Twin rollbar hoops

[alphatopher]

I'm thinking about having twin rollbar hoops fabricated. Any pointers here? I really like this design and it makes a four point harness setup quite easy. There is an company in England that makes these rollbars, but the shipping to the states makes them not worth the money. Can Miata, Porsche, or similiar hoops be modified to fit a TR6 easily?

 

[crj7driver]

I don't know if one can be easily adapted but I am interested in a twin hoop as well. PRI Race makes one for the Spitfire https://prirace.com/project8610-1a.htm

Keep me updated, my car is not put back together enough, so this is pretty far down on my to do list.

 

[alphatopher]

Too cool. That is exactly what I'm talking about. I am about a year away from the point where I need to be concerning myself with rollbars...have to finish body work first. I'm thinking that I can find a local welder to bend the tubing and weld plates for cheap.

 

[Guest]

The welding is the easy part. Finding someone that can mandrel-bend tubing that is thick enough to be considered rollbar quality is the tough part, without making it look like a cheap muffler bend. Pretty much the roll bars we all use are vanity rollbars because of the way they are fixed to the car body and not the chassis. There are guidelines for the thickness of the tubing that have to be followed if you are going to create a sanctioned rollbar, and then you won't be able to put your top up. So, agreeing that what you want is a slick-looking double hoop rollbar, you might be better off just digging deep and buying the one you admire. Not that it would happen to you but I have a friend that attempted to fabricate his own unique rollbar and the end result was butt-ugly because of the poor bend quality of the tubing. By the way, Moss-UK has a double rollbar that they market they call an "aero" style that has vinyl coving the double bars. It is quite slick looking. (Mossmotor UK is sometimes tricky to bring up on the web. They keep changing the access.)

Bill

 

[Alan_Myers]

Hi,

Dual hoops are great looking, but simply aren't tall enough to get past the safety inspection in any formally sanctioned race. So you might not be too concerned about the actual thickness or other specifications of the rollbars, either. Twin hoops will be "show bars", not legal for racing.

SCCA rule book can be downloaded from their website (it's a very big pdf), if you plan to go racing and want specs on legal roll bars. I seem to recall 1.75" tubing needs to be used for the primary hoop in all but the lightest cars and .090" is the required thickness. Bends can't be any tighter than 3 times the bar diameter (so a 5.25" radius with 1.75" tubing). There are also requirements for mounting, assembly and bracing. It varies depending upon class.

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[bobh]

Check with Kirk Racing in Alabama. They make headers, roll cages... Classic Motorsports used them to fabricate the header for their TR3 racer. CM said they were one of the best tubing fabricators around.