The stock Evo lower control arm is a pretty great part from the factory and very importantly have factory spherical bearings in the inner/outer mounts with a solid center. The sphericals are needed to account for the fore/aft movement through travel caused by trailing arm position. And the center solid mount is important for keeping the arm clocked in rotation. In engineering terms, its perfectly or fully constrained.
The primary reason people seem to upgrade is to increase camber adjustment range but in all my searching there isnt much option for something that doesnt have one of these critical features.
- Inner/Outer spherical bearings
- Solid center bushing
- Adjustment threads pushed to end. (minimized bending loads on threads)
When making an aftermarket arm there needs to be some amount of improvement with minimal compromise from the OEM part. The threads in bending is one example, I see a lot of double adjusters with threads near the middle of the arm. Bending forces increase linearly from zero at the ends to max at the shock mount. And if you don't know, threads in bending absolutely minimized as much as possible if not fully eliminated from any application.
We design the SSB parts around estimated failure loads of factory parts plus a factor of safety to ensure our parts can at least survive what we know to be strong enough for OEM use.
Key features we ended up with on the SSB RLCA are,
- Inner/Outer spherical bearings with stainless bushings.
- Outer bearing follows our common design of a bolted cover positively clamping spherical in place. There's no chance of moving like with a snap ring design
- Inner spherical uses a common 3/4" rod end for easy sourcing of service parts.
- Center Delrin bushing with zinc plated sleeve and 10% wheel rate adjustment
- The bushing can be pushed out by using the shock mount bolt and rotating 180deg. This gives an effective 10% spring rate change for quick track adjustment.
- (Dallas) I wanted this feature specifically for my high rear AutoX spring rates and to be able to quickly tame it for track or wet days.
- Delrin bushings are new to us but seem common in the aftermarket industry. Its designed to be a "snug" fit, but can be inserted by hand with a good grip.
- The bushing can be pushed out by using the shock mount bolt and rotating 180deg. This gives an effective 10% spring rate change for quick track adjustment.
- 0.5" droop change
- With the solid center, we can move the relative position at the upright mount.
- It seems far more people are struggling with droop travel than compression travel. This is especially true with the SSB Rear Uprights that also effect wheel vs shock mount.
Caveats to watch out for, it seems the rear swaybar bracket on the passenger side can get close to the control arm depending on your specific combination of ride height, sway bar mount, and rear upright.
In the pictures shown with SSB Uprights and WL bracket there is plenty of room. On another customers car with OEM uprights and same bracket some trimming of the bracket was needed to ensure adequate clearance.