Husqvarna 521557501 Spring – Genuine OEM Replacement Equipment Spring

Part Number: 521557501
Category: Chainsaw Clutch, Drive & Engine Components
Type: Clutch Spring – Genuine OEM Replacement Chainsaw Spring

The Husqvarna 521557501 Spring is a genuine OEM clutch spring designed for select Husqvarna and RedMax chainsaws. Husqvarna’s official T435 illustrated parts list identifies 521 55 75-01 as the spring used within the clutch assembly, with three springs specified for that particular clutch configuration.

Product Specifications

• Part Number: 521557501
• Manufacturer: Husqvarna
• Product Type: Clutch Spring
• OEM Description: Spring
• Alternate Description: Chainsaw Clutch Spring / Clutch Shoe Spring
• Component Type: Clutch / Drive System Component
• Function: Provides Tension Between Applicable Clutch Shoes
• System: Centrifugal Clutch / Chainsaw Drive System
• Application: Chainsaw
• Compatible Brands: Husqvarna / RedMax – Model Dependent
• Material: Metal
• Component Location: Clutch Assembly
• Associated Components: Clutch Shoes / Clutch Assembly / Clutch Drum / Roller Bearing
• Replacement Type: Direct OEM Replacement
• OEM Status: Genuine Husqvarna OEM Part
• Condition: New
• Quantity: 1 Spring
• Part Number Reference: 521557501
• Alternate Number Format: 521 55 75-01
• Alternate Reference: 5215575-01
• UPC: 705788536290

Parts references confirm UPC 705788536290, while Husqvarna’s official documentation uses the formatted number 521 55 75-01.

Features & Benefits

• Genuine Husqvarna OEM replacement clutch spring
• Factory-designated 521557501 Spring
• Designed for compatible chainsaw clutch assemblies
• Provides tension between applicable clutch shoes
• Supports proper centrifugal clutch operation
• Helps keep clutch shoes retracted at lower engine speeds
• Allows clutch shoes to engage as engine speed increases
• Supports proper transfer of engine power to the cutting system
• Helps maintain the factory clutch engagement characteristics
• Metal construction
• Manufactured for application-specific fit
• Designed to work with compatible OEM clutch components
• Suitable for chainsaw clutch repair and maintenance
• Ideal replacement for stretched, weakened, distorted, or broken springs
• Direct replacement for equipment requiring 521557501
• Genuine OEM component rather than an unspecified universal clutch spring

Documented Applications

The Husqvarna 521557501 Clutch Spring is documented for select chainsaws including:

• Husqvarna 439
• Husqvarna T435
• RedMax G3200
• RedMax G3200EZ
• RedMax GZ3500T
• RedMax GZ360
• Select additional Husqvarna-produced equipment requiring 521557501

PartSelect specifically lists these Husqvarna and RedMax chainsaw models for 521557501.

L&S Engineers independently lists the spring for the Husqvarna 439 and T435, while Husqvarna’s official T435 parts documentation confirms its position within the clutch and oil-pump assembly.

Exact compatibility should still be verified using the complete model, product number, serial number, and production revision before ordering.

Clutch Spring Function

Chainsaws commonly use a centrifugal clutch to automatically engage the cutting chain as engine speed increases.

Within the applicable assembly, the 521557501 Clutch Spring helps:

• Hold the clutch shoes inward at low engine speed
• Maintain tension between the clutch shoes
• Control movement of the clutch shoes
• Allow centrifugal force to move the shoes outward as RPM increases
• Support engagement with the clutch drum
• Help disengage the clutch when engine speed decreases
• Maintain the intended clutch operating characteristics

When the spring is functioning correctly, the clutch should remain disengaged at the appropriate low engine speed and engage as engine speed rises.

Husqvarna T435 Clutch Assembly

Husqvarna’s official T435 illustrated parts list identifies the following components within the clutch and oil-pump section:

• 521557401 – Clutch Assembly
• 521557501 – Spring
• 521779401 – Plate
• 523082601 – Clutch Drum
• 520967301 – Roller Bearing

The official diagram specifies a quantity of three 521557501 springs within the applicable T435 clutch assembly.

This listing, however, should be treated as one individual spring unless the seller explicitly states that multiple springs are included.

