Question about roll cage gussets and racing rules Options

[MichiganMat]

Racers,

Im putting an 8-point cage in my 914 and I have a few questions about roll cage gussets:

- Are there rules about what the gussets should be made from? Must be DOM? Pipe ok?
- Id like to triangulate my joints with smaller diameter 1" OD pipe than what the cage is made of.
- Are there regulations on where the gussets can and cannot be located? Im thinking of adding to the halo area above the driver, and the connection point of the halo to the main hoop.

Id hate to add a bunch of gussets only to have it flagged for removal by SCCA or another racing org.


Something like these:

(IMG:http://www.914world.com/bbs2/uploads_offsite/image.fourwheeler.com-6222-1455665527.1.jpg)

(IMG:http://www.914world.com/bbs2/uploads_offsite/image.mustangandfords.com-6222-1455665527.2.jpg)

(IMG:http://www.914world.com/bbs2/uploads_offsite/www.miatacage.com-6222-1455665528.3.jpeg)

[Bill's Racing 914]

I am an aerospace structural engineer. Been doing this stuff for 30+ years. I have designed a lot of flight hardware and also welded ground support equipment. I have also been involved in a ton of static and fatigue failure analysis

I have also met a lot of welders who think they know structures and they don't. If they try to argue with you, just walk away and find someone else.

Your tubing should be DOM and not seam welded..even for the gussets.

So that it uniformly transfer the load to the pipe to which it is welded, a gusset should be the same diameter. This way, the load is transferred to the outside of the neighboring tube by shear. If the gusset is smaller in diameter, under compressive load it can punch through the thin wall of the neighboring tube. Under tensile load, It will pull itself from the neighboring tube.

If you are to use plate stock, it is better to use two triangles, on on either side of the joint. A single triangle in the middle of the joint like the one shown in your lower photo will cause a stress riser and can punch through the thin wall of the tube and also will eventually lead to a fatigue crack. (IMG:style_emoticons/default/welder.gif)

[stownsen914]

As mentioned above, use DOM for everything. 1020 DOM, specifically.

Scott