Alternator Decoupler Pulleys (ADP)

Gates Alternator Decoupler Pulleys Provide Vibration Isolation Within the Accessory Belt Drive System Resulting in Smoother Engine Performance and Efficiency and Increased Belt and Component Life

Alternator Decoupler Pulley

The line consists of overrunning alternator decoupler pulleys and one way clutches (not interchangeable)

  • Exact OE replacement
  • Patented design unmatched by any other supplier
  • Torsion spring absorbs engine vibration for quieter, smoother ride
  • Chosen by OEM to reduce noise, vibration and harshness

How to inspect and replace an Alternator Decoupler Pulley.  


Want to see more videos on ADPs?  Click here.  

Why Replace with Gates ADP Pulleys?

  • Replacing the ADP instead of the entire alternator saves you time and your customers hundreds of dollars.
  • You must use the same type of replacement ADP as found on the vehicle originally. Pulley types are not interchangeable, and failure to install the correct replacement can cause damage to accessory drive components.
  • Gates ADP pulleys are the OE replacement part you need. It's exactly what came on the vehicle from the factory.

  • Overrunning Alternator Decoupler (OAD) Pulleys & One-Way Clutch (OWC) Pulleys

    Traditionally, original equipment manufacturers (OEMs) have used solid serpentine belt alternator pulleys and automatic belt tensioners. However, recent advancements in alternator pulley technology have paved the way for one-way clutch (OWC) pulleys and overrunning alternator decoupler (OAD) pulleys, which improve the performance and efficiency of car and light truck engines.

    The OWC pulley allows the rotor of the alternator to coast when the engine is decelerating, and the OAD pulley utilizes the one-way clutch technology while also providing engine vibration absorption. As the clutch mechanism engages and disengages the alternator, the OAD's patented torsion spring isolates vibrations throughout the system to ensure peak engine performance.

    Gates ADPs create a quieter, smoother ride and lower system tension, reducing overall wear and improving the life and longevity of all accessory components. 

    Identifying, Diagnosing and Replacing ADPs

    When it comes to ADPs and Solid Pulleys, looks can be deceiving. While these parts are similar in appearance, they operate quite differently.

    Identifying an ADP - A Solid Pulley is about the same width as the engine's serpentine belt and usually attached to the alternator shaft with a hex nut, while an ADP has a flange that protrudes in front of the belt grooves. The end of the ADP’s shaft is recessed and will have a hexagonal socket or fluted hole that engages the installation/removal tool.

    Diagnosing ADP Failure -You should suspect ADP failure in the following situations:

    • If you hear a buzzing noise immediately following engine shutdown, the bearings in the ADP have failed and the ADP will need to be replaced. In this situation, if you turn the pulley by hand, you'll feel grinding or roughness.
    • When you hold the alternator still and the pulley spins in both directions, it should be replaced. The pulley should spin freely in only one direction and engage the alternator in the other.
    • If the pulley won't spin freely in either direction you’ll need to replace it. You'll experience increased tensioner movement or belt slap when the engine is operating with a seized ADP pulley.

    Replacing an ADP - When replacing an ADP remember the following facts:

    • In most cases, a special tool is needed to remove and install a decoupler. Contact your local parts supplier, or contact your local Gates representative for more information.
    • The plastic cap can't be reused after it has been removed from the pulley. A replacement cap is supplied with the new part.
    • Solid Pulleys, OWC pulleys and OAD pulleys are not interchangeable. Avoid costly damage and comebacks by using the proper pulley for the specific vehicle.

    Solutions for Your ADP Challenges

    We’ve compiled a list of frequently asked ADP questions.

    Q: Are OADs, OWCs and Solid Pulleys interchangeable?
     No. Each pulley is designed for specific vehicle applications.

    Q: What is the service life of an ADP?
     ADPs should be inspected at 50,000 miles along with the belt and tensioner. Service life is dependent on the duty cycle (city vs. highway), driving conditions, and seasonal temperature variations. Always install a new ADP when rebuilding the alternator and ensure the same ADP type pulley is installed on any new replacement alternator.

    Q: Is there a special tool required to replace an ADP?
     Yes. Visit your local parts store or contact your Gates Representative to purchase the toolkit.

    Q: Where can I find information on which ADP "socket" goes with which ADP?
     There are three ADP sockets to choose from: 91024-1(spline), 91024-2 (21mm Hex) and 91024-3 (17mm Hex). By matching the ADP configuration with the tool configuration, it should be easy to tell which socket fits which ADP. A technician should also be able to look at the ADP and figure out which socket will fit.

    Q: Why does the tool kit show eight part numbers when there are only seven tools in the kit?
     Tools 91024-4 (socket) and 91024-5 (driver with hex on one end, flared on the other) are located on the bottom left side of the kit. They are snapped together but if you pull them apart, you have eight tools.

    Q: Which driver goes with which application?
     The configuration of the shaft depends on the brand of the alternator. Once a technician determines which driver works for the application, it is likely that the driver will be the same one next time. However, there is always a chance the driver will not be consistent across all applications, so the driver may not be associated with specific applications.

    Q: The Ford Crown Victoria uses a 17mm Hex driver but the Hex driver in that kit is not big enough. What do I do?
     Part 91024-5 has a 17mm Hex on the end opposite the driver with the flared female end. The Hex end goes through the ADP and mates up with the alternator shaft and an Allen wrench is used in the female end.

    Q: My customers are not sure how to use the tools. Where should I direct them for help?
     Send them to the informative ADP Removal and Replacement video here. It will clearly explain how each tool is used in various applications.

    Q: Why Gates?
     As one of the world's leading manufacturers in the Automotive Aftermarket industry, Gates offers the most complete line of OE quality products, backed by unmatched field sales support and training program

    Alternator Decoupler Pulley Tool Kit

    This handy tool kit contains all of the tools required for ADP removal and installation.

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