rear firewall

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wedgie

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The rules say that I need a .024 steel or .032 aluminum rear firewall because I have a trunk mounted fuel cell. Can I just make covers for the three speaker openings in the package shelf and then fab a three piece cover for the opening behind the seat or does it need to be one piece? Does it need to be welded solid or can I stitch weld it and silicone any minor openings?
 
The rules say that I need a .024 steel or .032 aluminum rear firewall because I have a trunk mounted fuel cell. Can I just make covers for the three speaker openings in the package shelf and then fab a three piece cover for the opening behind the seat or does it need to be one piece? Does it need to be welded solid or can I stitch weld it and silicone any minor openings?
This is what I did with my drag car. I think it also depend on the track you go to.
 
:clock:
They only care about thickness- I pop riveted all with small pieces, with caulk.

Can I carpet over it then, or do I need to leave it exposed for the tech inspectors?
 
well for mine i just used steel, then used self tapping screws to hold it on through the cross brace and all that, then i put my back in and never had any questions, The track i go to most the time dosnt even notice if your battery isnt in the engine bay or if your running a fuel cell but for a more strict track i would just throw carpet over it and let them look at it through the trunk, they will have a little less to see that way and if theres no light shining through indicating gaping holes through it then you should be ok.
If you make an effort and put something solid there you should be alrite i think but every track is different, im going to run carpet over also so when i remove my seat it will look decent..
 
The goal here by NHRA is to separate the drivers compartment from the trunk area in case of an accident,battery explosion etc. If your car is ever tech inspected accurately, YES they have to be two separate compartments meaning sealed drivers compartment from the trunk area.
 
So what about the wiring that goes back there? Just use a rubber grommet at the bottom or can there be no rubber in the firewall? Also does the package tray have to be permanent or can you use Zeus fasteners? I'd like to have speaker back there for the cruises and most of the use of the car and then be able to take them out and cover it for the track. Is that allowed?
 
well depends track to track like alot of rules. some are more leanient, more are real strict, find out by other racers at the tracks your hitting, becasue thats where your getting inspected. The idea is to seperate the cab from the truck like mentioned, not 100 % would mean everything welded shut, Even if your putting screws or something then unless you weld the screws after its not 100 % and if you used any cauking for the edges instead of welding, then thats not 100% either same as a rubber grommet for wiring... some nhra rules are not very super clear on the requirments and if thats the case go ask the track your racing at. when it comes down to it they are the ones inspecting the car, not us, not the people on the tech line for nhra, but the track or tracks your going to,
m2c
 
If you wanna keep speakers and a backseat then put the firewall in the trunk and make it semi-premanent. What I mean is, drop steelangle, or flat stock, down from the trunk lid seal area and attach a sheet of your favorite metal from the wheel tubs and inner rear quarters, to the trunk seal and floor, with aluminum rivets, or Dzus fateners. Might even consider making it 2 pieces with a lap joint in the center, under the rear window. Easily removable and yet seperated from the passenger area. If it's done nice, the tech guys'll be so impressed, they'll leave the rest of the car alone.
 
it can be one or several pieces of aluminum or steel and can be fasten by welding, rivets, screws or bolts. it'll have to cover the whole area with no big holes. the wires can fit through, under or around it. you can use the same metal for the package tray and mount your speaders in it and none of it needs to be covered unless you want to spend the money or have a "class car".
 
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