Boogielander Build - Part 13 - Suspension Updates

Introduction

This suspension update was done in April 2025.

The Fox 2.5 DSCs on Boogielander have been flawless. On pavement, the truck rides plush and floats through dips, cracks, and expansion joints. In the twisty canyons, it feels supported. Off pavement, it gives me the cloud-like ride I wanted when I am full-sending it.

The problem is that the truck I have now is not the truck I had when I installed the suspension. The expedition setup, which was supposed to come and go, has become the truck's constant load. We are pushing toward 1,000 pounds overall, with an estimated 800 to 900 pounds over the rear axle. The Fox springs up front and Carli Rebel HD springs in the rear were no longer holding the truck at the ride height I wanted.

On normal roads, the sag was not a big deal. Ride quality was still good, and the truck looked close to stock height. I never wanted a tall, lifted look anyway. But the suspension had a different opinion once I started moving quickly through the desert. The front tires began rubbing the fender liners before the coilovers reached their internal bump stops. That was not something I wanted to keep testing.

The Weight Problem

The truck gained weight over the years after the suspension went in. Two electrical systems are now permanently installed, and the camping and overlanding items stay in the camper. What started as Expedition Mode eventually became Standard Mode.

The load over the rear axle is my estimate, not a scale measurement. It is around 800 to 900 pounds, which is well beyond the 500-pound constant bed-load setup Carli describes for the Rebel HD rear springs. There is also weight inside the cab: a custom floor plate, an aluminum-extrusion shelving system, and an EcoFlow Delta 2 with its add-on battery. Those items are not directly over the front axle, but the added weight still affects the front suspension. The rock sliders and underbody skid plates add weight too.

The original plan was to pull these items out for day trips and high-speed desert runs. In reality, I leave them in the truck because I am too lazy to keep moving everything between short trips and long expeditions. That plan lasted about as long as you would expect.

Why the Original Springs Were Not Enough

The stock Fox 2.5 DSC package came with 450 lb/in front springs. With the right adjuster settings, they gave me a great balance between pavement comfort and off-road control. They soaked up road imperfections, handled whoops and jumps without tossing everything around, and let me carry speed without the truck bucking all over the place.

That spring rate worked well when the truck was lighter. With the added constant load, the springs were sitting more compressed at ride height. The truck sagged, and the front suspension used up more of its compression travel before a hit even happened.

In the desert, especially over whoops, the front end could compress far enough for the 35-inch tires to contact the fender liners. I had already turned the Fox adjusters up for off-road use, but that did not stop the contact. The adjusters change how the shocks resist movement; they do not change the spring rate or bring a sagging truck back to its intended ride height.

My concern was that repeated tire contact could tear through the liner. On this setup, the coilover's internal bump stop was the final limit in compression, and the tire was reaching the liner before the suspension got there. I needed the truck to sit at a better ride height and have more support under the load.

Why Change Springs?

There were three ways I could address the problem: add preload, revalve the shocks, or install springs with a higher rate.

Increase Preload

Preload is the initial compression put on the spring when it is installed on the coilover. Turning the preload collar changes how much force the spring is already applying and can raise or lower the truck's ride height. It does not change the spring's rate.

Cranking up preload can be a quick way to raise a truck that has sagged, but it does not make an undersprung setup into the right spring for the load. Too much preload can also leave less droop available before the suspension tops out. In my case, I did not want to use preload as a shortcut for carrying the constant weight.

Revalve the Shocks

Revalving would let me change how the shocks control compression and rebound. It is probably the most complete way to tune how the suspension behaves, but it means removing and disassembling the shocks, changing the shim stack, and testing the new setup. That process can take time, and Fox parts are not always easy for non-dealers to get.

More importantly, revalving would not bring the truck back up to ride height under a constant load. I decided to leave that for a future suspension rebuild.

Increase Spring Rate

A higher-rate spring takes more force to compress a given distance. It can support more weight while keeping the suspension closer to its intended ride height. That was the middle-ground fix I could make now.

