How do you anchor a bolt in roll bar?

[TheJDMan]

According to SCCA rules if you bolt in a roll bar or cage the mount pads must be backed up with a plate of equal size on the back side of the panel. My Question is, since the roll bar main hoop pads set on top of the rocker panel boxes so how do you get a plate on the back side? It occurs to me that I could weld a mount plate to the surface of the rocker box then bolt to the welded plate. How does everyone else mount their bolt in roll bar? Does anyone have any detailed pictures of your roll bar mounts in a 1st gen they would be willing to post?

[Gitter Dun]

Look into the Auto Power bolt in cage. It is NASA and SCCA approved.

Mounting Plates-Bolt in cage

The attaching points of a bolt-in cage to the body must use reinforcing plates to sandwich the body. At least 3 bolts are required for each bolt in plate and the plate must be 3/16 inch thick. All hardware must be SAE Grade 5 or better with 5/16" diameter minimum. All nuts must be held securely by a locking system such as safetey wire, lock washer, Ny-lox, or jam nuts.

Mounting plates-welded

Mounting plates shall be no greater than 100 square inches and no greater than 12 inches or less than 2 inches on a side. Welded mounting plates shall be at least 0.080 inch thick. Plates may extend onto vertical sections of the structure. Any plate may be multi-angled, but shall not exceed 100 square inches total.

[exwestracer]

Steve,
Typically, the bolt in cages are designed to sit on a (relatively) flat area on the floor itself. Did you buy the bolt in unit you are referring to? If it sits over a boxed section of the floor, I suppose you could use some LONG bolts (not so good), but with the rockers you are still dealing with angled sheetmetal on the bottom...

Welding the plates in is by far the best way to mount a roll bar.

[nine lives johnny]

exactly^! the scca expects if your not going to weld the cage to a mounting point, you'll need to sandwich the stock sheet metal. for an example you can see the bottom of a mounting point on a miata https://static1.pt-content.com/images/pt/2011/11/backingplate-1.jpg if you cannot use the 2 plate method you'll need to weld it.

[Gitter Dun]

I agree. Welding the base plates is the best way to go. I am running an Auto Power cage but had it entirely welded together. At the time it was the most economical NASA and SCCA approved custom fit cage to buy.

I'll post some pic's of the base plates later on tonight.

[GaRys69]

I'll post some pic's of the base plates later on tonight.

Can you also include pics that show how it fits the lines of the interior?

[TheJDMan]

Thanks Guys! I know about sandwitching the mount plates, I read and understand the SCCA rules regarding bolting them in and that is great if you can access the back side of the panel. But my question was, how to you backup the mount pad when it is located in a place where you don't have access to the back side such as the rocker panel boxes. I think the answer is, you don't. Welding is probably my only option and is not a problem, I was just exploring the option of removing it if possible. The pads of my main hoop rest directly on top of the rocker panel box and the rear supports actually align with the rear outboard seatbelt bolts which puts them directly over the rear frame box. These locations are very stong points in the body, but they do not provide access behind them for a backup plate. It looks like my only option is to weld them.

[Gitter Dun]

Hope these pics can answer some of your questions.

https://static1.pt-content.com/images/pt/2011/11/Rollcagebasemounts460-1.jpg
https://static1.pt-content.com/images/pt/2011/11/Rollcagebasemounts459-1.jpg
https://static1.pt-content.com/images/pt/2011/11/Rollcagebasemounts458-1.jpg
https://static1.pt-content.com/images/pt/2011/11/Rollcagebasemounts457-1.jpg
https://static1.pt-content.com/images/pt/2011/11/Rollcagebasemounts456-1.jpg
https://static1.pt-content.com/images/pt/2011/11/Rollcagebasemounts455-1.jpg
https://static1.pt-content.com/images/pt/2011/11/Rollcagebasemounts454-1.jpg
https://static1.pt-content.com/images/pt/2011/11/Rollcagebasemounts453-1.jpg
https://static1.pt-content.com/images/pt/2011/11/Rollcagebasemounts452-1.jpg
https://static1.pt-content.com/images/pt/2011/11/Rollcagebasemounts451-1.jpg
https://static1.pt-content.com/images/pt/2011/11/Rollcagebasemounts450-1.jpg
https://static1.pt-content.com/images/pt/2011/11/Rollcagebasemounts449-1.jpg