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  1. Vehicle Suspension
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Timbren Suspension Enhancement System - Rear Axle

Timbren Suspension Enhancement System - Rear Axle

Item # T28MR
Our Price: $252.45
You Save: $44.55
Vehicle Suspension

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8,600-lb Capacity. These hollow rubber springs sit above the rear axle to help stabilize and level your vehicle. They also provide a more comfortable ride by absorbing road shock and improving roll stability. Easy to install and use. Great Prices for the best vehicle suspension from Timbren. Timbren Suspension Enhancement System - Rear Axle part number T28MR can be ordered online at or call 1-800-940-8924 for expert service.
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Timbren Vehicle Suspension - T28MR

  • Jounce-Style Springs
  • Rear Axle Suspension Enhancement
  • Heavy Duty
  • Timbren

8,600-lb Capacity. These hollow rubber springs sit above the rear axle to help stabilize and level your vehicle. They also provide a more comfortable ride by absorbing road shock and improving roll stability. Easy to install and use.


  • Improves suspension, handling, and safety
  • Provides additional support as needed so you always have a smooth, comfortable ride
    • Allows the leaf spring ample movement while cushioning light loads
    • Becomes more rigid as more weight is added for great performance when you're hauling a heavy load
      • Increases stability
      • Reduces vehicle sag
  • Works independently - side-to-side adjustment
    • Helps compensate for off-center loads
    • Reduces body roll when swerving and turning corners
  • Acts as shock absorber, taking the brunt of bumps and rough roads
    • Extends the life of your vehicle's suspension
  • Includes 2 Aeon hollow rubber springs, custom-fit brackets, and hardware for a simple installation
    • Installs directly onto frame
    • No drilling required


  • Load-leveling capacity: 8,600 lbs
    • Timbren springs will not increase your vehicle's weight-carrying capacity. Do not exceed the manufacturer's recommended weight limit.
  • Lifetime warranty
  • Satisfaction guarantee

An example of sag on a vehicle's rear axle under a heavy load

Whether you're hauling heavy loads in your bed or cargo area or you're towing a trailer, you will often see the rear of your vehicle sag while the front end rises. In these cases, the rear axle is handling not only the weight of the cargo, but also more of the vehicle's weight. Because less weight is on the front axle, the front tires are making less contact with the road. Overall handling - traction, steering, and braking - is negatively affected. But the resistance from Timbren's Suspension Enhancement System works with your factory suspension to keep your vehicle level and improve your driving experience.

Diagram of the Timbren spring installed

The Timbren system comes with custom-fit brackets that are bolted onto each frame rail above the rear axle. Hollow rubber springs are bolted to the bottom of the bracket and hang down to where the bottom of the spring sits, 1" above the axle. The inch of clearance allows the existing factory suspension to operate normally under light loads and standard terrain, ensuring the smooth, comfortable ride that you are used to.

Animation of a standard Timbren rubber spring

Timbren Suspension Enhancement Systems are designed to work progressively. When the hollow rubber springs are compressed, the convoluted design causes them to quickly collapse along the folds. Once the folds are compacted, the stacked barrel shape increases resistance, stiffening the suspension and keeping your vehicle level.

Timbren suspension system works to prevent body roll

Each hollow rubber spring works independently to support the driver's side or passenger's side of your vehicle. This is helpful when you swerve or make sharp turns. Each spring is activated when it is needed, so body roll is greatly reduced. The independent action also works well when you are hauling off-center loads.

An example of a trailers swaying

Because the vehicle handles better with the springs, less turbulence will be passed along to the trailer, and this helps to keep the trailer in line. Your driving comfort is further enhanced if the trailer does begin to sway (from a gust of wind or a passing semi), because the movement from the trailer is not transferred to your vehicle. This also works to make the sway subside more quickly.

An empty truck on a bumpy road without Timbren

Another great feature of the rubber construction is that the springs absorb most of the road shock, creating a smoother, more stable ride overall. Wear and tear on the factory suspension is also lessened because the rubber springs work to prevent bottoming out on rough roads.

Timbren Suspension Enhancement Compared to the Competition

Timbren's Suspension Enhancement Systems are much easier to install than air springs - there are no air hoses to run, no compressors or gauges to hook up, and no manual adjustments to make. The rubber construction makes Timbren's springs more elastic than similar products constructed of microcellular urethane. And more elasticity allows for a more comfortable ride because the rubber has more travel.

