mdbickell

I know there's been a lot of discussion here re: roll cages, but I'm interested in what people have to say about my specific situation.

I currently have a DAS rollbar and I'm looking move to a full cage. I mostly attend POC events (time trials right now, but I'll probably start racing next season), so a roll-bar is all that's mandated, but I think I want the extra protection of a full cage.

To stay in my class (Improved) I can't have any suspension points attached to the cage and I can't have anything going through the bulkhead. Additionally, I have to leave most of the interior intact. I think this pretty much follows the requirements for PCA stock class.

From what I gather, a welded cage is preferable to a bolt-in cage. How big of a difference is there in both safety and adding chassis rigidity?

I'd also like some suggestions on manufacturers? Autopower sounds like the standard fallback, but who else is out there? I don't think I'm in a position to get a fully custom cage. Any suggestions on who to call for installation and/or fabrication in Southern Cal?

thanks.

P.Po

mdbickell wrote: "I don't think I'm in a position to get a fully custom cage."

IMHO...I don't understand that comment. It only costs about $500 more. The custom cage would actually FIT the car, do less damage to the interior, and most likely be safer. That assumes of course you have a knowlegable builder. I believe that you are in a position to ONLY consider a fully custom cage.

mdbickell wrote: "From what I gather, a welded cage is preferable to a bolt-in cage. How big of a difference is there in both safety and adding chassis rigidity?"

The bigger variable is the construction and design of the mounts and the mounting area not the mounting type. That is one reason why I would stay away from pre-fabbed cages. The mount locations are usually a compromise for ease of install. All things considered equal welding is most likely better... but one can argue either way...

-Patrick

mdbickell

Patrick - I haven't priced out my options yet, but my guess is that a custom built cage is significantly more expensive than an off-the-shelf unit. Perhaps I'll be proven wrong... which would be nice. If the price difference is only $500, I'll probably go that route. If I can't find a good fabricator close to home, my shipping costs will be far more than $500.

Right now, I'm in an information collection stage. I need to get a better understanding of what my options are before I can compare prices and figure out what works for me.

Thanks for your thoughts.

Lefty's Deceiver

I bought an autopower roll cage from eBay and installed it myself. The hardest part was drilling all the holes. Works and fits fine and only cost $600. A custom cage is $3000.

Tristan

DJF1

I may have a different view than some on this, but IMHO the cage is of paramount importance to be safe. Let me explain. There was an accident last year at a club race. The car had a fully "custom cage" in there and the impact was severe. The driver fortunately survived, barely and some of the comments I heard were that the cage was too stiff. Up until that point I was not aware of any issues with too much stifness, but apparently there is according to some people I have spoken with.
While I'm not claiming to be an expert, this incident alone prompt me to buy a cage from Heigo with the logic that if Porsche trust them as a supplier, then there is some R&D involved here with crash testing etc. The $$ that Porsche alone is spending in R&D cannot be matched by any shop in my view. While I do not claim that shops are doing a bad job or building unsafe cages, but for me alone, I trust an OEM supplier more than anyone else.
Again I know this is a touchy subject and I do not want it to be viewed that I want to discredit any manufacturer...

JackOlsen

Call Dave at TRE Motorsports, 818 509 0257. They built me a great cage, incorporating my existing roll bar, and putting in bolt-on side bars that I can take out in street driving.

They're in North Hollywood.

kary993

Here is San Diego I had a custom welded in cage done by Tim at RacerX. The cost was $2000. Fits car very well, got custom bars where I wanted them and it made the car very stiff for track use. I feel much safer in this car and the handling is awesome.

James Achard

Danny brings up a very good point in regard to cages being too stiff. The popularity of NASCAR style door bars is a prime example. If you look at a new Cup Car, they have a simple, gusseted X protecting the driver from side intrusion. NASCAR style bars are designed for NASCAR's; 3400lb car going around an oval. A Porsche is not 3400lbs. Also, All Porsche factory cages are DOM 1020 steel( I can't remember the Euro steel spec). No one uses 4130 Cromoly since it transmits more impact into the driver.
Any cage designer should be running some kind of FEA on their design to ensure proper functionality. They should also supply the client with ALL the material specs for the material they used. This includes welding rod.

Cheers, James

Cheers, James

Alan C.

When you decide on what you want to do be sure to get a firm price. The shop I went to wanted to get into the PCA and BMW groups and offerred to put a cage in my car at a good price. The shop does outstanding work and builds NHRA certifide cages.

When it was done the price was DOUBLE the quote at $4000 .

I negotiated it down to $2800. At that price I was happy and I had a good custom cage. But it was a pain in the rear I hadn't anticipated.

SGOGT4

Jack... do you have any pictures of your cage?

sjanes

I have a Safety Devices bolt in cage in my 911. A buddy of mine had a custom cage built for his 930 around the same time. Cages are similar (i.e. single door bars, not tied to suspension, harness bar, single diagonal in rear). His cage cost about $500-600 more than mine, but is stiffer, and is closer to the car than mine (by a bit). If I had to do it again, I would have done the custom cage. For now, I'm going to see if I can get my bolt in cage welded to add some chassis stiffness. The thing about custom cages is that you can get what you want depending on your budget.

JackOlsen

Here it is when it was going in:





The side bars are removeable:



The armrests are cheapo models that just slide in for long trips.

Cory M

This would be ideal, assuming (and this is a BIG assumption) that the builder had an engineering background, good FEA software, proper training on that software, time to run and optimize several iterations, run tests to correlate their results, etc. If people expect this from the average cage builder they are going to be very disappointed.

Some cheaper simplified software like Grape is made just for spaceframe and cage design and it allows you to make quick comparisons of different designs and tubing sizes, but it makes a lot of assumptions and I wouldn't use it for more than a relative analysis comparing different design possibilities against each other.

A lot of people "oohh and ahhh" when they see pretty pictures of CAD and FEA models, but the results are only as good as the underlying assumptions. As the saying goes: "garbage in, garbage out".

In my opinion you are better off finding a cage builder who is an excellent craftsman and has a good understanding of the theory behind cage design, regardless of whether or not he owns a computer.

MJR911

I agree with Cory. Pay particular attention to the welds and look at past product.

Russ Murphy

Ditto. I'll take a excellent fabricator over an engineer with mediocre fabricating skills any day in this situation. In fact I did with my cage and I'm extremely happy with it. You don't become a outstanding fabricator without understanding materials and their limitations. Both attributes of course would be swell.