Gusset Length as per 3.B.1

[unobtainium]

Just looking for a little clarification here...
Reading along in the roll cage section and I found this part confusing...('13 rulebook)
"Tube gussets shall be constructed such that the outside edge of the tube be at least 4" from the tube junction point."
Then, later it states..." Gussets may not be used as aerodynamic aids and shall not exceed 6" in length.."
Why does this rule exist? The 4" from junction point makes sense to me, but the 6" length limit makes it tough on obtuse angle junctions.
Pictured below is an example. The front upper windshield bar junctions to the A pillars is well over 90 degrees. Mathematically it's not possible to meet the 4" rule and meet the 6" rule. Does this mean the member to support the junction should be made out of full size tubing and just be considered a brace, not a gusset?


Cheers,
Chris

[salt varmint]

i believe they are talking about open cars,,,roll cage around the drivers helment being gusseted with flat plate,,which could be used as an aero aid..??

[unobtainium]

i believe they are talking about open cars,,,roll cage around the drivers helment being gusseted with flat plate,,which could be used as an aero aid..??

I had assumed as much at first, but after reading this thing a zillion times, it's just not real clear to me. Common sense says they wouldn't put a length limit on a tube gusset, but that 6" thing is jumbled in there along with the rest.

[salt varmint]

always learned ,,Dont add no words,,,never leave out no words,,& if all else fails ASK!!!

[Kiwi Paul]

Have you contacted Kiwi Steve Davies, Chief Car Tech, and sent him pics of your build and questions you may have? We are all here to help, but that route is the right one....

[unobtainium]

Have you contacted Kiwi Steve Davies, Chief Car Tech, and sent him pics of your build and questions you may have? We are all here to help, but that route is the right one....

Yes sir.

[unobtainium]

I'll post his response in here as well for any others wanting to know.

[salt varmint]

please do !!!     will look back later..

[unobtainium]

Ok. Well Steve doesn't see a problem with what I'm doing.
Here are a few pics...
These pics show that the gusset is still not quite at the 4" to center of the outside edge of the tube, but is longer than 6" in length.


I'm assuming then that the "outside edge" described can actually be the edge of the gusset. He had no problems with me exceeding 6" in length either, but these are tube gussets and it's a closed cockpit.
Ideally this is what I do with any junction that is not supported by a brace.

Here is an example of an NHRA cage I did over and above the rules as the guy asked me to build it how I would want it.

Gussets basically everywhere possible...

[saltracer1]

Geee, that weld is like welder's porn or something! Phil

[Peter Jack]

Geee, that weld is like welder's porn or something! Phil

These welds are excellent. On the other hand if the tig welds on your cage aren't at least similar to these, should you really be comfortable climbing into your car?

The same goes for mig welds. If they don't flow and tie in at the edges or they have to be ground to look acceptable then maybe you should be less than comfortable climbing aboard to make a fast run.

A roll cage isn't the best place to learn to weld!

Pete

[unobtainium]

Geee, that weld is like welder's porn or something! Phil

These welds are excellent. On the other hand if the tig welds on your cage aren't at least similar to these, should you really be comfortable climbing into your car?

The same goes for mig welds. If they don't flow and tie in at the edges or they have to be ground to look acceptable then maybe you should be less than comfortable climbing aboard to make a fast run.

A roll cage isn't the best place to learn to weld!

Pete

Excellent points.

[NathanStewart]

Think of what a plate gusset looks like.  They're supposed to be 4" long on whichever side is welded to the cage structure.  So, on a 90 deg tube junction, your triangular plate gusset is 4" x 4" x 5.65".  The idea behind the tube gusset wording is to have tube gussets that provide at least the same amount of "triangulation" as a plate gusset.  It's supposed to be 4" out from the tube junction along each tube that is being triangulated, not a tangental point that's 4" from the junction point as you've pictured.  Again, the point was the have tube gussets that at least support the same area as a 4" plate gusset would and not less.

Nonetheless it looks like you have that well covered.

[Rex Schimmer]

Boy you do nice welds!! what rod diameter are you useing? and what is the welder? Do you "cope" the ends on a milling machine?

Rex

[saltwheels262]

would not need to hide or grind any of those welds. Wow !