis? You left out one very important detail. #3. Mass/momentum. If you change the mass or momentum of the pully you change the resonance frequency/amplitude of the crank and its natural damping factor. (with or without damping materials such as rubber.)

If the Nissan engineers analysis indicated to them they needed a rubber band glued to their damping pully, should we assume your professional analysis to be more valid?

Your arguments appear more entrenched than objective.

 

This is definitly true. This is why I would like to get one.

Makes me think a diametric design could be utilized for drag racing. A very heavy flywheel or even a momentum wheel spinning at redline RPM could be a good way to store a lot of energy before launch.

 

Damn Hydrazine, don't be so hard on poor ol Al. I've almost got him ready to buy my plastic/cardboard overdrive pulley and Ionalyzer intake system.

right you are guys, small displacement engines for drag racing- high mass fly wheel (or high stall converter) for energy storage, long tube smaller diameter headers, long collector, and high gear ratio. large displacement can live with smaller flywheel, same or larger diameter headers and short collector and less rear ratio.Road racing is generally (but not always) the opposite for rapid response to RPM, inertia changes. Note I left out the pulleys? Either can be tough to live with on the street when carried to extremes as are all true race cars.

 

For those interested in how elastomers (rubber) can dampen or isolate engines you can check out a simplified discussion here;

http://www.earsc.com/HOME/engineerin...dex.asp?SID=61



Ballistic shocks are a whole nother matter!

 

JCV, Forgive my shortcoming on not being able to take something that you possibly (taken in the best light) said tongue in cheek or in good humor. I take offense to this and although it probably doesn't mean anything to you, I'm frankly disappointed.

 

OOOKKK. Sorry Al. Still friends?

(I need to stay away from these pully threads.)

 

It's the dark power of The Pully Thread. We must resist!...

 

Al, nothing demeaning to you personally intended. Just trying to lighten up the endless pulley thread. And pedal CISMO auto parts, you do remember Cheapo International Motorsports Organization don't you?

 

What I stated in the post your quoting is based on my common sense. The greater the integration of the rubber into the pulley, the more dampening qualities it should have all other things being equal. Hopefully, others will agree with me.

As mentioned above, the company I work for does a lot of work on seismic retrofits of older bridges. The most common way to reduce harmful vibration and frequencies is with an elastomeric bearing material that is built (sandwiched) into the abutments. There is a reason the engineers at Caltrans (and other DOT's) does this. If this material would do just as well on the surface of the abutments, then they would design it that way, which would save them a huge expense in design and manufacturing costs.

If you read my post from which you quoted again, I did state 'all other things being equal.' Here's a question for you: do you disagree with my original assertional that ALL OTHER THINGS BEING EQUAL a pulley that has a dampening material that is sandwiched through it will have greater dampening qualities than one that has the rubber mostly on the surface? Again ALL OTHER THINGS BEING EQUAL

Respectfully, right back at ya.

 

Well this is my last post here until I get the pulley and follow through with what I promised. I'll post the pic(s) then.

 

You really do know you're stuff. We'd could BS about cars for hours

 

Thanks for all the great info. My only concerns are:

1. Does it bogg down the engine at all?

2. Is it easier now to stall with the UR pulleys on?

3. Does the rpm fluctuate on idle...meaning does it go up and down by it self when the car is not in motion?

4. Who should I have install this? A friend who is a mechanic or the dealer?

Thanks!

 

Seems like any problems don't happen immediately (unless installed wrong), but instead are more of a long term concern. I haven't seen one person with a G35/350Z (NOT an x year old Maxima) that has had problems using pulleys. Not sure about you guys, but I'm not keeping this car more than 60K miles (already have 21K with stock pulleys). There are lot more things to worry about around 100K miles than an under drive pulley. If someone has provable evidence (service records, lawsuit, proof of prematurely worn bearings etc etc) speculating is a waste of time. Same type of arguments can be made for aftermarket plenum's, cold air intakes, rear diffs, any any other mod not "approved" by the vehicle manufacture.

If there was a problem I'm sure we would have heard about it from Unorth. When Injen had problems with their initial design they let everyone know. People are bolting on forced induction components, blowing Nitrous etc and were worried about how three pulleys MIGHT cause problems in 50-100K miles. Come-on... I wouldn't buy some crap made in a guys garage like on EBay, that's why I went with Unorth. Cant wait to have my local Nissan dealer install them this spring.