cage Ideas?
 

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.
https://www.miataturbo.net/attachmen...ine=1316492111
https://www.miataturbo.net/attachmen...ine=1316492111

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):
https://www.miataturbo.net/attachmen...ine=1316521582

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:
http://www.pipermotorsport.com/upload/56driver.jpg

Alternatively, if there isn't enough space for that, you could do something like this (Koni Challenge Civic):
https://www.miataturbo.net/attachmen...ine=1316521582

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?

One of the best collections/discussions on cage design I've seen, including X-bar/NASCAR hybrid doorbars:
http://roadraceautox.com/showthread....highlight=cage

In the SE those porsches run in SPO. SPO is more heavily attended than SPU since that is the "catch all" for all the pro series sports cars, along with the PCA and BMW club cars etc.

U vs. O has to do with maximum displacement, right? I don't know where the cutoff is, but I thought SPU was under 2.0L (or whatever), and SPO was over 2.0L?

Yes, but boost is an automatic bump up to O. I think the cutoff is 2.0L. Also rotaries have a multiplier. When I ran my GrandAm Cup Miata with the SCCA I ran in SPU, but that was the same class World Challenge cars ran in - which were making ~100hp more than my Miata. I believe that most SP rules specify the car must be a fendered, production based car (since it is a Production class). That would keep out the formula cars and prototypes- but not things like x-stock cars, which run in the class here often.

Ah, I forgot about boost changing that. For sure in those more open classes the cars are not as evenly matched. GrandAm Cup Miata, when was that around? Built motors, or relatively stock?

More pictures of your GrandAm Cup Miata please. And what power level did you have?

Bob

Correct. But in Bob's case he can build the car for the class. IMO it seems like a good challenge given his fab/engineering skills and driving experience. The Miata will show up as the underdog no matter the driver or the build in SPO. ;)

Hate to disappoint but it wasn't too much more than Spec Miata. Engine mods allowed were spec'd cams (aka sunbelt cams), a retro fit of the Mazda Comp Production valve train, deck head/block to get 10:1 static compression and a header that one of Bosal/Brospeed's fabricators custom built. That with a crank triggered LINK stand-alone got us 155whp. Don't have any real build photos- spent every available moment doing something to/on the car.
https://www.miataturbo.net/attachmen...ine=1316624143
https://www.miataturbo.net/attachmen...ine=1316624143

There's me knocking lightyear's bent-type door bars, when that's what's used in current WRC: https://www.miataturbo.net/attachmen...ine=1316631625

Although I still think (goddammit!) that the bend at the rear of the uppermost bar in lightyear's cage can't be good for anything except for a way to dissipate front-impact energy.
Overall though, sorry for knocking your bent bar design, when clearly it must be the best solution.

Thats what I've been saying! Those cars are bigger though and have more room for your elbows. I"m really curious what its like having X door bars in a miata.

Another cool concept (though it wouldn't fly in the US) is this WRC greenhouse design that they talk about in the thread stinkycheezemonkey posted earlier.

https://www.miataturbo.net/attachmen...ine=1316631934

It's funny how this newest kind of WRC cage wouldn't hold up in the US (due to the lack of a main hoop, right?) as mentioned in that thread, even though they can stand being rolled off a mountain, ha.

Actually upon further research the WRC cages are back to using a main hoop now. Drivers were having to retire their cars due to roll cage damage too frequently with that design and one driver died (not sure if it ended up being related to the cage or not).

I just got pwned again. I'd better stay out of this thread, huh :P

Actually, a lot of those WRC cages are FIA-certified, which will pass in a lot of US-sanctioned organizations. The trick with that is it has to be EXACTLY to FIA specification, and may or may not need an FIA stamp (don't remember on that last bit). You see this with some imported race cars. The design isn't necessarily inferior (the lack of a main hoop I mean), just a different take. From a practical standpoint, if you're in the US stick to US-spec cages with respect to main hoop stuff.

Ok, well here is what I have been thinking. I dont want to take the car off the street but the speeds I have at the track are concerning and I want to stiffen the car. I still want to get in and out of the car on a daily basis so I am thinking of having that upper door bar removable.

