Lightweight crank pulleys....

[DRFT - 86]

Just something that came up when I was looking at lightweight crank pulley options for my 20v silvertop....
What is the go with using a lightweight pulley that does not have the harmonic balancer like the OEM pulley... ?
Someone questioned this and mentioned something about the internals/bottomend needing balancing if a pulley like this is used..? is this correct or can a lightweight crank pulley be installed without doing anything else besides reaping the benifits of quicker throttle response n what not...?

A clear answer on this subject would be greatly appreciated..

Cheers
Niz

[rthy]

I have seen a massive topic in this before I think it was on toymods. Many people are saying that without the vibration insulator the the stock one has it can lead to failures in the crank, but the verdict was still out.

[rthy]

heres a bit:

http://www.ae86drivingclub.com.au/board/in...showtopic=31480 (http://www.ae86drivingclub.com.au/board/index.php?showtopic=31480)

[ke70dave]

interesting this should come up again.

i was doing an advance vibration's course at uni last year, and a group of guys analysed a harmonic balancer for their project thing.

from what i gathered the verdict they came up with was that because engines are mass produced there are differences in all of them, and thus there is a possibility that they are slightly out of balance. and over a long time (ie life of the motor) these differences/out of balancedness can cause damage.

this is why you hear people saying "i changed my crank pulley for a solid one, and didn't notice any differences at all". they probably wont untill a few years when their bearings are roooooted...

so i think solid ones are to be used when the engine has been balanced to take out the defects/out of balance..ness, and also when performance is more important than life of engine.

having said that..what is the advantage of a solid/lightweight one anyway?

a stocko one isnt all that heavy, and its radius isnt all that big.

[LAZY]

You don't want to mess with the engines harmonics, keep it standard.

[rthy]

<div class='quotetop'>QUOTE (ke70dave @ May 27 2008, 10:02 PM) <{POST_SNAPBACK}> (index.php?act=findpost&pid=537666)</div>
interesting this should come up again.

i was doing an advance vibration's course at uni last year, and a group of guys analysed a harmonic balancer for their project thing.

from what i gathered the verdict they came up with was that because engines are mass produced there are differences in all of them, and thus there is a possibility that they are slightly out of balance. and over a long time (ie life of the motor) these differences/out of balancedness can cause damage.

this is why you hear people saying "i changed my crank pulley for a solid one, and didn't notice any differences at all". they probably wont untill a few years when their bearings are roooooted...

so i think solid ones are to be used when the engine has been balanced to take out the defects/out of balance..ness, and also when performance is more important than life of engine.

having said that..what is the advantage of a solid/lightweight one anyway?

a stocko one isnt all that heavy, and its radius isnt all that big.[/b]


thats really interesting Dave, thanks for the post

as for why.... its shiny, it looks sporty, so why not

people buy rear strut braces don't they?

[ke70dave]

<div class='quotetop'>QUOTE (Sam_Q @ May 27 2008, 10:27 PM) <{POST_SNAPBACK}> (index.php?act=findpost&pid=537681)</div>
thats really interesting Dave, thanks for the post

as for why.... its shiny, it looks sporty, so why not

people buy rear strut braces don't they?[/b]

yeah but rear strut braces you kinda add stuff in.

i don't like the idea of replacing something that I'm not exactly sure how it works, on the basis that the new one is shiny and looks sporty...

think ill just paint my stock one if i feel i need shiny things to enhance the sporty'ness of my engine. :2thumbs:

[rthy]

my point being people add stuff because they think it looks cool.

Anyway your pulley, theres always the option get it coated with one of these:

nickel
silver zinc
black zinc
gold zinc
gold!!! hehehe
chrome

[ke70dave]

now we're talking...

platinum would be nice....

one of these days I'm gonna anodise anything aluminium i can see, just need to get my hands on a bunch of sulphuric acid.....

havnet looked into plating much, but i assume its not much difference, electrolysis is great fun.

