under pulleys, are they worth it?
Thread Starter
Instructor
Joined: Jul 2007
Posts: 246
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From: belews creek nc
under pulleys, are they worth it?
My crank pully wabbles so I was wondering if I should replace it with just a gm part or look into those under pullies that they claim adds hp.
Drifting
Joined: Nov 2003
Posts: 1,539
Likes: 3
From: South al
i would add one ,every mod that u add helps most of the time ,i Just sold 1 to Corvette Don a 25 % pulley ,Powerbond they normally Sell for around 200.00 ,U may wanna go over to sales c5 sales section ,& Look for 1 ,i just sold mine for $ 70.00 ,This 1 is a 25 % UD pulley 
Last edited by fsuforever; Oct 13, 2007 at 11:53 AM.
Team Owner
Joined: May 2001
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From: Dear Karma, I have a list of people you missed.
St. Jude Donor '08-'09-'10-'11-'12-'13-'14-'15-'16
No more "wabbles" either.
Drifting
Joined: Jun 2002
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From: Corinth TX
Race Director
Joined: Oct 2002
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From: Gone
CI 6-7-8-9-10 Veteran
St. Jude Donor '03
Even if there's no gain...It's worth it just for the sake of installing a much higher quality part.
Burning Brakes
Joined: Aug 2006
Posts: 901
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From: Oxford PA
If going as far as changing the underdrive pulley for a bit more power and fix the wobble. Throw a cam in there while the rack is out. That will add some more power and your only and hour away from it while the pulley is off...
Race Director
Joined: Jul 2007
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From: Texas Hill Country
I agree about a higher quality part. I guess I meant stock spec rather than stock part. And I agree that there is no point in changing it unless you are doing multiple things....
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Melting Slicks
Joined: Aug 2006
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From: Powell TN
Cruise-In VIII Veteran
). He had had them on for over a year with no problems. After about 20 minutes of sitting in stop and go traffic, his car started running rough and then actually died. Luckily, we were at a turning lane and got the car out of the main flow of traffic. A police officer showed up, and after jumping the car off succeeded in re-starting it, he stopped traffic long enough for us to get across the road into a parking lot. We removed both the alternator and the battery and took them to a local auto parts place, where they both tested good. It turned out that, at a 700 rpm idle, the underdrive pulleys turned the alternator too slow for it to charge the battery. We spent about 4 hours all together messing with it, because of several stumbling blocks, and we missed a lot of the car show we went to see because it was outside and it got dark on us. Turning the idle up a little eventually fixed the problem.
Le Mans Master
Joined: Feb 2006
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From: USA
Pro
Joined: Nov 2003
Posts: 513
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From: Hotlanta GA
Hmmm, I'm gonna weigh in with a nay vote. 
Stock pulleys incorporate a dampening ring that most aftermarkets do not. Those rings are there to absorb high order vibrations. I'm not saying it will happen on the LS1, but if one were to hold just the right resonant frequency - well, bad things can happen. Google Tacoma Narrows bridge for a larger demonstration of this phenomenon.
If it were more than 5 ponies, I'd be interested, but for that little, no thanks.
Just my humble opinion....
Dan
Stock pulleys incorporate a dampening ring that most aftermarkets do not. Those rings are there to absorb high order vibrations. I'm not saying it will happen on the LS1, but if one were to hold just the right resonant frequency - well, bad things can happen. Google Tacoma Narrows bridge for a larger demonstration of this phenomenon.
If it were more than 5 ponies, I'd be interested, but for that little, no thanks.
Just my humble opinion....
Dan
Team Owner
Joined: May 2001
Posts: 36,836
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From: Dear Karma, I have a list of people you missed.
St. Jude Donor '08-'09-'10-'11-'12-'13-'14-'15-'16
Hmmm, I'm gonna weigh in with a nay vote.
Stock pulleys incorporate a dampening ring that most aftermarkets do not. Those rings are there to absorb high order vibrations. I'm not saying it will happen on the LS1, but if one were to hold just the right resonant frequency - well, bad things can happen. Google Tacoma Narrows bridge for a larger demonstration of this phenomenon.
If it were more than 5 ponies, I'd be interested, but for that little, no thanks.
Just my humble opinion....
