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:

[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.

[rthy]

<div class='quotetop'>QUOTE (ke70dave @ May 27 2008, 10:02 PM) </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?

[ke70dave]

<div class='quotetop'>QUOTE (Sam_Q @ May 27 2008, 10:27 PM) </div>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:

[LAZY]

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

[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.