This article is one in a series that have been released in conjunction with Wayne's book, 101 Projects for Your Porsche 911. The book contains 240 pages of full color projects detailing everything from performance mods to changing your brake pads. With more than 650+ full-color glossy photos accompanying extensive step-by-step procedures, this book is required reading in any Porsche 911 owner's collection. See The Official Book Website for more details.
If you ever want to step up to the next level in weekend racing, you will most likely have to install a roll cage in your car. Depending upon the class and rules that you are racing under, you may be required to have the roll cage and associated 5-point harness installed before your car hits the track.
The installation process of the roll cage is really not too difficult, and most can be installed with without any major alterations to the chassis. They are usually mounted to the floor of the car, and also to the rear shelves, just outside of the rear seats.
There are several different types of roll bars available, but most can be put into two different categories: street and competition. The competition bars have a cross brace that extends about shoulder height across the width of the car. The street roll cages usually don't have this cross brace. The competition cross brace strengthens the roll cage, and also provides a very convenient spot to tie your 5-point harness to.
Installation of the roll cage can be done in an afternoon, but it's important to work carefully, as you don't want to accidentally drill holes in the wrong spots. Both of the front seats need to be removed, and you will have to carefully maneuver the roll cage a bit in order to insert it into the rear of your car.
When you are ready to mount the roll cage to the car, make sure that you follow the directions of the manufacturer very carefully. Improper installation can affect the safety and structural integrity of the entire setup. Before you decide to drill any holes in your car, carefully measure the bar to make sure that your holes will be symmetrical on both sides. You may want to remove some of the fabric from where the rear mounts attach before you start drilling into the car.
Most roll cages have pretty large mounting flanges, but you may want to reinforce them with plates underneath the chassis floorboard. This will help prevent the floorboards from tearing from any unforeseen stresses placed on them. I recommend reinforcing any attachments to the floorboards, whether you are bolting in a roll cage, or adding seat belts to your car. The floor of the car can be surprisingly weak.
Roll cages not only make the car safer, but they look cooler too. The addition of the roll cage also allows you to easily attach your 5-point racing harness. One of the more popular additions to the roll cage is the addition of a camera mount so that you can videotape your driving performance for evaluation later.
Most roll cages are very similar and relatively easy to install. Removal of the seats is a must, and you should make sure that everything fits before you start drilling holes in your chassis. Make sure that you really want to install one before you jump into the process. Removing and reinstalling the roll cage can be a pain. This photo shows a competition roll bar with the cross brace installed.
The roll cage is mounted to the floor of the car. Backing plates on the floorpan underneath the car are usually a wise idea to prevent the floor from buckling under a significant load. The good news is that you probably won't care too much about damaging your floorpan if there is a load on the roll cage: your car will be upside down with the roof completely crushed! (let's hope not)