Over time, the comfort of your car seats can diminish, especially in older vehicles. One common culprit behind sagging and uncomfortable seating is broken seat springs. While the upholstery might hold up remarkably well, particularly in models known for durability like older Mercedes-Benz vehicles with MB Tex, the underlying seat spring box can succumb to wear and tear. The combination of age and repeated pressure, especially from heavier occupants, leads to spring fatigue and eventual breakage.
Replacing the entire seat spring box can be a costly affair. Fortunately, a simple and effective DIY repair can restore your seat’s comfort without breaking the bank. This guide will walk you through a straightforward method to repair broken auto seat springs using readily available materials and basic tools, saving you money and extending the life of your car seats.
Before we begin, remember to prioritize safety.
Safety First:
- Always wear safety glasses when working on your car.
- Ensure the vehicle is parked on a level surface and the parking brake is engaged.
- Use wheel chocks to prevent the car from rolling.
- Utilize approved jack stands if you need to raise the vehicle (though seat removal usually doesn’t require this).
- Recycle any used fluids responsibly at a designated recycling center.
Let’s get started on repairing those broken seat springs!
Step-by-Step Guide to Repairing Auto Seat Springs
1. Removing the Seat from Your Vehicle
The first step is to safely remove the car seat from your vehicle to access the broken springs.
-
Locate and Remove Front Bolts: Begin by sliding the seat all the way back to expose the front seat mounting bolts. Typically, there are two bolts at the front of the seat rails. Use the appropriate socket wrench to remove these bolts. Keep the bolts in a safe place for reinstallation.
-
Access Rear Bolts: Slide the seat fully forward. You may need to use the seat height adjustment handle or lever to raise or move the seat to gain better access to the rear mounting bolts.
-
Remove Rear Bolts and Seat Belt Guide: Locate and remove the two rear mounting bolts. Additionally, remove the bolt securing the seat belt guide anchor, often found on the transmission tunnel or near the seat mounting area.
-
Prepare and Carefully Remove the Seat: Before fully removing the seat, raise the seat back to an upright position, fold up the armrest (if equipped), and lower the headrest to minimize bulk and make handling easier. Carefully lift and remove the seat from the vehicle. If your seat has electrical connections (for seat heaters, power adjustments, or sensors), disconnect them before completely removing the seat. Place the seat upside down on a protected surface, like a towel or blanket, to prevent damage to the upholstery.
2. Identifying the Broken Seat Spring
With the seat removed and upside down, you can now inspect the seat spring box to locate the broken spring(s).
- Inspect the Spring Box: Carefully examine the seat spring box. Broken springs are often visually apparent. Look for springs that are snapped, detached, or significantly deformed compared to the surrounding springs. The area closest to the door on the driver’s seat is a common location for breakage due to frequent entry and exit.
3. Preparing the Repair Collar
To repair the broken spring, we’ll create a collar to join the broken ends. The original article cleverly used old Mercedes fuel injection line. This guide will stick with that method due to its effectiveness and readily available nature in many workshops, but you can also consider using robust rubber or plastic tubing with similar inner diameter and wall thickness.
-
Select Fuel Injection Line (or Alternative): Obtain a section of old fuel injection line. The inner diameter is surprisingly small, smaller than a pencil tip.
-
Enlarge the Inner Diameter: To fit the fuel line over the seat spring, you’ll need to slightly enlarge its inner diameter. A drill bit that is just smaller than the outer diameter of the fuel line works well for this. Carefully ream out the inside of a section of the fuel line with the drill bit. Cut off a piece of the reamed fuel line to create a collar of suitable length (around 1-2 inches should suffice, adjust based on the break). This process creates a sturdy and snug collar for the repair.
4. Preparing the Broken Spring Ends
To ensure a secure fit with the collar, slightly grind down the broken ends of the seat spring.
- Grind the Spring Ends: Using a grinder or file, carefully grind down the ends of the broken spring where the collar will be fitted. This “try-fit-grind” process ensures a snug fit for the collar on both ends of the spring. Work incrementally, testing the fit frequently until the collar slides onto both spring ends with a tight fit.
5. Installing the Repair Collar and Securing the Spring
Now, assemble the repair by installing the collar and securing it to the spring.
-
Install the Collar: Slide the prepared fuel line collar over one end of the broken spring, then align the other broken end and slide the collar over it, encasing both broken pieces. Ensure a tight and snug fit.
-
Secure with Wire (Safety Wire Recommended): To prevent the spring from separating from the collar, especially when the seat flexes, use safety wire (or strong wire) to wrap tightly around the collar and the spring on both sides of the break. This wiring is crucial to maintain the repair’s integrity and prevent the spring from pulling out of the collar under pressure. The collar provides stiffness, and the wire ensures the spring angle remains consistent, maintaining the proper spring rate and seat feel.
6. Reinstalling the Seat
With the spring repaired, the final step is to reinstall the seat back into your vehicle.
- Carefully Reinstall the Seat: Lower the seat back into its original position in the vehicle. Reconnect any electrical connectors if applicable.
- Reinstall Bolts: Reinstall the rear seat mounting bolts and the seat belt guide anchor bolt. Then, slide the seat back to access and reinstall the front mounting bolts. Tighten all bolts securely.
7. Test and Enjoy
- Test the Seat: Carefully test the repaired seat by sitting in it and applying pressure. The seat should feel noticeably firmer and more supportive.
- Enjoy the Improved Comfort: Enjoy the restored comfort of your car seat, thanks to this simple and cost-effective DIY seat spring repair!
Tips for Longevity and Prevention
- Address Multiple Breaks: If you find more than one broken spring, repair them all using this method for optimal seat support.
- Regular Inspection: Periodically inspect your car seats for signs of sagging or spring issues, especially in older vehicles. Early detection and repair can prevent further damage.
- Weight Distribution: While unavoidable in many cases, try to distribute weight evenly on the seat to minimize stress on specific spring sections over the long term.
By following these steps, you can effectively repair broken auto seat springs, restoring comfort to your car seats and saving yourself the expense of a full seat spring box replacement. This DIY repair is a testament to resourcefulness and the longevity of even older vehicle components with a bit of care and ingenuity.
