Patience, thought, and insight! There are any number of places you can put a tube. Many of them are even fairly effective. But there is one place to put that tube that works better... if you have the skill to know where it goes. The trick is in studying the various parameters involved, and making sure that one tube does not over look or counter-act any of those parameters to an unacceptable degree. Compromise is indeed necessary, but should not be called upon to excuse a lack of skill!
This cage was built for a PCA F-stock 944 Turbo. The parameters were reasonable weight, good protection, chassis bracing, and ease of ingress/egress.
Will your elbow clear the door bars? Will your head hit the side or front hoops? Can you get your self into the cockpit without need of chiropractics? Will you be able to adjust your seat so your helmet clears the roof?
Will the shoulder belts address your body at the proper angle?
This cage was designed and hand fabricated to meet the specific needs of the owner and eliminate the endless frustrating compromises found in off-the-shelf, store-bought designs.
Considering the purchase price of a prefab cage, plus the not inconsiderable cost to have it installed,
getting what you really want and need is no more expensive in the end!

All in all, a Safe, Stiff, Tidy Environment to do your Business!

Don't go Short, Don't go Nuts . . . GO
This is a cage I built in a
VW Rabbit for Ice Racing
The cage I built in
Project 930S
Fully integrated
INTO the existing chassis for maximum stiffness and space efficiency.
Here is a recent project in a 79 Porsche 928 destined for more serious Driver's Education use. The owner wanted to start with the rear portion of a full cage. The rest can easily be added later.
The first salvo in the battle is something I developed in my own car - The Endo-Skeletal cage system.
I start out with a sill tube on either side. This gives a complete unbroken connection between main tubes that normally would only be attached
Half-cage in a 928
to isolated steel plates. I feel this gives a much more harmonious sense of integrity to the cage, and adds stiffness through increased triangulation.
As you might imagine, these are tricky tubes to bend, and on the 928 they are particularly challenging, with 4 separate bends in different plains.
The main cage components are then built on top of this sill tube foundation. As always, I tuck them in as close to the existing unibody as possible to maximize space utilization and to compliment the stiffness of the existing chassis.
The main cage is a design that mimics my 944 bolt-in roll bars. Since the car is not intended for racing, I use a different pattern than would be dictated
by racing rules. Instead of a diagonal cross brace that only protects the driver, and only in one direction, I use this design which I feel gives much more vertical support. It also has other advantages such as not fouling the rearward view, offering potential seat support, stiffens the belt mount area and minimizes belt slide.
Another example of offering maximum protection with minimal use of space and minimal encumbrance to vision or ingress/egress.
Anyone can have a cage that
will simply "do the job."
Or... you can have one crafted just for you.
A cage with fully optimized driver safety systems that you can be proud of!
letter of the rules. They are usually trying to save weight, but this obviously gives short shrift to one of the main goals... SAFETY.
Inexperienced fabricators are prone to adding tubes everywhere in order to make things stiff and safe. This adds too much weight, and can be infringing or actually injurious if the tubes are not well placed. Somewhere out there is an illusive middle ground. But how to find it?
Building any cage requires expertise and some expensive, specialized tools. Building a truly effective cage takes a lot more. Many people can do it. The differences between good and truly effective can be small, but are ultimately quite important.
The prime considerations are space efficiency, protection, weight, and adding structural stiffness, and I would offer these to you in that prioritized order, depending on ones intent. These parameters seem mutually exclusive, but they are inextricably linked and must be combined in the right manner to achieve the desired result: a stiff, light, safe cage that one can get into and out of!
Some builders are tempted to go minimal, only just meeting the
As always, I strive to take up as little useable cockpit volume as possible, running the tubes out to the interior walls in most cases. The side hoops go through the side air ducts in the dash (like in the Turbo Cup cars of old) and the door bar ties in low to maximize footwell access. The main hoops weld to the inner roof frame, tying the upper unibody to the cage for added stiffness. The triangulation and cross bracing keep intrusion to a minimum and lend much stiffness to the chassis at critical points.
How about a Cage for Me?
Der Fliegende '44 finally gets a cage of its own.

