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When you’re hauling gear or towing a trailer, sag and squat can throw off your ride. The Coil SumoSprings Custom Helper Springs fit between your existing coils to add extra support and cushioning. Their microcellular polyurethane foam adjusts progressively—the more weight you add, the stiffer they get—so your suspension stays level and controlled without harshness. They help reduce rear-end drop and keep steering and braking stable when the load is heavy.
The inner core of microcellular polyurethane foam acts like a shock absorber inside your coils. It cushions impacts from rough roads, reducing body roll and harsh jolts that can wear you out on long drives or when carrying heavier loads. Because the springs work with your existing suspension, you get comfort and stability without losing the factory ride quality when unloaded.
Unlike air systems that need hoses, compressors, or pressure checks, these helper springs are completely maintenance-free. Once installed, they quietly go to work supporting your suspension every time you hitch up or load down the back. No air lines to route, no PSI to monitor—just consistent support whenever the weight shows up.
These springs hold up through years of use thanks to their abrasion-, oil-, road salt-, and UV-resistant polyurethane construction. They withstand extreme temperatures and stay flexible through everything from winter slush to hot summer asphalt. Once in place, they keep doing their job trip after trip without cracking, leaking, or breaking down.
Installation is simple—each wedge-shaped insert slides between the individual coil loops on either your front or rear suspension. They’re designed to work with a suspension system that’s in good condition and require no special upkeep once installed. Two helper springs are included along with a limited lifetime warranty and 30-day satisfaction guarantee.
Customer Satisfaction Score:
85% were satisfied with this product
15% of customers were not satisfied
Ratings & Reviews
Bruno F.
1/28/2020
So far so good it eliminates sag while towing or having heavier objects in the vehicle.
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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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