Subaru WRX Forum banner

GoFastBits Underdrive Pulley Kit

4K views 9 replies 6 participants last post by  Haw1es 
#1 ·
So my accessory belts are starting to squeak and need replacing. Im considering the gfb Underdrive Kit because its 3 lighter pulleys.
Are there any adverse effects of the kit in a daily? Will Underdriveing the ac and power steering cause any drivability issues?
 
#3 ·
Any reason why? Will it harm the engine/components the pulleys are attached too?

Edit: Just did a little more research and found the GFB crank pulley is undersized. Dont really want to undersize that. Looks like the grimmspeed one it is.
 
#4 ·
yea underdrive pulley's are not good at all.

a smaller diameter pulley will cause less rotations of a normal cycle. so your alternator, water pump, and such will not be working correctly. your alternator will send less power to all your components. that included ecu, sparks, etc... and if your water pump is underdriven your going to encounter cooling issues. you could only imagine an underdriven oil pulley would cause.

maybe on 100% custom built application, but not for a factory built car.
 
  • Like
Reactions: Haw1es
#6 ·
Im sorry this is wrong. A crank pulley that is a smaller diameter only effects the PS, alternator and your A/C. Your waterpump runs off of your timing belt which runs off of your crank not your crank pulley.

The only thing that will cause you an issue is when you are at low idle with Full load on the car. It will put a strain on the alternator and battery that's it and that's only under load.
 
#7 · (Edited)
yea i had my belts mixed up lol... my bad. i gotta stop commenting before my morning tea lol.

none-the-less though... a smaller diameter pulley on any of the components will cause problems. stressing the alternator under load isnt a good thing. the physics i mentioned are still correct. the pulley wheel will complete fewer rotations.
 
#8 ·
Im with BooKey, dont under drive your alternator unless you like your headlights flickering on cold evenings. If you really want to drop some weight you could pull your AC entirely but I wouldn't sacrifice my alternator effeceincy or my AC in California heat for a few OZ saves pulley weight.
 
#9 ·
Even with light weight pulleys, they don't address the problem that the factory pulley also acts as a harmonic dampener. There was a series of posts a long time ago proving this. Now, whether or not it's actually bad for your vehicle was still up to debate. But the best advice from it all was to save the money for proven gains. Leave the small stuff for the race cars when they're pinching everything they can get.

Found it. Refer to this thread on light weight pulleys
http://www.wrxtuners.com/forums/f52/perrin-crank-pulley-30415/
 
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top