If you've lifted a 5th gen 4Runner more than 2 inches and the alignment shop tells you caster is at the lower spec, you need adjustable upper control arms — the stock arms run out of caster adjustment before you do.
The 5th gen 4Runner is a double-wishbone IFS truck. When you raise the front by extending the coilover, the upper control arm pivots downward at the spindle end and the caster angle goes negative. The alignment cam adjustment at the lower control arm can recover a little caster, but at about 2"–2.5" of lift you'll max out the cams and the alignment shop will hand the truck back with caster at 1° or below. The truck will feel vague at highway speed, wander when crowned roads transition, and won't self-center coming out of a turn.
Aftermarket adjustable UCAs solve this by either re-locating the ball joint higher in the arm body (Dirt King) or providing a uniball at the spindle end that lets the arm swing through a wider range (Total Chaos, Camburg). Either way, you recover 2°–3° of caster and the truck drives like Toyota intended again. SPC's arms are the budget pick at $600–$700, use a sealed ball joint, and are quiet. Total Chaos and Icon use uniballs that flex more on articulation but make noise as they wear and need rebuilding every 30K–50K trail miles. Dirt King's ball joint version splits the difference — quiet like SPC, more articulation than stock.
The choice between sealed ball joint and uniball isn't really about caster — both give you caster back. It's about how the truck will be used. A 4Runner that's daily-driven 25K miles a year with occasional trail trips wants SPC or Dirt King. A 4Runner that lives off-road wants Total Chaos or Icon, with the understanding that you're committing to a uniball rebuild program. Anyone telling you uniballs "don't wear" is selling them.
Installation is straightforward IFS work. The upper ball joint comes apart with a pickle fork or tie rod separator. The two pivot bolts at the frame are 19mm and torqued in the 80–90 ft-lb range. Brake hose bracket relocates to the new arm. ABS sensor wire either re-routes or gets a new bracket from the UCA kit. None of the kits require modifying the frame — these are bolt-in. After install, the alignment shop will dial in caster between +2° and +4° depending on whether you want quick steering response (low) or stable highway tracking (high).
The KDSS-equipped 4Runner (Trail Premium, TRD Off-Road Premium, TRD Pro) doesn't change the UCA install — KDSS is a sway bar system, not a control arm system. You don't need to bleed KDSS to install UCAs.
| Part | Vendor | Est. price |
|---|---|---|
| SPC Adjustable UCAs 4Runner 5th gen | SPC | ~$650 |
| Total Chaos UCAs 4Runner (uniball) | Total Chaos | ~$850 |
| Icon Delta Joint UCAs 5th gen 4Runner | Icon | ~$900 |
| Dirt King Ball Joint UCAs | Dirt King | ~$700 |
Written and maintained by an AZ wheeler and driveway wrencher. Always cross-reference your factory service manual — modifications affect vehicle safety and warranty. Work at your own risk.