The Evidence will be apparent After I have replaced the original pulley, I will let y'all know if I still have a bad vibration (therefore my blaming the pulley would be inaccurate) If the vibration stops, and I get the pulley tested for balance (at this point I am assuming it is balanced)& if it persists I really have to get the advice of a true specialist. Thanks everyone for the interesting replies to my posting. To those who have no problems and are happy with their choices :YD your engine is really well balanced. The final point I would like to establish with hopefully the agreement of all is that 'the vibration I am getting will ultimately cause damage and shorten the good running life of my motor and I should do all I can to rectify the problem before I am by the side of the road in tears'. I will post the results. Cheers All...
To me 1 problem out of all those with... ud pulleys is hardly convincing that ud pulley's are dangerous. To me if they were really that bad, there would be many more stories of problems than just one bloke with 3 bottom end rebuilds... and really 3 is a hell of a lot and whats to say he wouldn't have had to have them with the ud pulley anyway?I mean mine has a slightly loose crankshaft but that was like that without the ud pulley on... I guess then by your logical I should conclude that a standard z pulley is dangerous and causes bottom end rebuilds and should not be used?
I agree with you on factory cost cutting So I can't help but wonder why Nissan would choose the more expensive option for a pulley. Assuming we wish to drive the accessories at 100%, it could have saved thousands of $ by fitting a standard size alloy pulley (not UD) in preference to the complicated two piece internally dampened OEM pulley that graces every 300zx they manufactured, but they didn't; WHY:?) Cheers Ian
Comprehension & objectivity..... Wake up and open your mind to the fact that there is two sides to every coin.I remember when smoking, asbestos and lead were "safe" due to the lack of overwhelming evidence to the contrary. :N( This "fool" (your words) also remembers when you stated the FACT relating to low temp thermostats making your engine run cooler ! 8-} Huh, must be that scientific mind at work again. :s
Actually... Its still objective data that lower temp thermostats run your engine colder. Proven quite often during engine runs with digital thermometers. Its only when the heat exchange between the coolant and the radiator/air exchange reaches a steady state that a same flow thermostat cant cool any more than another.If you remember that thread then you'l remember it was a logical argument however I was missing the step of including the final steady state reached. You might also remember that when this was pointed out I could see my error and was big enough to immediately admit it. Unlike you I might point out. Your either too foolish or too stupid or too little to admit your error. Not sure which is worse.That old saying keeps poping into mind. You know the one about arguing with idiots. I think I will just leave it here since it is obviously the case.
:!) Cripes, can we make a forum rule that anyone wanting to debate UD pulleys be horsewhipped with one... enough:NNN(. There are pros and cons ...we get it.:><:><:><:><:><:><:><Searching for UD Pulley brings up over 500 posts. Surely that's enough for anyone.Goodnight|O
You were right. I am quite a bit smarter> than that. Your assumption that you will "educate" me, is based at best, on a false premise, at worst, on incredible arrogance. As you claim to base you remarks on carefully analyzed case histories, I will have to accept the arrogance option.There was an old saying from my early childhood (somewhere between grunting and arm waving, and early speech) that states "Never try to teach your Grandmother to suck eggs." I'll leave you to analyze that, and if you really do have the qualifications to educate me, you should be able to tell me from whence it came, and what it implies.
Rob, my dear and respected friend,> If you can find one single remark from me, that comments about U/D pulleys being harmful, or otherwise, then I am going to be found naked on the cover of Popular Mechanics Magazine. As far as Nathan is concerned, I'd leave him alone, if only he wasn't such a great target.