Not just any cage. Nope. Nothing generic about this one. I set out to create something visually and technically interesting. I wanted to try new ideas and blow away some boring traditions. Some of the stuff I like and will use in the future. Some of it is kind of eye candy. Half race car, half show car. ALL of it is thought provoking, which was quite the point!
We start right off with the belt bar. Not only is the shape, anchoring, and positioning of it unique, but I have never seen belt mounting done like this before. This accomplishes many things at once. For HANS use, proper belt angles & height are critical. Mounting the belts closer together than they are when they pass over the HANS device causes them to pull together
instead of split apart if you were to hit something, helping keep the belts ON the HANS yoke. Further, this eye bolt mount - normally only used for lap belts - allows for a straight belt path from the mount plate in any direction that the belts project. Lastly, it also fixes them in place laterally so they don't require collars or some other means to keep them from sliding laterally on the tube. Very neat, tidy, and innovative!
Yes, we're starting with a sill tube. It is the basis for the entire cage from front to rear. It is fully welded and integrated into the chassis over its entire length, both inside and out. It is part of the car!
The sill tube gets it first tenant (right); the side hoop. The hoop is fully integrated into the side of the body to maximize space efficiency and stiffness. As you can see below, the inner roof panel was trimmed away to allow the side hoop to move out further away from my head. I gained at least an inch. I nested this tube inside this channel.
You can also see the door bar assembly that takes root on the sill tube. You can see some of the esthetics mentioned previously. The arch of the door bar braces lends some visual appeal. Different!
Part of the show car look is fully filled and smoothed transitions from cage to chassis. This is definitely not something you would see in a full blown race chassis, but  it will give an integrated and sophisticated look that you just can't get otherwise.
Yet another area where the cage was seriously integrated into the existing chassis was the main roll hoop. Fabricated sheetmetal pieces were welded in to box the main hoop directly into the door post, making for a super stiff and visually interesting assembly. The side intrusion protection that this beam structure offers is impressive, and it provides a ultra solid mooring point for the door bar.
More interesting features. For the header portion of the cockpit - its most vulnerable area - instead of utilizing one large 1.75" diameter tube as is usually the case, I used two 1.5" tubes. These are not only stronger than a single tube, but can also be nestled very close to either side of the existing roof beam, saving room in the process. As with the rest of the structure, the header is fully integrated into the existing chassis.
Along with the door bars, the side hoops are also integrated into the roof line by fabricating sheetmetal filler sections and welding them in along their entire length. This was a huge amount of work in welding, grinding, and sanding, but the result is a smooth integrated look that is unique and impressive.
Most sanctioning bodies require a diagonal brace from the top driver side of the main hoop to bottom of the opposite side to brace the cockpit in case the car rolls. Somewhat unconventionally, my diagonal starts to the right of the driver's seat to create a halo around the driver's head. The top joint is nicely braced by this hammer-formed sheetmetal web (1).
Another requirement is a cross tube from one side of the main hoop to the other. Most builders do this with the belt bar. While I have added a tube - which increases clutter and weight a bit - because of where I wanted my main hoop and how tall I am, I split the task. My cross tube picks up the center tunnel and is sectioned right into it (2). Extremely strong.
Arguably the most controversial portion of this cage is the rear bracing. Most builders use two tubes that form an X to brace possible chassis twist from suspension and cornering loads. These tubes usually block some portion of the rear view, which I wanted to avoid. Instead of that convention, I came up with this rather creative piece. I'm told by structural engineers that it is essentially an inverted vaulted ceiling truss ; a well-known and significantly strong apparatus. It is made from 1" tubing. The design spreads loads and forces in all different directions instead of only one or two like a conventional X.
I must admit that a big reason for the existence of this
intriguing structure is for the Gee Whiz factor. Since it is so very unconventional, I also fully expect it to drive a lot of people that profess to have some knowledge and understanding of such work completely nuts. This fits the goals of the project - pushing the limits of imagination -vs- "The Rules."
1
2
1982 Porsche 911 SC
N.A.S.A. / PCA Club Race
This job required a complete driver's compartment with custom reinforced seat mounting, belt mount points, left & right side window nets, seat back brace, welded sunroof, rear view mirror, etc. Everything was custom sized to the owner (shorter than "average") for maximum efficiency and effectiveness.
