Hi all track heads! Planning on getting my cage started this winter. Wanted to toss around some ideas and get some input on how you have made decisions on specific design area on your cage, what do you feel works and does not work on a Z.

Here is a collection of images I have found to help myself and others with ideas.
http://www.pinterest.com/mhulbrock/350z/

I would like to start the conversation focusing on the main hoop and rear cage area, as I feel this most dictates the rest of the construction process. I will be following established rule books as a good safety baseline when constructing the cage.

I have noticed alot of Z's main hoop are welded to the floor board area, thus making the main hoop and harness bar area VERY close to the seat. FIA rule dictates I feel moving the main hoop back would be the best way to start the cage, much like this example.

AND


What is your opinion of giving the main hoop some lean back to furthur aide in seat clearance, maybe 10deg. I have seen many track cars with main hoops that have a lean back to them. Others swear by plumb upright.

What is your opinion of the gas tank directly below the main hoop in this configuration?

 

Rear cage is also an area I have noticed some different design choices. Mostly those who attached the rear down tubes directly to the strut towers, as show above and the most common.
And those who attach the down tubes to the more beefy "frame" area, like below.


In my eyes the main benefit to attaching to the strut towers is the ability to create a node at each tower for the cross bracing to attach too. Also a closer proximity to the C pillars for better crash protection and the ability to attach gusset plates to the C pillars.

whats your opinion?

 

Cage A will be like the one I'm building. I like the rear design better and think that it will allow behind the strut tower to be more of a crumple zone. Then it will also be gusseted into the C pillar to stiffen the chassis.

 

Also note that Class Rules are a major influence the cage design, For example NASA Spec Z rules require that NO metal can be removed from the car. So the rear strut cross member that many folks remove, then add a tube cross brace as part of the cage would be illegal.

So if you don't care about class rules you can build any cage you want. (that is hopefully safe) But if you are building to a specific race classification...read the rules 4 times BEFORE starting the build

 

Right, for sure. Rule books are also a great way to get the basic safety ideas that are proven, into your cage design.
The questions I asked should be relevant to both Spec Z and non rule books.

 

Retaining crush zones is important to reduce the g-loads on the driver in a rear end collision. I would opt for the shock towers for the rear braces. You can also lean the main hoop back about 10 degrees. Keep in mind that there are some differences between FIA and SCCA rules for roll cages.

 

When welding in the base plates, you any one advise in removed the gas tank first? It would be directly below the welding area.

 

Great topic, trying to get my cage done this winter

Nice link also

 

Yes, remove the fuel tank.

 

Who was that guy that lost his brakes at the end of a long straight (I think at Ohio) and flipped a bunch of times? From what I remember reading, he was fine after that fairly outrageous crash, save for a few bumps and bruises. Seems like his cage would be a good example of how to make one. Don't have time at the moment to search for that thread, but I can post it next time i have a chance.

 

Here it is
https://my350z.com/forum/autocross-r...hio-crash.html

 

Cage was built by Ralph Provitz/V2 Motorsports. That crash is a big reason why I'm going to him for my safety gear.

 

Two ideas to keep the tank in place. Fill it up with fuel to have NO gasses inside. OR drain completely let it air out for a good amount of time.

 

more concern for safety and stiffness, not so much the added points,

what about firewall to front struts, tying in that all together

 

Why a pic of a S30? What you reinforce in the front of a Z33 is different from what you reinforce on the front of a S30.

 

Picture updated.

Just giving examples, thats it

 

Any other specific experience or decisions made that you regret or felt was the right way to go for your cage?

 

I am in the process of gathering data right now, I want this thing to be safe.

I watch a lot of racing and see a lot of wrecks, I always like to see the wrecked cars to see exactly what happened to the car. By day I am a mechanical engineer, so I probably over examine things by nature.

My opinion is tying in the front struts is probably the way I am going to go, I like the idea of having more cage in front of the firewall and me

 

Don't eliminate the crush zones built into the car. The point is to reduce the instantaneous g loads on the driver and the more you delay those loads going into the cage and thus to the driver (through the belts, seat, and seat mounting) the less chance of injury.

Use the SCCA Production and GT rules for typical wreck speeds of under 80 mph (90% of what happens here in the USA) and the FIA Article 253 rules for typical wreck speeds over 80 mph (Road America, Road Atlanta, Willow Springs...)

 

BTW... my discussions above are in the context of safety. There may be performance, stiffness reasons to integrate the strut towers into a roll cage but be aware of the trade offs. You can also use thinner wall tubing for those kinds of chassis stiffness upgrades.