[Gilly]

somewhat related question and seeing dave has done harmonics he might be one to answer as too would Sam seeing he knows all the dark arts.

when making larger pulleys for 4AGZE's its common to grub screw a new ribbed outer section for the belt to run on and increase the diameter of the pulley (equally more boost) would this extra piece majorly effect the harmonic absorbtion of the insulator agent used in stock pulleys? if it helps, the new outers are commonly ally and weigh sweet fk all.

[rthy]

ok I don't know much about this but I would think that would be a pretty safe bet, assuming the grab screws can handle it

[ke70dave]

<div class='quotetop'>QUOTE (Gilly @ May 27 2008, 10:53 PM) <{POST_SNAPBACK}> (index.php?act=findpost&pid=537697)</div>
somewhat related question and seeing dave has done harmonics he might be one to answer as too would Sam seeing he knows all the dark arts.

when making larger pulleys for 4AGZE's its common to grub screw a new ribbed outer section for the belt to run on and increase the diameter of the pulley (equally more boost) would this extra piece majorly effect the harmonic absorbtion of the insulator agent used in stock pulleys? if it helps, the new outers are commonly ally and weigh sweet fk all.[/b]

thats interesting you should mention that gilly, i always had it in my mind that when people "added another pulley to up their boost" they got a smaller pulley for the supercharger end.

i know ive heard of people getting "a bigger pulley" but never occurred to me.....oh well learn something new everyday!

as for your question, I'm not exactly sure hey.

from what i remmeber, it wasn't the fact that the solid ones were heavy/lighter it was the fact that they didn't have the rubber inbetween the layers of steel.

the harmonic balancer is acting as a mass damper system on the shaft (look up mass damper in relation to the formula 1's, this was my project, very cool also)

so mass damper is essentially a mass attached to the end of a spring (mass being the outside of the harmonic balancer, spring being the rubber inbetween, in the simple case these are the 2 variables)

like everything this will have a natural frequency, so essentially is what the system vibrates at if its left to its own devices, ie if you smack it with a hammer it will vibrate at a certain frequency (same as the tuning forks in primary school music, or when you smack a lump of metal and you get a certain noise out of it)

so the harmonic balancer would have been "tuned" for a specific frequency in order to "Damper" the out of ballance-ness of the engine.

now if you add a bigger pulley, you would be changing the weight of the pulley, and thus changing the natural freuquency of the system. and thus changing what frequencies the mass-damper system is able to damp out of the engine.

so my thinking is that, the only thing that changing the pulley will do, is change the frequency range that the mass damper is working.

as for if this is bad, i have no idea, it would depend entirely on where the new "damping frequency range" is. if originally it was designed to have a natural frequency at 5000rpm, and with the extra weight its now at like 10000rpm, then its not going to be as effective.

but i have no idea on how much the weight will effect the natural freuquency, from experience on calculating natural frequency it doens't change that much with small changes of variables. but yeah woudl need to model it and see what the computer program spits out.

and i think ive typed "natural frequency" enough times now....

that make any sense?

edit: grub screws? that sounds dodgy as! wanna hope you do them up straight or you'll throw the whole thing out of balance! why don't people get smaller pulleys for the supercharger end?

[Gilly]

nice read

i should weigh a factory item and my big pulley and check out the difference

as for the grub screws, its all pressed together and the grub screws are there as a failsafe i guess.

[toyomad]

whoops

[slydar]

i wouldn't run one.

Chris O'Shanessy doesnt think its a good idea either, as far as I'm concerned, Chris is about as likely to know whats good for a 4a as anyone, not only with his experience but also with being in racing circles, and with using the engine builder he uses..

i don't think the comparison to the rear strut brace is valid.

1 thing.. (the strut brace) basically, can't really hurt anything.

the other has the scientifically proven potential to damage your engine.

i also don't think youll notice the difference.

i can supply you a billet flywheel that will make a difference for about $400.