GMRS15 Timbren SES with Aeon Hollow Rubber Springs - Rear Axle

Installation Details T28MR Installation instructions

This Product Fits The Following Vehicles

Customer Satisfaction Score:

Customer Reviews

Timbren Suspension Enhancement System - Rear Axle - T28MR

Average Customer Rating:  4.3 out of 5 stars   (58 Customer Reviews)

8,600-lb Capacity. These hollow rubber springs sit above the rear axle to help stabilize and level your vehicle. They also provide a more comfortable ride by absorbing road shock and improving roll stability. Easy to install and use.


My helper was finally available today for installation. Box had a ton of tape on it. Opened it and only one of the large blocks was in the box. I was warned about your company sending out returned crap that is missing parts. Too bad I didn’t listen. I guess Monday morning will be wasted getting a replacement. Don’t look for any return business

Etrailer Expert

Katrina B.


Well that is news to me! I can assure you that we do not sell used or returned parts. You know what probably happened here, is that our demo and install teams used product to make video content for our site. It is possible that the items just got misplaced during that process. I am sorry you were missing pieces to your kit. Let me get you over to our customer service department.


Very high quality product. Recommend using a lift to install. Easy install instructions. Very pleased with purchase. I have a 2021 Chevy Trail Boss, after installing the suspension enhancement system there was a gap of about 2 inches, so iam going to order another rubber spacer to close the gap up to around 1 inch.

2022 Chevrolet Silverado 1500

Complete lost of faith in once was a reliable brand (Timbren). Not impressed with returns offered for customer satisfaction from this online reseller either. This product may help for heavy loads but simply ruins a comfortable ride expected with rear passengers only. The gap (about 3/4") on these stiff rubber springs is just enough the make a harsh impact with the axle when travelling over a slight bumps. Passengers complained of a 'punch to the back' when hitting a slight bump (like a simple bridge deck transition). On the other hand, as a brick and mortar parts retailer, while it's very difficult to compete with online merchants, I'm encouraged that our customer service and warranty coverage far out weights the e-online world.

Jenny N.


Honestly when it comes to Timbren springs, it is either a love them or hate them kind of thing. They do create a rougher ride when they are not in contact with the axle like they would be under a heavy load. I will have our Customer Service team reach out to you about the return policy and see if we can find solution that works for you.

2016 Ram 2500

These are my second set of Timbren suspension. First one's I bought in 2016 went on a GMC 2500 and worked as advertised. This set I just purchased went on a 2021 GMC 1500 with the same results, stabilized the trailer weight on the leaf springs and erased the sag so it sits level with a loaded trailer. The only thing that I would improve upon is the instructions for installation. You need a 10mm socket with a short extension to remove the old ones and a 17mm socket with a short extension to install the new Timbren's on a GMC. This info could be added to the instructions very easily and you wouldn't necessarily need to watch the installation video.
Would buy again!


They work. It helps level out the load in my truck and when towing. I carry around 1000lbs daily. I have had air bags pryor to these. After a year I have realized how much better air bags are. These can make the truck very bouney. Seems to me there is never enough weight or to much weight for these to work right. Definitely going back to air bags.


I don't understand the good reviews. I originally installed with the extra spacer, drove my truck unloaded and the ride was noticeably rougher so I removed the extra spacer, that worked well unloaded. I then hooked up my RV trailer, the ride was so rough that we didn't make it 10 miles down the road and and had to turn around and go back home and remove these and go back with the original ones that came with the truck.

Etrailer Expert

Katrina B.


It is recommended to have 1 to 1.5 inch gap between Timbren and the contact spring. If you have too much of a gap, this could cause a rough ride. If the ride is too rough for your preference, then I would recommend sumo springs like part # SS65FR for your application.


The Timbren suspension enhancement system was brought to my attention by a friend who highly recommended the product. Received mine today and they have not yet been installed. I ordered from etrailer as I have ordered from them before and was very satisfied. My order that arrived today was here two days early. They get orders shipped out in a very timely manner. Look forward to doing future business with them.

2021 Chevrolet Silverado 1500

I started with Sumo Springs which did great up to about 3500lbs and off road. I went with these to assist with a 6500lb loaded camper in keeping it level which it’ll certainly does good at. When I’m not loaded my 1/2 ton feels like a 3/4 ton ride with them. I’ve a feeling off road they are gonna be too stiff. It’s a give and take on what’s more important to the driver. The good news is it’s a 17mm and 5 minutes to change out of needed.


Has worked well for towing my camping trailer. Do occasionally have rear end contact blocks while driving unloaded but expected that to happen.


I am not happy at all with the product I received today. These are used parts. You can tell from the packaging that these are used parts and you can tell by the marks on the part itself. This is so freaking disappointing! I want a refund immediately.

