Why are roll cages so expensive?

[magnetic1]

LABOR. A LONG LONG time ago, I used to think the same. It takes LOADS of time to measure, notch and then have MULTIPLE notches that all fit together in ONE node.

You can go on the cheap and have bars that terminate inches away from one another, but not me.

[99MPower]

...notch and then have MULTIPLE notches that all fit together in ONE node. You can go on the cheap and have bars that terminate inches away from one another, but not me.

THIS THIS THIS... people have no idea how difficult this is, and how many cages are built that are WRONG because of this

[PflaumerBMW]

THIS THIS THIS... people have no idea how difficult this is, and how many cages are built that are WRONG because of this

Ditto, one of the hardest practices I've designed for and fabricated.

Here's some fitting I've done in the past, personally, and tube fitting is an art if you are doing it all by hand. I am lucky enough to have access to tools that allowed me to design these in 3D space, and I made my own CNC cutting equipment to profile these. Why? It was quicker to design a machine that would cut these, than to try to cut 60+ individually coped/fish mouthed tubes by hand, no joke. Even with machine cut tubes, some fitting was required. The second picture is 8 tubes coming together into a single node. FML. BTW, the few tubes that look like they are not matched up, they are floating and turned a bit, they did actually get within less than a 1mm gap all the way around.
So if you want to spend time at the track and have your cojones all together by the end of a slip up on the track, give the money to the guys that do this well, unfortunately it's the price to pay to have speedy fun in a safe way.
Lastly... in case the OP didn't figure this out before, most (not all...) of the products and items out there, material cost is almost the smallest % of what makes up the price.

[jrkoupe]

Ditto, one of the hardest practices I've designed for and fabricated.

Here's some fitting I've done in the past, personally, and tube fitting is an art if you are doing it all by hand. I am lucky enough to have access to tools that allowed me to design these in 3D space, and I made my own CNC cutting equipment to profile these. Why? It was quicker to design a machine that would cut these, than to try to cut 60+ individually coped/fish mouthed tubes by hand, no joke. Even with machine cut tubes, some fitting was required. The second picture is 8 tubes coming together into a single node. FML. BTW, the few tubes that look like they are not matched up, they are floating and turned a bit, they did actually get within less than a 1mm gap all the way around.
So if you want to spend time at the track and have your cojones all together by the end of a slip up on the track, give the money to the guys that do this well, unfortunately it's the price to pay to have speedy fun in a safe way.
Lastly... in case the OP didn't figure this out before, most (not all...) of the products and items out there, material cost is almost the smallest % of what makes up the price.

nice first post:

[HandsomeMike]

Bringing this back for a question after reading this post. In the pic with the Mustang upside down and the backing plates and roll bar tubing sticking through the floor board causing the roof to crush in, what was done wrong with the install of that bolt in cage to cause that to happen? Just want to know as I plan to install a bolt in 4 point sometime in the near future and want to be sure to avoid this. Thanks!

[snaponbob]

Bringing this back for a question after reading this post. In the pic with the Mustang upside down and the backing plates and roll bar tubing sticking through the floor board causing the roof to crush in, what was done wrong with the install of that bolt in cage to cause that to happen? Just want to know as I plan to install a bolt in 4 point sometime in the near future and want to be sure to avoid this. Thanks!

Over the years, this has been discussed. IIRC, the owner admitted to allowing a less than perfect installation. ANYONE who installs custom cages should know how to do so properly. As for "bolt in" 4 and 6 point cages, you would be well served discussing this well know installers or vendors. I chose a Kirk 4 point (for various reasons) but it is for Timer Trials and track day events, not "real" racing.

So, the question is --- what will you be doing with your car?

[pbonsalb]

When you install them, you have to make sure the load is spread a certain amount. If the feet on the Kirk are 3x4 inches, for example, you should install 4x6” plates underneath the feet. You also sandwich the chassis by having a plate inside the car and a plate outside the car. I installed a Kirk in my 99 M3. Mine is just 4 point mounting with a cross bar in the main hoop. I have bolt in door bars but have not installed them.

A proper cage that is welded into the chassis is much better, but costs a lot more and takes a lot longer to install.

[golgo13]

I have a rollbar in my car that's a four point. The plates are bolted through the body and (I learned this later) the fact that the plate ends are pointed corners are a weaker design, as they help cut the body under load (be it static or shock) so you want rounded edges for the plates.

Some pictures of my rollbar from Ben Sipson in Florida from when I got it in 2016:

[snaponbob]

I actually assumed that the sharp edges could NOT be good --- and rounded the ones on the inside of the car.

[Michael9218]

When you install them, you have to make sure the load is spread a certain amount. If the feet on the Kirk are 3x4 inches, for example, you should install 4x6” plates underneath the feet. You also sandwich the chassis by having a plate inside the car and a plate outside the car.

Good advice that anyone installing a bolt in cage should heed. Especially in an E36. The floor sheet metal is very thin and the fenders not much better. Distribute the load as much as you can. At least double the area as stated above. Weld in cages are attached to the side sills that are structural. Never the floor.

[The sage]

I bought a kirk racing bolt in kit for m3 e36 after seeing an old pic of an e36 after a rollover.

2012-11-04_16-34-59_629.jpg2012-11-04_16-35-17_210.jpg

[HandsomeMike]

Snaponbob - I do track days and SCCA TT. From what I've read and what I've seen on here I am pretty sure Kirk 4pt roll bar will be the way I go.

Golgo - Great pics and info!

I am two years into HPDE and TT and my car is basically done being setup for the classes I plan to do with various groups, so I want to put my focus on safety now. Roll bar, seat, harnesses, etc. Sounds a little backwards to do safety last, but it's my current focus. Even with a stock E36 M52, the speed is still enough to matter.

Thank you all!

[bimmerboy318]

Ben Sipson bar here. He will greyhound your bar to you and you can paint yourself or have someone powder coat.

[topfuelman]

I have a bolt in 4 point auto power with harness bar - for e36 sedan for sale. However I’m in alberta Canada…hit me up if you can figure a reasonable cost way to ship it wherever.