RE: Info on Underdrive pulleys

[Tim Irwin <timi@Interlinq.com>]

The underdrive pulley goes on the drive side of the gear ratio, reducing the
gearing of the system.

Let's go back to cycling for another gearing reference. Think of the normal
pulley as your large front chainring (higher gears), and the underdrive
pulley as the smaller chainring (lower gears). With the normal
pulley/chainring, you work harder, but also spin the accessory/rear wheel
faster. With the underdrive/small chainring, you spin quite easily, but the
accessory/wheel doesn't turn as fast. 

The last part is important to note. The accessories don't turn as fast, so
your AC may not get quite as cold, your alternator won't put out quite as
much power, and your steering won't have as much assist. It may or may not
be noticeable depending on how your car is set up, but I'd check carefully
into alternator output with the underdrive pulley if you're running extra
lighting or a high-wattage stereo system.

Tim Irwin
> -----Original Message-----
> From:	Billy T. [SMTP:btylaska@onramp.net]
> Sent:	Wednesday, October 21, 1998 8:39 AM
> To:	jettaglx@igtc.com
> Subject:	Re: Info on Underdrive pulleys
> 
> Stewart MacLund wrote:
> > 
> > Uhm.  If the pulleys are smaller, that would mean that the accesories
> turn
> > faster....  Which would rob the engine of power...  The pulleys diameter
> > should actually be bigger, yes?
> > 
> > Sundie
> 
> yeah, that does make the most sense.  I will check the page again
> 
> Billy T.