Spool Performance – Mercedes AMG 725 9G FX-RT Upgraded Clutch Kit
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Spool Performance – Mercedes 725 9G FX-RT Upgraded Clutch Kit
Note: Please email customer_service@spoolperformance.us for details on scheduling training for installation of this component.
Rated for up to 1,700 Nm input torque
The Mercedes 725 9G transmission is a strong unit from the factory—but once torque levels push past the mid-700 Nm, the stock frictions and limited plate counts begin to slip, especially under repeated high-load, high-temperature conditions.
Spool Performance has developed a complete upgraded clutch system for the 725 9G using our FX-RT high-coefficient, high-energy friction material, the same proven technology that transformed the 8HP50 platform into a competition worthy transmission.
This new kit increases both the coefficient of friction (+20%) and the clutch counts across all six elements, dramatically increasing the torque capacity of every gear.
Clutch Count Increases
| Clutch | Stock | Upgraded | Increase |
|---|---|---|---|
| A | 4 | 6 | +2 |
| B | 4 | 7 | +3 |
| C | 5 | 7 | +2 |
| D | 6 | 9 | +3 |
| E | 6 | 9 | +3 |
| F | 7 | 10 | +3 |
Combined with the FX-RT friction upgrade, the resulting torque-capacity increases are substantial.
Torque Capacity Gains (Per Gear)
Based on clutch engagement logic for the 9G and the combined friction + plate-count increases:
| Gear | Engaged Clutches | Torque Increase |
|---|---|---|
| 1st | B C E | +68% |
| 2nd | C D E | +68% |
| 3rd | B C D | +68% |
| 4th | B C F | +68% |
| 5th | B D F | +71.4% |
| 6th | D E F | +71.4% |
| 7th | B E F | +71.4% |
| 8th | A E F | +71.4% |
| 9th | A B F | +71.4% |
Final Torque Rating
The factory 725 9G is rated for 1000 Nm.
With the FX-RT clutch packs installed:
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1st–4th gear clutch-limited rating: ≈1680 Nm
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5th–9th gear clutch-limited rating: ≈1714 Nm
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Overall clutch-pack system capability: ≈1,700 Nm
This upgrade raises the clutch-limited torque threshold by +68–71%, depending on gear.
Why FX-RT?
Our FX-RT friction material was engineered specifically for high-torque, high-energy, fast-shift transmissions. It has been proven in our 8HP50 kits, where customers reliably push 900–1000 Nm. Now the same technology elevates the Mercedes 725 9G into a new performance class.
Benefits include:
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20% higher μ for dramatically improved static and dynamic holding power
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Higher thermal stability under repeated high-load upshifts
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Reduced shift flare and reduced clutch slip
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Smoother, more consistent clutch apply characteristics
Who This Kit Is For
The Spool Performance 725 9G upgraded clutch kit is ideal for:
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High-power M177 builds
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GLE63 / GLS63 high-boost setups
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Tuned E63 / S63 running hybrid turbos
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Track-driven or heavy-use AMG applications
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Anyone targeting 1000+ crank hp with headroom
Your 725 9G is no longer the limiting factor. With Spool Performance FX-RT friction technology and increased clutch capacity, the transmission becomes capable of safely holding ~1700 Nm, giving your AMG the drivetrain headroom it needs to push big-power, high-boost builds confidently and repeatedly.
What’s Included
The Spool Performance 725 9G FX-RT Clutch Upgrade Kit includes all components required for a complete drop-in installation. No machining or custom fabrication is needed.
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Clutch A [B08] Pack (6-plate upgrade)
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6 x FX-RT friction discs
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6 x Upgraded Steel plates
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1 x Custom Pressure Plate
Clutch B [B05] Pack (7-plate upgrade)
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7 x FX-RT friction discs
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7 x steel plates
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1 x Custom Pressure Plate
Clutch C [B06] Pack (7-plate upgrade)
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7 x FX-RT friction discs
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7 x steel plates
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1 x Custom Pressure Plate
Clutch D [K81] Pack (9-plate upgrade)
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9 x FX-RT friction+steel internal spline discs
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9 FX-RT friction+steel external spline discs
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1 x Custom Pressure Plate
Clutch E [K38] Pack (9-plate upgrade)
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9 x FX-RT friction discs
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9 x steel plates
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1 x Custom Pressure Plate
Clutch F [K27] Pack (10-plate upgrade)
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10 x FX-RT friction discs
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10 x steel plates
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1 x Custom Pressure Plate
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Everything is pre-measured and packaged by clutch pack to ensure consistent clearances and simplified assembly. The kit is fully compatible with factory drums, pistons, and snap-ring locations.
Shipping Methods
At OEM Car Parts USA, we are committed to ensuring that your orders reach you quickly and safely. To provide you with reliable delivery options, we use trusted carriers including UPS, USPS, and FedEx.
Shipping Times
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Standard Shipping: Most orders are processed and shipped within 1-2 business days. Delivery times vary based on your location, but you can generally expect to receive your order within 3-7 business days after it has been shipped.
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Expedited Shipping: If you need your parts faster, we offer expedited shipping options. Depending on your choice, delivery times can range from 1-3 business days. Expedited shipping rates will be calculated at checkout.
Shipping Costs
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Standard Shipping: Enjoy free standard shipping on all orders within the United States. We believe in providing value to our customers without additional shipping costs.
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Expedited Shipping: The cost for expedited shipping will be calculated based on the weight of your order and your delivery location. You will be able to review the shipping cost before finalizing your purchase.
Order Processing
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Order Confirmation: After placing your order, you will receive a confirmation email with your order details and tracking number.
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Tracking Your Order: Once your order has shipped, you will receive an email with a tracking number and a link to track your shipment through UPS, USPS, or FedEx. You can use this information to monitor your order’s progress until it arrives.
Shipping Restrictions
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Delivery Locations: We currently ship to addresses within the United States. Unfortunately, we do not offer international shipping at this time.
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P.O. Box Addresses: For security reasons, we recommend providing a physical address for delivery. While we can ship to P.O. Box addresses, please note that some shipping carriers may have limitations or additional processing times.
Missing or Damaged Orders
If your order is missing or arrives damaged, please contact our customer service team at info@oemcarpartsus.com or call us at +1 (934) 201-2903 within 5 business days of receiving your shipment. We will work promptly to resolve any issues and ensure your satisfaction.
Contact Us
For any questions or further assistance regarding shipping, please don’t hesitate to reach out to us:
- Email: info@oemcarpartsus.com
- Phone: +1 (934) 201-2903
We are here to ensure a smooth and enjoyable shopping experience. Thank you for choosing OEM Car Parts USA!
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