XRAY X4 2026 CFF2 Medium Rear Lower Arm: Tuning Rear Grip for Carpet and Asphalt
When you're dialing in your XRAY X4 2026 for varying track conditions, suspension arm compound selection is one of the most effective tuning tools at your disposal. The XRAY X4-2026 CFF2 Rear Lower Arm in medium compound (right side, part #XR-303186-M) delivers the balance most racers need for indoor carpet and higher-grip asphalt surfaces.
Why Medium Compound Matters
Medium compound rear lower arms sit in the sweet spot between hard and soft options. On tracks with decent grip, you need compliance in the rear suspension to keep the tire loaded through sweeping corners, but you don't want so much flex that the car feels vague or disconnected. The medium compound provides exactly that—enough structure to support aggressive driving while allowing the suspension to work over bumps and transitions.
Where you'll notice the difference most is in long, flowing corners where maintaining momentum matters more than pure rotation. A hard arm might skip or push in these situations, but the medium compound keeps the tire working and the rear end planted.
CFF2 Carbon Fiber Construction
XRAY's CFF2 carbon fiber reinforced composite material is engineered specifically for the demands of competitive touring car racing. This construction delivers:
- Excellent durability through full race weekends
- Consistent flex characteristics that don't degrade quickly
- Optimized weight without sacrificing strength
- Resistance to impact damage and wear
The CFF2 material holds up to the kind of abuse racing dishes out—hard landings, curb strikes, and sustained high-speed cornering loads.
Right Side Specific Geometry
This is the right side rear lower arm, designed with geometry matched exactly to the X4 2026 bulkhead mounts. The right side positioning means it handles specific cornering loads differently than the left side. During right-hand corners, this arm is on the outside, managing weight transfer and maintaining tire contact through the turn.
When to Choose Medium Compound
Reach for the medium compound rear lower arm when:
- Racing on indoor carpet with moderate to high grip
- Running on prepped asphalt with good traction
- The track has sweeping corners where rear stability matters
- You need more rear compliance than a hard arm provides
- Conditions call for balanced rear-end feel without excessive rotation
If you're swapping between compounds to tune for changing track conditions, this is a quick change that can make a real difference in how the car behaves. The installation uses the same hardware as any other X4 suspension arm, making compound swaps straightforward at the track.
Technical Specifications
- Chassis: XRAY X4 2026
- Position: Rear lower, right side
- Compound: Medium
- Material: CFF2 carbon fiber reinforced composite
- Part Number: XR-303186-M
Fine-Tuning Your Setup
Suspension arm compound is one of several variables in your touring car setup. The medium compound rear lower arm works well as a baseline for most carpet and high-grip asphalt conditions. From there, you can fine-tune with:
- Different front arm compounds for balance
- Anti-roll bar adjustments
- Shock oil and piston changes
- Ride height and droop settings
The beauty of the X4 2026 platform is how these adjustments work together. The medium compound arm gives you a solid foundation to build your setup around.
Proven Performance
XRAY's reputation in touring car racing speaks for itself. The X4 2026 chassis represents years of development and real-world testing at the highest levels of competition. Components like this CFF2 rear lower arm benefit from that engineering focus—they're designed to perform consistently under race conditions, not just look good in the box.
Whether you're running club-level racing or competing at regional events, having the right suspension components matched to track conditions gives you the confidence to push hard and focus on driving.
Ready to dial in your X4 2026 rear suspension? The medium compound CFF2 rear lower arm is available now and ships ready to install.