owenwilliams

There was probably at least some thought put into that cage design.
I understand the fire issue. I just can't see how you could alter that particular cage to make egress easier while maintaining the same level of stiffness and impact protection.

bbundy

It’s interesting I haven’t seen a cage that really incorporates all the details I’m looking for yet. One of the things I’m focusing on is shoulder width and aft placement. With all the weight I intend on removing I think I want to sit far back to improve weight distribution. I don’t want the main hoop interfering with the seat.

I looked at this but the rules clearly state in the first part of the definition “The main hoop must Maintain a single plane” I don’t think this would fly based on how the rules are written.


But I can’t see how this would not be ok per the rules. Both Autopower and hard dog don’t extend the main hoop all the way to the floor. Many others lean the hoop back to do it. I sort of like this Idea then lean the hoop forward a bit. The bar could be wider and further back where it would interfere with the wings on my seat and my shoulders.

Baxt3r

I had a hard dog cage before I made my own and grew to really dislike it. One of the main reasons was the fact the main hoop didnt extend down to the floor. Using that type of main hoop design really screws up your options for door bars. Either your ingress/egress sucks, or you wind up having some ridiculous s-shaped bends in your doorbars. With the way I bent and placed my main hoop the very top of my Kirkey hits the rear diagnol support bar before the seats shoulder bolster makes contact with the leg of the hoop. This is with the seat almost touching the rear bulkhead/firewall. This is probably the roomiest cage I have seen in a miata while fully abiding by the scca's cage rules.

BBundy- If youre ever in Bellingham and youd like to take a look at my cage just let me. Im actually a close friend of Eric Urness's.

cucamelsmd15

Baxt3r, not cage related per se, but how did you paint your cage/interior? How is it holding up?

stinkycheezmonky

The diagonal in the main hoop here is also bent, which is either a rules no-no, a really bad idea, or both. The single plane main hoop rule would definitely be violated by the cage in your pic.

bbundy

I hear what you’re saying with the door bars but this is what I am thinking.

I’m building a cage more like it is for a tub GT car than a street touring or Spec car. The street touring rules limit the size and number of backing plates I assume to limit the ability to improve the non-crash related performance aspect of chassis structure with the cage. GT rules on the other hand place no limit on size or number of backing plates and there is this rule in the side impact section (“Tubes that are welded to any part of the same mounting plate are considered to be connected to one another”) so what I was figuring was making the upper tube go to the main role hoop at the base of the high connection point sort of the same height as yours. The lower tube can go to a backing plate extending down the front of the rear bulkhead firewall.
I believe my sparco seat where I want to put it would go with into your bar. The other thing I have noticed is leaning the main hoop back to get it to reach the floor puts the top of it further back where it can’t be as tall and fit under the hard top. My intent is to move engine and transmission aft in the car along with pedals, steering wheel, and seating position.

The back of my car is losing a lot of weight with no trunk floor or unibody structure just floppy exterior panels and an even lighter rear sub-frame. I think maintaining weight distribution is going to be challenging. It will be tube frame in the front as well but it is hard to take any weight out of the engine and radiator stuff to balance weight removal.

PS. do you have access to a tube bender?

Bob

Savington

iTrader: (31)

Bob, this is how TC does it:



Ingress/egress is just slightly worse than stock+race seat. Removing the steering wheel is optional. I cannot stand cages that have a tall doorbar like pretty much everything else I've seen in this thread - it makes ingress and egress so much more difficult.

More:

orion4096

iTrader: (22)

I have the TCD cage with the same door bar setup. I didn't realize how annoying it was to have taller door bars or less room for my feet until I sat in some other caged cars in Lemons last year. My only regret is not being baller enough to get chromoly.

bbundy

Ok I had not seen that detail of TC cage before. Yep that is exactly what I have been determining as the way to do the main hop and door bar. Actually this looks far and away better than any other cage I have seen in a lot of areas of detail.
Bob

ThePass

iTrader: (3)

I hadn't ever noticed how TC does that main hoop. Quite interesting, I like it.

The only thing I don't like is 3 bends per door tube.

-Ryan

bbundy

Would TC do a weld it yourself kit?

Savington

iTrader: (31)

I doubt it. You'd be better off having him weld it in - he only charges $1600 for the entire thing (tube+labor) and he's very open to small custom changes. The Red Rental has narrowed doorbars so the power windows still work, and the black car has a straight dashbar+custom column mount instead of the standard SM bar that hugs the firewall a bit more. He will also TIG the cage in, or do it in chromoly if you want.

Tony's cages are awesome - I actually can't think of a single thing I would want to change about my cage. It is very well thought-out in a lot of places, and incredibly affordable to boot.

Baxt3r

Bob- Eric has a JDsquared bender that I have a 1.5" od 4" radius die for. I also have access to a hydraulic bender and a mandrel bender at my work.

I think the arguement concerning ingress/egress is kinda splitting hairs. The difference in height of the top door bar when comparing my cage and Savington's cage is literally only a couple of inches. Mine is above the door striker where his is below. However, where my top door bar tube attaches to the a-pillar by the dash is actually lower making it easier to swing your feet in. Back to back theyre probably not drastically different. Personally I think its a terrible design flaw to put an s-shaped bend in a tube tho and refused to do it. If I were to run the TC style hoop I think I would actually run a hole saw thru the door jam where the latch is located, and run my tube at an angle from the base plate thru the door jam and locate one bend where the latch is so the bar can be run straight across inside the door skin. If I knew how to use paint this would be easier to describe.

bbundy

The metal removal process has begun.

ThePass

iTrader: (3)

This is what I was trying to get at that bugged me about the TC door bars. I think that would be a great design change to improve the door section. You could do one bend per bar then.

dgmorr

iTrader: (4)

Seriously?? WTF, the cheapest I can find up here from known people is $3500.

GT42R

$200 - $250/point for chromoly I think is the standard...

dgmorr

iTrader: (4)

Mind PM'ing a known shop where that rate is available?

RyanRaduechel

iTrader: (10)

In for following this build, looks like a lot of material being removed, I like it.

Savington

iTrader: (31)

TCDesigns > *