Educate me on rollcages

[82SC]

well I plan to put a full roll cage in my non-exsistant project car...

I was wondering if you guy can post pics and opinions, venodrs and approx prices...

I know there are full roll cages...
partial roll cages
weld in roll cages
bolt in roll cages

there are ones that bolt to the floor pan
others that bolt to suspension points

roll cages that can have parts removed for street use

I guess what to look fo in a roll cage and stuff to avoid...

I thought a cage like this would be cool...since it is subtle and I think RUF hides it with the headliners and upholstry...



But I have been told it is pretty expensive going custom....

I guess I just don't want my car screaming RACE CAR while I use it day to day....

Thanks

MJ

[stormcrow]

Steve

[Don Wohlfarth]

If cost were no object (yeah, right) I don't think you'd be able to afford to do a concealed cage the way RUF does it.
Even if you did decide to install a concealed cage you could possibly run into a problem with PCA, POC, whoever, that would accept it before they'd let you on the track.
Trying to minimize the intrusion into the cabin would require a custom cage and it would be fairly expensive. The prefab cages are designed to fit a variety of different years and saving space in the cabin is not a priorty.
You also want to consider what you want to do about the sides, removable bar, welded in bar, NASCAR style bar. Climbing over a bar on a street car gets old real quick.

[jluetjen]

MJ:
Since you said "Roll Cage" and not "Roll Bar", I assume that you want something substantial. Looking at the picture that you attached -- that's not substantial. It looks like a roll cage but will do virtually nothing in a serious accident. Here are a few "rules of thumb" regarding making a real "Roll Cage". BTW; Having bought an Autopower in the past versus pricing out a cage done the way I want it done, a good welder is not that expensive. Especially if you consider that an Autopower or similar cage is not a whole lot better then the picture that you included. Steve's picture is worth a 1000 words, but I'm going to share a few words on top of that. These define a pretty good cage. Where you chose to take shortcuts will be your decision. (Note that I've paraphrased a lot of this from the SCCA General Competition Rules).

1) The main hoop (behind the driver) shall be the full width of the cockpit. The main hoop shall be a near to the roof as possible on closed automobiles and not less then 2 inches above the drivers helmet on open automobiles with the driver seated normally and restrained by seat belts and shoulder harness.

2) Front hoop (3 options: )
a) The front hoop shall follow the line of the front pillars to the top of the windshield and be connected, by horizontal bars, to the op of the main hoop on each side (as close to the roof as possible.)
b) Two side hoops following the line of the front pillars to the top of the main hoop may be used. These two side hoops are to be connected by a horizontal bar over the top of the windshield.
c) A top "Halo" hoop following the roof line from the main hoop to the windshield with forward down tubes following the line of the front pillars to the floor.
d) Double "ear-type" joints are allowed, provided that they are fully welded at all mating surfaces.

3) Fabrication:
The main hoop shall be one continous lenght of tubing with smooth continuous bends with no efidence of crimping or wall failure. The minimum radius for all bends shall be 3-times the tube diameter measured from the tube centerline. Whenever possible the roll hoops shall start from the floor of the vehicle. (Take note of "Mounting plates" below). For a Porsche 911 of between 1500 and 2500 lbs, the material shall be 1.50 x .095 mild steel or 1.375 x .095 Alloy steel. If the car weighs more then 2500 lbs, the material shall be 1.5 x .120, 1.625 x .120 or 1.75 x .095 mild steel or 1.5 x .095 Alloy steel. The steel shall be seamless or DOM mild steel tubing (SAE 1010, 1020, 1025) or equuivalent or ally steel tubing (SAE 4130). (Using the right materials is key! I once say a roll-hoop from an early '70's McLaren CanAm car. It was comparable to the tubing used on an average home vacuum cleaner!)

