There was a thread somewhere on MT.net where somebody I think from Australia posted some pictures of a totally incredible looking cage that involved some reworking of some chassis details. Such as cutting out most of the seat belt area structure and some of the rear deck package tray and trunk, also had great looking gussets to the chassis in various areas.

I can’t seem to find it and now I would like to find it again to study some of the great work and ponder out some Ideas of my own. Anybody remember where I could find that.

Bob

 

Are you thinking of lightyear's Carbon fiber time attack twins build?

Funny you mention this as i'm looking at tube bending equipment as I type =P

 

Yea that’s it. I’m liking some of the things done with that cage.

Bob

 

Ya it is built like a cage you'd see in a rally car more so than a road race car. The X door bars, the roof and rear cross bars that meet at one point on the main hoop, the taco gusseting, etc.

 

Wayne, jd squared makes a pretty good unit that is relatively cheap. I have the model 3 and used it to build a couple of cages and the bolt in door bars I sold a while ago.

 

Ya I was looking into that specific one actually since someone locally has one for sale. My only problem is that My garage is way too small for cage building. Perhaps Bob wouldn't mind letting me store it at his shop =P

 

There are some good ideas in that cage, but for the sake of creating as much room for the driver as possible I would not go with a symmetrical main hoop. I offset 3 of the bends in my hoop towards the driver which created more headroom and allowed me to run my diagonal brace from one of the bends to the floor. Here's a link to see some pics of what I'm talking about: http://smg.photobucket.com/albums/v7.../Spec%20Miata/

Here's what I did to mount the bender that I used, it worked and its also good for a laugh.

 

I have a couple of huge problems with the cage done in that carbon fiber time attack car. The 6 (7?) bends in the main hoop, and the fact that they total over 180*, for starters. I also hate the doorbars.

This thread:
https://www.miataturbo.net/race-prep-75/cages-do-not-cut-door-51100/
is filled with TC Designs glory. Note the door bar design, downtube pad design, and general excellence.

 

I tend to agree with Savington. I also believe that cage would be illegal to race in SCCA or NASA. Bob, if your going to cage it why not build it to SCCA/NASA specs and incorporate some of the rally specs you like. I find it hard to believe you wouldn't want to W2W. As far as those door bars that look like an X or straight bars they absolutely suck getting in and out of. I would do something similar to the snowboarder if you want to keep working windows as I know you like to DD your rig. Nascar bars are where its at.

 

What's wrong with miatacage? I've climbed in a few and was amazed at the room.

 

Operative word being "climbed". There's just as much room in a TC cage, more room in the footwell, and ingress/egress is about a bajillion times easier.

 

X bars are used primarily for drag racing to keep the car from flexing during hard launch. I can attest to the suck factor of getting in and out. Better have a removable steering wheel.

 

Its hard to see from the pics in the other threads, but I thought there was one big flaw in the doorbars of some of those designs: that wonderful little "S" bend toward the back of the door. I know notching the door frame there isn't necessarily legal depending on sanctioning body, but there are potentially other better ways of doing it where you don't compromise the strength/design of those bars by throwing in that bend. Only thing is, I'm not familiar enough with Miata cages to know if it'll fit or not with seat placement.

This is the best picture I could find of my favorite design, from Piper Motorsports here in VA (Grand AM M3):


Note how the door bar attaches to the main hoop. They put an extra downward bar between the harness bar and the "floor bar" (for lack of a better name) to keep the NASCAR design solid and without the extra bend, and triangulated that extra bar to the lowest door bar and maybe the rear lower arm.

A top shot of the same door bar:


Alternatively, if there isn't enough space for that, you could do something like this (Koni Challenge Civic):


Again with a downward bar placed to add structural support right at that S-bend. No additional cabin intrusion on this one either.

 

That dash bar looks like a knee-cap-cracker to me, at least from the pax side. I assume it goes up into the dash on the driver side and then back down to weld in.

 

I would like to see proof that all that extra welding makes the car faster and or safer. That looks like way too much tubing for a four cylinder powered race car on pavement.

 

This is a Grand Am M3, not a 4-cylinder anything. I don't know anything about the dashbar, other than that it looks like you'd have to be 7 1/2' tall to worry about it based on the location of the seat.

Edit: Unless maybe you're talking about the red Civic's gussetting on the B-pillar? That is known to be beneficial and doesn't add that much weight. For an example, in Honda Challenge you incur an additional 50lb weight penalty if you want to have your cage tied in like that. Lots of racers opt to take the hit, so...

 

My intention is to make a sanctioning body legal cage. But I do not necessarily want a spec Miata/showroom stock cage but more like cage for a GT style Simi tube frame chassis retaining only portions of the stock structure. For example like the window frame I am intending to remove everything but the outer skin and integrate the structure into the cage.

I haven’t studied every detail of the rules yet I’m still in the thought process which will likely take more than a year to hatch. I want to build the car based on 23.5X11 or 12 R16 tires. For SCCA looks like to run in GT2 no turbo is allowed and the only mazda engine allowed in a Miata would be a rotory. So matching the car I want to build with available classes might be an extreme challenge and end my attempts.

Bob

 

If you want to run your car as it sits mechanically (with the turbo), you could run SPO (super production over), also referred to as ITE in some regions. This is a regional-only catch-all class. The catch is that it will require other safety items beyond the spec'd cage, like a fuel cell, fire system...

 

Fuel cell and fire system were intended to be part of the build.

The problem with ITE is looking at past race results I currently crush the field with my street miata by many seconds but I dont entend to run my car as it sits it will be a new car from scratch and should be much faster. SPO might have some competition. Also what is SPM looks like 911 GT3 Cup cars that also run in GT2.

Bob

 

Sav, I just had a look at lightyear's cage. I understand why you're not a fan. I thought the door bars looked ok from a stiffness perspective, until I realised they utilise bent tube, which then bends again at the rear. I guess the bend at the rear might help it crumple decently in a front end crash.
I gather that your hatred of X-type bars comes from two factors: 1) an ingress/egress point of view, and 2) a side-impact point of view. Is there another negative of this type of design that I'm missing?