Installing a functional roll bar in a Spider is far more complex than it seems, but it is certainly achievable. First, you need to determine if you plan on using this for street safety, or track safety. Plain and simple, a track legal roll bar is impractical for the street, and there is no design that meets track requirements and fits underneath the car’s top, with a stock seat configuration. (This holds true even for Murray’s, aka “msiert”, roll bar.) A bar that doesn’t meet track requirements, but could support the weight of the car presents a whole set of additional issues. Of course, anything can be fabricated.
There have been various roll bar designs offered for our Spiders over the years, but today, the usual USA vendors have reduced these and only offer two designs: the “street” or “show” bar that offers no rollover protection, and the Autopower competition bar which requires removal of the Spider’s top frame.
An off the shelf “show” bar can be reinforced to withstand a rollover, but you will have to ensure that it does not present any danger to the occupants, as their heads could come in contact with the bar. (Impacting the bar would more than likely kill the person.) Dealing with the comfort concerns, since the “show” bars limit seat travel and seat recline is another issue. Last, but most important, the Spider rear deck, behind the seats, is inadequate to support a functional roll bar. The rear deck has a “double” floor, and any mounting design must take this into account in order for a bar to be properly secured.
The commercially available Autopower roll bar is for a dedicated race car, and its mounting points require that the entire top and even the top frame be removed, so it is not even an option for most of us. At one point, Autopower made a track legal bar that could be mounted to the rear deck, but they discontinued that years ago. Thus, for those of us who want to place a street Spider on the track, the only option left is to have a roll bar custom made. And that’s what we’ve done.
A track legal roll bar requires that the bar be above the driver’s helmet. With a stock seat, and a roll bar that allows the top to go over it, this requirement is impossible to meet, unless the driver’s torso is abnormally short. Thus, either the bar is made taller and the top won’t fit, or the seat track arrangement is modified and different seats are used. Murray’s bar does fit under the top, but he swaps out his stock seats for different seats when he goes on the track, and the arrangement is way too uncomfortable for any type of extended driving. Other people with bars that allow the top to go up remove the seat cushion when they go on track events, but this may or may not provide the proper clearance. Others with a bar that doesn’t allow the top to go up simply fit the bar when they go to track events.
As I said, you will find that many of us have come up with a solution that works for whatever our purpose is, and you can certainly learn from what we’ve done. Be prepared however, for a pricey endeavor, unless you bend pipe, weld pieces to it, and also can cut and weld your Spider.
You will find specs and a description of what the Alfa Romeo Owner’s Club considers a safe track bar in the AROC-USA Competition Code. This is the link: http://www.aroc-usa.org/library/docu...deJuly2007.pdf
Below are some pictures of the bar that I use. It doesn’t allow the top to go up, and I only use it for Time Trials. It takes 16 bolts to secure it to the car.