Looking for quicker acceleration from your Dodge Neon, Mitsubishi Eclipse, or Chrysler PT Cruiser? Our MPx 4.12 Final Drive Ring Gear and Output Shaft Kit is designed to deliver a noticeable improvement in acceleration by replacing the factory 3.55 or 3.94 final drive gearing with a more aggressive 4.12 ratio.
The shorter 4.12 final drive increases torque multiplication at the wheels, helping your engine pull harder through every gear. Whether you're building a spirited street car or looking to improve acceleration at the track, this upgrade makes better use of your engine's available power without requiring additional horsepower.
Built for Strength and Durability
This isn't just a gearing upgrade. Our 4.12 final drive kit is manufactured using premium Japanese SAE 8620 alloy steel, selected for its strength, toughness, and suitability for high-load transmission components.
Each component is forged and double-tempered for exceptional toughness, while advanced shot-peening technology helps improve surface durability and resistance to fatigue.
Key Features:
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Aggressive 4.12 final drive ratio for improved acceleration
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Direct replacement for factory 3.55 and 3.94 final drive gearing in compatible T350 transmissions
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Manufactured from premium Japanese SAE 8620 alloy steel
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Forged construction for superior strength and toughness
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Double-tempered for enhanced durability
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Advanced shot-peening treatment for improved surface fatigue resistance
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Includes matching 4.12 ring gear and output shaft
Vehicle Applications
Fits T350 manual transmissions found in:
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1995–2005 Dodge/Plymouth Neon, 2.0 Liter equipped with the T350 transmission
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1995–1999 Mitsubishi Eclipse, non-turbo models equipped with the T350 transmission
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2001–2010 Chrysler PT Cruiser, non-turbo models equipped with the T350 manual transmission
How Much Difference Does 4.12 Gearing Make?
Compared with the factory final drive ratios:
| Factory Ratio |
New Ratio |
Increase in Torque Multiplication |
| 3.55 |
4.12 |
16.1% |
| 3.94 |
4.12 |
4.6% |
The result is stronger acceleration and improved responsiveness, particularly when upgrading from the taller 3.55 gearing.
Please Note: A shorter final drive ratio also increases engine RPM at a given road speed. In our test car which originally came with a 3.55 gas saving transmission with .72 fifth gear ratio and with this 4.12 final drive, we were turning 3000 rpms at 70mph.
This output shaft and ring gear requires transmission disassembly and professional installation is recommended.
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