[Jonny Rochester]

I admit the stock harmonic balancer seams like a good idea, but a lighter flywheel/crank/pulley is also a good idea for better acceleration in a sports/race car. Also lighter static weight is an advantage also. I like to take off all the things I am not using on my car, so I have machined the A/C drive part off my stock pulley. The harmonic balancer part is retained. But I would just as soon use a solid aluminium one if it was lighter, and if I had the time/money to make/buy it.

Consider this, Toyota engines in the 70s, such as 2T-G did not have a harmonic balancer. The crank pulley was solid.

Another thought: I have seen a couple of 4A-FE engines with snapped cranks. The front of the crank where the pulley goes snaps off, with the standard setup.

[rthy]

slydar: thats not what I was saying at all, someone asked why would people fit them and I said "my point being people add stuff because they think it looks cool." he didnt ask what would go wrong, what it was like or what it was comparable to. Like usual I could of used some more carefull wording

[LAZY]

<div class='quotetop'>QUOTE (Sam_Q @ May 27 2008, 10:59 PM) <{POST_SNAPBACK}> (index.php?act=findpost&pid=537701)</div>
ok I don't know much about this but I would think that would be a pretty safe bet, assuming the grab screws can handle it[/b]


the first thing to go on a sr20det is the only, a lot of engineering has gone into the factory engine, they have engineered the engine to a point were it meets its warranty.

[rthy]

"is the only"?

typo?

a lot of engineering and they couldnt even fit a proper oil fitting for the turbo instead of that stupid tapered system they have now that loves to strip out. Fine if you never touch it (during warranty) but you better watch out if your not careful and you work on it. From what I have seen typical nissan style of engineering, do something so right and some things so wrong. Also how is it a cheapish aftermarket kit thats main part is a pressed peice of spring steel can sopposedly stop the rockers failing no-where near as much exist? why isnt it stock? piss poor if you ask me.

[af300e]

Lets make no mistake, Nissan engineering is bizarre at best. Does anyone remember the 3 litre diesels that (recent) that didn't run enough oil in the sump? Many blown motors. I think the resultant fix was to replace the dipstick with one that had the marks higher up to increase the amount of oil at "full".
What a monumental fuck up!

I have a D40 turbo diesel Navara, bought new but not my choice (i would have bought a hilux). It's a dog. Electronic 4X4 shit itself only time i really need it (wouldn't disengage, had to drive at 30kmh for 2 hours), turning circle is larger than the radius of the earth, needs front discs and pads every 40,000km regardless of how it's driven and they cost the same as the brakes in mum's 2006 mercedes 4x4 (which are about 40mm larger and last 80,000km). Also, abs light keeps coming on, dealership can't fix it (they are dills though. I suspect it's just a faulty wheel speed sensor). Speedo needle flaps to about 20km/h and back to zero when the car is stationary.

On the plus side, it handles very, very well for the type of car it is, it uses 10L/km of diesel and the seats are very comfortable.

I won't get another one............

Oh, and i don't give a flying fuck how fast the new GTR is, it looks shit and it's too heavy/big. I sat in one when I was in Japan and it felt like I was in a Maxima. I'd rather an R34, rx7, NSX.

EDIT: Sorry for the off topic.

[kaibeecee]

as said, theres better places to eliminate rotating mass (all 800g or so of extra pulley?) from the driveline without having to panic about your bearings

bottom end harmonics is something best left to toyota to deal with.

[biggo]

on a related note, someone once told me (i think it was ken) that if you change something at the front of the crank, then would you do the same to the rear ie. flywheel?

I remeber on toymods, an old 2tg kept snapping flywheel bolts after the setup was balanced. Solid harmonic balencer?

[DRFT - 86]

Hmm interesting......

Oh and I couldnt care less about the looks of it to be honest, not in it for tha shinyness...........

mixed opinions, would like to hear from people who have used a lightweight 'crank' pulley and their opinions....? I have read roadtests in a few magazines in the past where they have fitted these aftermarket pulleys so I'm interested to hear from people with 1st hand experience.....

And please try to stay on topic, was drifting into some other bullshit there for a while..

Cheers