Roof box mounted straight to T track crossbar

[El Chupacabra]

Anyone here mounted a rocketbox type roof box to T track crossbars, using bolts that slot into the track - - instead of using the "around the crossbar" type of clamp that comes with the box? Bolts like this:

https://www.amazon.com/Zhengmy-Stain.../dp/B0B5YZPB7M

^^ and run straight through a hole in the bottom of the box. Thinking I'd sandwich the box floor with some metal plates to spread the load.

Anyone tried this and had catastrophic failures, or a bunch of cracks? It should be strong enough, but it's also eliminating half of the mount points on the box by not using a U type clamp.

I have an old Thule box I got free, without the mount clamps, and thinking about how I can mount it on the truck. Amazon has cheap clamps too, if I go that route.

[shank]

Yep, did exactly this with an early 90s Thule that I inherited. It’s held up for near about 10 years now, one crack repaired with gorilla tape that seemed unrelated to the bolt holes. My one concern was that the wing nut wouldn’t cover enough surface area and would rip out, so I drilled a 6” flat plate to make a washer to distribute some of the pressure. At this point I’m more confident in the T-bolt attachment than in the much newer clamp-attached box on wife’s car. The direct connection to the bars is super sturdy. Only challenge is getting holes to line up, it helped to find T-bolts with just a little bit of wiggle in the rack slot.


Sent from my iPhone using Tapatalk

[Cocximus]

I used t-nuts for bike carriers. No issues.

[j0z77]

I mounted Packline roofbox with T-bolt mouting kit instead of attached clamps.
Because the clamps are too bulky to store many skis in the low profile roofbox.
There is no issues so far.

I like the black rubber coated metal plates because they're strong enough and not slippery.
Some metal plates and sheets of rubber will work in same way.

The nuts with white handgrip is easy to install but still a little bulky.
So I uses standard stainless M8(IIRC) nuts instead of the grip nuts.

I think you can buy similar T-bolts, nuts, metal plates and rubber sheets much cheaper.

https://www.packline-roofbox.com/pro...bolt-11009006/

https://youtu.be/IGMuPDH3vIw


Sent from my iPhone using TGR Forums

[El Chupacabra]

Thanks - I think I'll give it a try this winter. There are cheap metal reinforcing plates available at Home Depot etc, which should work to help spread the load on the box.

[waveshello]

Thule makes a direct mount kit for the boxes that use the uh... Power click... Clamps that grip the bars and have a nob inside to twist open/close.



I use that with mine.

[stuckathuntermtn]

That seems rather overpriced, but that's how Thule do for a long time now.

[El Chupacabra]

I saw that adapter kit, but I think I'll try the straight through T track bolt. Much cheaper.

[singlesline]

This is exactly what I do as I wanted the sleekest look for the box.

Mine came with a crappy U bolt clamping system, but I repurposed the plates for the T bolts. I'll see if I can find pictures, but basically I got some binding barrel screws to hold the plates and some Thule T bolts: https://www.etrailer.com/Accessories...53-208909.html (although when I bought them they were $1.38 a piece...) and some M6 knobs for easy removal https://www.etrailer.com/Accessories.../753-0783.html (again, these were $1.25 each in 2019...).

I'd probably try to buy bolts from a rack company (Thule, Yakima, whatever) just to avoid relying on 4 suspect Amazon chinese bolts for something you take on the highway...these aren't that unreasonable: https://www.etrailer.com/Accessories...ck/RR25XB.html

The front plates I just used the center of 3 holes (binding barrels in the other 2). The rear plates I cut a slot that is about 1.5" long just so I don't have to be super accurate when installing the crossbars. You'll want some kind of plates...don't want to screw directly to the ABS. Could cut them from home depot stock with a hacksaw/drill/dremel just fine.

Installation is pretty easy--slide the T bolts onto the cross bars into approximately the right position. Drop the box on top and adjust until the holes are lined up. Spin down the knobs. Takes marginally longer than the fancy systems but looks super clean on your roof (and takes up almost no space inside the box).

[singlesline]

Here is what I could find--hope it makes sense
These are the plates that came with the box--they match up to a series of holes made every ~2" or so. Wide plate outside the box, narrow plate inside. For the rear, I had to cut out a slot in the plastic around the length that fit my car's rack spacing.


Then I cut out a slot in the rear plates (inner and outer):


And clamped them to the box using these:


Finished result looks like this (best picture I could find, from when a built a lift to store it on the garage ceiling above my car). Also added some cheap sticky-backed foam sheet where the crossbars go to stop any vibration noise.


End result is a box that's stuck to the bars without any clamping mechanisms sticking out:

[El Chupacabra]

Thanks for the details and pics - very helpful. Question: are you using the binding barrels solely to help hold the plates in position while you put the box on the crossbars?

And for each of the four places on the box where there used to be a clamp: you're using two T bolts at each? (so 8 T bolts total?)

[singlesline]

Thanks for the details and pics - very helpful. Question: are you using the binding barrels solely to help hold the plates in position while you put the box on the crossbars?

And for each of the four places on the box where there used to be a clamp: you're using two T bolts at each? (so 8 T bolts total?)

Binding barrels are just to hold the plates in position when off the car and stop them from moving/rotating during assembly. Might add some better structure by binding them together (one can't flex without the other moving), but mostly I think it would be a PITA to put it on the car if you had a bunch of loose plates.

Could rivet them as well, but if you change cars to something with different crossbar spacing, you'd want to be able to relocate the plates...but a 10 pack was <$5 from McMaster Carr and I don't have any rivets big enough to fill the holes on the plates (since they were already drilled big).

Only 1 T bolt per corner (4 total). Through the middle hole (or slot) in each plate:

[El Chupacabra]

Got it - thanks!

[bennettc14]

Good thread. I have the claw clamps on my Thule box, feel like it still bounces a lot a highway speeds. Going to try the T bolts instead this year. I leave my box on for the season.


Sent from my iPhone using TGR Forums