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When your suspension starts to sag under a heavy load, these Coil SumoSprings step in to help. Each insert uses an inner core of microcellular polyurethane foam that gets stiffer the more weight you add. That progressive support helps your suspension carry extra load while keeping your ride level and comfortable. You’ll notice less squat and better steering control when hauling gear or towing a trailer.
Stock coil springs can bottom out and send every jolt straight through the vehicle when loaded down. These helper springs fit snugly between each coil loop to absorb shock and smooth out rough roads. The cushioning takes the edge off bumps and vibrations, helping reduce driver fatigue on long drives or when working over rough terrain.
Heavy loads can make your vehicle feel loose through turns or sway over uneven ground. These inserts help stabilize body movement by adding firm but flexible resistance within each coil spring. The result is a more planted ride with less roll in corners and less bounce when braking or hitting dips.
Adding load support doesn’t have to mean adding maintenance. These Coil SumoSprings install easily on either the front or rear coil springs with no air lines, valves, or tanks to worry about. Once in place, they require no ongoing adjustments or monitoring—just dependable support every time you load up.
Road salt, oil, UV rays, and temperature swings can wear down ordinary rubber parts fast. The durable polyurethane material of these helper springs resists abrasion and damage from the elements so they keep working season after season without cracking or leaking performance over time.
Customer Satisfaction Score:
92% were satisfied with this product
8% of customers were not satisfied
Ratings & Reviews
Carl
11/7/2022
My experience with these are still good. I did notice that one side had rolled off the coil despite having the zipties still in place, but they still work as well as I could have expected. I still experience some sag while towing a trailer, but it is not as bad as if I did not have these installed. This vehicle seems to be very sensitive to tongue weight even when the trailer is empty
Lazer S.
3/24/2026
Sorry to hear about the install difficulties, Robert. I do have to say that this kind of suspension supplementation will never lift the vehicle they are installed on though. They will really only "tighten" up the compression of the coil springs to offer more support. Have you tried towing anything with your Promaster yet to see if there is any difference? They do have a 30-Day satisfaction guarantee in case they don't perform to your liking.
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Bruno F.
1/28/2020
So far so good it eliminates sag while towing or having heavier objects in the vehicle.