Underdrive Pullies

Foster98GT · Jan 16, 2007

Who has them? What are the good and bad to them?

Lightning Struck · Jan 16, 2007

i have had them on EVERY stang I have ever had. 1 V-6 car / 3 5.0 cars / 5 4.6GT's / and 2 4 valve 4.6 Cobras and I have NEVER had a problem with them other than the alt pulley not charging enough for a big stereo. They are a good way to " free " up about 10hp for a low price. They average about 100 bucks....some a little more just depends on where you get them from. I would suggest them for a nice bolt-on.

scarface · Jan 16, 2007

how will you run pullies with a blower?

Lightning Struck · Jan 16, 2007

scarface said:
how will you run pullies with a blower?

im pretty sure the stockers will have to go back on :-\

scarface · Jan 16, 2007

gotcha

ju015dd · Jan 16, 2007

Snakebit said:
scarface said:

how will you run pullies with a blower?

Click to expand...

im pretty sure the stockers will have to go back on :-\

yeap

fixthedoor · Jan 16, 2007

Snakebit said:
i have had them on EVERY stang I have ever had. 1 V-6 car / 3 5.0 cars / 5 4.6GT's / and 2 4 valve 4.6 Cobras and I have NEVER had a problem with them other than the alt pulley not charging enough for a big stereo. They are a good way to " free " up about 10hp for a low price. They average about 100 bucks....some a little more just depends on where you get them from. I would suggest them for a nice bolt-on.

O0 I second that. I just put a set on this past weekend. So far, engine runs like it did, except with a little extra oomph. Cheap, quick, easy way to get some extra ponies.

95-stang · Jan 17, 2007

I put some on mine, only downside [i'm sure everyone knows] as the alternator is going pretty slow at tickover,
if your out at night and sitting still, its best to put it in neutral, if you sit in drive, the voltage drops and the lights can dim quite a bit.
No problems in the day though.

Foster98GT · Jan 17, 2007

So a Stereo is out of the question then?

Matt94GT · Jan 17, 2007

Well I got a stereo and its fine but at a stop light my voltage does drop down low, and I know its as a result of adding underdrive pulleys, I run a optimia battery and a 170amp alt. A capacitor should help me though.

scarface · Jan 17, 2007

yeah get a cap, and you wont drain so much on the battery from the amp and subs

Nacho · Jan 17, 2007

Some company sells an OVER drive pulley for the alt. I compensates for the other 2 small pullies and doesn't give you charging problems. I've never used it but I was told it worked. Try leaving the stocker on as well, that was also said to work.

G_94_T · Jan 18, 2007

underdrives alone dropped my e.t.'s .15 in the 1/4......but yeah the voltage drops considerably at idle

Stopsign32v · Jan 18, 2007

Just don't put on the alt underdrive pulley. duh

blackfang · Jan 21, 2007

I will not run a UDP for a 4V. The potential for the damage they cause isn't worth the 10 hp for me. They have been known to cause oil pum gear failure being the balancers aren't that great and have chewed up some gears and caused engine failures. Al Papito wont run them unless he has an ATI Dampner along with others. However atleast 9 motors have gone to the sh!tter because of them and Bob Cosby's motor was damaged but luckily he had billett oil pump gears which saved him.

Lightning Struck · Jan 21, 2007

blackfang said:
I will not run a UDP for a 4V. The potential for the damage they cause isn't worth the 10 hp for me. They have been known to cause oil pum gear failure being the balancers aren't that great and have chewed up some gears and caused engine failures. Al Papito wont run them unless he has an ATI Dampner along with others. However atleast 9 motors have gone to the sh!tter because of them and Bob Cosby's motor was damaged but luckily he had billett oil pump gears which saved him.

I have heard about that too, but from everything I have read that is caused by IMPROPER INSTALLATION, and NOTHING ELSE.

AaRoN · Jan 21, 2007

I have BBK's and noticed an immediate difference. Charging is an issue at idle.

Midnight_Cobra · Jan 21, 2007

MARCH PULLIES!!!!!

Their craftsman ship is beautiful, I got the polished and I got a little wood when I opened the box for the first time! Install was easy and I felt a SOTP feel from them.

blackfang · Jan 21, 2007

Snakebit ] [quote=blackfang ] I will not run a UDP for a 4V. The potential for the damage they cause isn't worth the 10 hp for me. They have been known to cause oil pum gear failure being the balancers aren't that great and have chewed up some gears and caused engine failures. Al Papito wont run them unless he has an ATI Dampner along with others. However atleast 9 motors have gone to the sh!tter because of them and Bob Cosby's motor was damaged but luckily he had billett oil pump gears which saved him. [/quote] I have heard about that too said:
Here's a pic of the crankshaft that came out of Bob Cosby's Cobra.
This engine had 12-15 dyno runs, 200 street miles and 32 1/4 miles passes.
The engine was torn down under an official NMRA protest in Kansas city after Bob reset the National record five times in one weekend and winning the event.
This engine had a small dia underdrive damper. The damage to the flats that drive the pump are obvious. Also obvious are the witness marks on the opposite side of the flats. (As EDO pointed out in one of the many oil pump threads) The crankshaft drives the pump, The pump does not drive the crank.
So.. There should be marks on the crank in only one direction ( Where all the damage is in the picture) Why are there marks on the opposite side?
The answer is the front of the crank is sizzling with harmonic vibration, Just like a giant tuning fork.
This vibration is passed on the the pump,Chains,sprockets,cams,valvetrain.
after the pump the next thing that fails are the cam sprocket bolts. Myself, Carlos Nazerino, and Joe Lynch come to mind. I warned Joe after i blew a very expensive engine. Joe's ran a year or so and was killed when a sprocket bolt failed.
This pic shows the beating the crank took. The only thing that saved this engine was the billet oil pump gears. Bob's engine was the last to leave my shop with a u/d damper, that was 2004.