Attachment 25862

The thought is to cut out the seat belt towers and use that area for the hoop giving me more room for the sholder support on these style seats and letting me push the seat all the way to the rear.

Attachment 25863

IF you could do it, I would think it would be extremely cramped. I certainly wouldnt want to test my luck with a side impact crash and x-bars.

I think a removable steering wheel is a necessity in order to get in and out with X-door-bars, even then... well lets just say I'm glad I don't dd mine. Getting in and out of an exige everyday is about the same thing imo.

This is a timely thread. Another winter cage build going on here and I'm looking at the alternatives.

X Bars are still pretty common with the TT crowd here in the Northeast. I have the Hard Dog roll bar/door bars in mine now, and they run just under the edge of my seat (RaceTech 4009W). I could live with a similar setup on the cage. Rollover protection is my top priority though, and I'll go through the X bar/mini/maxi NASCAR bar discussion with the builder. Ideal setup will have better legroom and headroom than afforded by the HDHCDD setup in there now, while adding A pillar support.

Savington - thanks for posting the earlier cage thread. Those TC Design pics will be very helpful.

I forwarded the snowboarder cage pics over to my local builder to start the process. He's done a lot of SM cages but mine will be a little different. Like the original poster in that thread, I'll still be street driving to the track for at least another year and need those photos for ammo when he wants to go all NASCAR on me.

My cage will be a bit different as I intend it to be integrated into a simi Tube frame conversion of the chassis. Not allowed in ST, IT, or Spec Miata Classes. Much of the existing structure in the Unibody will be gone. car will be prepared to the limit of the XP autocross rules to the best of my ability and I hope to be near the minimum 1760 lb limit for a boosted 2.0l while still retaining a windshield and also meeting road race rules for SPO which is basically a GT car. Problem is the only way a Miata can run in a GT class is to drop a rotory in it and it would more likely be a full tube frame.


Example GT3 miata full tube frame.
http://www.pennon.com/products/bodyw...zda/Mazda.html

Bob

A bit off-topic, but if you are going custom, I like some of the things these guys did:


http://carpentermotorsports.com/gall...serialNumber=2

http://carpentermotorsports.com/gall...serialNumber=2

http://web.archive.org/web/201110052...4c5ece2e7ff024

http://web.archive.org/web/201110052...4c5ece2e7ff024

As long as we're going there:

https://www.miataturbo.net/attachmen...ine=1317860039

Im also doing a winter cage. My main concern is side penetration since Im planning on doing W2W racing at some point in the near future.

looks like a chassis for drag racing.

Bob

Yea, drag car project.

That is very much like what I am talking about. I have my donor chassis now. It is basically trash from the front sub frame attachment forward but I didn’t plan on using any of that part anyway. Also now looking at all the metal that I will be removing from other places in the unibody.

Bob

What I do like about the carbon fiber time attack car main roll hoop is that it is pushed out wider in the chassis and integrated into the structure of the aft door B-post. Note there is no seat belt tower like in a Spec Miata or IT ruled cage.

I intend for most of the unibody structure to be gone in that area and I want the roll bar out there so it can replace the missing structure with some more ties to the chassis. I’m looking at removing significant portions of inner structure like the two inner walls of material behind the rear quarter panels along with the rear inner fenders and a bunch of the other stuff with about the only thing left of the stock anybody is the two box section rails that the sub-frame mounts too. Everything else that is not external shell will be removed or replaced with something lighter or more purpose fictional. I plan to go a bit further than many others have gone that I have seen pictures for but not quite a full tube chassis. Allot of the using the cage to re-engineer the chassis structure stuff is not allowed in spec miata or IT rules but in the GT rules and Solo Prepared rules it is I want to take advantage of everything I can.

