Underdrive pulley
03-29-2006, 12:25 PM
#21
Originally Posted by Iron Sights
The crank pulley is the one you want to change; some guys go with a smaller alternator pulley in addition, but it is easy to turn in the first place (most of the gains come from the smaller crank pulley, anyway).
03-29-2006, 12:50 PM
#23
TECH Apprentice
Join Date: Dec 2004
Location: Evansville, IN
Posts: 309
Likes: 0
Received 0 Likes
on
0 Posts
Originally Posted by GuitsBoy
The smaller alternator pulley is actually an overdrive pulley. It is used to up the alternator RPMs when the underdrive crank pully slowed the alternator down too much. And while the alternator is easy to turn by hand with the belt off, its easily the accessory that takes the most power to turn, once its under load. Assuming of course the a/c is not on.
03-29-2006, 01:27 PM
#24
Originally Posted by Iron Sights
Sorry, by "smaller" I meant an underdrive alternator pulley. I didn't know that about the alternator, for I've never actually tried to spin it with the belt on. So, if the alternator absorbs the most power, why is there not a stronger emphasis on changing it (instead of the crank)?
if you were to put the alternator pulley on a motor with a stock crank pulley, you would reduce HP and would be spinning the alternator much faster.
03-31-2006, 01:24 PM
#26
On The Tree
Thread Starter
iTrader: (2)
Join Date: Mar 2006
Location: Celebration, FL
Posts: 176
Likes: 0
Received 0 Likes
on
0 Posts
Hey I just noticed the owner only included one new belt with the SLP underdrive pulley. (Hey removed the a/c before) Eventually I'll reinstall the A/C and need a new belt to go with the underdrive pulley, anyone know the size? (or the size of the main belt too to make sure its the right size he gave me)
2000 Trans Am
Also, wheres the best place to pickup a pulley puller?
Thanks!
2000 Trans Am
Also, wheres the best place to pickup a pulley puller?
Thanks!
03-31-2006, 02:05 PM
#27
12 Second Club
iTrader: (21)
Join Date: May 2005
Location: Indiana
Posts: 813
Likes: 0
Received 0 Likes
on
0 Posts
if your going gatorback belts, the part #for serpentine belt is 19-760K6. and the part # for a/c belt is 19-K040378. if you have a autozone near you, they will rent you a 3 jaw puller or go to a harbor frieght and buy one.
04-01-2006, 07:30 PM
#29
On The Tree
Thread Starter
iTrader: (2)
Join Date: Mar 2006
Location: Celebration, FL
Posts: 176
Likes: 0
Received 0 Likes
on
0 Posts
Ugh, the SLP instructions show needing two special GM tools, can I fake it with something else?
3. Use GM tool J 41665 to install the SLP crankshaft balancer.
...
8. Tighten the bolt a second pass to 140 degrees using a GM tool J 36660-A.
3. Use GM tool J 41665 to install the SLP crankshaft balancer.
...
8. Tighten the bolt a second pass to 140 degrees using a GM tool J 36660-A.
04-17-2006, 06:20 AM
#30
On The Tree
iTrader: (3)
Join Date: Jul 2005
Location: St. Louis, MO
Posts: 171
Likes: 0
Received 0 Likes
on
0 Posts
Hahaha, those tool numbers are a joke. I think that's basically a torque wrench, and maybe a longer crank bolt. You don't need anything special, don't get crazy. GM tools like J xyz, are usually nothing special.
04-17-2006, 07:29 AM
#31
TECH Apprentice
Join Date: Dec 2004
Location: Evansville, IN
Posts: 309
Likes: 0
Received 0 Likes
on
0 Posts
Originally Posted by tcossair
Ugh, the SLP instructions show needing two special GM tools, can I fake it with something else?
3. Use GM tool J 41665 to install the SLP crankshaft balancer.
...
8. Tighten the bolt a second pass to 140 degrees using a GM tool J 36660-A.
3. Use GM tool J 41665 to install the SLP crankshaft balancer.
...
8. Tighten the bolt a second pass to 140 degrees using a GM tool J 36660-A.
), but if you keep the wheels on the ground you should be good to go. Just take your time, and be careful not to strip anything. 
04-17-2006, 09:39 PM
#35
This seems like such an unclear topic all the time.
My big questions are:
1: Do autos with the underdrive pulley and without the alt. overdrive pulley have charging problems?
2: Do autos with the underdrive pulley and WITH the alt. overdrive pulley see any signifigant / worthwhile power gains ?
It seems to me that adding the overdrive pulley and underdrive pulley might effectively reduce the amount of underdrive you are adding to a point that it is no longer worthwhile to even do this on an auto. Am I wrong here??
My big questions are:
1: Do autos with the underdrive pulley and without the alt. overdrive pulley have charging problems?
2: Do autos with the underdrive pulley and WITH the alt. overdrive pulley see any signifigant / worthwhile power gains ?
It seems to me that adding the overdrive pulley and underdrive pulley might effectively reduce the amount of underdrive you are adding to a point that it is no longer worthwhile to even do this on an auto. Am I wrong here??
04-17-2006, 11:23 PM
#37
11 Second Club
iTrader: (5)
Join Date: Jul 2005
Location: Crestview, FL
Posts: 510
Likes: 0
Received 0 Likes
on
0 Posts
march ud pulleys throw belts also, btw. i have checked now and then to see if the belt is working it's way off, and sure enough i keep having to put it back in place. i need the "katech" solid tensioner, and will probably make that my next mod. i am unable to go WOT for the fear of throwing the belt again... that was not a fun experience @ 11 o'clock @ night in the middle of nowhere.
