Hey guys, I have a 06 z71 crew cab fully loaded, heated leather, power everything etc. So it has the 145amp alt. and electric fans from factory. Well the truck has a under drive crank pulley and a small 8 inch sub and 400w amp system. The truck charges fine when the fans arent on (14.5). But when the fans come one it drops to about (12.5). So my ? is...

Why would I want to "overdrive" the the alt. pulley?? To me, that does not make since. You would think you need to underdrive the alt. pulley as well.... The smaller the pulley, the faster the alt will spin and charge better. Plz correct me if im wrong. Thanks!

 

yes you want to overdrive (make spin faster) the alt. for better charging. it will be smaller than stock most come with a part number for a new belt. have you had any problems with your P/S with the smaller crank pulley.
some say its hard to turn the wheels???

 

That would be a underdrive pulley if its smaller just like the crank. All the pulleys ive seen for sale are underdrive alt. Pulleys.

 

And no problems with steering yet

 

You're just thinking about "underdrive" and "overdrive" backwards.

Yes, the smaller pulley on the alternator will spin the alternator faster. Because the smaller pulley spins it faster, it is called an "overdrive" pulley. A larger than stock pulley for the alternator would be considered an "underdrive" pulley.

It's the opposite of the crank pulley.

 

Ok well the only pulleys I can find are underdrive pulleys for thr alt. Where can I find a overdrive pulley. Why is it the opposite from the crank.

 

http://www.texas-speed.com/p-146-asp...or-pulley.aspx

 

The simplest way that I can think of to explain is: Look at a 10 speed bike, the different sprocket sizes on front & rear, and how it all works.

 

Does the voltage drop occur only at idle?

 

I guess this is why im confused...is this not the same thing but its called a underdrive pulley...

http://speed-eng.com/store/asp-under...9d59b1d527f795

And no its not only at idle