4) Bracing: All required bracing shall be the same diameter and wall thickness as the main hoops. All main hoops shall incorporate a diagonal brace (same diameter and thickness as the main hoop) to prevent lateral distortion of the main hoop.

a) Main hoop bracing: Main hoops shall have 2 braces extending to the rear attaching to the frame or chassis (Often the rear shock mounts). Braces shall be attached as near as possible to the top of the main hooop (not more then 6 inches below the top) and at an included angle of at least 30 degrees.

b) Removable Bracing: Removable bracing shall incorporate connectors of the double lug, tapered or muff type. The double-lug type shall include a doubler, gusset or capping arrangment so as to avoid distortion or excessive strain caused by welding. (Keep in mind Carroll Smith's point about never ever mounting a bolt in single sheer. There should always be plates on both sides which the bolt passes through so that all bolts are always in double sheer.)

c) Front Hoop Bracing: There shall be 2 braces extended forward from the front hoop to protect the drivers legs. It is recommened that this bracing extend to teh bulkhead in front of the driver's feet; but in any case it shall be integrated into the frame or chassis to provide substantial support for the front hoop. (These are often extended to the tops of the front struts).

5) Side Protection: The minimum side protection shall consist of a side tube connecting the front and main hoops across both of the door openings. Additionally, there shall be also either a diagonal tube from the front hoop to the main hoop bisecting the door opening below the horizontal side tube , or not less than 2 horizontal side tubes. Additional tubing may be added. NASCAR style door bars are recommended.

Mounting Plates: The thickness of mounting plates bolted to the structure of the car shall not be less than the thickness of the roll hoop or brace that they attach to and shall be backed up with a plate of equal dimensionson the opposite side of the panel, with the plates through bolted together. A minimum of 3 bolts per mounting plate is required for bolted mounting plates. All hardware shall be Grade 5 or better with 5/16" diameter minimum. Mounting plates welded to the structure of the car shall not be less than .080" thick. Whenever possible the mounting plates should be extended onto a vertical section of the structure (such as the door pillar). (Often boxes are made that tie in the floor to a vertical section of the car and then the tubing is welded to these boxes.) (Note that these cages are often gusseted to the car's frame, so the main hoop will also be gusseted to the B-Pillar/Door-jamb as well as the car's frame where it goes around the roof.)

(Other thoughts: Note that triangleation is good. So running braces from the top of the main hoop to the rear shock mounts is required. But running a horizontal bar from the shock mounts back to the main hoop (forming a triangle) opposite the door bar(s) is even better. The same applies elsewhere. This is where the cage that you pictured is lacking. None of the bars are triangleated. A good hit could cause that cage to just fold right up!)

Short of cranking up some CAD software, that is the best description of a good cage that I am aware of.

[MMARSH]

I have a $1200-$1300 Saftey Devices Cage. Believe me, Nobody is more concerned about my well being then me. That being said, I have complete confidence in this cages ability in a roll over. I have seen cars that have rolled with this kind of cage and it has done its job. They have been building cages for along time and have race series in Europe that are required to run their cages. if they were not good they wouldn't still be around. (But then again MM has been around for awhile too )If I had a car that was doing 180mph down the front straight at Willow Springs and was 100% full race, then I would probably have a cage that tied all the suspension points together and was completely triangulated. On another thread someone mentioned that Bolt in cages dont do anything to help chassis flex. That is wrong. They do.

The places that I know of that do custom cages for 911's start at about $2500. It may be done less expensively, but I have not seen them.

Most of the Autopower cages I have seen bolt to the floor. Thats a weak area and I wouldn't suggest it. I know that you can have Autopower make you a cage that will bolt to the sills, like the Safty devices and the OG racing cages do.

Bottom line is it's your money and your head. What do you feel comfortable with. There are many options out there. People have alot of different opinions about this. I think the key is to look at how you are realistically going to use the car and get a cage that match your needs and safty requirements.

[stormcrow]

One more pic with more detail

steve

[82SC]

sweet looking ride...post some full pics from the outside...

wow...lots of great information...thanks

I am achiving this for when I build my full time track car...

But now I guess I am looking for the best options for a car that will be 30% track, 70% street...

offer good protection

and be minimally intrusive

I know some cages have a mid section you can bolt in and out...

I just don't want a car that screams race car when I use it on the streets....

MJ