Smooth out the ride and keep your hardworking rig planted with the Monroe Magnum Front Suspension Shock Absorber 66458. Built for class 3-6 commercial trucks and buses, it's gas-charged for quicker response and a more stable, comfortable ride, and it drops in as a front-position replacement for the 2018-2024 Freightliner Cascadia (see the Buyer's Guide tab for engine-level detail). Designed to handle the demands of high-mileage, severe-use vehicles, it replaces worn-out units to help reduce excessive vibration.
- Nitrogen gas-charge: helps maintain tire-to-road contact by reducing aeration and shock fade for improved ride and handling.
- 10-stage valving: tuned to each vehicle to adjust to road extremes, while the larger 1-3/8 in. bore provides more efficient damping control on most applications.
- All-weather fluid: special additives assist with extreme temperatures and help reduce oil breakdown; a 2 in. or 2-1/4 in. reserve tube holds more fluid when required.
- Strong and durable: shouldered bushing and bonded bushing with sleeve protect against bushing walkout, with arc welds up to 360° for durability.
A PTFE-coated bearing reduces friction between the rod and rod guide, and the design isolates impact-related noise, vibration, and harshness under most driving conditions. Backed by Monroe's 90-day Risk Free Ride Offer and Limited Commercial Warranty.
Interchange: HD12140845 · 98031020 · AMS66458 · 1014193000 · 1014282000 · 1014317000 · A90193 · X900700973 · 83396 · 89396 · 5107857
This part cross-references / interchanges with the following part numbers:
Frequently Asked Questions
What vehicles does the Monroe Magnum 66458 fit?
It's a front-position shock absorber for the 2018-2024 Freightliner Cascadia. Check the Buyer's Guide tab to confirm the exact application for your truck.
Is this a front or rear shock?
The catalog lists the 66458 as a front suspension shock absorber, designed for class 3-6 commercial trucks and buses.
Is the 66458 gas-charged?
Yes. It uses a nitrogen gas-charge to help maintain tire-to-road contact by reducing aeration and shock fade for improved ride and handling.
What are signs my shock absorber may need replacing?
Excessive vibration, a bouncy or unstable ride, and impact harshness can be signs of worn shocks. Diagnose the cause before replacing, as other components can produce similar symptoms.
Should I replace shocks in pairs?
Shocks are sold individually. Replacing both sides on the same axle together as a matched set is recommended for balanced, consistent handling.
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