Rhino-Rack Backbone installation issue (bad design?)

[Gasior]

I am installing Backbone on my JLE following instructions. When I install the inner washer (see this video @6:25) one of my rear castings is a bit lose. The problem is, the washer (22) is the size of screw (C), not 5/16, like the section A, so if the fiberglass (B) is thinner, it will hold the bolt in place, but the casting will not be pulled tight to the roof, because A is wider than B. When I install without the inner washer, 5/16 (A) part goes into the bracket (1L,2R) and casting is firmly attached to the roof. Anyone else had that problem? Should I just let it be lose or do it my way? Seems to me that this is a bad design. Not happy about short 6mm screws or plastic legs either...

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[Upnarms]

Just pick up a bigger washer. Did you apply butyl tape under the leg? Been awhile since i installed mine. Seems your bolt is going too far into the hard top. I think i put a ring of butyl tape under the bolt head to increase water tightness but again i can't recall exactly. I would definitely not want anything loose though.

Are all the bolts included (17) the same length?

 

[Gasior]

Yes, they are the same length.
I could put a washer or butyl tape under the head or get a bigger washer, but I am wondering if it is better to have no washer. That way, the whole area of the bracket makes contact with fiberglass.

The drill size they tell you to use is also a bit small. I think there should be some extra room to avoid stress on fiberglass.

Finally, I think the front casing is a bad design. I thought that the job of the front casing was to put the load on the roll bar. However, rollbar casting supports the inner fiberglass layer, and the casting rests on the outer. The domehead bolt (19) is slightly below the casting's top surface, so all it does is hold that casting in place. Only if you put enough load on the casting to compress the foam or fiberglass, will the bottom of the crossbar leg make contact with the top of the domehead bolt (19) and will transfer load onto the rollbar through spacer bushing (13). Am I right?

 

[Upnarms]

I'm not totally understanding the question. I just followed the instructions and torque it down every now and then. Use a thread locker (blue) especially on the little bolts holding your rack onto the castings. To me that is the weak link... those tiny bolts (1 per casting) and I've had them loosen up before. I've been running the rack for over 4 years with a free spirit rtt on top. No issues if you check it now and then.

 

[MntGoat]

For anything smaller than 1/4-20 or 8mm use purple loctite...bolts will shear before loctite falls. Small bolts are better off using nylock type nuts IMHO

 

[dstevens]

Looking at the original question, the bolt is a shoulder bolt and the washer is deliberately smaller than the shoulder. This is so you can tighten the bolt down without crushing the fiberglass.

If the shoulder section of the bolt is loose, which is not a big surprise because the thickness of anything fiberglass can vary, then I would shim under the smaller washer with another washer of bigger diameter until the assembly clamps the fiberglass without crushing it.

 

[Upnarms]

Looking at the original question, the bolt is a shoulder bolt and the washer is deliberately smaller than the shoulder. This is so you can tighten the bolt down without crushing the fiberglass.

If the shoulder section of the bolt is loose, which is not a big surprise because the thickness of anything fiberglass can vary, then I would shim under the smaller washer with another washer of bigger diameter until the assembly clamps the fiberglass without crushing it.

Great point you make.

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