about under drive pullys on an LS?

I was told a long time ago that if you get an uder drive pully you need to get a light wight flywheel or you will mess up you harmonic(spell) balencer. is that true? is it worth even getting one? i hear that they work pretty good on N/A cars.

http://files.automotiveforums.com/gallery/watermark.php?file=/503/275359pulley_9600civic.jpg

Ok my dumb ass as done a surch and seen this was descused before. i guess my only question would be thin is would or could this be corected by a light wight flywheel? That is what i have herd before and if you think about it, it kinda makes sence.

I don't know about the flywheel thing, but I've heard the aftermarket pullies are bad. Because they are not properly balanced, so when you're at a high RPM it throws your crank into a wobble. I know there are some out there that are balanced, but I've never seen them for very cheap.

that's what i herd to, but if you think about it. If the underdrive pullys is lighter and you put on a light wieght flywheel it would even out the sides.

Ok i found something on overboost.com that might just tell us everything we need to know, well kinda.


this is a quote from the site.

(Note that we've avoided the topic of underdrive pulleys, one of the most hotly debated items on automotive chat forums. Not that underdrive pulleys are a bad thing in and of themselves, but most of the pulleys out there are not dampened, and that's what leads to hot arguments online. If nothing else, why save weight on a pulley when you can save more weight in a larger diameter at the flywheel? Anyway, let the email flow to [email protected] for now.)

here is the rest of the site
http://www.overboost.com/story.asp?id=1283

the only thing worse than me buying cheap used tires was an underdrive pulley kit back in my youngin days.

Read this (http://www.automotiveforums.com/vbulletin/showthread.php?t=182675&highlight=torsional+vibration) thread, you will find some helpful info there. There are some good points made by both sides, so you read and decide what you want to do. But what ever you or anybody els does, DO NOT POST A REPLY IN THAT THREAD! I don't want to see a 1 year old post come back to the top.

Read this (http://www.automotiveforums.com/vbulletin/showthread.php?t=182675&highlight=torsional+vibration) thread, you will find some helpful info there. There are some good points made by both sides, so you read and decide what you want to do. But what ever you or anybody els does, DO NOT POST A REPLY IN THAT THREAD! I don't want to see a 1 year old post come back to the top.


that's the one i read, and i desided to do some resurch and see what the hipe is. i see what you are saying and id go with you on the subject. i will not be getting one because what would be the point if it will give me a little power and a lot of probs. i'm still gonna see if i can find something about the flywheel being lighter if it will weigh it out.

The weight is not the problem, it is the damping of the torsional vibrations. The flywheel being lighter will not affect the torsional vibrations. There is a "harmonic balancer" inside the stock pulley, it is really a torsional vibration damper, but is called a harmonic balancer. You can run a lighter flywheel and it will not cause problems with torsional vibration, it is when you reaplce the crankshaft pulley that you run into problems.

Got Ya Thanks

ok help me out i heard someone say that our crank shaft is "internaly ballanced" and there isno harmonic balancer on the pulley is there any truth to this? and does the power gain come from the loss in weight or from underdriving (size diference)