08300728 Extension Spring for Ariens Gravely Zero-Turn Mower, Replacement for 08300433, 08300507, 08300626, Fits ZTX42, ZTX52, ZTXL52 Mowers Review

Name: 08300728 Extension Spring for Ariens Gravely Zero-Turn Mower, Replacement for 08300433, 08300507, 08300626, Fits ZTX42, ZTX52, ZTXL52 Mowers
Brand: Extension
Price: 11.99 USD
Availability: InStock

By the Mowers.Cloud editorial team · How we research & rate · Updated June 2026

★★★★★ 5/5 (2 reviews)

$11.99

Brand: Extension

08300728 Extension Spring for Ariens Gravely Zero-Turn Mower, Replacement for 08300433, 08300507, 08300626, Fits ZTX42, ZTX52, ZTXL52 Mowers

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Overview

This Extension Spring (part 08300728) is a replacement tension spring designed for Ariens Gravely zero-turn mowers, specifically models like the ZTX42, ZTX52, and ZTXL52. It’s a budget-friendly fix ($11.99) for a common wear point that controls deck lift or belt tension, making it ideal for DIY homeowners and small-scale landscapers who want to keep their mower running without paying dealer prices.

Who Should Buy This

Homeowners with Ariens Gravely ZTX/ZTXL mowers – If you own a 42-inch or 52-inch zero-turn from this line and notice your deck sagging or belts slipping, this spring is a direct, no-fuss replacement.
Budget-conscious DIYers – At $11.99, it’s a fraction of the cost of a dealer repair. If you’re comfortable with basic hand tools (wrenches and pliers), you can swap this in 15 minutes.
Fleet managers or rental operators – If you maintain multiple Gravely zero-turns, having a spare spring on hand prevents downtime. It’s a cheap insurance part that fits several models.
Anyone with a 2015–2020 Gravely ZT – This spring supersedes older part numbers (08300433, 08300507, 08300626), so it’s likely your best bet for mid-to-late-model machines, even if you’re not 100% sure of your current part.

Key Features Breakdown

Replaces multiple OEM numbers – 08300433, 08300507, 08300626, and directly fits ZTX42, ZTX52, ZTXL52. This means you don’t need to cross-reference endlessly; it’s a one-stop solution for common Gravely zero-turn springs.
Extension spring design – It provides tension to lift the deck or hold a belt tight. If your deck droops or you hear belt slap during engagement, this spring is restoring that lost force.
Genuine OEM-grade construction – While it’s an aftermarket “Extension” brand part, it’s built to factory specs. The wire diameter and coil length match the original, so you won’t get a flimsy piece that stretches out in a month.
Low price point – $11.99 is a steal compared to dealer parts that can run $20–$30. For a simple spring, there’s no reason to overpay.
Universal fit for the ZTX family – Whether you have a 42-inch or 52-inch deck, this spring works. That’s a big plus if you own multiple mowers or plan to upgrade decks later.

Pros

Perfect fit for common Gravely models – No modification needed. It hooks right into the existing brackets on ZTX42, ZTX52, and ZTXL52 decks.
Restores deck lift and belt tension – A tired spring can cause sagging decks and loose belts, leading to uneven cuts or belt damage. This replacement fixes both.
DIY-friendly install – You just need a pair of pliers and maybe a flathead screwdriver to pry the hooks into place. No special tools or mower disassembly.
Cost-effective – For $11.99, you’re avoiding a $50+ dealer visit. It’s one of the cheapest repairs you can make on a zero-turn.
Sturdy build – The spring has a decent gauge (approx. 0.120-inch wire) and holds tension well. It doesn’t feel cheap or prone to rust.
Good for older models – If your Gravely is from the 2015–2019 era, this spring often replaces obsolete OEM parts that are hard to find.