Etrailer Expert

Katrina D.


Let me get you over to our customer service department for them to get you a refund.


Driving loaded is great! Highly recommend.
Driving empty is a little harsh/rough. They sit about 1" away from the axle empty and I think hitting bumps and they come in contact with the axle is where the jolt is.

2020 Chevrolet Silverado 1500

15 mins to install and what a difference…. Went from a few inches of sag in the rear to only an inch and over 1000lbs tongue weight didn’t know the trailer was attached to the truck


Parts delivered as promised. And Easy to install
Great customer service

2023 Chevrolet Silverado 1500

I have used timbrens before excellent product did exactly what I wanted. The no maintenance is great.


The system was easy to install. The only issue I had was that one of the smaller bolts was missing. But a quick trip to the hardware store took care of that. And yes , I would recommend this product.


Had this installed by mechanic. We think it will help when hauling our new, heavier travel trailer. Picking it up in a week or two. Will know how well they work then.

GMC Sierra

I wanted to address the issue of the soft rear end of my 2021 GMC Sierra when pulling my small and relatively light travel trailer (@4500lbs loaded) without a weight stabilizer hitch. The rear end would drop only @1.5 inches and the front would rise @.75 inches, but especially when driving at highway speeds where there was construction with lane detours and uneven surfaces, the truck would bounce excessively, feel light and lack good control. Also, noted that the braking was diminished and required more attention and effort than I would've thought at all speeds.

The installation of the Timbrens was easy and their bottom edges rested @1 inch above the axle. When loaded with the trailer the Timbrens rested on the axle and the rear end dropped @1 inch and the front end rose @.5inch. Immediately noticed that the brakes worked much better and the reduced rolling on corners and highway entrance ramps - the truck almost felt like it had a sports car suspension. The lane detours and uneven pavement areas on the highway became non issues - the truck and trailer tracked steady and the 'whoops' were now gone; along with my tension and sometimes slightly white knuckles.

2022 GMC Sierra 1500

Easy install, this is my second set I have put on. Could not wait to put these on my new truck. Really works when you put a load on your truck.

2019 Chevrolet Silverado 1500

Worked great with pulling my camper, but the ride with no load is a little rough.

2019 GMC Sierra 1500

I have the worst ride with my truck.than ever before. It is not what I expected

2021 GMC Sierra 1500

I received this item which I thought was new but someone had been through my item its an open box. SO I don't know if this came directly from etrailer or Timbrem its for sure an open box I should send it back just because. I am not happy getting an open box item someone has been through.


Product was delivered fast, top quality


I opted for the heavier duty model and it was a bit too stiff. By removing the included spacer, it smoothed out fine. Thanks for fast delivery on the original order.