The tradeoff is ride quality. A stiffer spring can make the ride firmer, and the shocks still need to be adjusted around the truck's weight and how I drive it. The advantage of the Fox DSC setup is that I can still use the adjusters to tune the damping after changing springs.

New Front Springs

I went with Eibach 600 lb/in springs up front, part number 1600.300.0600S. In theory, 500 or 550 lb/in springs probably would have been enough for my current setup. I went a little higher because I was also thinking about adding a winch to the front.

There were two things going on when I first installed the 600s. First, the new springs took more force to compress than the original 450s. Second, I initially kept the Fox preload setting that had been used with the 450 lb/in springs. With the new springs and that much preload, the front sat higher than I wanted and rode too harshly.

I backed the preload collar almost all the way up. The front ride height came down, and the ride quality improved significantly. The spring was still a 600 lb/in spring; I had simply reduced the initial preload. That adjustment made a noticeable difference in how the truck felt.

The driver-side spring also has a little more preload to compensate for the driver's weight and the fuel tank, which helps keep the truck from leaning.

New Rear Springs

Once I had changed the front springs, the truck sat nose-high. My Photoshop line test showed about 0.37 degrees of angle, and a tape measurement showed about an inch of height difference between the front and rear. That was not acceptable to me, so I replaced the rear springs too.

I chose Clayton's 2.5-inch HD triple-rate rear springs for the Jeep Gladiator JT. They are designed with three spring rates through their travel, rather than one rate throughout. The HD version has higher rates than Clayton's standard 2.5-inch triple-rate spring, and Clayton describes it for vehicles carrying around 500 pounds or more of additional accessories and overlanding items. That description matched the kind of constant load I was trying to support. The idea behind a triple-rate spring is to offer a softer initial rate and more support deeper into compression. Clayton says the HD springs are designed to carry added accessories and items without giving up comfort, but that is the manufacturer's design claim, not a ride-quality result I can promise for every truck.

These springs are sold for the Jeep JT, but the Ram 1500 DT and Jeep JT use the same rear end. That is why the JT rear springs fit the Ram. Clayton does not list this spring as a Ram application, so this is a cross-platform fitment based on the shared rear end.

With the new front and rear springs, the truck returned to the level stance I wanted. The before-and-after photos show the difference across the fender line and from hub to hub. The rear springs brought the back up to match the front instead of leaving the truck nose-high. I did not notice a change in rear ride quality after the spring swap. I suspect that is because the rear high- and low-speed adjusters are maxed out, which may be masking any difference from the springs.

Adjuster Settings

Here are the settings I run with the Fox DSC adjusters:

For each setting, I count clicks from fully open: turn the adjuster counter-clockwise all the way until it stops, then turn it clockwise. The first click is Click 1.

Front

• On road: 1 click high speed, 1 click low speed.
• High-speed off-road: 5 clicks high speed, 5 clicks low speed.
• Slow-speed off-road: same as on-road, 1 click high speed and 1 click low speed.

Rear

• High speed and low speed are both maxed out. I am too lazy to crawl under the truck and change the settings every time I air down or air up.

The Tradeoff

The main drawback is reduced down travel. I now have about four inches of down travel, compared with about six inches before. That is a real tradeoff, but the front end still feels compliant to me, and I no longer get tire contact with the fender liners when the suspension compresses.

I may add hydraulic bump stops down the road. For now, the spring changes solved the problem I was trying to solve, even though they did not give me more suspension travel.

Conclusion

The Fox 2.5 DSCs were still working well for the kind of driving I wanted to do. The truck got heavier, and the original spring rates no longer matched the way I use it. The 600 lb/in front springs and Clayton HD triple-rate rear springs brought the truck back to the ride height I wanted and stopped the front tires from rubbing the fender liners in compression.

The setup is not a free upgrade. I gave up some down travel, and there is still more shock tuning I may do when the suspension is due for a rebuild. The truck stays level with its everyday load, and the front end still feels compliant to me. I should have expected the expedition setup to become permanent. It always does.