A tonneau cover that flaps violently at high speeds is a common problem that can leave truck owners baffled and concerned. Though it may seem alarming, some degree of movement in a soft tonneau cover is normal, especially at freeway speeds. However, excessive flapping that makes loud noises or causes damage needs to be addressed. In this article, we’ll explore the reasons behind a flapping tonneau and solutions to stop it.
What Causes Tonneau Covers to Flap at High Speeds?
Is it just wind resistance against the cover?
Wind resistance is the main reason tonneau covers flap at high speeds. As a truck moves faster, air flows over the bed creating an area of high pressure. This pushes down on the cover, while low pressure under the cover pulls it upwards. The opposing forces make the fabric flap strongly.
Could it be a loose installation?
Yes, a loose tonneau cover installation can allow too much movement and flapping. When installing a cover, the rails, clamps and snaps need to be tightened properly per the manufacturer’s instructions. Uneven tightening or loose screws can lead to a loose fit and excessive flapping.
Do weather conditions like rain contribute?
Absolutely. Things like rain, snow and even morning dew can cause a wet tonneau cover to flap more violently at freeway speeds. The additional weight and surface tension of the water exacerbates the pressure differences over and under the cover. Once the cover dries out, the flapping may reduce.
How Can I Stop My Tonneau Cover From Flapping?
Should I tighten the cover evenly during installation?
Proper even tightening of the rails, clamps and snaps is crucial during tonneau cover installation. Follow the manufacturer’s guidelines to ensure everything is tightened correctly. Uneven tightening can lead to a warped cover fit and loose areas that flap easily.
Will lubricating the snaps and hinges help?
Lubricating the snaps, hinges and moving parts can help reduce friction and stiffness. This allows the cover to open and close smoothly. Less resistance means the cover will not catch the wind as easily and flap around. Use a dry lubricant like silicone spray.
Should I check for damage, erosion or stretching?
Inspect your cover for damage like erosions holes, rips and loosening of the fabric. Long periods of flapping can stretch and wear down the material. If damage is extensive, the best solution is to replace the cover. For minor damage, patches or seam sealant can temporarily repair small holes and tears.
What about adding support bows or straps?
For soft covers, adding support bows or straps across the width of the bed can help reduce flapping. The bows create arched sections that make the cover more rigid. Straps limit upward movement. But be careful not to over-tighten straps as that can warp the cover.
When Should I Consider Replacing My Tonneau Cover?
If the cover has extensive damage or erosion
If the flapping has caused large holes, rips or tears in the fabric, it’s best to replace the cover. Damage spanning larger than a few inches cannot be reliably patched. Anything that compromises the waterproofing ability means the cover needs replacing.
When the cover no longer seals tightly against the bed
Over time, repeated flapping can stretch fabric and cause the cover to fit loosely. Snaps, hinges and clamps also get worn out. If this affects how well the cover seals and secures to the bed, a new cover is needed.
If there is damage to the truck bed or payload
Excessive flapping may bang the cover forcefully against the truck bed sides. Look for signs of paint damage or dents. Also inspect cargo inside the truck bed for water damage or impact damage from the cover. If the flapping has caused collateral damage, replace the cover.
Conclusion: Prevent and Address Tonneau Cover Flapping
A flapping tonneau cover can be annoying and even dangerous if it causes damage. Strong winds at high speeds make covers flap, but proper installation and maintenance can prevent excessive movement.
Regularly inspect for looseness and damage. Lubricate components and use support aids if needed. Ultimately, replace excessively worn and damaged covers. With a bit of care, your truck’s tonneau cover can serve you reliably for years before needing replacement.