Ummm, I presume that you are using non UDP fitted Zeds as the control group? How then would you compare wear and tear between the control group and the 'UDP' group? Your discussion to date has been quite lopsided.It makes an interesting discussion, but the huge number of variables involved with Zeds make it academic at best - the probability distribution would be very wide and very flat. For instance I could argue that Zed owners who fit UDPs do so because they like driving more often, and driving faster and using higher revs than the control group, and therefore any wear and tear to the UDP group is attributable to the driving characteristics. Equally, I could say that the UDP group is an enthusiast subgroup which takes a stronger interest in their car, cares for it better (warms it up properly, uses good fuel and oil, etc), is prepared to spend money on it, and has problems attended to sooner than the control group, so the UDP group will have less failures than the control group.Two perfectly reasonable arguments, one on each side, and neither having anything directly to do with the UDP itself. Nathan, I'm interested in your opinion of why Nissan fitted a heavy damper, instead of a light pulley. Not stirring, not having a go at you, just interested. :-Z
:><That'll B the end of Popular Mechanics magazine as we know it ... can you imagine the uproar/disgust/dry retching when people open their new magazine expecting to see pictures of the latest gizmos and there's Chili draped across a pile of hard drives in his birthday suit ..."Hot tamales" alright}D }D }D }D }D }D }D }D
Good and bad There have been a few BIG Z motors built in Australia that had bearings fail and suspected under drive alloy pulley. Changed to normal pulley with harmonic balancer and believe all good since. Bottom line is there is a question mark with lack of rubber in the alloy ones especially with big hp engines. There have been many fitted and no probs although some have mentioned vibration in motor noticeable since fitting, but this may be due to crank bolt not being torqued up enough. They can wear motor out earlier than normal, but so does boost and some other mods that make power, but not enough to worry about in most engines. We did some custom alloy ones with stainless sleeve and vulcanized rubber to absorb resonance from crank and weighed around 1300 grams instead of 840 od so grams with the alloy only ones and aver 6KG factory one which is a least two piece with rubbery the way. Unfortunately the company who did these no longer will do as not viable as take too long to make. We do know that alloy pullies are a big NO for Nissan RB series motors as they do cause engine failure.
it's strange that the RB engines self destruct being an inline 6 and hence are a naturally balanced design without the harmonics that V4, V6, V8, Inline-8 and Inline-4 engines have. I guess that nissan just did a sloppy job of any internally balancing they may have used in the RB engine and left it up to the flywheel and crank pulley to balance it. All V6's suffer from 2 harmonic frequencies unless you use common journal crankshafts producing an odd fire sequence of 150 deg./90 deg. It looks like that now the only aftermarket crank pulley with dampening is the Fisher Concepts crank pulley
then you can ask, why did nissan use a huge and bulky restrictive air filter? Why did nissan use a heavy fly wheel? The list goes on and on, i think the only answers which will be legit are the ones from the designers of the car
Well, I can have a go at those. with a few educated guesses.Air Filter - to comply with induction noise restrictions in each country that the Zed was to be sold in, plus to better ensure that water was not ingested by the engine in each country that the Zed was to be sold in. Quite possibly also to minimise turbulence of the intake air by having long intakes and wide, flat filters before the intake air hits the MAS. Heavy Flywheel. Heavy flywheels make a car much more driveable for the average driver. The flywheel stores energy, which assists smooth takeoffs from standstill or low speeds, even if the driver doesn't get the revs and/or clutch release quite right. Even though the Zed's a sports car, it still has to be pitched at a target market, and that includes non sports oriented drivers. Also (and hopefully sidestepping more detailed arguments), the flywheel, pressure plate, crank and harmonic balancer are designed as a unit, to best cope with the wide range of loads that the crank is subjected to. The flywheel acts as a damper as well by virtue of its mass. I agree with your point though - conjecture's fun, but absolute truth would be better :-Z
The RB probably suffers because of the length of the crank. Inline 6s may be inherently naturally balanced, but they still cop three combustion hits each revolution along the length of the crank, which is much longer than the V6 crank. It also probably doesn't help that they can easily be made to put out relatively big HP for a 3 litre, which probably wasn't designed to cope with so much hp increase.
John, have you ever heard of a crank failure in a Zed? They look pretty damn strong to me, but they do get a harder time when the rotating mass is reduced.
