well, it was a though. how about a good way to mount lead? i was thinking a steel box welded in the backseat area, a bolt, very large bolt through the floor and box and then a lid for said box. also have it re-enforced by tying into cage? no? then on top of said weight box, i plan on mounting two water tanks. now here is a n other one of my thoughts. what if i used two aluminum fuel tanks?
It all depends on how much ballast you want to be able to attach, how likely it will need to be changed (add or subtract weight during the event) etc.
First you need to figure out a ball park number regarding how much weight you want to be able to attach.
Weight of lead per unit volume -- 0.4092 lb/cubic inch. 2.44 cu. in. of cast lead weighs1 lb.
One method is to get some large size square tubing, cap the end of the tubing and fill with cast lead then cap off the open end. Drill a couple cross bolt holes through the tubing or weld mounting tabs to the square tubing and bolt in place. A piece of 2x2 square tubing filled with lead would weigh around 1.2 -1.5 lbs per inch of length depending on wall thickness of the steel tubing
I personally would mount the ballast with more than one bolt, so you don't have a single point of failure if one bolt comes loose or pulls free in a crash.
With properly fabricated square tubing segments you could have removable bars that are manageable by one or two people and lots of options for mounting them.
I would definitely have some sort of containment structure for the bars and a VERY stout box if you decide to go that route. Think about the shock load on the box if you undergo a 5G crash impact, and brace and gusset accordingly.
You really don't want there to be any chance at all that the ballast would break loose in a crash, and end up bouncing around inside the cars drivers compartment.
I would mount them as low as possible near the center of the car on the outside frame structure, so if they come free in a crash they leave the car to dissipate energy.
Larry