Alternator Overrunning Clutch Pulleys or Decoupler Pulleys to Solid Pulley Conversion

Alternator Overrunning Clutch Pulley or Decoupler Pulleys to Solid Pulley Conversion

Note from AlternatorMan: I've been around auto electric for many years, long before Overrunning Clutch or Decoupler Pulleys were ever invented and for the life of me I cannot understand what overall good Cluch / Decoupler or Overrunning Pulleys do other than beak and cost money and trouble. I've been told by many engineers what the purpose of these clutch pulleys are but it never holds up to annylasis. For instance, I've been told that the clutch is to allow the alternator to "freewheel" when you quickly let off the gas. I can assure you that alternators are under such a large electric generation load that they do not "freewheel". As soon as you let off the gas the alternator slows down from the electric load they are under and do not free wheel.You may have a situation where a multi component pulley is not needed. Email us with your application to see if we have a conversioon pulley to fit your needs.

I reciently read and article in Counterman Magazine titled:

Alternator Pulleys: Not So Simple Anymore

Alternator pulleys are not so simple anymore. Many late-model vehicles are equipped with special pulleys that are engineered to reduce NVH (noise, vibration and harshness) and extend the life of the alternator.

“An Overrunning Alternator Pulley (OAP) has a one-way clutch mechanism inside the hub that allows the belt to turn the alternator in one direction, but allows the alternator to free-wheel and spin at its own speed when the engine suddenly decelerates. A good OAP pulley should lock up and turn the alternator rotor when it is turned one way, but release and free-wheel when it is spun in the opposite direction. If the internal clutch mechanism is bad, the pulley may slip and fail to drive the alternator, or it may remain locked all the time – increasing noise, vibration and stress on the belt drive system. Another type of special pulley is an Overrunning Alternator Decoupler (OAD). This type of pulley also has a one-way overrunning clutch inside the hub as well as an internal torsion spring to further dampen vibrations in the belt drive system. The spring acts like a shock absorber to cushion the hub. This reduces noise at idle and low engine speeds, and helps dampen harmonic vibrations at higher speeds. If the clutch or spring inside the pulley has failed, the pulley may fail to drive the alternator, or it may create vibrations and noise.”

I have issue with some of these points: The first thing the article says is that clutch/decoupler pulleys reduce NVH ( noise, vibration, harshness).

Here is my opinion.


How much noise are we talking about? I've run clutch/decoupler pullied alternators along with solid pulleys and they sound the same to me, I cannot tell the difference.


Overrunning Clutch/decoupler pulleys have a much greater chance of making noise and vibration in the alternator, such as when they are about to fail. Solid pulleys do not fail, they are solid steel, no clutch in them, I've never seen any vibration in an alternator other than when the clutch/decoupler pulley fails.


What are they talking about? It says in the conterman magazine article that clutch/decoupler pulley drives the alternator one direction and slips in the other direction. It says that this allows the alternator to "free wheel" when the motor slows down rapidly. Well I can tell you that alternators do not "free wheel" when they are charging. People think alternators are easy to spin, this may be true when they are sitting on the counter at the auto parts store but in real life when alternators are mounted on the vehicle and turned on charging, they are very hard to turn, so they do not "free wheel" while charging on the vehicle. As soon as you slow down your motor the alternator is under such charge load that the alternator itself will slow down the motor.

They Say Clutch/Decoupler Pulleys Will Make Your Alternator Last Longer?

How will clutch/decoulpler pulleys make the alternator last longer? The clutch in the clutch/decoupler pulleys fail all the time potentially leaving you stranded. I reciently spoke with a customer that purchased a solid pulley conversion to replace his failed clutch pulley. He was quite upset in that the alternator works just fine but the clutch pulley failed and he couldn't find a clutch pulley for his alternator. He thought he would have to buy another nearly $300 alternator before he found us. Solid pulleys do not have a clutch that can fail. They won't leave you stranded from a failed clutch. We have many clutch/decoupler to solid pulley conversions that are not shown. If you have a clutch pulley that has failed and want to replace it with a solid pulley and you do not see the one you need, call 616-785-7990 or email INFO@QSALTS.COM

Clutch Pulley Remoal Tool
purchase price part # description
$19.95 12623

33 Spline Head, 1/2"  Drive and 7/8" hex drive, Alternator Clutch/Decoupler Pulley Removal/Replacement Tool





17mm Hex Head impact grade, 1/2" Drive, Alternator Clutch/Decoupler Pulley Removal/Replacement Tool.

Clutch/Decoupler Pulley to Solid Pulley Conversion Kits
purchase price part # description
$34.95 242278191SLD

Clutch/Decoupler Pulley to Solid Pulley Conversion Kit for Ford 4G Series Alternators.

$26.95 2481107SLD

Clutch/Decoupler Pulley to Solid Pulley Conversion Kit for Hitachi Alternators.

$29.95 2483278SLD

Clutch/Decoupler Pulley to Solid Pulley Conversion Kit for Denso Alternators On Chrysler, Dodge, and Jeep Vehicles.



$26.95 3275242SLD

Clutch/Decoupler Pulley to Solid Pulley Conversion Kit for Mitsubishi Alternators On Ford Crown Vic and others, Mitsubishi alternators.