A tonneau cover flapping at highway speeds can be a frustrating issue for truck owners. The noise and damage from the flapping can ruin the purpose of having the tonneau cover in the first place. Fortunately, there are several ways to prevent and stop your tonneau cover from flapping at high speeds.
What Causes Tonneau Covers to Flap at High Speeds?
Tonneau covers flap when air gets underneath them while driving. This air flow causes the material to billow up and flutter. There are a few main reasons tonneau covers can start flapping at highway speeds:
Improper Installation
If the tonneau cover is not installed correctly, it can lead to flapping. Make sure to follow the directions precisely and securely fasten the cover. Verify clamps, rails, and snaps are tight with no gaps.
Stretching or Loosening Over Time
Even a properly installed cover can start to loosen and stretch slightly over time and use. This allows air to get underneath and create flapping. Periodically check for tightness.
Damage or Wear
Rips, cracks, missing hardware, warped panels, etc. anywhere on the cover can allow air flow to get underneath and make the material flap. Inspect for damage regularly.
Missing or Worn Seals
Seals and weatherstripping fill gaps that air can get through. Old, missing, or deteriorated seals around the bed rails, tailgate, and seams can all contribute to flapping at high speeds.
How to Stop Tonneau Cover Flapping
If your tonneau cover already suffers from flapping at highway speeds, there are ways to troubleshoot and stop the problem:
Inspect Entire Cover and Re-Tighten
Do a thorough inspection of the whole cover looking for any installation issues or damage that could allow air flow. Re-tighten any clamps, adjust hardware, replace seals, etc. as needed.
Adjust Latches and Tensioners
Many tonneau covers have adjustable latches or tension knobs that can tighten the fabric. Adjust these tensioners for a tighter, drum-like fit and reduced wind flapping.
Add Wind Stops/Deflectors
Wind stops and deflectors can be installed on the truck bed sides and tailgate to reduce air blowing under the cover edges.
Apply Protectants to Seals
Protectant sprays help keep vinyl, rubber, and foam seals soft and supple to better fill gaps. Applying periodically can stop flapping.
Install Support Bows
For roll-up covers, support bows go across the width of the bed under the fabric to keep it drum tight. Adding more bows can sometimes eliminate flapping.
Replace Deteriorated Cover
In severe cases with a very worn or damaged tonneau, it may need complete replacement if adjustments do not solve the flapping issue. An intact cover should not flap excessively.
Tips to Prevent Tonneau Flap
It is always better to prevent tonneau flapping in the first place. Here are some useful tips:
- Carefully follow install directions for secure, even fit
- Regularly check tension and condition of cover
- Use quality weatherstripping and seals, replace when worn
- Store cover properly when not in use to avoid damage from elements
- Clean vinyl tonneaus and apply UV protectant regularly
- Ensure proper alignment of retractable and folding cover panels
- Drive a reasonable speed during windy conditions
Common Tonneau Cover Flapping Questions
Here are answers to some frequently asked questions about dealing with tonneau covers that flap at highway speeds:
Why does my tonneau cover flap so much at highway speeds?
The most common causes are improper installation, cover stretching over time, damage/cracks that allow air flow, deteriorated seals, and missing hardware. Thoroughly inspect the cover and do any re-adjustments needed.
What is the best way to stop a soft roll up tonneau from flapping?
On soft roll up covers, make sure the bows are straight and properly tensioned. You can add additional bows for more drum-like support. Seal the tailgate edge to prevent air intrusion.
How can I stop my hard folding tonneau from flapping at highway speeds?
Ensure the panels are aligned correctly with good panel seals. Adjust the latching mechanisms for optimal tension. Lubricate the hinges if sticking. Check for cracks at the hinges or edges.
Why won’t adjusting the latches stop my tonneau flapping?
If the latches are very loose or stripped and cannot tighten adequately, they may need to be repaired or replaced. Also ensure the cover frame/panels are not warped, obstructing proper closure.
What is the best way to repair a torn tonneau that is causing flapping?
For vinyl tonneaus, liquid vinyl repair kits can patch small tears. Larger rips may need professional vinyl welding. For fabric covers, reinforced vinyl patches with adhesive backing often work well.
When should I consider replacing a tonneau cover that flaps at high speeds?
If the cover has extensive cracking, rips or missing pieces that cannot be adequately repaired, replacing the cover is the best option to permanently stop flapping and prevent further damage.
Conclusion
It can be annoying and damaging when tonneau covers flap at highway speeds. But there are many effective troubleshooting tips to stop the flapping – inspecting for proper installation and condition, adjusting hardware, using weatherstripping, and making any necessary repairs. With some maintenance and care, your tonneau cover should stay drum tight and flap-free at highway speeds for maximum performance.
