The Acura RSX A-Spec suspension package is a popular OEM upgrade that improves handling and lowers the ride height. Whether you're replacing worn components or upgrading to A-Spec specifications, knowing the correct RSX A-Spec suspension part numbers is essential. This guide covers the factory part numbers for front and rear struts, springs, and associated hardware, along with tips for identification and installation.
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What Is the RSX A-Spec Suspension?
The A-Spec suspension was offered by Acura as a factory-installed option or dealer accessory for the RSX (2002-2006). It features stiffer springs and specially tuned dampers that lower the car approximately 0.5 inches front and rear. The package also includes revised bump stops and dust boots. Owners often seek these parts for restoration, replacement, or to add the A-Spec handling characteristics to a base RSX.
OEM A-Spec parts are discontinued from Acura, but the part numbers are still used by dealers and aftermarket suppliers to identify correct replacements. Note that aftermarket equivalents (such as KYB or Monroe) are available, but this article focuses on the genuine Acura part numbers for reference.
RSX A-Spec Suspension Part Numbers List
Below are the official OEM part numbers for the Acura RSX A-Spec suspension components. These numbers apply to both the base RSX (2002-2004) and the RSX Type-S (2002-2006) unless noted. Always verify compatibility with your VIN before ordering.
Front Strut and Spring
The front suspension uses a MacPherson strut design. The A-Spec front assembly includes a specific strut and spring combo.
- Front Strut (Left): 51611-S6A-A21
- Front Strut (Right): 51605-S6A-A21
- Front Spring (Left): 51401-S6A-A21
- Front Spring (Right): 51402-S6A-A21
- Front Strut Mount (per side): 51621-S6A-A01
- Front Bump Stop: 51634-S6A-A01
- Front Dust Boot: 51635-S6A-A01
These springs have a higher spring rate and shorter free length than the base RSX springs. The struts have specific valving for the A-Spec rate.
Rear Shock and Spring
The rear uses a coil-over shock design (separate spring and shock).
- Rear Shock (each): 52601-S6A-A21
- Rear Spring (each): 52401-S6A-A21 (Note: same for both sides)
- Rear Shock Mount (each): 52621-S6A-A01
- Rear Bump Stop: 52634-S6A-A01
- Rear Dust Boot: 52635-S6A-A01
Rear springs are also progressive rate and lower the car slightly.
Additional Hardware
When replacing A-Spec suspension, it's wise to replace the following wear items:
- Front Sway Bar Bushings: 51306-S6A-A01
- Rear Sway Bar Bushings: 52306-S6A-A01
- Front Control Arm Bushing (LCA front): 51316-S6A-A01
- Rear Trailing Arm Bushing: 52624-S6A-A01
These bushings are the same as base RSX, but if your car has high mileage, they contribute to handling feel.
How to Identify Genuine A-Spec Parts
Because A-Spec parts are discontinued, counterfeit or incorrect parts may be sold as A-Spec. Check for the following:
- Strut body stamping: Look for "A-SPEC" or an "A" suffix on the part number (e.g., -A21).
- Spring color code: A-Spec springs often have a yellow or blue paint mark (but aftermarket may match).
- Ride height: After installation, the car should sit about 0.5 inches lower than a base RSX.
- Part number verification: Cross-reference with the numbers listed above and ensure the seller provides the exact OEM number.
If you buy used, inspect for leaks and damage. Springs can sag over time, so check free length.
Compatible Models and Years
The RSX A-Spec suspension fits all 2002-2006 Acura RSX models, including base and Type-S. However, the Type-S already has a slightly stiffer base suspension; the A-Spec upgrade provides an additional 10-15% increase in spring rate. Note that the A-Spec suspension is not compatible with the 2005-2006 models that have electronic stability control? Actually, it is compatible – no issues.
If you own a base RSX, the A-Spec parts will bolt directly on. For the Type-S, the only difference is the front anti-roll bar (stiffer on Type-S), but the A-Spec struts and springs work with either bar.
Installation Tips for RSX A-Spec Suspension
Replacing suspension components requires mechanical skill and proper tools. Here are key pointers:
- Spring compressor: Always use a spring compressor when removing factory springs. Do not use impact guns on the strut shaft nut.
- Alignment: After installation, get a professional alignment. The A-Spec geometry changes caster and camber slightly.
- Torque specs: Follow service manual torque values. For front strut fork bolts: 54 ft-lbs. Rear shock bottom bolt: 40 ft-lbs.
- Camber correction: If you lower the car further (not A-Spec), you may need camber bolts. For A-Spec only, stock camber adjustability is sufficient.
- Break loose hardware: Use penetrating oil on rusted bolts, especially the lower strut bolts.
- Replace mounting hardware: The strut mount nuts and shock mount are recommended to be replaced if they are corroded.
Expect about 3-4 hours of labor for a DIY replacement if you have experience. It's often easier to remove the entire knuckle/hub assembly from the car rather than working in tight spaces.
Aftermarket Alternatives vs. OEM A-Spec
Since Acura has discontinued the A-Spec parts, many owners turn to aftermarket equivalents. Common options include:
- KYB GR-2/Excel-G shock absorbers with OEM A-Spec springs (if you can find them).
- Eibach Pro-Kit springs (lower about 1 inch, stiffer than A-Spec).
- Koni Sport adjustable dampers paired with A-Spec or aftermarket springs.
For a direct replacement, you can use Monroe OESpectrum shocks (part numbers 37277 front, 37005 rear) with A-Spec springs. However, ride quality may differ.
If you want the exact A-Spec feel, the best approach is to find a used but low-mileage set of original A-Spec struts and springs. Auction sites and RSX forums are good sources. Expect to pay $300-$500 for a complete set in good condition.
Practical Final Recommendation
For owners seeking to restore or upgrade to A-Spec suspension, use the part numbers in this guide to verify OEM parts. If you can find a complete, undamaged set of original A-Spec components, that is the most authentic choice. For new parts, consider KYB dampers (front: 334250, rear: 341168) combined with A-Spec springs or Eibach Pro-Kit (part 3843.880). This combination yields similar handling improvement with available new parts.
Before buying, always confirm part numbers with a dealer using your VIN, as production changes occurred during the RSX's lifespan. Properly installed A-Spec suspension transforms the RSX's handling without sacrificing daily comfort—making it a worthwhile upgrade for enthusiasts.