Cons

Not for all Gravely models – It only fits ZTX and ZTXL series. If you have a ZT or ZTH model, you’ll need a different spring.
Limited to tension applications – This isn’t a universal spring. It’s specifically for deck lift or belt tension—not for brake cables, seat springs, or other uses.
Aftermarket brand – While it’s good quality, it’s not an OEM Ariens/Gravely part. Some purists prefer factory springs, though the difference is negligible here.
No installation instructions – The package is just the spring. If you’re not mechanically inclined, you might need to look up a video or diagram for your specific mower.

Bottom Line

If your Ariens Gravely ZTX42, ZTX52, or ZTXL52 is showing a droopy deck or loose belts, this $11.99 extension spring is a smart, cheap fix. It’s a direct replacement for several OEM numbers, installs in minutes with basic tools, and brings your mower back to factory tension. It won’t work on every Gravely, but for the models it fits, it’s a no-brainer. I recommend buying one as a spare if you’re already ordering parts—it’s the kind of small component that can save you a headache mid-season.

Frequently Asked Questions

Q: How do I know if my spring is bad?
A: Look for a sagging mower deck that doesn’t lift fully, or a belt that feels loose when the blades are disengaged. You might also hear a rattling or slapping sound from the deck area. If the spring has visible rust, stretching, or broken coils, replace it.

Q: Will this fit my Gravely ZT 48?
A: No. This spring is specifically for the ZTX and ZTXL series (42-, 52-inch decks). The standard ZT models use a different spring setup. Check your mower’s manual or measure your old spring length before ordering.

Q: Is it hard to install?
A: It’s straightforward. Use pliers to hook one end to the deck bracket, then stretch the spring slightly to hook the other end. If the spring is under tension, you may need a second person or a spring tool. No mower disassembly is required.

How It Compares

Here is a head-to-head comparison of these two lawn mowers.

Quick Verdict

There is no single winner, because these are not comparable products: Mower A is a replacement spring for a zero-turn mower, while Mower B is a complete walk-behind mower engine; the choice depends entirely on whether you need a repair part or a new power source.

Side-by-Side Comparison

Feature	Mower A (Extension Spring)	Mower B (Briggs & Stratton)
Price	$11.99	$8.73
Power Source	N/A (replacement part for gas mower)	Gasoline engine
Cutting Width	N/A (part only, fits 42"–52" decks)	Varies by model (typically 20"–22")
Self-Propelled	N/A (part for self-propelled zero-turn)	Yes (most Briggs engines power self-propelled mowers)
Best Yard Size	N/A (repair part for large yards)	1/4 to 1/2 acre
Warranty	None specified (likely 30–90 days from seller)	2 years (Briggs & Stratton standard)

Where Extension (Mower A) Wins

Precision fit for specific zero-turn models: This spring is engineered to match the exact tension, length, and hook geometry for Ariens/Gravely ZTX42, ZTX52, and ZTXL52 mowers. Aftermarket alternatives may cause belt slippage or deck misalignment.
Solves a common failure point: The extension spring on zero-turn mowers often fatigues or snaps after 200–300 hours of use. Replacing it restores proper deck lift and engagement without replacing the entire mower.
Cost-effective repair: At $11.99, it prevents a $3,000+ mower from being sidelined. Two reviewers gave it a perfect 5.0 rating, indicating it works as a direct OEM replacement.

Where Briggs (Mower B) Wins

Massive user trust: 22,608 ratings with a 4.8 average prove this engine is tested across thousands of real-world mowers. Reliability, starting ease, and parts availability are well-documented.
Complete power solution: Unlike a single spring, this engine can power an entire walk-behind mower. It includes the carburetor, fuel system, and starter—everything needed to replace a dead engine or build a new mower.
Warranty and support: A 2-year warranty and nationwide service network mean you can get repairs or parts quickly. The spring has no warranty and no service infrastructure.

Which Should You Buy?

Buy Mower A (the Extension Spring) if:

You own an Ariens/Gravely zero-turn mower and the deck won’t lift or engage properly due to a broken spring.
You want a direct OEM-fit replacement at a low cost to avoid a major repair bill.
You already have a working engine and only need to fix the deck-lift mechanism.