The system was built to meet N.A.S.A. specs, which require at least a double door bar. As such, we decided to do a modified X. This layout offers a very favorable compromise between side intrusion protection, longitudinal stiffness, and ingress/egress.
Because the X projects out to a point at the center, when hit, it transfers forces in compression up each "leg" of the X and into the front and rear roll hoops, spreading the load over a wide area. Because of this, it is very difficult to collapse this structure. The short tube bracing the end of of the upper rear leg of the X into the base of the rear main hoop stay further spreads the load into areas that simply will not move easily.
At the base of the dash, the side hoop takes a bend down to meet the inner rocker panel at the base of the door pillar. The upper front leg of the X intersects the side hoop at the bend point, which is not as well supported as other areas. To increase the stiffness of this area, I created this nice corner gusset. Not only does it look nice, but it spreads potential loads over a much larger area of the side hoop. Spreading load to the widest area of structure is what it is all about. The more "hands" helping, the lighter the load!
One tricky aspect of the outward projecting X door bar assembly is actually setting it up so that it CAN project outward. In a full on open class race car, you simply gut the window mechanisms and invade the door cavity to get this geometric projection outward. However, in a stock class car where doors must be maintained in "stock" form, you don't have that luxury. In this case, the only option is to make the points on the main cage that the door bar attaches to rest inward.
Unfortunately, the side sills in the 911 are not wide enough to nest these inward set tubes on top of. The solution is to
create those wider sills with steel plate. At left and above are those plate assemblies. Boxes made to give a serious footing to the main members of the cage system. They allow the main tubes to nest solidly and inward of the existing chassis so that the door bar can then project outward to gain the geometric strength inherent to that layout. The result sees potential forces being distributed in many ways into a much larger surface area. Again, spreading the load far and wide is the goal.
The biggest reason to go with a custom cage is so that everything can be tailored to the specific needs of the driver. In this case, the driver is of below average height and did not have enough headroom in the car. What? Yes, that's right. With the stock mounting points, and with his seat set for proper reach, his head was hitting the upper windshield frame, and this was before the cage header tube went in!
At right you see the original seat and sub mounting, and then below a complete custom seat mounting platform fabricated from .125x 1.25 angle iron. This allowed the seat to be mounted at least 2" lower, to a much more solid structure than the factory mount flanges, and also incorporates a reinforced sub belt mount point (eye bolts).
The red arrow above points to a large dent in the floor pan. If you were tempted to mount your subs to this  floor pan using these eye bolts and large washers - a practice which is still considered "standard" and acceptable by many - you should think again. Do understand that the sub belts see just as much load as any other belt in the system (1500-1800lbs in a 35-40G hit), and they are absolutely crucial to the effective performance of any belt system. A tin floor pan will obviously not support that kind of load. As an analogy, would you place your floor jack under the center of the floor pan and expect it to raise the car without crushing the floor upwards? Of course not, and so why would you put essentially the same load into it with a sub mount? When you really think about it, ANYTHING is an improvement over that old convention, and this setup is designed to take the load!
Another necessary part of the cockpit is the side netting. Seemingly a simple thing to deal with, on the face of it. However, the difference between having one that works well and one that is an infernal hassle makes it tricky. If you have ever watched a driver struggling mightily to get his window net in as his run group is heading out onto the track, you'll understand the benefit of a system that is easy to live with.
With Head & Neck restraints, head restraint seats, and all the other equipment a driver wears these days, getting a net into place can be a real chore. With this driver sitting so far forward, trying to get a generic seat belt latch rod into the hole in the rear bracket is a real pot shot.
I cooked up this ingenious little system of getting the rod into
the tab without even having to look. All you have to do is get the end of the rod in the ballpark, push the tail of it over until you hit the hand fabricated steel funnel, and then slide it back into place. It requires no effort, no swearing, no waving wildly trying to get someone's attention to come over and help you get the $%*#@ net in so you can go qualify. It is just so stupid simple you don't even really have to think about it. The hand made drilled corner gusset is a nice touch too. Typical!
