SKU: 32455411855

537185801 Bump Knob - Fits Husqvarna T35 Trimmer Head (2003-05, 2005-01, 2007-04) - 4 Pack

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Description

537185801 Bump Knob - Fits Husqvarna T35 Trimmer Head (2003-05, 2005-01, 2007-04) - 4 Pack537185801 Bump Knob Replacement Key Features High Impact Blue Polymer: Manufactured from a high density, abrasion resistant plastic specifically designed to withstand thousands of high velocity "bumps" against asphalt, gravel, and packed soil. Reinforced Structural Ribbing: The internal geometry features reinforced walls to prevent the knob from cracking or shattering under the extreme centrifugal force of commercial grade trimmers. Precision Spring

537185801 Bump Knob Replacement

Key Features

  • High-Impact Blue Polymer: Manufactured from a high-density, abrasion-resistant plastic specifically designed to withstand thousands of high-velocity "bumps" against asphalt, gravel, and packed soil.
  • Reinforced Structural Ribbing: The internal geometry features reinforced walls to prevent the knob from cracking or shattering under the extreme centrifugal force of commercial-grade trimmers.
  • Precision Spring Seating: Engineered with a centered internal recess to perfectly secure the T35's heavy-duty spring, ensuring a consistent and responsive line-advancement "snap" every time.
  • Commercial-Grade Multi-Pack: This 4-piece kit provides a cost-effective solution for landscaping fleets and large residential properties, ensuring you always have a spare on hand to prevent downtime.
  • Snap-In Tool-Free Installation: Designed as a direct-fit replacement that clicks into the existing T35 housing by hand, allowing for rapid field repairs without the need for specialized tools.

Replaces / Cross-Reference Part Numbers

  • 537185801

Compatibility & Fitment

This bump knob is the standard replacement for the professional "T35" series trimmer heads. Key compatible models include:

  • Husqvarna 100/200 Series: 123L, 123LD, 225L, 232L, 232R.
  • Husqvarna 300 Series: 322L, 323L, 324Lx, 325L, 325Lx, 326L, 326Lx, 327LS.
  • Husqvarna 500 Series: 522L, 525L, 525LS, 525LST, 535LS.
  • Historical Production Dates: Compatible with T35 heads manufactured during the 2003-05, 2005-01, and 2007-04 production cycles.
  • Note: Specifically for the T35 head. If you have the smaller T25 or larger T45, this knob will not fit correctly.

When to Replace

  • Worn-Through Bottom: The center of the blue knob has ground down from pavement contact to the point where the internal metal spring is visible or falling out.
  • Broken Retaining Tabs: The plastic clips that lock the knob into the housing have snapped, causing the knob to fly off while the trimmer is spinning at high RPM.
  • Seized Mechanism: Significant buildup of dried sap, dirt, and debris has fused the knob to the internal spool, preventing it from releasing new line.
  • Rounded Indexing Teeth: The internal plastic "teeth" that click against the spool have rounded off, causing the head to dump all the line at once during use.
  • Visible Stress Fractures: White lines or cracks appearing in the blue plastic, indicating the material has become brittle and is prone to catastrophic failure.

Installation Tips

  • Clean the Housing: Before installing the new knob, use a stiff brush or screwdriver to remove all dried grass and mud from the locking slots and spring area to ensure a 100% secure lock.
  • Inspect the Spring: Ensure the internal metal spring is not rusted or collapsed. If the spring is weak, the new knob will stay "compressed," causing the line to feed uncontrollably.
  • Snap-Lock Check: Press the new knob firmly into the housing until you hear a distinct "click" on both sides. Give the knob a firm tug by hand to verify it is fully seated before starting the engine.
  • Manual Feed Test: With the engine off, press the knob in and pull the trimmer line manually to ensure the indexing mechanism is releasing the line smoothly.
  • Avoid "Riding" the Head: To maximize the life of your new knobs, try to avoid letting the trimmer head drag on the ground while trimming; only make contact with the surface when you need to advance the line.
Shipping Notes
  • Free Standard Shipping on $100+ Orders to the USA.
  • Except Preorder products are shipped in 48 hours.
  • Delivery to the USA:
  1. Standard Shipping : 3-10 business days
  • If time is of the essence, please consider selecting expedited delivery for faster service.
Exchange/Return Notes
  • We offer a 30-day return/exchange service after receiving.
  • Final sale items are not eligible for returns or exchanges.
  • To process your return/exchange, please contact us at [email protected]
  • Please click here for more details>>> Return & Exchange Policy
SKU: 32455411855

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4.4 ★★★★★
Based on 15 reviews
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A
Verified Purchase
Amazon Customer
Alexandria, US
★★★★★ 1
Poor Quality
Size: 40 Cards Display Case Standard, Size: 40 Cards Display Case Standard
One shelf was broken. The other 3 were very loose and cracked. Very bad quality. Don’t bother purchasing this
WAS THIS REVIEW HELPFUL?YesReportShare
Reviewed in the United States on May 26, 2026
B
Verified Purchase
Big_Gregg_B
Los Angeles, US
★★★★★ 2
Lots of defects in construction
Size: 40 Cards Display Case Standard
I bought two of these, and at the time of writing this review, currently I've only loaded one with graded cards. First thing, the appearance looks decent, though some minor cosmetic issues here and there on the wood. After I got the display mounted on the wall, I started putting in the graded cards I wanted to display, and at first everything was going well; until I got to the 4 row. I noticed the first card I placed was wobbly, and would lean to the right. I looked at the card case, and figured it must be the case itself, until I put in the 3rd & 4th cards, and they to were wobbly, I ran my finger where the card sit and noticed either chipped wood, or excess glue, which prevent the cards from sitting flush against the rail. I continued to insert more cards, and one the bottom row, I noticed right away that there was a spacing issue between the 4th and 5th rows, and that the board between the two rows is bowed downward. I put a level on it and verified... which absolutely is is bowed. NOT COOL! Let's see how the return process goes now...
WAS THIS REVIEW HELPFUL?YesReportShare
Reviewed in the United States on November 24, 2024
R
Verified Purchase
Raegansmommy
Belleville, US
★★★★★ 5
Buy if you collect cards and want to display
Size: 40 Cards Display Case Standard
Arrived as pictured. Very nice display case for baseball cards or whichever types of cards collected. Gifted to husband who collects baseball cards. Hold quite a bit of cards. Mounted on wall just fine. Glass is clear and we put a light strip on the inside, which added to it. Bought two of these.
WAS THIS REVIEW HELPFUL?YesReportShare
Reviewed in the United States on February 21, 2025
S
Verified Purchase
Susannah
Belleville, US
★★★★★ 4
Not frosted glass
Size: 40 Cards Display Case Standard
This display case is not too bad for the money. Just be aware that when you freak out because it’s frosted glass, it isn’t. It’s just cling film to protect the glass.
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Reviewed in the United States on June 13, 2025
L
Verified Purchase
Lester O
Port Orchard, US
★★★★★ 5
Nicely made perfect for what we wanted.
Size: 40 Cards Display Case Standard
This is perfect for my son’s room to keep and showcase his cards. It’s larger than anticipated but my son was thrilled and fit all his favorite cards
WAS THIS REVIEW HELPFUL?YesReportShare
Reviewed in the United States on July 17, 2025

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