Fixing a Sagged-Out TRD Pro: Building a Proper Suspension Solution for a Fully-Loaded Overland 4Runner

Posted by Sean Law-Bowman on January 12, 2026

Position-sensitive shocks don’t like surprises, and the stock Fox 2.5s on this TRD Pro 4Runner were deep into their unhappy zone. With more than 600 pounds of constant overland load, the truck’s ride height collapsed, the shocks lived in their stiffest ride zones, and the once-comfortable PRO ride became harsh and unforgiving.

Luckily, we knew exactly how to fix it.

Who We Are

We test everything we sell on our own vehicles. We daily drive it, tow with it, street it, trail it, and load it down with gear… exactly the way customers do.

Our goal is simple: Give you real-world answers about what suspension is right for your needs - not someone else’s.

There is no single “best” suspension system: but there is a best system for you. Helping you find that match is what we do.

Shock Surplus: Now Installing, Tuning, and Dialing-In Suspensions In-House

You already trust us to help choose the right shocks. Now you can trust us to install and tune them too.

Shock Surplus now offers a wide range of installation and setup services. With thousands of test miles on dozens of vehicles across every major brand, we know how to build a suspension that sits at the right height and rides the right way the first time.

Want comfort? Support? Payload handling? High-speed control? We set the height, the preload, and the damping to your needs—not just the manufacturer spec.

Today’s TRD Pro build is the perfect example of why this matters.

The Problem: 600 lbs of Constant Payload + Position-Sensitive Shocks

This customer is a heavy-duty overlander; weeks-long trips, rooftop tent, awning, fridge, tools, recovery gear…the whole lifestyle. All told, the truck carries about 600 lbs of static weight at all times. We call this “constant load”.

Here’s why that became a problem:

1. TRD Pro Fox Shocks Weren’t Designed for This Much Load

Fox’s TRD Pro 2.5 Internal Bypass shocks are fantastic, but their bypass ports are indexed around the factory ride height. Drop the truck several inches due to weight, and the shock sits in its bottom-out zone aka the stiffest portion of its stroke.

Result?

Harsh impacts
Reduced comfort
Less usable travel
Poor body control

2. Sumo Springs Helped…But Created New Issues

The owner added Sumo Springs to compensate for sag. They did help prop the truck up, but they also:

Added harshness over small bumps
Reduced available upward suspension travel
Didn’t truly fix the shock position issue

We love Sumo Springs on varying-load rigs, but for a constant heavy load and a customer who wanted a subtle lift above TRD Pro height, we needed a more holistic, permanent solution.

The Solution: A Purpose-Built Suspension System for a Heavy Overland 4Runner

Fixing this truck required choosing parts that complemented each other, not just slapping in an off-the-shelf “Stage 4” kit. Here's how we approached it.

Fox 2.5 Factory Race Series Internal Bypass Coilovers & Shocks

Since the owner liked how the TRD Pro rode when stock weight was on board, we stayed with the Fox family and stepped things up to the new 2.5 Factory Race Series Internal Bypass system.

Why These Shocks Were the Move

Bypass Port Positions for Lifted Ride Heights

Perfect for the taller stance we were targeting.
600 lb Springs Up Front

Slightly stiffer coils give back proper ride height and support.
Wide Preload Range

Lets us dial in height precisely even with static load.
Remote Reservoirs for Heat Capacity
Dual Speed Compression Adjusters

Essential for tuning low-speed compression to offset a high center of gravity.
Inverted Coilover Body + Spherical Bearings

Much stronger, smoother, and far less prone to binding than the TRD Pro strut plate + rubber bushings.

This upgrade alone drastically improves strength, control, and adjustability especially with 600 lbs on board.

Icon Tubular Upper Control Arms

Because the Fox coilovers are slightly longer travel and use a lower spring perch, upper control arm clearance becomes an issue. The owner didn’t need adjustability, but they did need strength.

Enter the Icon Tubular UCAs with Delta Joints.

Why We Love Delta Joints

Metal-on-metal strength like a uniball
Sealed, greasable, and long-lasting like a factory ball joint
Huge articulation range
Quiet operation
Incredibly durable

We have personally tortured a set for over 40k miles - broken wheels, bent knuckle bolts, hard off-road impacts - and they never made a peep. If they survive our abuse, they’ll survive anything.

Bilstein B12 Heavy Load Rear Springs

The rear springs were the key to the whole system.

The Bilstein B12 Heavy Load coils are designed for:

1.5” of lift with ~400 lbs of constant weight

With the customer’s load and our target height of just slightly above stock TRD Pro, these springs put us right in the sweet spot:

About ½–1” over TRD Pro height
Far more support than stock
No need for Sumo Springs
Shocks operating in the correct bypass zones
Tons of damping adjustment left to fine-tune comfort and stability

And if we miscalculated? We have multiple spring options ready to swap in at no extra cost. That’s the beauty of a custom-tuned build.

Installation, Adjustments & Ride Results

With the new shocks, UCAs, and rear springs installed, we fine-tuned:

Ride height
Preload
Low-speed compression
High-speed compression

After some click-tuning time, the 4Runner sat exactly where the owner wanted—and the ride quality was everything they hoped for:

Controlled but still plush
No more harsh bottom-outs
Far better support with the rooftop load
Stable cornering despite the tall roof setup

This is what a purposeful suspension solution looks like.

Final Thoughts: Custom Builds Always Win

Even the best shocks in the world will ride poorly if paired with the wrong springs or geometry. That’s why we don’t push “Stage 17 kits” blindly - most builds don’t fit always fit the mold.

This TRD Pro needed: