CMC Rules - Ballast, Fire, Battery and Accusump placement

[Al Fernandez]

Fire bottle as in for an extinguisher system can be mounted anywhere. Fire extinguisher, as in hand-held, must be mounted within the driver's reach when they are in the seat (technically and strapped in but that I've not seen enforced very much, so just be reasonable).

Mike hit it on the head, the point is not to create mounts or assemblies that quite obviously are designed intentionally to add weight. The marine box is a good idea but keep in mind a plastic box goes around the battery, it does not have anything to do with securing the battery. Most marine boxes come with little J hook mounts and these are not allowed. If you want to go with the simple two point strap type mounting, use 3/8" threaded rod and washers > 1.5" on the underside of the car.

[Gerno]

I don't plan to use J-hooks. I was thinking to use Riv-nuts in the floor to secure things. I've found them to be very solid when installed correctly but has anyone had issues with riv-nuts coming lose on impact? If so I could thru bolt them but that's always a pain to tighten by yourself

[Al Fernandez]

the failure mode of a typical battery mount is the strap pulling out of the fairly thin sheet metal floor. For this reason nasa techs are instructed to look for how thick over how much area the mounts have in order to eliminate that pull through. It’s up to you how you make them comfy given a lack of an actual spec.

[Fbody383]

I was thinking to use Riv-nuts in the floor to secure things. I've found them to be very solid when installed correctly but has anyone had issues with riv-nuts coming lose on impact?

If you were talking about a threaded fastener in 1/4" material I might be able to agree, but not the sheet metal on these cars. I would not personally use a riv-nut to mount anything substantial - I did use them to mount the brake prop valve. For the battery, I ran a strap of 0.90" from bolt to bolt, so a giant "washer."

You don't want that stuff coming loose.

[Gerno]

I'll take your advice and thru bolt it for sure...Thanks for the feedback

[Supercharged111]

Anything that goes through the floor should have fender washers ideally. They also make heavy duty fender washers, I found those at Fastenal. I like using those for ballast.