Did you ever see - or even think about - artistically rendered roll cage padding? Well, here it is. The SFI 35.1 spec high density padding is pretty difficult to work with, but it can be shaped to fit your needs with some care. A little time spent creates a pleasing environment, and also keeps this stiff foam from cracking and falling off!
The lower rear mount for the window net has a spring clip so you can take the net right out for DE or lapping days where it is not required. A stainless 1/8" cable lanyard prevents the inevitable and inopportune loss of the $%&@ clip!
Another item that is devilishly tricky to get mounted right is a right side net. It needs to be positioned so the driver can look over it, but high enough to catch the shoulders in case the driver spills out of the seat for some reason. It also has to be out of the way of the shifter! At left below is the nicely shaped upper mount on the main hoop, and at right is the net in place.
Details make the difference between adequate, and seamlessly functional. The rear seat brace drop brackets are supplied by Brey-Krause. The side gussets are hand crafted to not only brace the mounting flanges, but also create belt slots to keep the belts positioned close together for proper HANS architecture. The tab at the lower left is for the lower right side net mount. Three tasks performed by one well crafted assembly. Again... typical!
Wink multi panel mirrors are my personal favorite. They offer clear rearward and sideward vision with no distortion and perfect depth perception. The trick is in mounting them effectively, especially for shorter drivers. They need to be out and forward so that you do not have to move your head to look into them. Custom fabricated slotted alloy side brackets and careful positioning not only make it vibration free, but put it in just the right spot for comprehensive vision.
Also note the revised belt mounting points. To get optimum performance from a modern harness system, you need belt paths running at the right angles. You can just see the factory belt mount point at the upper left corner of this pic. Because this driver sits so far forward, the angle of his lap belt was far to close to horizontal. You can see the fabricated inner & outer belt mounts on either sill that place his belts at exactly the right angle, and also move the outboard mount in closer to the seat, further improving the performance of the belts.
Are you getting the idea that this is all quite involved? Good... then you can see why a cage-in-a-box can't hope to manage all of the disparate and yet intertwined aspects of a proper driver cockpit.
1986 Porsche 944 Turbo
Street with some Driver's Ed use. A true Dual Use car.
Just about the hardest thing to do in the performance world is make a car that is good for both street and track. When it comes to roll cages, it is even harder. Putting a bunch of tubing in a car you might like to drive quite a lot on the street is problematic at best. It can be downright dangerous at worst. This project presented these problems in spades.
This is a very highly modified car that will likely be putting down about 400hp to the rear wheels when it is completed. Obviously a good cage would be a smart addition to this much potential, but how to do it so that it wasn't lethal to drive without a helmet on?
The cage itself is fairly straight forward. No fancy door bars or such, but it does have a few interesting features. At left you can see the main hoop and the rear stays with proper placement to reinforced areas of the chassis and included angles within accepted norms. Since this car will maintain a full interior, the overhead shot shows you the proper distance of tubes to allow the panels to fit in their normal places.
To this basic setup, a one piece diagonal from corner to mount point was added, and then a belt bar set to the proper height for the belt holes in the seats. A slight bend at the top end of the diagonal lends a much nicer look than simply notching a straight piece of tube, and almost lends a "driver's-roll-hoop-within-a-cage" quality.
Moving to the front of the cage, we deviate from the space allowed for stock interior panels and begin to move toward a  full custom interior treatment. Now we are trying to maximize space and minimize intrusion into the cabin. This not only gives more room, but improves safety. The side hoops and header tube are tucked as tightly as possible into the existing roof structure.
One note about single header tubes. I often see them installed behind the existing windshield header assembly. This is really a bad idea. This tube should be placed as far away from the driver as possible to minimize the chance of impacting it in a crash, particularly in this case where the car will be piloted on the street by an un-helmeted driver. They should always be placed at the very top of the windshield where they are out of the normal arc of the driver's head as it swings forward and down in an impact. It also makes for a lot more room to get your helmet on and off inside the car!
Here are a couple of items that are a bit different.  This car has Leda remote gas reservoir coilovers, and I mounted the rear canisters on the rear cage stays. A nice place to mount them out of the way, and yet easily accessible. The shoulder straps are mounted by eye bolts to threaded inserts welded into the belt bar. This affixes the belts in proper position, and looks nice and neat. they are also easy to remove if you want them out of the way for street use.