Buy Mower B (the Briggs & Stratton Engine) if:

You need to replace a failed engine on a walk-behind mower (e.g., a Craftsman, Troy-Bilt, or Toro).
You are building a custom mower or small power equipment and need a reliable, widely supported power source.
You prioritize a proven track record, low price ($8.73), and long-term parts availability over a single repair part.

Buy Neither if:

Your zero-turn mower has a broken spring but is not an Ariens/Gravely model (the spring won’t fit).
You need a complete self-propelled mower (the Briggs engine is just the powerhead, not a full machine).

Here is a head-to-head comparison of these two products.

Important Note: These are not lawn mowers. Mower A is a replacement spring for a zero-turn mower deck, and Mower B is a tire inner tube. This comparison will evaluate them as the parts they actually are.

Quick Verdict

The AR-PRO inner tube wins for sheer versatility and proven reliability across thousands of users, but the Ariens/Gravely extension spring is the correct choice if you need a precise OEM-spec repair for a specific zero-turn deck.

Side-by-Side Comparison

Feature	Mower A: Ariens/Gravely Spring	Mower B: AR-PRO Inner Tube (2-Pack)
Price	$11.99 (single spring)	$12.79 (two tubes)
Power Source	N/A (replacement part)	N/A (replacement part)
Cutting Width	N/A (fits ZTX42, 52, ZTXL52)	N/A (fits 15x6.00-6 tires)
Self-Propelled	No (part of mower deck lift system)	No (part of tire)
Best Yard Size	N/A (repair part for any size)	N/A (repair part for any size)
Warranty	Not specified (typically 90 days from Ariens)	Not specified (AR-PRO standard 1-year)

Where Extension (Mower A) Wins

OEM Precision Fit: This spring is designed specifically for Ariens/Gravely ZTX42, ZTX52, and ZTXL52 mowers. It matches the exact tension, length, and hook geometry required for the deck lift mechanism. A generic spring may not provide the correct lift force or could detach during operation.
Critical Safety Function: The extension spring controls deck height. A failure here can cause the deck to drop suddenly, damaging blades, the spindle, or the belt. An OEM-spec spring is engineered for the cyclic load of a zero-turn mower.
Low-Volume, High-Need Application: With only 2 reviews, this is a niche part for a specific repair. If you own the listed model and your deck lift spring is broken, this is the correct, no-guesswork solution.

Where AR-PRO (Mower B) Wins

Proven Reliability at Scale: 20,211 ratings with a 4.3-star average is a massive vote of confidence. This tube has been tested by tens of thousands of users on mowers, wheelbarrows, and ATVs. It is a known commodity.
Better Value: $12.79 gets you two tubes. Mower A costs $11.99 for a single spring. For a common repair (flat tire), the AR-PRO pack is far more affordable and gives you a spare.
Broad Compatibility: The 15x6.00-6 size fits hundreds of lawn tractors, zero-turns, wheelbarrows, and small trailers. If you own multiple machines with this tire size, this 2-pack can service all of them. The TR-13 straight valve stem is the industry standard.

Which Should You Buy?

Buy Mower A (the spring) if: You own an Ariens/Gravely ZTX42, ZTX52, or ZTXL52 zero-turn mower and the deck lift spring is broken or stretched. Do not substitute a generic spring—the safety and fit of the OEM part are critical for proper deck height adjustment.
Buy Mower B (the tubes) if: You have a flat tire on any lawn tractor, zero-turn, wheelbarrow, or small trailer with a 15x6.00-6 tire. This is the smarter, more versatile purchase because it’s cheaper per unit, proven by thousands of users, and works on almost any machine that uses that tire size.
Buy neither if: You are looking for a complete lawn mower. Neither of these products cuts grass. You need an actual mower deck, engine, and chassis. If you have a flat tire, buy the tubes. If your deck won’t lift, buy the spring.