Missing Roof Rack Piece??? Yes, No, or Maybe?

[BroncoKong Jr.]

And yet, their dynamic weight rating stays the same

No it doesn't. 264 lbs for the Backbone. Much more for the exo racks.

Sponsored

 

[WuNgUn]

No it doesn't. 264 lbs for the Backbone. Much more for the exo racks.

K....

 

[BroncoKong Jr.]

K....

You don't seem to be understanding that those racks aren't attached to the roof, they're attached to the tub and roll cage. You have to drill through the roof to mount them.

 

[WuNgUn]

You don't seem to be understanding that those racks aren't attached to the roof, they're attached to the tub and roll cage. You have to drill through the roof to mount them.

I totally know they are... But I don't see how that helps with dynamic limits with regards to tipover or evasive road manoeuvres... They don't.
400lbs on your roof is 400lbs on your roof. It doesn't matter where the weight is anchored, it's all to do with COG.

 

[zfischer]

My understanding is the same. I thought factory roof loads had more to do with rollover risk. I'm sure the Bronco rack will support more than 110/400.

No doubt those Jeep racks are well-engineered and incredibly stout. I don't doubt the load ratings they provide are accurate and even conservative estimates as far as how much weight they can tolerate.

But the more weight you put higher up on the vehicle....

Maybe I'm wrong, but I always thought low factory dynamic loads were about rollover. And that static loads are just generally conservative.

 

[Rocketeer Rick]

Maybe that is the case. My assumption has been that the dynamic limits are based on structural fatigue as that weight is bouncing down the road. If so, then the structure supporting the load is critical to the rating. But its probably a combination of factors, vehicle dynamics may play a big part.

 

[WuNgUn]

Maybe that is the case. My assumption has been that the dynamic limits are based on structural fatigue as that weight is bouncing down the road. If so, then the structure supporting the load is critical to the rating. But its probably a combination of factors, vehicle dynamics may play a big part.

This makes the most sense... Dynamic loads such as emergency braking may push the limits of the mounting point and this may be a limiting factor.
However, considering a 4D Squatched V6 can't have a rack and this points to gross vehicle weight limits as well.
What is important to note is the load ratings (I think) are the same from a 31" tire base and a 35",lifted Squatch.
However you slice it, both numbers are probably conservative

 

[BroncoKong Jr.]

Maybe that is the case. My assumption has been that the dynamic limits are based on structural fatigue as that weight is bouncing down the road. If so, then the structure supporting the load is critical to the rating. But its probably a combination of factors, vehicle dynamics may play a big part.

That's correct. Removable tops just aren't built to support weight. When you eliminate that from the equation, then you can carry more stuff.

Sponsored