under drive pulley?
Melting Slicks
Joined: Jul 2004
Posts: 2,826
Likes: 39
From: Central NJ
St. Jude Donor '05-'06-'08-'10
Underdrive pulleys are known to give modest gains, but are generally done as part of a package. (eg. when swapping a more aggressive cam) I wouldn't go through the trouble (expense) unless I was already going to have the crank pulley off for another mod/repair. 
Melting Slicks
Joined: Jul 2004
Posts: 2,826
Likes: 39
From: Central NJ
St. Jude Donor '05-'06-'08-'10
The underdrive pulleys won't effect your charging or AC performance. At that price, you might as well do it. Good luck. (PS. Keep note of the "new" belt sizes for your next replacement.)
Race Director
Joined: Oct 2002
Posts: 16,477
Likes: 26
From: Gone
CI 6-7-8-9-10 Veteran
St. Jude Donor '03
Originally Posted by pin75us
I have a mechanic that will do it for $90 (install).
Team Owner
Joined: May 2005
Posts: 23,682
Likes: 9
From: Flagstaff Az.
UD pulley.
I would be cautious of the mechanic. It sounds like he is not familiar with C5s. The steering has to be loosened to get to the pulley. Also the crank should be pinned at the time of the install. You have to have a new bolt for the pulley, the old one is a one time only deal. Most shops that do C5s have a longer bolt to start the pulley on so as not to strip the crank snout or the new bolt. I would do a search here on the forum for pictures so you have an idea of the procedure. The UD pulley will work fine with the alt. and A/C.
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Race Director
Joined: Oct 2002
Posts: 16,477
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From: Gone
CI 6-7-8-9-10 Veteran
St. Jude Donor '03
Pinning is usually only done with supercharged applications because of the much increased load on the pulley to drive the blower, which can overcome the press fit and spin the pulley on the crankshaft.
Just installing the pulley on a n/a car actually lessens the applied load, and makes it even less likely to slip than a stock pulley, so pinning is not at all eeded.
Just installing the pulley on a n/a car actually lessens the applied load, and makes it even less likely to slip than a stock pulley, so pinning is not at all eeded.
Drifting
Joined: Jun 2002
Posts: 1,945
Likes: 41
From: Corinth TX
Try TSP for your underdrive pulley. They have pretty good prices on them.
http://www.texas-speed.com/shop/item...d=629&catid=20
They are extremely friendly and sent mine out quick.
http://www.texas-speed.com/shop/item...d=629&catid=20
They are extremely friendly and sent mine out quick.
Le Mans Master
Joined: Aug 2002
Posts: 8,222
Likes: 0
From: Norfolk VA
what I was told on here a while back, it's not worth the trouble unless you are doing a cam at the same time, but if you are doing a cam you might as well do it at the same time. I'm not sure I would trust a shop that would do it for $90.
Le Mans Master
Joined: Apr 2003
Posts: 6,001
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From: Palm Bay FL
St. Jude Donor '05-'06-'07-'08-'09-'10-'11
Team Owner
Joined: May 2005
Posts: 23,682
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From: Flagstaff Az.
[QUOTE=Y2Kvert4me]Pinning is usually only done with supercharged applications because of the much increased load on the pulley to drive the blower, which can overcome the press fit and spin the pulley on the crankshaft.
Just installing the pulley on a n/a car actually lessens the applied load, and makes it even less likely to slip than a stock pulley, so pinning is not at all eeded.
I'm not a C5 mechanic buy I will go along with Andy's(as in A&A) sugestion to pin the crank when you install a pulley. Not much work for a lot of security, cost me $50.00.
Just installing the pulley on a n/a car actually lessens the applied load, and makes it even less likely to slip than a stock pulley, so pinning is not at all eeded.
I'm not a C5 mechanic buy I will go along with Andy's(as in A&A) sugestion to pin the crank when you install a pulley. Not much work for a lot of security, cost me $50.00.
Last edited by tiojames; Aug 18, 2006 at 08:08 PM.
Team Owner
Joined: Feb 2003
Posts: 37,329
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From: Plano Texas
CI 6-7-8-9 Veteran
CI-VI Car Show Winner
St. Jude Donor '07-'08-'09-'10-'11-'12-'13
Originally Posted by pin75us
I have a mechanic that will do it for $90 (install).
I need to get belts anyways. Will installing the underdrive pulley hamper the charging from the alternator?
I need to get belts anyways. Will installing the underdrive pulley hamper the charging from the alternator?
Not worth it if you have an auto (A4).
Not really worth it unless you have engine mods.
Le Mans Master
Joined: Aug 2003
Posts: 9,298
Likes: 4
From: American Canyon Lethal Injection
Originally Posted by AC54ME
No
Not worth it if you have an auto (A4).
Not really worth it unless you have engine mods.
Not worth it if you have an auto (A4).
Not really worth it unless you have engine mods.
SC5