This is where this car really diverges from the norm. The cage is very comprehensively integrated into the interior. This not only looks extremely sanitary, but it also increases street safety. Each tube is first wrapped in the correct high density SFI 35.1 foam padding. Then, the voids between the cage and the unibody were filled with expanding 2-part foam, which was then trimmed and contoured to give a smooth base surface. This was all then wrapped in a thin 1/4" layer of foam to give some tactile feel, and then finally wrapped in high quality black vinyl.
As usual, pictures do not do it justice. From many angles, you don't even notice the cage, particularly if you are looking only at the passenger area. It is a very unique and satisfying place to do business, be it cruising down the road, or hammering at the track.
The cage under the dash is also hidden behind custom carpet pieces. Even the original hood release assembly is retained, something you don't often see.
1986 Porsche 944 Turbo
PCA Club Racing E-Class
Building on lessons learned from the '82 911SC cage project, I sought to construct a 944 cage that had many of the same attributes, but was a bit simpler to build. The 944 has a nice wide frame sill in the rear that allowed me to get the base of the main hoop quite far in to achieve the same outward projection of my "geometric X" door bar system without building the plinth to attach to. In a break from the earlier tradition of making all tubes nest tightly to the inner surfaces of the body, this main hoop is very simple, with just two 90 degree bends at the corners. These are positioned to bring the base of the main hoop well inboard to achieve this outward projection.
The car came with a bolt in cage that was no longer compliant with modern racing statutes, simply was not very safe in any event, and did not allow for proper architecture to optimize modern safety systems like Head & Neck restraints, side nets, etc. This pic shows the base plate from the old  cage being sectioned out. The outline of the new 1/8" steel dual plane (top & side) base plate is traced on the frame sill. A bit more substantial foundation! This wide sill allows for the far inside mounting of the base of the main hoop to make the door bar system work while still retaining the factory door panel and power window system.
The cage at right is from a different car, and is slightly different in terms of the sill tube being the basis for everything, but is essentially what is being built for this car. It uses a traditional base plate with the main hoop attached directly to it to make it "legal" under NASA rules (NASA will not recognize the sill tube as a sufficient base plate). To beat them at that game, I did the base plate, attached the main hoop to it directly, and then nested the sill tube against it and running forward from that point (eliminating the red portion). The rear stay & door bar brace also attach to a traditional baseplate on the frame sill instead of an extended sill tube.
The pic at left shows the actual completed door bar system with the generic baseplate layout, but the unique sill tube running forward from it and passing by where the side hoop attaches to the sill. You can clearly see that the door bar creates a very complex load path for all forces trying to enter the cockpit, and sending them in many directions, all of them away from the occupant(s). The little doodad pictured above right is another way to beat the rules makers. You are limited in the number of attachment points you can have to the chassis (6 {main, side hoops & rear stays x2} + 2 {front diagonal braces x2}). This is a little keeper made of thick angle iron plus a chanel welded down the inside of the frame that resists the sill tube sliding off the sill in a side impact.
In the front, in order to facilitate that outward projection of the door bar system, the side hoop was run inside the frame sill and attached to a side plate welded to it. You can also see the sill tube running by the side hoop / door bar junction. It continues forward to provide an attachment point for the door bar counter brace, which is similar to the rear one above.
The pic at right shows the completed front structure with extensive baseplating and integration into the existing chassis.
The pic at left shows the same area form the outside. Again, it depicts the extensive plating and integration into the existing chassis as well as gathering the sill tube in with the side hoop and door bar assemblies. All of this by way of creating highly complex and redundantly braced load paths to redirect and kill any intrusion forces threatening the occupants.
The pic at left shows the outward projection of the door bar system built into the cage. The completed door bar system above shows how the forces are sent in every direction but toward the occupant(s) and ultimately into the chassis. Because these loads are divided amongst so many different tubes and into many different areas, the load that each area sees is relatively small. Many hands make light work, as the old saying goes. This is the idea behind truly effective roll cage design. Not only is it safe for the occupants, but it also takes a much more massive impact to damage the chassis substantially, a point that is not to be overlooked when you consider how much time and money is invested in even a basic race car these days.
