lowrider

iTrader: (3)

After talking with some Gurus, I came to the conclusion a couple of months ago, that the pulley was not a good idea due to balancing problems. I don't see the same issues with the Flywheel, as mentioned above.

Now with this evidence, however anectodal, IMO, the pulley is just not a good idea. If somehow, it could be balanced with the engine or were harminically balanced, maybe I would change my mind.

Lou

genxnympho

iTrader: (3)

I agree with many of you here. It sounds like the 3.5 engine has been balanced very vigoruosly and that balance has a very finite window open to misque. It may not be a huge offset to the balance and that is why overtime the brearings are starting wear and fail,30,000 mi or so. A very minute change my not be noticeable at first but over time things tend to evolve and with machinery, well they don't grow or just adapt to changes. It will either sieze or fail alltogether. Just think if you removed a weight from your wheel and drove at 20mph. Well drive at 100mph for 1000 mi and tell me your hands are not numb from the steering wheel.


Life is a delicte balance. Some things should be left alone..............

al503

iTrader: (4)

Here's a link to the thread:

http://g35driver.com/forums/showflat...sed&sb=5&part=

FairladyZ

A lot of guys on here say they get choppy idle, and blame it on the CAI. According to the "tech" the pulley causes a chopy idle. I wonder how many guys complain about there idle have a pulley.

In defense of the pulley one guy said he bought all three had it installed at the dealer and has had no problems. So install can be a factor?

I still refuse to get it.

Apexi350z

iTrader: (3)

I thought according to UR, there has not been a proving case that said their crank pulley caused any engine failure..

can anyone remember this?

neffster

iTrader: (2)

AL503 provided the link above in his post. Yesterday I also posted the link (under another thread) but this thread died real fast. I will be sending my pulley back to Performance Nissan as soon as I get confirmation that they will allow me to send it back (it's still in the box - never unpacked or installed).

I can't believe the response this post has received in only one morning. Thank you everyone for taking the time to respond. I've been sitting on the fence for a long time about doing this install, InfinitiTech and you guys have helped me make the choice that's right for me.

Thanks Again...
Neffster

UsafaRice

Thanks for all the information, it looks like you have certainly cleared up concerns for a lot of owners out there.

Now, I have had to weigh the information myself and come to a decision like everyone else.

So, does anyone have the 3 pulley set in chrome, black, or red and is looking to get rid of it? PM me...

DrVolkl

This is funny...people are so quick to diagnose the problem.

Is this the 1st two Vq's that have died at 30k miles?

What about the STOCK engines that have died at 30k miles with no mods? What are we to blame??? Oh my goodness...I heard he took off the stock plastic engine cover! Better not do that!

Please...two modified cars have similar problems..you can not pick out one common mod and blame it on that. That's really poor science.

Also, I hate having posts about "I heard from this guy who said this"...that gets everyone all upset for basically no reason.

(Not to discredit anyone, I'll give the benefit of the doubt....but lets not jump to conclusions already)

boyze

Interesting. A couple of comments regarding the technical aspects of the pulley and presumed problem (I aplogize if they have been covered before):

A separately balanced pulley installed on a balanced shaft doesn't quarantee a balanced system. The system is only balanced if the 2 rotational axes are coincident.

An equal amount of unbalance mass on the smaller pulley will actually have a higher unbalance force because of the rotational speed squared effect.

I suspect the damper on the OE pulley is for rotational vibration damping not linear. Unbalance would result in linear vib and not torsional. The smaller pulley would, however, have an affect on the torsional vibration with the lower mass - could be bad, good or indifferent. The mention of the rough idle, if related to the pulley, is likely the torsional mode and not the linear.

Also, the pulley has a steady side load from the pulley drive torque which will be higher for the smaller pulley for the same torque.

350zluvr

This thread is about a N.Y. meet.

PoWeRtRiP

they will believe anything they hear if they believe it is a qualified source. its sad truly...

sixfive

Thank god there are reasonable people who drink the frikkin kool aid just cuz some preacher tells you to!

RE the quote posted on G driver and this particular point: "I turned a blind eye to the matter and warrantied his motor"

Anyone wonder what he replaced? What do you replace when the internal balancing goes awry and why isn't that discussed. I dont usually call BS like I did on G35 but this guy has been flaming people who contribute dearly to the hyperground thread and I found some holes worth investigating. LIKE THE FACT THE DEALERSHIP HE WORKS AT NEVER HAS SEEN A CRANK PULLY EXCEPT ON ONE VEHICLE ACCORDING TO THE SERVICE REP!

Same dealer is installing a supercharger for thier own project car...does that require a new pulley that is not babalnced?

jesseenglish

No, it uses the stock crank pulley.

I don't know the truth of the post that started all of this, but I have always believed that this could be a cause of long term engine failure. However, it's very hard to diagnose the culprit.

sixfive

make that DONT drink the kool aid

Alang

iTrader: (1)

While one post regarding failures does not a problem make, this argument has been raging for years. Its not specific to mfrs or motors, and there is very good evidence that pullys can cause problems, just nothing scinetifically conclusive.

The biggest issue is that I have never seen a car that had only pullies on it. There are always other mods, so no conclusive evidence is out there. For me, I am convinced that there is additional wear from pullies. How much, I can't tell. Will it make a 200K mile motor fail at 150K or 30K? Don't know. For my daily driver, no pullies, if I had a weekend car, I would probably put them on and lose a few miles of life on the motor.

Like any mod out there, there are risks and rewards.

VandyZ

iTrader: (2)

Things like this can be debated to no end. The fact that there is even a reasonable doubt should tell most people that it may not be the best thing you could do to get a few HP.

You can internally balance all you want but when you introduce vibrations anything can happen. I would hope that UR tested this product on a motor and found that they were within the limits that were set. But there are certain things that I would say you should not mix a under drive pulley with. Here are a few:

Increase Rev limiter (or sustained periods at high rpms . . .track events)
Nitrous
Supercharger
Turbocharger
Cams
Etc

BriGuyMax

iTrader: (4)

I (for 80K miles) and MANY MANY other maxima owners have used UR pullies on VQ30DE and VQ35DE motors for nearly 10 years now. I have NEVER heard of any documented engine failure that was even associated with a pullied maxima.

The engine is internally balanced as already states so as long as each item installed (lighter pully, lighter flywheel) is balanced itself there should be no problems. If lighter pullies are breaking motors than lighter flywheels would do the exact same thing.

jckolnturn

iTrader: (1)

sorry let me get the right one, it was actually worth reading
try this:
https://my350z.com/forum/showthread....hlight=pulleys pulley&pagenumber=6

DrVolkl

Thank you! I also had a pulley on my 2k2 maxima...NO PROBLEMS.

If the balancing was SO IMPORTANT, the wrong belt tension could easily throw things off.

But, let this continue...because people get so hyped up when something goes wrong with their engine, the immediately try and find an external cause...like it's impossible to fathom that Nissan might have just made a bad engine or two.

jckolnturn

iTrader: (1)

I've heard way more cases of nitrous and superchargers blowin up engines but only one forum member (maxHax) has had a problem with the pulleys and he wasn't 100% that's what it was. If they are so bad where are the blown motors and pages and pages of complaints?