Gave me the firm ride I was looking for in a half ton pickup


Easy to install

Show More Reviews

See what our Experts say about this Timbren Vehicle Suspension

  • Will Timbren Suspension Enhancement Help Reduce Trailer Sway
    Timbrens like the # T28MR that you referenced are not known to make a huge difference with trailer sway. If you are experiencing trailer sway most likely it's due to improper trailer loading which you can fix by moving forward any cargo weight in the trailer so that the tongue weight is higher. You should also make sure that the trailer is sitting as level as possible too. The Timbren will give more support to the rear axle which will help with towing but not specifically for sway.
    view full answer...
  • How Does Factory Jounce Bumper of 2021 Chevy Silverado 1500 Remove for Install of Timbren
    There is a bolt head in the center of the factory jounce bumper of your 2021 Chevy Silverado 1500 that you will need to remove to remove the factory jounce bumper. You can see this in the attached install video for the Timbren kit part # T28MR.
    view full answer...
  • Are Spacers Needed to Install Timbrens on 2024 Chevy Silverado 1500
    Additional spacers are not needed for your 2024 Chevy Silverado 1500, but you will use the spacers that come with the Timbrens that fit your truck, the Timbren Suspension Enhancement System # T28MR. The spacers are common on Timbrens and won't affect the performance in any way, they're just to ensure a good fit.
    view full answer...
  • Will Timbrens for a 2021 GMC Sierra 1500 Work with Elevation Package
    Yes, the Timbren Suspension Enhancement System part # T28MR which is a fit for a 2021 GMC Sierra 1500 will work on models with the elevation package. I checked with Timbren to confirm this for you as well. The only models which are lifted from the factory and would create issues for the suspension enhancements are AT4.
    view full answer...
  • Correct Timbren Suspension Enhancement For 2021 GMC Sierra 1500 AT4
    I reached out directly to Timbren for you, and they told me the correct fit for your 2021 GMC Sierra 1500 AT4 was indeed the Timbren Suspension Enhancement System # T28MR.
    view full answer...
  • Recommended Suspension Enhancement System For A 2019 GMC Sierra 1500
    When installing a Suspension Enhancement System on your 2019 GMC Sierra 1500 The Timbren Suspension Enhancement System - Rear Axle # T28MR are confirmed to fit. The system has a 8,600 pound capacity that reduces vehicle sag, and increases stability. Using these springs will not increase your vehicle's weight-carrying capacity.
    view full answer...
  • Is the Timbren Suspension Enhancement System Compatible With Max Tow Package on 2020 Silverado 1500
    Yes, the Timbren Suspension Enhancement System # T28MR is compatible with the max tow package on your 2020 Chevrolet Silverado 1500. This fits 2 wheel and 4 wheel drive models and is also compatible with an in-bed hitch. These have a load leveling capacity of 8,600 lbs and come with a lifetime warranty.
    view full answer...
  • Comparing Timbren Suspension Enhancement For a 2023 GMC Sierra 1500
    The Timbren Suspension Enhancement System # T28MR is designed for your 2023 GMC Sierra 1500 both for heavy loads and unloaded. Do note that unloaded ride quality will be more stiff. The Timbren System # T53MR is their severe service kit. This is designed for vehicles that will always be carrying heavy loads. If you are adding a service bed, slide in camper or salt spreader this is the better option. Without a heavy load on the suspension you will notice a much stiffer ride for the rear...
    view full answer...
  • Recommended Suspension Enhancement for a 2022 GMC Sierra Denali 1500 w/ Adaptive Ride Control
    I have an option for you but the Adaptive Ride Control on your 2022 GMC Sierra Denali 1500 severely limits your choices. I recommend the Timbren Suspension Enhancement System item # T28MR. I confirmed with Timbren that these do fit your Sierra. This are typically only used for service vehicles or trucks that routinely haul heavy loads. If you are not towing regularly you should look into a weight distribution system. They will do a great job of providing support for towing or hauling...
    view full answer...
  • Recommended Rear Suspension Enhancement For a 2021 Chevy Silverado 1500 With 2" Drop Shackles
    You will need to use as system like the RoadActive Suspension Custom Leaf Spring Enhancement Kit # RAS54FR on your 2021 Chevrolet Silverado 1500 with having the Belltech 6416 2" lowering shackle. The Timbren Suspension Enhancement System # T28MR is only designed to work on your Silverado at stock ride height. While there are spacers that will allow you to use it with a small lift, using it on a lowered truck would create a very harsh ride since the springs would be in contact even without...
    view full answer...
  • Timbren or RAS for a 2021 Chevy Silverado 1500 Pulling a Trailer
    The Timbren Suspension Enhancement item # T28MR and the RoadActive Suspension item # RAS54FR can both be used in tandem on your 2021 Silverado 1500 but I wouldn't recommend it. The Timbrens are great to reduce sag but they only engage when your suspension is weighed down so there will still be some sag no matter what. Timbren's are also bouncy and will negatively affect the comfort of your truck's suspension when you are not towing. I recommend only using the RoadActive Suspension item...
    view full answer...
  • Can Timbren Jounce Springs be Trimmed on a 2019 GMC Sierra 1500 AT4
    The Timbren Kit # T28MR is a great product for assisting with vehicle squat but it isn't designed to be cut. You can try it if you want but the only kit I know of that fits your 2019 GMC Sierra 1500 AT4 and is okay to trim to specs is the SumoSprings Solo Custom Helper Springs # SS45FR. Timbren jounce springs are more of a thick rubber while the SumoSprings have more of a foam-like feel to them and SumoSprings has said their kits will still function as intended if they are trimmed. Attached...
