Japanese vs USA Roll Cages

Now,  don't think I'm jumping on the JDM bandwagon--there are many things they do that doesn't sit well with me.  For example,  mounting shoulder harness bars almost vertically to the floor behind the seat.

However,  I'm curious about the frequent use of bolts and gussets in roll cages in Japan.  As such:

http://www.speedstar-racing.com/store/catalog/images/cusco_6pt_rollcage_harness_ap.jpg

My Starlet is a small car and getting a rear cage--main hoop, harness bar, main hoop diagonal, and rear down tubes is pretty tight.

I was thinking, to make access and get a good weld on top of the main hoop's joints,  welding on  6" piece of the appropriate tubing,  weld those up, and insert in car.  Then, use a roll cage slug bolted and welded to the 6" piece of down tube from the main hoop to the rest of the down tube.  

http://www.tmrcustoms.com/store/images/id_tube_clamp_tmr.jpg

So,  would that fly?  Also,  making tabs and simply bolting in the cross bars would be immensely easier but something tells me those tabs are going to the first thing to let go...

Thoughts?  Opinions?

While it may be perfectly effective and safe, if the rules and sanctioning body don't allow for movable or removable sections and joints, the question is moot.

Right up there beside the use of other materials than DOM steel. Is that the best material to use? No. But the rules don't allow for anything but.

When, clearly, muffler tubing is the best to use.

Follow SCCA rules if you ever expect to see any competition with the car. There are provisions for how to do removable sections. That being said, for the first time ever I just built a cage as I saw fit instead of what the rule book says. Its in a high performance street car/occasional track day car where the biggest requirements were safe, stiff, and as far out of the way as possible. There is 100 feet of tubing and most of this cage can disappear into the interior coverings if I choose to reinstall an interior. It has about 30 welded points of contact before I even start on the dimple die gussets.

The cage in that link also has a ton of unnecessary bends - I wouldn't hold it up as an example of a good design. It looks more like something intended from a street driven show car than a proper competition cage.

MadScientistMatt wrote: The cage in that link also has a ton of unnecessary bends - I wouldn't hold it up as an example of a good design. It looks more like something intended from a street driven show car than a proper competition cage.

It's full of 'S' bends, AKA built in failure points. 100% style, 0% effective and 80% dangerous. It's worse than ineffective, it should be removed to increase safety.

I think when it comes to cages, the best thing is to talk to not only someone that builds them, but also has experience with the specific chassis you are dealing with.

With that being said (and I am not standing behind this particular roll bar), I was there when this happened. The roll bar is a Cusco like the one linked.

It was quite an impressive fall from over 50 ft. The guy walked out with no major injuries.

Cusco "cages" are hilariously badly designed with lots of extra bends so that they fit around interior parts for easy assembly, with bolt together design for easy shipping. As was said, look to SCCA, NASA or other sanctioning body regulations for roll cages to get ideas on how to do it properly so that it'll be safer and pass tech if it ever needs to.

So, tabs and bolts for show. Gotcha. While the car won't see timed head to head racing on a road course, it will see high speed touring days at Hallett Raceway, which might as well be head to head. It'll also see autocross duty.

I haven"t read anything n the SCCA rule book or Foruma D rule book that forbide my idea of using slugs that are bolted and welded. This wouldn't be removable once installed...it would just make welding the top joints easier. I see a lot of guys that wels in a full cage but don't weld the seams near the roof and halo. I'd like my idea would be a bit safer.

Thanks

My cages were built by dropping the main hoop through holes in the floor . The top joints were welded all the way around and the the cage was lifted back up and the anchor plates slipped under the hoop. Weld the plates over the holes and weld the hoop to the plates and you're done.

DeadSkunk wrote: My cages were built by dropping the main hoop through holes in the floor . The top joints were welded all the way around and the the cage was lifted back up and the anchor plates slipped under the hoop. Weld the plates over the holes and weld the hoop to the plates and you're done.

This is how many fabricated FIA App J Art 253 cages are built into rally cars...

That's how most good cages are built into race cars.

To weld the top of the halo I would tack the roll bar to the floor, then I weld most of the halo to the roll bar, then cut the tacks at the floor tip the roll bar forward and finish welding the top of the halo.