C5 Tech Corvette Tech/Performance: LS1 Corvette Technical Info, Internal Engine, External Engine, Tech Topics, Basic Tech, Maintenance, How to Remove & Replace
Sponsored by:
Sponsored by:

alternator pulley question

Thread Tools
 
Search this Thread
 
Old Oct 17, 2023 | 06:53 PM
  #1  
Fast one's Avatar
Fast one
Thread Starter
Le Mans Master
25 Year Member
Liked
Loved
Community Favorite
 
Joined: Jan 2001
Posts: 5,011
Likes: 508
From: Hilton NY
Default alternator pulley question

Is the alternator decoupling pulley a better choice than a solid pulley on an automatic C5?
Reply
Old Oct 17, 2023 | 11:58 PM
  #2  
Vetteman Jack's Avatar
Vetteman Jack
Administrator
Supporting Lifetime
Veteran: Navy
St. Jude 20 Year Donor
25 Year Member
Veteran: Reserves
 
Joined: Mar 2001
Posts: 368,324
Likes: 24,777
From: In a parallel universe. Currently own 2014 Stingray Coupe.
C7 of the Year - Modified Finalist 2021
MO Events Coordinator
St. Jude Co-Organizer
St. Jude Donor '03 thru '26
NCM Sinkhole Donor
CI 5, 8 & 11 Veteran
Default

Moved to C5 Tech for discussion.
Reply
Old Oct 18, 2023 | 09:09 AM
  #3  
Bobbo76's Avatar
Bobbo76
Pro
Veteran: Canadian Forces
Liked
Loved
Community Favorite
 
Joined: Sep 2018
Posts: 668
Likes: 302
From: Nova Scotia Canada
Default

I believe the later models all came with the decoupler. I just bought the unit attached and it comes with the decoupler and many suggest it's beneficial for supercharger applications. I've been using it for about 2 months and all levels of use and zero issues.

Powermaster 58969 Powermaster High-Amp Alternators | Summit Racing
Reply
Old Oct 18, 2023 | 09:12 AM
  #4  
grinder11's Avatar
grinder11
Race Director
Liked
Loved
Community Favorite
Top Answer: 1
 
Joined: Oct 2004
Posts: 12,864
Likes: 4,667
Default

Originally Posted by Fast one
Is the alternator decoupling pulley a better choice than a solid pulley on an automatic C5?
It's there for NVH reasons, and probably extends belt life. Basically a sprag clutch that stops the belt from chirping when the upshift changes crankshaft rpm from, say 6,300rpm, to, say 5,000rpm, when the next higher gear is selected. Not essential, but...
Reply
Old Oct 18, 2023 | 01:44 PM
  #5  
Route99's Avatar
Route99
Race Director
Supporting Lifetime
St. Jude 10 Year Donor
Photogenic
Loved
Community Favorite
 
Joined: Apr 2017
Posts: 10,247
Likes: 888
From: Hickory NC
2025 C5 of the Year Finalist - Modified
2022 C5 of the Year Finalist - Modified
2020 C5 of the Year Finalist - Modified
St. Jude Donor '17 thru '26
Default

GM Tech Service Bulletin #99-06-04-029A addresses the decoupling alternator pulley. This revised pulley was on all late model year 2000, and all 2001-2004 C5s with the A4 transmission. It took care of the squeal on earlier model C5s with Auto when shifting from Park to Reverse or Drive as well as other “rumble noise” that occurred when the AC kicked on, etc.
This retrofit was performed on our ‘99 many years ago and we have had no noise or vibration and without cranking mine up to check it right now, I believe it lets the alternator coast to a stop when the engine is turned off rather than having an abrupt hard stop.

Perhaps someone is aware of a workaround, but otherwise, it takes a special tool to make this conversion. A great benefit to having a son with a large, full-service garage is the plethora of tools in his gigantic tool box. 😉
Reply
Old Oct 18, 2023 | 04:37 PM
  #6  
grinder11's Avatar
grinder11
Race Director
Liked
Loved
Community Favorite
Top Answer: 1
 
Joined: Oct 2004
Posts: 12,864
Likes: 4,667
Default

Originally Posted by Route99
GM Tech Service Bulletin #99-06-04-029A addresses the decoupling alternator pulley. This revised pulley was on all late model year 2000, and all 2001-2004 C5s with the A4 transmission. It took care of the squeal on earlier model C5s with Auto when shifting from Park to Reverse or Drive as well as other “rumble noise” that occurred when the AC kicked on, etc.
This retrofit was performed on our ‘99 many years ago and we have had no noise or vibration and without cranking mine up to check it right now, I believe it lets the alternator coast to a stop when the engine is turned off rather than having an abrupt hard stop.

Perhaps someone is aware of a workaround, but otherwise, it takes a special tool to make this conversion. A great benefit to having a son with a large, full-service garage is the plethora of tools in his gigantic tool box. 😉
Can verify my 2000 vert, which was a March, 2000 build, has the decoupler.....
Reply

Get notified of new replies

To alternator pulley question





All times are GMT -4. The time now is 04:39 PM.

story-0
10 Ugly Corvettes That We Still Kinda Love

Slideshow: 10 ugly Corvettes that we still kinda love.

By Joe Kucinski | 2026-06-03 10:34:17


VIEW MORE
story-1
Top 10 Most Expensive Corvettes Ever Sold on Bring A Trailer

A lot of money has changed hands at the online auction house over the years.

By Brett Foote | 2026-06-03 10:21:50


VIEW MORE
story-2
10 Things Every Corvette Owner Needs (2026 Edition)

Slideshow: 10 great gifts Corvette enthusiasts actually want for Father's Day!

By Michael S. Palmer | 2026-06-03 15:43:40


VIEW MORE
story-3
8 Most "Only Corvette Owners Understand" Quirks and Problems

Slideshow: These are the quirks, annoyances, and oddly lovable problems that every Corvette owner eventually learns to live with.

By Pouria Savadkouei | 2026-05-28 09:31:39


VIEW MORE
story-4
10 Reasons the C6 Z06 is Still A Performance Benchmark After 20 Years

Slideshow: 10 reasons why the C6 Z06 is still a performance benchmark after 20 years.

By Joe Kucinski | 2026-05-27 17:20:09


VIEW MORE
story-5
How Much Horsepower Every Corvette Engine "LOST" in 1972

Slideshow: How much horsepower every Corvette engine lost in 1972.

By Joe Kucinski | 2026-05-27 16:54:53


VIEW MORE
story-6
Top 10 DOs and DON'Ts for Protecting Your Convertible Top!

Slideshow: How to Protect A Convertible Top: 10 DOs & DON'Ts

By Michael S. Palmer | 2026-04-03 00:00:00


VIEW MORE
story-7
Top 10 Most Explosive Corvettes Ever Made: Power-to-Weight Ratio Ranked!

Slideshow: The 10 most explosive Corvettes ever built based on power-to-weight ratio.

By Joe Kucinski | 2026-05-20 07:23:03


VIEW MORE
story-8
150 hp to 1,250 hp: Every Corvette Generation Compared by the Specs That Matter

Slideshow: From C1 to C8 we compare every Corvette generation by the numbers.

By Joe Kucinski | 2026-05-12 16:54:12


VIEW MORE
story-9
8 Coolest Corvette Pace Cars (and Replicas) of All Time

Slideshow: Some Corvette pace cars became collectible legends, while others perfectly captured the look and attitude of their era.

By Verdad Gallardo | 2026-05-11 09:50:51


VIEW MORE