Dan
Stock pulleys incorporate a dampening ring that most aftermarkets do not. Those rings are there to absorb high order vibrations. I'm not saying it will happen on the LS1, but if one were to hold just the right resonant frequency - well, bad things can happen. Google Tacoma Narrows bridge for a larger demonstration of this phenomenon.
If it were more than 5 ponies, I'd be interested, but for that little, no thanks.
Just my humble opinion....
Dan
You might want to check into the subject a bit more before saying that.
Melting Slicks
Joined: Apr 2007
Posts: 3,290
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From: Willow Springs IL
I'll share an experience I had with them. This may be uncommon. I went with a buddy of mine to a car show in Pigeon Forge (you're in NC, I'm sure you know Pigeon Forge when there is an event there. ). He had had them on for over a year with no problems. After about 20 minutes of sitting in stop and go traffic, his car started running rough and then actually died. Luckily, we were at a turning lane and got the car out of the main flow of traffic. A police officer showed up, and after jumping the car off succeeded in re-starting it, he stopped traffic long enough for us to get across the road into a parking lot. We removed both the alternator and the battery and took them to a local auto parts place, where they both tested good. It turned out that, at a 700 rpm idle, the underdrive pulleys turned the alternator too slow for it to charge the battery.
We spent about 4 hours all together messing with it, because of several stumbling blocks, and we missed a lot of the car show we went to see because it was outside and it got dark on us. Turning the idle up a little eventually fixed the problem.
). He had had them on for over a year with no problems. After about 20 minutes of sitting in stop and go traffic, his car started running rough and then actually died. Luckily, we were at a turning lane and got the car out of the main flow of traffic. A police officer showed up, and after jumping the car off succeeded in re-starting it, he stopped traffic long enough for us to get across the road into a parking lot. We removed both the alternator and the battery and took them to a local auto parts place, where they both tested good. It turned out that, at a 700 rpm idle, the underdrive pulleys turned the alternator too slow for it to charge the battery. We spent about 4 hours all together messing with it, because of several stumbling blocks, and we missed a lot of the car show we went to see because it was outside and it got dark on us. Turning the idle up a little eventually fixed the problem.
Team Owner
Joined: May 2001
Posts: 36,836
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From: Dear Karma, I have a list of people you missed.
St. Jude Donor '08-'09-'10-'11-'12-'13-'14-'15-'16
I agree with you very much for the need for this ability and the aftermarket folks do to. The biggest things that appeal to me are (other than any HP gains from their size) is the manufacturing quality (dimensions, etc), durability and materials used. Some also have an extended edges (like a fence so-to-speak) providing an additional guard against a serpentine belt's sideways movement on the pulley.
Like the others have said, if you're going to have to replace an obviously bad OEM pulley assembly anyway, it just makes sense to get one of these and to also key the crank snout while you're there as well.
Pro
Joined: Nov 2003
Posts: 513
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From: Hotlanta GA
Let's agree to agree. 
Sorry if my earlier statement caused anyone to be concerned. I've seen problems develop from those cheap aluminum/steel only parts on other platforms and just wanted to raise a possible drawback. I know, for example, that a damper-less crank pulley installed on a beemer straight-six will result in a destroyed crank.
Lots of twisting forces over a long distance there....
Anyone have large pics of the powerbond? I may have to add one to the pending h/c parts list...
Also, for those concerned about charging issues - I believe you can fit an overdrive pulley on the alternator which would sidestep that problem nicely. Me, my ac-less idle speed is 525 and I love the fuel savings.
Cheers!
Dan
Sorry if my earlier statement caused anyone to be concerned. I've seen problems develop from those cheap aluminum/steel only parts on other platforms and just wanted to raise a possible drawback. I know, for example, that a damper-less crank pulley installed on a beemer straight-six will result in a destroyed crank.
Lots of twisting forces over a long distance there....Anyone have large pics of the powerbond? I may have to add one to the pending h/c parts list...
Also, for those concerned about charging issues - I believe you can fit an overdrive pulley on the alternator which would sidestep that problem nicely. Me, my ac-less idle speed is 525 and I love the fuel savings.
Cheers!
Dan
Administrator
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From: Bel Air (by way of Fort Worth, TX) Maryland
St. Jude Donor '12 thru '21
IMHO, I think the 5 HP gain is a little optimistic. UD pulleys, especially on a mostly stock engine (I assume) have a tendency to cause engine overheating and battery drain. The safe bet is to stay stock.
