Pulley's for Dumies?

I have a Scion Tc and what exactly does a pulley do and would it beniefit* a scion tc?

Any feedback is great!

A pully? As in your belt drive? Makes everything work.

I'm assuming he means under drive pulley. They will not drive your accessories at full potential (they under drive them) and cause them to draw less power from the engine. Less power drawn from the accessories equals more power to the wheels.

Not sure how much they help a tC.

pully like the belt drive... something about a preformance one being lighter than a regular one... thats about all the info i got...

They are lighter and smaller , they turn the AC /power steering and alternator slower , Unfortunately it can cause troubles with large stereo systems, hot climates ect the lighter also lessens parasitic drag

i think the one for the tC is the same one as the newer xBs .. it is the same size as OEM it just weighs less, therefore it takes less power to turn it.

but i'd think a tC is more of an accessory mobile, why use an underdrive pulley

underdrive pulleys can also throw off harmonic balance

JSewell wrote:

but i'd think a tC is more of an accessory mobile, why use an underdrive pulley

If it's the same size as the stock pulley, then it's not an underdrive pulley.

UDP do quite a bit on a Neon in terms of performance. So I would imagine you would see a noticeable gain on your car.

so you know how opera singers can break glass, same theory can be said here if you aren't careful

JohnCuePublik wrote:

so you know how opera singers can break glass, same theory can be said here if you aren't careful

You hit the resonance frequency of the accessory and it breaks it? How does that apply when the motor RPM is constantly changing and never settled at one frequency?

cruise control haha jk

you hit the resonance frequency of the crank usually, don't ask me how I just know I've read my fair share of angry posts about wtf the dealer voided my waranty and my engines fried because my pulleys threw off the harmonic balance.

JohnCuePublik wrote:

you hit the resonance frequency of the crank usually, don't ask me how I just know I've read my fair share of angry posts about wtf the dealer voided my waranty and my engines fried because my pulleys threw off the harmonic balance.

Here's the thing about harmonic frequencies, you have to hold the rpms at that specific level. Unless you have the CVT (continuously variable transmission), the rpms are going to be constantly changing.

While I do agree that UDPs are can cause damage, it's not from resonance frequency. It's from poorly designed pulleys and replacing the harmonic balancer. The balancing is off and causes vibrations in the crank at ALL frequencies. Since it's at all frequencies, it's completely different than resonance frequency.

What you're reading online is a bunch of people that don't truly understand why it's breaking. They just know what's breaking and how to fix it. One person figures it out and tells people online. People read it and spread it on further. Pretty soon everyone's talking like they know why the problem's caused.