    view full answer...
  • Timbren or Roadactive Kit for 2019 Chevy Silverado 1500 with Sag when Towing
    Both the Timbren and he Roadactive part # RAS54FR would work for getting rid of the sag you mentioned but the RAS kit is for sure the winner. The Timbrens get the job done but they are notoriously harsh when loaded and unloaded whereas the RAS kits actually improve loaded and unloaded ride quality and improve handling. They are also adjustable too unlike the Timbrens.
    view full answer...
  • Comparing SumoSprings and Timbren Springs For a 2023 GMC Sierra 1500
    Personally I feel the SumoSprings Solo Custom Helper Springs # SS45FR are a better option for your 2023 GMC Sierra 1500. These are not as stiff as the Timbren Springs # T28MR and will not cause such a harsh ride when not hauling additional weight or under light loads. These particular SumoSprings are rated for 1,500lbs which is more in line with the payload capacity for your Sierra. The Timbrens are rated for 8,600lbs which is far more than your truck would ever be able to carry.
    view full answer...
  • Comparing SumoSprings and Timbrens for a 2021 GMC Sierra 1500 AT4
    The Timbren Suspension Enhancement System part # T28MR and SumoSprings Solo Custom Helper Springs part # SS45FR are both great options for a 2021 GMC Sierra 1500 AT4. I recommend the SumoSprings as they don't typically ride as rough as the Timbrens but the Timbrens also offer more support. They are both however bolt-on, no maintenance options. Please note, a leveling kit won't warranty any additional spacers to be added to the rear suspension enhancements. These kits are also not compatible...
    view full answer...
  • How to Fix a Rough Ride with the Timbren Suspension Enhancement System on 2019 Chevy Silverado 1500
    It's pretty normal to experience a rough ride with the Timbren Suspension Enhancement System part # T28MR on a 2019 Chevrolet Silverado 1500 while going over bumps unloaded. There isn't much that can be done to stop that with these springs but we do have a similar style which are much more forgiving when going over bumps in the road while unloaded, the SumoSprings Solo Custom Helper Springs part # SS45FR. The Sumo's are progressive unlike the Timbren's which means the first few inches of...
    view full answer...
  • Recommended Suspension Enhancement for 2021 GMC Denali 1500 With Adaptive Ride Control
    For suspension enhancement that is compatible with the Adaptive Ride Control on your 2021 GMC Sierra Denali 1500 I recommend the Firestone Ride-Rite Air Helper Springs - Double Convoluted - Rear Axle # F2609. These air bags will keep you level while towing and improve steering and stability. These have a load leveling capacity of 5,000 lbs and feature a simple, no-drill installation. I also highly recommend adding an air compressor like the Firestone Air Command II # F2178. This will allow...
    view full answer...
  • Troubleshooting Fastway e2 Weight Distribution With Movement in L Brackets
    The bolts that hold the L brackets for the Fastway e2 Weight Distribution w/ 2-Point Sway Control - Round - 6,000 lbs GTW, 600 lbs TW # FA94-00-0600 need to be torqued to a specific setting which you can find in your installation instructions (as well as the linked instructions on this page). If you haven't torqued them specifically then that would explain why things are slipping. You also need to be sure that the brackets are square with the trailer frame during the installation. The...
    view full answer...
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  • Will The Timbren Jounce Springs Fit on a Factory Lifted 2021 GMC Sierra 1500 AT4?
    The Timbren Springs # T28MR has an overall height of 5-11/16". With your 2021 GMC AT4 having the factory lift you will want to measure the distance from inside the cup on your current jounce bumper to the pad on the axle. We do have a 1" Spacer # A25723-90AH00 and 1/2" Spacer # TA25722-90P00 which can be added to the jounce spring to give you the recommended 1" of air gap between the jounce spring and axle pad. You will likely need to source a longer M10 - 1.50 bolt locally to account for...
    view full answer...
  • Are Spacers Needed for Timbrens on 2021 Chevrolet Silverado 1500 Z71 Trail Boss
    Yes, the Timbren Suspension Enhancement System # T28MR will be the best option when it comes to cost-effectiveness. This will fit with your 2021 Chevrolet Silverado 1500 Z71 Trail Boss but you'll want to make sure these fit the gap properly. The Timbrens measure 5-5/8" high overall and you need a gap of 1/2" to 1-1/2" for the Timbrens to be effective. If you find that you have more than 1-1/2" of a gap then you can use the 1/2" Spacer # TA25722-90P00 and the 1" Spacer # A25723-90AH00 as...
    view full answer...
  • Will the Timbren Suspension Enhancement System Fit a Lifted 2019 Chevy Silverado 1500
    The Timbren Suspension Enhancement System part # T28MR will work on a lifted 2019 Chevrolet Silverado 1500 but you will need spacers to match the lift in order for them to engage properly. These are avavailbe as the Timbren Spacer part # A25723-90AH00 for 1" or part # TA25722-90P00 for 1/2".
    view full answer...

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Info for this part was:

Employee Jeff D
Installed by:
Jeff D
Employee Jameson C
Expert Research:
Jameson C
Employee Joshua S
Video Edited:
Joshua S
Employee Jacob T
Video Edited:
Jacob T
Employee Dustin K
Video by:
Dustin K
Employee John S
Video by:
John S
Employee Wilson B
Updated by:
Wilson B
Employee Carrie F
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