The one chassis with the re done front end looks cool but It looks to me like those tubes would be much thicker and potentially heavier than stock. I think it is more than necessary. I think I would make it lighter but still very similar. I’m starting with a chassis that hit a telephone pole and everything in front of the front sub frame attachment is wadded up garbage anyway. In the end I still think I might end up front heavy with all the weight reduction I’m planning so I am also looking at shifting the engine back. Looking at the rules I think I can do that. The rules say I can’t modify the firewall for head or cylinder block clearance but I can for the cam angle sensor electrical cooling or the bell housing. Might be able to move the engine back 4 “ I’m guessing.

Bob

http://www.customcages.co.uk/Rollcag...ype=Multipoint

I don't understand the door bars in this design. I can only presume that no bar was located where the seat base would sit because.... well... that's where the customer's seat base sits. I can't argue with the rest of it though - not least because it's been designed by a reputable firm and is all FIA and MSA approved, so frankly it must be pretty sound.

This is interesting... what is it?
Is it Miata subframe based?

is there a build thread somewhere?

I think there might be some issues with SCCA rules with that But I think FIA approval will supersede. The big issue I see is for a LHD car that design would make use of the dead pedal impossible with where the bar attaches down in the foot box area.

Bob

Did they deliberately design the door bars that way to make the car a huge, huge bitch to get in and out of?

Looks more like they forgot that people have to actually get in and out of it. :giggle:

I think you're all just bitter that you're not as young and nimble as you once were :giggle:

But serimeowsly, I think the door bars have been designed for someone who wanted X bars (note the non-stripped doors) but who couldn't locate the lower bar by the seat because of packaging constraints. All seems a bit compromised to me, but equally, I don't know how else they could have done it given the space.
Also, you all need to get in and out of Caterham or Elise road cars a few times. Then sit back and have a think about why you're moaning about ingress and egress in a flippin' race car!

Pfft, a caged Caterham is something to manage at 6'3" ... :D (trough the top circular braces is easiest).

I sadly only have this old (2005) picture of my AMP-cage (bolt in, that's why the front part is not further forward.
https://www.miataturbo.net/attachmen...1&d=1318275677
It's also tight toward the wheel, that's why I use a 300mm (a bit too small), not in this picture, I was just happy to get it together back then.
The seatbelt towers are removed to get the cage in (but can be bolted back with the cage in place... Not the safest option though...). The rear supports (going all the way back to the rear part of the subframe mounting point) are separation points.

The driver area is ok for me at 6'3" with 34" inseam (the bulb on the cage is needed), but the passenger side is useless with the roof diagonal.
Better seatbelt attachment would be a plus (HNRS is hard to get working now).
And having a complete cage all the way to the front shock towers is a dream (the front of the cars have a life of its own now), but I need to take the cage out for inspections... We all have our demons...

https://www.miataturbo.net/attachmen...ine=1318276878
:D

Sounds interesting Bob. Sorry if I missed it, but will this be an open-top car or will you run a hard top? If you are planning on a hardtop, is an Autokonexion fastback an option?

I have an AK fastback on my car, which I installed years after the cage was built. That cage was built to fit under an OEM hardtop. If/when I build my next car, it will also have an AK fastback, and I'll build the cage around it. There is a good bit more that can be done under the AK fastback, and the placement of the back glass is quite different.

I haven’t decided on a fast back yet. but I think this picture is good for showing a big chunk of stock metal bits that I intend to be gone along with trunk floor etc. car will mostly just retain the outer skin. The inner fender and two inner layers of quarter panel will be gone. Depending on what I decide on for wide body kit to fit 23.5X11 R16 slicks much of the outer fender is likely to be gone as well.

https://www.miataturbo.net/attachmen...1&d=1318279370
Bob

Care to elaborate a little? I'm waiting for my AK FB to arrive before I take my car to the cage builder. They have done plenty of SM cages, but I'm wondering what can they do differently under the fastback.

thanks!

Specifically?

https://www.miataturbo.net/attachmen...ine=1318289853

Cages built without thought towards rapid egress in the case of a fire are cages built without thought.

Impacts do not scare me. I have a containment seat, low NASCAR bars, and a HANS device. Fire, on the other hand, scares the shit out of me, and I have a 6-nozzle AFFF system.