Lancisism Roof Box U-Bolt Clamps Kit, 4-Pc 85mm U-Brackets with Lock Nuts & Straps — Corrosion-Resistant, Vehicle-Safe Fit

These four heavy-duty U-bolt clamps and full accessory kit secure a rooftop cargo box to your vehicle quickly and reliably.

When you need a dependable way to fasten a roof cargo box without replacing factory rails, this Lancisism kit supplies metal U-brackets, rubber gaskets, plastic back plates, lock nuts and straps sized for most common roof box anchor points. Built from corrosion-resistant metal and paired with protective rubber and plastic components, the set is intended to reduce movement, protect vehicle finish and simplify fitment on cars and vans with through-bolt mounting holes.

How do these U-bolt clamps attach a roof box to my car?

Installation is straightforward and designed for basic hand tools. You position the box, feed each U-shaped bolt up through the box floor, add the rubber washer and plastic backing plate beneath the roof, then tighten the lock nuts down to clamp the assembly.

• Place roof box centrally on the roof; open lid to access mounting holes.
• Insert U-bolts from inside the box and push through the vehicle roof opening.
• Fit rubber washers and plastic support plates under the roof and secure with heavy lock nuts.
• Pass supplied straps through bracket gaps and tighten for extra restraint.

What are the key measurements and materials I should check before buying?

Confirm your roof box's bolt spacing and hole diameter so the parts fit properly. The kit’s U-bolts have an internal width of about 83–85mm and a center-to-center screw spacing near 98mm, with an M8/5/16in threaded bolt diameter.

• Inner bracket width: ~83mm (3.27in) — fits many universal roof boxes.
• Center-to-center screw spacing: ~98mm (3.8in).
• Bolt diameter: M8 / 5/16in — standard roof box thickness compatibility.
• Materials: iron (metal U-bolts), rubber gaskets and plastic backing plates.

Will these clamps protect my vehicle and withstand outdoor conditions?

The combination of metal hardware with rubber and plastic components is intended to minimize abrasion against the roof and resist corrosion from road exposure. Rubber gaskets cushion contact points while plastic backing plates distribute pressure to avoid concentrated dents or scratches.

• Rubber gaskets shield paint and increase friction for a firmer hold.
• Plastic support boards spread load to prevent localized stress marks.
• Iron U-bolts offer robust clamping strength for highway driving loads.
• Lock nuts secure the assembly and resist loosening during travel.

Who is this kit for? If you own a rooftop cargo box with through-bolt mounting holes and want a compact, reusable mounting solution that avoids permanent roof modifications, this Lancisism 4-piece U-bolt kit is a practical choice. It works well for drivers who transport luggage, sports gear or camping equipment and need a low-cost, serviceable mounting option that can be stored in the trunk when not in use. Always measure your box and mounting hole spacing before ordering, and consult an installation video or a professional if you’re unsure about fit or roof compatibility.