Common Reasons for Replacement

Replacement of the 521557501 Clutch Spring may be appropriate if the original spring has:

• Broken
• Snapped
• Stretched
• Become weakened
• Lost tension
• Become distorted
• Sustained heat damage
• Developed corrosion
• Become damaged during clutch removal
• Become unable to properly retract the clutch shoe
• Developed excessive wear at its attachment points
• Been lost during clutch service

A failed clutch spring can affect how the clutch shoes engage or disengage from the clutch drum.

Possible Signs of Clutch Spring Problems

Depending on the chainsaw and condition of the clutch assembly, a damaged or weakened spring may contribute to:

• Chain movement at idle
• Abnormal clutch engagement
• Clutch engaging too early
• Clutch shoes failing to retract correctly
• Irregular engagement
• Excessive clutch vibration
• Abnormal noise from the clutch area
• Visible loose or damaged clutch shoes

These symptoms can also result from incorrect idle adjustment, clutch-shoe wear, clutch-drum damage, or other drive-system problems, so the complete clutch system should be inspected.

Clutch System Inspection

When replacing the spring, inspect related components including:

• Clutch shoes
• Complete clutch assembly
• Clutch drum
• Roller bearing
• Clutch plate
• Drive sprocket
• Crankshaft
• Chain brake components
• Oil pump drive components
• Mounting and retaining hardware

A new spring should not be installed onto severely worn, cracked, distorted, or otherwise damaged clutch shoes.

Important Notes

• Verify compatibility with your exact chainsaw model, product number, serial number, and production revision before ordering.
• Match part number 521557501 directly with your equipment's illustrated parts diagram or OEM documentation.
• The alternate formatted part number is 521 55 75-01.
• 5215575-01 is another documented formatting of the same reference.
• Although the generic OEM description may simply state “Spring,” 521557501 is specifically documented as a clutch spring on compatible chainsaws.
• This is a clutch spring, not a recoil starter spring, chain-tensioner spring, anti-vibration spring, or general-purpose equipment spring.
• Do not select a replacement spring based solely on approximate size or appearance.
• Clutch springs can differ significantly in length, wire diameter, hook configuration, tension, and operating characteristics.
• PartSelect identifies the spring as a metal component used in the clutch assembly to connect the clutch shoes.
• Husqvarna’s T435 diagram specifies three springs per clutch assembly, but the replacement spring itself is sold individually by multiple parts suppliers.
• If replacing one failed spring in a multi-spring clutch, inspect the remaining springs for similar wear or deterioration.
• Do not assume that three springs, the clutch shoes, clutch drum, bearing, plate, or complete clutch assembly are included.
• Inspect the clutch shoes for cracks, glazing, excessive wear, heat damage, or distortion.
• Inspect the spring attachment points for wear or damage.
• Check the clutch drum for excessive wear, scoring, overheating, cracking, or distortion.
• Inspect the clutch drum bearing and replace it separately if it feels rough, loose, or damaged.
• If the chain moves excessively at idle, verify correct engine idle speed in addition to inspecting the clutch.
• A carburetor or idle-adjustment problem can cause the clutch to engage even when the clutch components themselves are serviceable.
• Clutch components can become hot during operation. Allow the chainsaw to cool before beginning service.
• Springs can release stored tension during removal and installation. Use appropriate tools and eye protection.
• PartSelect notes that pliers and an Allen wrench may be required for replacement on applicable equipment.
• Install 521557501 in the same position and orientation as the original spring.
• Make sure each end of the spring is securely seated in its applicable clutch-shoe attachment point.
• After installation, verify that the clutch shoes move and retract correctly.
• Confirm that the clutch assembly rotates and operates without binding.
• Reinstall the clutch drum and associated components according to the manufacturer's service procedure.
• Verify proper chain operation before returning the chainsaw to service.
• Shut off the chainsaw, engage the chain brake, allow the engine to cool, and disconnect the spark plug before servicing the clutch.
• This listing is for one Husqvarna 521557501 Clutch Spring only unless otherwise specified. Complete clutch assemblies, clutch drums, bearings, plates, sprockets, and other drive components are sold separately unless explicitly included.
• Match part number 521557501 with your equipment's illustrated parts diagram or OEM documentation before ordering to ensure proper fitment.