Timbren GMRS15 SES Rear Suspension Enhancement System - 8,600 lb Load Support, Progressive Rubber Spring

The Timbren GMRS15 SES Rear Suspension Enhancement System is a bolt-on, maintenance-free rubber auxiliary spring kit that adds up to 8,600 lb of load support and noticeably reduces sag, roll, and sway when hauling or towing.

Designed for heavy-duty truck owners who tow regular loads or carry payloads that push factory suspension to its limits, this Timbren SES kit uses a progressive rubber spring to engage as weight increases. It mounts to existing factory points using included hardware and requires no air lines, compressors, or ongoing upkeep. The result is steadier handling, improved braking response under load, and a smoother ride without the complexity of air systems.

How does the GMRS15 SES improve ride quality when towing?

As you add cargo or hook up a trailer, the auxiliary rubber spring compresses progressively to support extra weight and limit excessive bounce. That means less bottoming out and a more controlled chassis during acceleration, braking, and cornering.

• Progressive load curve: engages only as needed for comfort and control.
• Dampens road shock to reduce bouncing and vibration.
• Helps maintain factory suspension geometry for better steering feel.

Will this system eliminate sag and improve handling under heavy loads?

The GMRS15 is engineered to reduce rear-end sag and restore a level stance when carrying substantial weight. By supporting up to 8,600 lb of load, it helps the truck maintain ride height, improving braking stability and reducing trailer sway tendencies caused by excessive rear drop.

• Reduces rear sag for improved headlight aim and towing alignment.
• Improves braking stability by keeping suspension within optimal travel.
• Minimizes body roll for safer cornering under load.

What maintenance or upkeep does the Timbren SES require?

One of the standout benefits is zero routine maintenance: no air springs, hoses, or compressors that can leak or fail over time. Built from durable rubber compounds, the kit is designed to withstand temperature extremes and regular use without scheduled servicing.

• No air system components to inspect or replace.
• Durable construction resists abrasion and weathering.
• Installed once; performs reliably for years under normal conditions.

How difficult is installation — can I do it myself?

Installation is straightforward for anyone comfortable with basic tools and working under a truck. The kit mounts to factory attachment points with the supplied hardware; most owners complete both sides in under an hour without drilling or modifications.

• Mounts to existing frame points — no drilling required in most applications.
• Includes all mounting hardware and clear instructions for DIY fits.
• Typical install time: often under 60 minutes per side for a single installer.

Who this is for: The Timbren GMRS15 SES is aimed at heavy-duty truck drivers who frequently tow trailers, haul heavy payloads, or want a simple, long-lasting way to stabilize their rear suspension without the complexity of air systems. It’s ideal for fleet vehicles, contractors, recreational haulers, and anyone seeking improved control and confidence while loaded — especially those who prefer a one-time installation and hands-off durability.