JL Rear Lift Springs JL 2 DR 4.0 Inch JLU 4 DR 3.0 Inch Synergy MFG

Synergy Manufacturing SKU: FSVG_8864-30


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Synergy MFG Jeep JL Multi-Rate Rear Lift Coil Springs. Synergy MFG has designed these springs from a clean sheet for the new Wrangler platform. All springs are multi-rate and have been designed to make a great platform even better.

These springs are unique to the JL and not shared with the JK or other vehicles. Like OEM, our coil springs are unique lengths to account for load differences on each corner of the vehicle. There are right and left specific springs front and rear to guarantee the vehicle will sit level.

Multi-rate design has a soft initial rate which prevents the spring from coming loose in the coil tower, even with long travel shocks. The ride rate is slightly stiffer than the OEM springs to account for additional weight from bumpers, winches, skid plates and gear. Springs are proudly manufactured in the United States of the highest quality steel.

Springs are designed to be able to set solid (fully collapse) without overstressing the material and are pre-set from the factory meaning the springs will never sag or set.


  • Increased ride quality
  • Increased wheel travel/articulation/traction
  • No spring bowing
  • Lifetime warranty/guarantee against sagging and breakage


  • Multi-Rate coil springs allow for longer spring lengths and increased travel
  • Spring rates are only 5-10 percent stiffer than stock for superior ride quality
  • Coil spring block heights designed around common bump stop spacings to optimize wheel travel
  • Unique spring lengths for each corner of the vehicle so it will sit level side to side
  • Frequency balanced and tuned spring rates to maximize suspension performance on and off road
  • Abrasion-resistant black powder coat finish for maximum durability and corrosion resistance
  • Sold in pairs


  • Coil springs require proper bump stop spacing with Synergy 8057-10 Bump Stop Spacers.
  • Lift heights are based off fully loaded Rubicon models. Other models will see more lift.
  • Coil Springs retain the stock rake of the vehicle.
  • Up to .75 inch of front coil spring spacer can be added to level the vehicle using 8017-075 front coil spring spacers.
  • Min bump stop spacing listed is the minimum amount of bump stop spacing required to prevent the springs from going into coil bind. Do not use less bump stop spacing.

Additional Information:

The Jeep JL platform required a new approach to coil springs. We could have re-used existing coil springs already in our portfolio, and they would be close, but close wasn't good enough. Instead, we designed our JL coil springs from the ground up, to account for all of the differences in this new platform. We have gone through many iterations of spring rates, lengths and designs. Each of these prototypes was tested on road and off, all the way from the Rubicon to Colorado. These springs were not considered done until we were confident we had a part that is measurably better than anything else on the market.

Like most other high-end long travel coil springs on the market, we take advantage of using multiple spring rates to increase the extended travel of the spring. Gone are the days where coil spring retainers are required to keep your springs from falling out on the trail. From our experience, there is a lot of misunderstanding on how multi-rate coil springs work, and why they would be preferred over linear-rate coil springs and vice-versa. In short, it depends on the application and what constraints we are working with. With the new JL platform we were able to design a dual-rate coil spring with a softer initial rate that is effectively collapsed at ride height.

This softer initial rate adds to the effective overall length of the spring without adding more lift to the ride height of the Jeep. This allows us to keep a lower ride height and lots of down travel. At ride height the spring rate is effectively linear, which is desirable for tunability (shock valving), and predictability (driving feel). The springs are designed to maintain as much up travel as stock while adding to the available down travel, which increases traction, stability, and safety off road.

Our spring rates were kept just above stock Rubicon spring rates in order to maximize flex and traction off road. We did increase the spring rate slightly (less than 10 percent) in order to accommodate for the added weight of the typical accessories and armor (winches, bumpers, skid plates, gear, etc.).

Due to variances between Jeeps and how they are used, we designed these springs to match the stock rake of a fully loaded Rubicon. If you want the vehicle to sit level (without the stock rake) when unloaded, our front coil springs will accommodate up to a .75 inch front coil spacer without requiring additional bump stop spacing (8017-075). This means that the ride height and rake of the Jeep can be fine-tuned in order to get the perfect ride height without compromise.

Synergy MFG Jeep JL rear coil springs have very long free (extended) lengths. Due to this fact, we generally recommend that the end user make sure they are using the correct shocks in order to maximize available wheel travel. Our shortest springs will allow for around 12 inches of wheel travel front and rear. Taller springs will allow for more wheel travel.

Generally, aftermarket shocks are spec’d short in order to prevent typical coil springs from falling out. We recommend at least one length longer shock for a given lift height (For example: use a 3.5-4 inch lift Fox shock with our 2 inch springs). Make sure the shock mounts and bump stops are setup to prevent the shock from bottoming out before the bump stops do.