When you lift a 4Runner or Tacoma above 2–3 inches, the factory upper control arms stop working the way Toyota designed them. The ball joint angle gets pushed beyond its design range, the caster shifts, and your alignment shop will tell you they can't get the numbers right without aftermarket arms. This isn't a maybe — it's physics. Skip the UCAs and you're burning through ball joints and tires faster than you think.
What UCAs Actually Fix
Stock UCAs are designed for stock ride height. When you lift, three things go wrong that aftermarket arms correct. First, caster angle — most aftermarket UCAs add 2–3 degrees of caster correction, which restores straight-line stability and improves steering feel after a lift. Second, ball joint travel — factory joints run out of operating range when lifted; aftermarket arms use extended ball joints or uniball bearings that maintain safe angles through full suspension travel. Third, alignment adjustability — slotted frame mount adjustment lets your alignment shop actually dial in the geometry. Factory arms don't have this.
On the 6th gen 4Runner and 4th gen Tacoma specifically, the IFS geometry is tighter and less forgiving than the older platforms. Both hit their UCA threshold earlier — around 2.5 inches on the 6th gen 4Runner, 3 inches on the 4th gen Tacoma. Plan for UCAs from the start when pricing out your lift.
UCAs for the 6th Gen 4Runner
The 6th gen 4Runner is early in its aftermarket development cycle, but UCA options are already shipping. Here's where the community is landing.
Dirt King Fabrication Billet UCAs — $695
Dirt King's billet aluminum arms are the most commonly recommended UCA on the 6th gen forums right now. Precision-machined from 6061-T6 aluminum — corrosion resistant, lighter than steel, and strong enough for trail use. They're not the most aggressive option, but they're well-manufactured, priced reasonably, and have solid fitment reports for the 6th gen platform. For a 2.5–3 inch lift with 285s or 295s, this is a strong default choice.
OME Upper Control Arms — $680
Old Man Emu entered the 6th gen market with arms designed to pair with their MT64 lift kit. If you're running the OME MT64 system, their UCAs are engineered as a matched system — geometry corrections tuned to work together out of the box. Standalone, they're solid arms backed by a long Toyota track record. Less aggressive than Total Chaos, but reliable for the 2.5–3.5 inch range.
Total Chaos Fabrication — $950+
Total Chaos is the step up for builders going bigger. DOM tubing, precision uniball bearings, more aggressive geometry correction for lifts above 3.5 inches. The uniball design handles extreme angles better than traditional ball joints and holds up to significantly more trail abuse. If you're building toward 4 inches of lift or running 35-inch tires with real suspension travel, Total Chaos earns the premium. For a 2.5–3 inch street and trail build, Dirt King gets you most of the way there for $250 less.
UCAs for the 4th Gen Tacoma
The 4th gen Tacoma has been on the road slightly longer than the 6th gen 4Runner, and the UCA market is a step further along. Same logic applies: plan for arms at 3 inches and above.
Dirt King Fabrication — $695
Same brand, same quality, strong community consensus. The Dirt King UCA is one of the most commonly paired arms with the ReadyLift SST 3-inch kit on the 4th gen — the combo has well-established fitment data and plenty of community installs to reference. This is the default move for builders who want proper geometry correction without breaking the budget.
Camburg Engineering Uniball UCAs — $895–$1,100
Camburg is the arm for builders going serious. Their uniball upper arms offer more suspension travel, better angle range at larger lift heights, and are built for repeated rocky-terrain use. At 3.5 inches and above with 33–35 inch tires, Camburg is what you want if you're spending real time on trail. The price reflects the engineering. For casual trail use at normal lift heights, Dirt King is the more economical call.
JBA Offroad — $600–$750
JBA has a long track record on Toyota platforms and is the most accessible mid-range option. Slotted adjustment, reliable ball joint quality, and a price point below the premium brands. Fine for most use cases — where it gives ground to Camburg and Total Chaos is at extreme lift heights and high trail intensity. If you're building a trail-capable daily driver and not planning to push past 3.5 inches, JBA is worth considering.
Buy UCAs With Your Lift, Not After
Order your UCAs at the same time as your lift kit. This means one shop visit, one alignment, and you're not driving on compromised geometry while waiting for the next parts order. The alignment is part of the install — doing it in two phases wastes both money and time.
If you're already lifted without UCAs, the warning signs are aggressive inside tire wear, highway wandering, and an alignment shop telling you they've maxed out the factory adjustment range. That's your cue to order arms now.
If you're tracking lift kits, UCAs, and alignment specs across multiple vendors, Build List Garage is the easiest way to keep everything organized in one place — and share your full rig with one link when it's done. Download it free from the App Store.