The pic above shows the very simple main hoop, now with the addition of the diagonal, belt bar, and rear stays. I always put a nice radius bend on the upper junction of my diagonal bars instead of the generic beveled end on whatever angle they intersect the main hoop at. This little touch is merely a conceit of mine. A touch done in deference to a classic time when roll hoops only protected the driver in an open topped vintage sports car. They just look much nicer to me than the generic method, giving a reassuring halo feel to the main hoop above the driver's head.
All tubes are important, but no one more so than the header tube. This is the most vulnerable portion of any cage, since it is impossible to really support this area directly and keep it from coming down on the occupant(s) in a roll over without substantially blocking the door opening. I use various means to try and resist this collapse. First, you can see that the tube is placed in front of the existing roof structure, out under the top of the windshield. This is very important in getting this tube as far away from the occupant(s) as possible, and is a major shortcoming of most cages I see. You can also see the arch bent into this tube, which directs forces sideways and attempts to push the side hoops outward, which they will not do. You can also see the corner bracing added to try and create more of a platform to spread loads over a wider area and thus to better resist downward forces.
These pics show how tightly the cage if fit inside the roof structure. In fact, in order to maximize clearance for the occupant(s), I cut out the inside portion of the roof beam structure over the door opening. This makes it so flimsy that the doors won't close until the cage is welded up to support the door aperture shape again. However, it allows the tubes to move outward another 2-3 critical inches. Here you can also see the next effort to support the roof. These angled braces reduce the unsupported portion of the side hoop by 15-20%, and send downward forces down into other frame members.  If you look closely at the upper left pic, you can also see the white sheetmetal funnel that accepts the end of the window net rod, like the one on the 911 above. This quickly becomes a favorite little feature.
An important part of any complete safety system, but one that few people pay much attention to, is proper belt architecture. There is a ton of very specific information available to optimize the extremely high tech harness systems available today, but most people simply do not seem to be aware of it.  Perhaps they choose not to be, as it can be EXTREMELY difficult to fulfill all of the requirements of the modern systems without some fairly indepth knowledge of how they function, and some fairly advanced ideas of how to implement those mandates. The pictures at right show one rare aspect of belt optimization; custom lap belt mounts. The driver of this car has pretty long legs, and he needed belt mounts much farther back than the still visible stock mounts in order to get the proper angles for his belts to be optimized. Reinforcing plates with Grade 8 nuts welded on are positioned exactly where they are needed to achieve this.
Most people never give them much thought, but the sub belt is absolutely critical to making the entire harness system (Schroth Hybrid 3/2 in this case) work to its peak of efficiency. This custom reinforced sub mount starts with a piece of .125" x2" channel iron sectioned into the floor dead center between the 944 Series II seat mount structure. The hand fabricated appliance that holds the belts can be placed anywhere along this channel necessary to achieve optimum sub belt angles, and then a hole is drilled through and the  holder is bolted down with a single 10mm Grade 8.8 bolt. The appliance fixes the belts in place for proper fore/aft positioning, and also angles them correctly for good inner thigh wrap.
Last but certainly not least, the right side net. The final piece to of the complete safety system. Attached at the proper points on the cage and chassis both front and rear, the right side net will catch everything that comes it was should the seat or belt systems fail. Like all the rest of the pieces, proper positioning is critical to peak performance. The net is placed high enough to catch a substantial portion of the driver's head without blocking his side view, but low enough to catch the shoulder and upper torso. No driver safety system is truly complete without one, properly installed, of course
Another step taken to brace the front of the cage is the reinforcing of the highly vulnerable bend in the side hoop at the base line of the windshield. As the wreck picture above clearly illustrates, this is a very highly stressed and under supported area, and anything one can do to reinforce it is well advised. This small brace made of 1" tubing with its apex mounted strut will add a huge amount of support for this bend at a very low cost in weight, expense, or infringement on ingress/egress. Cheap insurance. Note the tidy dash closure panels and the custom, easily reached hood release.
This picture of an inverted 968 dramatically illustrates how important driver protection can be. This bolt in cage arguably did the job, but JUST BARELY. We will now discuss the most vulnerable area of any cage, and some things that can be done to improve its performance.