NHRA rear firewall question ???

It finally got above freezing today and i used the time to make a new rear firewall / bulkead for the Dodge .The rules say the trunk has to be completly sealed off from the driver ,and although i did my best and there are no gaps ,its not an air tight seal around the rollbars.I used 22 gauge galvanized sheetmetal (so i wouldnt have to paint it ),but i used sheetmetal screws to attach it ,so i could remove it easily if need be.Does it have to be welded together or not ? Anyone see a problem with this passing tech ?

 

Is the 22 gauge going to be thick enough. I dont have My rule book here its a work, But I dont think 22 will be thick enough... As far as the small gaps around the bars you can caulk it....JOhn

 

NHRA rulebook for 7.50 or slower says .024 inch steel or .032 aluminum. Bulkhead must isolate driver compartment from trunk. Doesn't say how to mount it.

 

22ga galvanized = 0.0336 and use fireproof caulking

reference

http://www.unc.edu/~rowlett/units/scales/sheetmetal.html

 

So the galvanized metal thickness is okay ? The reason i bought 22 gauge is because the S and W catalog sells a kit for a rear firewall and the ad says its 22 gauge steel or .040 in aluminum .I couldnt see paying $80.00 plus shipping ,for sum sheetmetal that i bought for $36 here in town...

 

I can't speak for every inspector, but if you pay attention to the rules and have all the big stuff done, especially the neutral safety and battery kill and safety harnesses done properly, they generally don't get too deep into the car. If it's clear you are conscientious about safety, they won't tech quite as hard. If you are a corner cutter, they will tech you to death. I have calked the rear firewall shut, welded it shut, and not put any sealer at all, and never had a comment made either way. The seat belt retention, neutral safety switch and grounding of fuel cell seem to be checked the closest in my experience. But that's a select group of inspectors, once again. I've only raced at 4 tracks.

 

The cars I have been involved in had the bulkhead at the back seat pop riveted in place , and all , 20 plus , have passed tech fine . As for the gauge I used .032 "aluminum like the rest of my tin work . Hope that helps , Rob.

 

You're good. Sheet metal screws should be ok. They just want you to make a decent effort on the firewall, yours is better than most.

You might want to caulk the bar areas to keep the noise from the sheet metal vibrating against the tubes quiet, if anything.

 

Metal gauge is fine, as far as sealing it up...I was told by a Tech to seal it up just for your own safety, anything to slow down the fuel if you are on ur top and fuel is trying to find you..... know what i mean.

 

Thanks guys ...

 

I am working on putting a rear firewall in my 64 fairlane, and I was curious if you need to put sheetmetal inbetween the outside of the wheel wells and the body sides? If i stick my head in the trunk and look forward I can see all the way up to the door jamb. I realize this will get closed off to the passenger compartment by the door panel, but I am planning on running factory rear panels and don't know if this is sufficient. Also, what brand do you recommend for fireproof caulk?

 

your ok without closing up those holes as long as you run rear door panels, pop rivets screws are all ok.

Use clear silicon for sealing up smaller gaps. get a big tube that goes in a caulking gun.

as for guage of metal,,, I have always used .040 aluminum, 2 guage steel is ok. (They never check thickness though)

 

Sheetmetal screws have a way of comming un-screwd and winding up in $licks

 

so do pop rivets, dzus fasteners, springs, jet motor parts, and just about anything else that has been put on a race car.