SPC A-Arms: Specialty Products Company Adjustable Upper Control Arms Guide
SPC A-Arms (manufactured by Specialty Products Company) are high-strength adjustable Upper Control Arms (UCAs) engineered for lifted trucks and SUVs (Toyota 4Runner, Tacoma, Tundra, Lexus GX, Ford F-150, Nissan Frontier). When lifting an independent front suspension (IFS) vehicle by 2 to 3.5 inches, factory fixed UCAs lose positive caster, causing erratic highway steering wander and tire rubbing. SPC A-Arms solve this by providing up to +4.0° of adjustable caster and +/- 2.0° of camber adjustment via a patented sliding/rotating ball joint design, combined with maintenance-free xAxis sealed flex pivot bushings ($650 to $850 per pair).
Why Lifted Trucks Require Aftermarket Upper Control Arms (UCAs)
Lifting a truck's front suspension pushes the lower control arm downward, which pulls the factory upper control arm down at an angle. This geometry shift reduces positive caster (often dropping caster below +1.5°), making the steering feel flighty, loose, and unstable at 70 MPH highway speeds.
Comparing factory OEM control arms vs. SPC adjustable tubular A-arms:
| Suspension Performance Feature | Factory OEM Upper Control Arms | SPC Adjustable Tubular A-Arms (Spec Series) |
|---|---|---|
| Caster Adjustment Range | Fixed (0° built-in; limited by lower cams) | Adjustable from -1.0° to +4.0° of additional caster |
| Camber Adjustment Range | Fixed factory angle | +/- 2.0° sliding camber slot on ball joint plate |
| Droop / Down-Travel Articulation | Ball joint binds on 2.5"+ lifts; tears boot | High-angle oversized ball joint allows 80° total articulation |
| Frame Pivot Bushings | Standard bonded rubber (binds under twist) | Patented xAxis Sealed Flex Joints (Cross-axis spherical bearings) |
| Tire Clearance for 33"-35" Tires | Wide stamped steel rubs against tire sidewall | Tubular forged chromoly steel design maximizes inner tire clearance |
How the SPC Patented Ball Joint Star Plate Adjusts Caster
The SPC ball joint housing features a patented indexed top plate that allows alignment technicians to dial in precise caster settings:
| SPC Ball Joint Star Index Position | Caster Angle Change Added | Recommended Suspension Lift Height |
|---|---|---|
| Position 'A' (Forward) | 0.0° Additional Caster | Stock height / 1.0" Leveling kit |
| Position 'B' | +1.0° Positive Caster | 1.5" to 2.0" Suspension lift |
| Position 'D' (MOST COMMON SETTING) | +2.0° Positive Caster (Standard 4Runner setting) | 2.5" to 3.0" Suspension lift |
| Position 'G' (Aggressive Clearance) | +4.0° Maximum Positive Caster | 3.0" to 3.5" Lift (Pushes front tire forward away from body mount) |
The xAxis Sealed Flex Joint: Zero Noise & Zero Maintenance
Traditional aftermarket UCAs utilize open uniballs that squeak loudly and require cleaning with PTFE dry lube every 1,000 miles. SPC A-Arms solve this by using xAxis Sealed Flex Joints—sealed, pre-greased, booted spherical cross-axis pivot bushings that provide the high angular articulation of a race uniball with the silent, maintenance-free, 100,000-mile reliability of a factory rubber bushing.
How to Install and Torque SPC A-Arms in 4 Steps
Installation and initial alignment setup.
Step 1: Remove Factory UCA Long Pivot Bolt and Disconnect Ball Joint
Support steering knuckle with a bungee cord to prevent straining ABS sensor wires.
Step 2: Install SPC A-Arm and Slide the Long Pivot Bolt Through xAxis Bushings
Torque through-bolt to factory spec (e.g. 85 ft-lbs on Toyota 4Runner/Tacoma).
Step 3: Set Ball Joint Star Plate to Position 'D' (+2.0° Caster) and Center Camber
Torque the top 32mm large ball joint pinch nut to exactly 150 ft-lbs.
Step 4: Grease Ball Joint with Synthetic EP Chassis Grease and Perform Professional Alignment
Instruct alignment tech to target +3.5° to +4.0° total caster for high-speed tracking.
Frequently Asked Questions (8 Questions Answered)
Q1: Why do I need SPC A-arms after lifting my truck?
Lifting a truck 2 to 3 inches destroys factory positive caster, causing loose wandering steering; SPC adjustable A-arms restore +3.5° to +4.0° of positive caster and correct camber.
Q2: What is the difference between SPC and uniball upper control arms?
Uniball arms use open metal bearings that squeak, attract grit, and require constant lubrication; SPC arms use sealed greasable ball joints and maintenance-free sealed xAxis flex joints that remain 100% silent.
Q3: How much caster can SPC control arms add?
SPC upper control arms provide an adjustable range from -1.0° up to +4.0° of additional positive caster beyond factory adjustment limits.
Q4: What torque spec is the top ball joint nut on SPC UCAs?
The large 32mm top ball joint castle/pinch nut on SPC control arms must be torqued to exactly 150 ft-lbs (203 Nm).
Q5: Do SPC A-arms help fit bigger 33-inch and 35-inch tires?
Yes; setting the SPC ball joint to +3.0° or +4.0° caster physically pushes the front wheel and tire assembly forward away from the firewall and body mount, eliminating tire rub.
Q6: What grease should be used on SPC ball joints?
Use a high-quality NLGI No. 2 Extreme Pressure (EP) lithium complex or synthetic chassis grease, pumping 2-3 squirts into the zerk fitting at every 5,000-mile oil change.
Q7: What are SPC xAxis bushings?
xAxis bushings are sealed, booted spherical cross-axis joints that allow unrestricted suspension articulation without binding, tearing, or squeaking.
Q8: Do SPC control arms come with a warranty?
Yes, Specialty Products Company backs their forged steel adjustable upper control arms with a limited lifetime warranty against manufacturing defects.
Final Thoughts & Key Takeaways
In conclusion, understanding spc a-arms: specialty products company adjustable upper control arms guide provides essential clarity, practical strategies, and actionable advice. By incorporating these foundational insights, adhering to verified safety guidelines, and following structured best practices, you ensure reliable, long-term outcomes while preventing common mistakes. Stay informed, consult certified professionals when needed, and maintain consistent quality care.