The SPL Rear Lower Control Arm Kit (RLCAK) significantly improves rear mechanical grip, provides greater stability under hard braking and acceleration, and precise feedback on what the rear is doing on turn-in and on limit. The use of PTFE-lined, F1-fit FK USA spherical bushings eliminates OEM rubber bushing deflection and bind, allowing the suspension to freely articulate without undampened rubber spring forces, while also preventing camber loss, bumpsteer, and vague feedback that occur due to bushing deflection.
The kit enables adjustable track width, camber, rear roll center, and anti-squat for a deeper customization of the rear suspension geometry to better suit your driving preferences and adapt to changes in tracks, aero loading, tires, and more.
Kit Contents
The SPL RLCAK 986 (Rear Lower Control Arm Kit) is a complete front or rear kit which includes:
| Part Number | Part Description | Quantity |
|---|---|---|
| LCA 996 V2 | Adjustable Rear Lower Control Arms | 1 |
| RTR 986 | Adjustable Trailing Arms | 1 |
Technical
Camber Adjustment
Increase Camber for More Peak Lateral Grip
One of the biggest improvements to rear cornering grip you can make is adding more negative camber. This also will significantly improve track event tire life by reducing heavy wear on the outer portion of the tread that occurs when there's insufficient camber angle relative to body roll.
Elongating the lower arm will add more camber without the need for adjustable camber plates or eccentric bolts that could potentially slip. However, pairing the SPL LCAs with camber plates allows you more adjustability options for inner and outer tire clearance as well as elongating the track width while retaining a specific camber angle.
Track Width Adjustment
Get More from the Inner Tire
Extending the rear track width promotes a more stable handling behavior and reduces the overall amount of weight that shifts off the inner tire and onto the heavily loaded outer. The SPL rear lower control arm (included), SPL trailing arm(included), and an adjustable camber plate allow you to properly adjust rear track width and set your ideal camber angle.
Rear Roll Center Adjustment
Reduce Body Roll with Geometry not Spring Rate
Roll center is the imaginary point that the chassis rolls about during cornering. The distance between the roll center and the center of gravity (front-view, vertical) is essentially the amount of leverage the chassis has to produce roll.
When you lower your Porsche the roll center drops further than the center of gravity, resulting in a larger roll moment (force). Using the roll center correction spacers to correct the angle of the rear lower control arm brings the roll center back up, resulting in less body roll at the same spring rate and less tendency to oversteer with fast transitions.
With the front and rear SPL kits, you can adjust the pitch of the roll axis which can have a significant effect on the car's handling behavior with respect to over and understeer, especially through esses.
Anti-Squat Adjustment
Fine Tune the Chassis Response Under Hard Acceleration
Put simply, anti-squat geometry is similar to roll center, but viewed from the side rather than the front. The more anti-squat (expressed as a %) a car has the less the rear suspension will compress under acceleration.
Anti-squat's effect will improve traction in most cases and prevent additional bumpsteer under acceleration. This can also have a stabilizing effect through rolling esses where you utilize throttle to rotate the car.
Benefits
- Adjustable Rear Camber, Roll Center, Anti-Squat, and Track Width
- Lightweight: 4.98 lbs (2.26 kg) per Side (Lighter than OEM!)
- Improved Rear Grip and Tire Wear on Track
- Precise Rotation and Steering Feel from Eliminating Bushing Deflection
- Sharper Throttle Response
- Improved Braking Stability
- Greater Adaptability for Wheel/Tire Clearance
Materials
- 6061-T6 Billet Aluminum Arms and Clevis (Anodized Black)
- 6061-T6 Billet, Hollow Aluminum Trailing Link (Anodized Black)
- 6061-T6 Aluminum Spacers and 360° Clamps
- 4140 Chromoly Steel Double Adjuster (Electroless Nickel Plated)
- 304 Stainless Steel Adjustment Spacers
- 4340 Chromoly Steel Studs (Heat-treated)
- Class 10.9 Metric Hardware / SAE Grade 8 Imperial Hardware
- Ti-6Al-4V Titanium 1/4"-20 Socket Head Allen Screws (Anodized Blue)
Noise, Vibration, and Harshness (NVH)
The rear lower control arms are an important part of mitigating NVH. By eliminating all bushing deflection the rear suspension will transmit more road noise, felt energy from bumps, and can increase tramlining in some cases. However, the reduction of bushing bind and reduced friction will improve ride quality over smoother roads and allow the shock to work more effectively over moderate bumps.
Tire choice, tire pressure, spring rates, and shock quality will have significant influence on ride quality as well. For daily driving, felt energy and noise can be reduced moderately by running a more compliant tire, either through reduced pressure (suitable for the load and tire) and/or taller or softer sidewalls, as well as optimized compression dampening on a quality shock.
Most drivers will find the NVH to be present and tolerable, similar to an OEM GT3 or GT4.
Applications
1997 - 2004 Porsche Boxster, Boxster S (986)
ADDITIONAL FITMENT INFO
WILL THIS FIT A ...
We limit the above applications to known fitments from testing and research. If you're unsure if this is the proper part for your application, send us an email.
THIS SHOULD FIT MY CAR
Occassionally, parts will fit other vehicles not listed above. If you believe, or know, this part will fit your vehicle, send us an email and we'll work with you to confirm proper fitment.
Replaces OEM Part Number(s)
This is a list of known OEM part numbers. OEMs constantly make changes to part numbers due to part updates, suppliers, etc so this may not be a complete list.
996 341 053 05
996 341 053 06
996 341 053 07
996 341 053 14
996 341 053 16
996 341 053 17
996 341 941 00
996 341 941 01
996 331 045 05
996 331 045 06
996 331 045 07
996 331 045 08
996 331 045 10
996 331 045 12
997 331 045 04
997 331 045 05
996 341 053 00
996 341 053 18
996 341 053 19
