Is There a U-Bolt Kit for the Yakima SkyBox 18 Rooftop Cargo Box
Updated 12/15/2025 | Published 11/10/2024
Question:
Can you recommend a U-bolt set up that has the width and depth clearance to accommodate Thule WingEdge crossbars? We own an older Mazda CX9 2013 with fixed points 42inch apart. We installed these crossbars and recently purchased from eTrailer the Yakima Skybox 18L, as it is the only 18L box on the market that will accommodate that wide center-to-center spread. We are finding the Yakima clamp system on these bars is a so-so fit and would like to add U-bolts for peace of mind. Thanks.
asked by: Melissa T
Expert Reply:
Hey Melissa,
The max 42" crossbar spread of the Yakima SkyBox 18 Rooftop Cargo Box # Y07336 is actually pretty rare like what you found. The SuperLatch system that comes with this box is the only mounting hardware option for it, so there unfortunately aren't any U-Bolt kits that can be used as a replacement.
It looks like Yakima has some other roof rack options that fit your 2013 Mazda CX-9 and offer a smaller crossbar spread so if you'd like to go that route I can recommend a new roof rack and a box that mounts either with U-Bolts or with T-Slot mounting hardware, OR if you send me some photos and what your concerns are with the current Yakima mounting setup I'd be more than happy to take a closer look into it for you.
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Jesse M.
12/15/2025
Hey Melissa, what ended up working with the Yakima SkyBox 18 on your CX-9 after learning U-bolts weren’t an option? Your update could make it easier for others trying to secure a similar setup.