Rear firewall with fuel cell?

Rich Schmidt

Veteran Member
Mar 27, 2010
4,285
Denville NJ
mrdragster1970 said:
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Exactly, like in the old days when guys used fence post for their cages.
The rules are there because we can be idiots.
If you're going to build the firewall, do it right.


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Fence post??? That's sounds kinda high end compared to some of the stuff I have seen. A lot of cars in the 70's including a few very prominent pro stock cars had roll cages made out of stick welded black pipe. That old SRD race cars 70 Camaro that I own has a black pipe cage. When I talked to Richie Zul about Grumpy's 70 Camaro when he had SRD build it,he said it had a black pipe roll cage too!
 

79supergasdriver

A Scholar and a Gentleman
Jun 22, 2005
768
Wichita, KS, USA
How much of that factory sheet metal (behind the seat backs and package tray) is structural? I have a trunk cell but no roll cage yet; I'm not nearly fast enough to require one. I'm wondering if I can cut all that stuff out and bend/cut my own rear firewall, or if that factory stuff provides structural bracing.
 

muscl car

Veteran Member
Lifetime Gold Member
Jul 8, 2001
23,894
Gallatin Tennessee
79supergasdriver said:
How much of that factory sheet metal (behind the seat backs and package tray) is structural? I have a trunk cell but no roll cage yet; I'm not nearly fast enough to require one. I'm wondering if I can cut all that stuff out and bend/cut my own rear firewall, or if that factory stuff provides structural bracing.


All you need is sheet metal to close off that bulkhead , this so in the event of a battery explosion or fuel cell fire that the pass compartment is safe that's all , nothing structural to build just closing off the trunk to the pass compartment

Most people will cover the package tray and bulkhead with sheets of aluminum and some will just use patch panels riveted to the bulkhead
 

79supergasdriver

A Scholar and a Gentleman
Jun 22, 2005
768
Wichita, KS, USA
muscl car said:
All you need is sheet metal to close off that bulkhead , this so in the event of a battery explosion or fuel cell fire that the pass compartment is safe that's all , nothing structural to build just closing off the trunk to the pass compartment

Most people will cover the package tray and bulkhead with sheets of aluminum and some will just use patch panels riveted to the bulkhead

Understood, thanks for the info! Now I need a brake and shear...
 

hypnotix73

New Member
Jul 2, 2012
14
Newbury Park, CA
Another question..

I cut a bunch of sheet metal and filled every hole, with the exception of one little piece. There are two wires which, I suspect, run to the rear brake lights (I'm not 100% on that yet). Anyway, the wires run through a little hole on the driver's side rear compartment. Do I need to get some sort of electrical firewall bulkhead or is there a better way to seal this off?

It is a very small opening so I was even thinking of putting some caulking or something to seal it off.

Any ideas?
 

hypnotix73

New Member
Jul 2, 2012
14
Newbury Park, CA
mrdragster1970 said:
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I know they make fire block silicone, not sure if that's legal???
I used rubber grommets for all my wires, and passed tech every time.
I have a few so I have multiple grommets.

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Awesome. Thanks. I was going to use the fire resistant sealant for the little gaps that I have (like where the roll bar goes through the rear firewall) so hopefully it is legal. The gaps are tiny (probably like 1/16") anyway but I figured that I should 100% have this thing sealed off.

I'll definitely use the grommets then. I'm probably over analyzing it, as my car will only be a mid 10 second car but I'd rather not drive two hours to the track only to be turned around.
 

Marv D

Veteran Member
Lifetime Gold Member
The goal is to give you a chance of survival until the safety crew gets there. I've seen lots of bulkheads with small holes for wires and chute cables etc. in the 0.032" aluminum bulkhead. It's not like the cabin is a 'safe-room' made of 'fire-board' that is going to keep you sealed in some O2 rich environment,,, it's to keep the flames somewhat contained and off your @$$ while the safety crew extracts you and gets the fire out.

Matti and others may remember this one at SCSN some 4 or 5 years ago when Eric Peterson (I believe) hit the wall about 1/2 track and was knocked out. It pinned the throttle at WOT and it was such a cloud of smoke, fire and engine screaming and wheels grinding into the track, tire smoke and fire that the safety crew coming from downtrack couldn't find the car. They had no idea where it was going to take off towards screaming at 8000RPM, IN GEAR. With tire smoke from the slicks and car burning and a blinding cloud no one could blindly run through to try and save the driver.Super scary wreck. He fortunately survived,,, but ONLY because the car was BUILT RIGHT!

This incident started when he hit the LEFT wall, and it jammed the throttle at WOT, the car (under full power) took off spinning and hitting BOTH walls at least once or twice. An insane thing to watch.

EPETERSON.JPG


Don't have to look hard to see the car had hit both walls and was IN MOTION and ON FIRE.

Here's another shot gust before it finally lost the slicks (and I was smart enough to raise the camera) and was finally stationary just grinding the wheels into the track (it it finally burned through the fuel lines or ignition wires or something and the engine died so they could approach.


EPETERSON2.JPG


The rules are there because bad things do happen. And you don't always have the opportunity to control the situation,,, give the rules a chance to save your life. Look at what they are trying to accomplish and don't just follow the 'minimum' word of the rule,,, Build it as though your life depended on it.
 
Last edited:

muscl car

Veteran Member
Lifetime Gold Member
Jul 8, 2001
23,894
Gallatin Tennessee
Marv D said:
The goal is to give you a chance of survival until the safety crew gets there. I've seen lots of bulkheads with small holes for wires and chute cables etc. in the 0.032" aluminum bulkhead. It's not like the cabin is a 'safe-room' made of 'fire-board' that is going to keep you sealed in some O2 rich environment,,, it's to keep the flames somewhat contained and off your @$$ while the safety crew extracts you and gets the fire out.

Matti and others may remember this one at SCSN some 4 or 5 years ago when Eric Peterson (I believe) hit the wall about 1/2 track and was knocked out. It pinned the throttle at WOT and it was such a cloud of smoke, fire and engine screaming and wheels grinding into the track, tire smoke and fire that the safety crew coming from downtrack couldn't find the car. They had no idea where it was going to take off towards screaming at 8000RPM, IN GEAR. With tire smoke from the slicks and car burning and a blinding cloud no one could blindly run through to try and save the driver.Super scary wreck. He fortunately survived,,, but ONLY because the car was BUILT RIGHT!

This incident started when he hit the LEFT wall, and it jammed the throttle at WOT, the car (under full power) took off spinning and hitting BOTH walls at least once or twice. An insane thing to watch.

EPETERSON.JPG


Don't have to look hard to see the car had hit both walls and was IN MOTION and ON FIRE.

Here's another shot gust before it finally lost the slicks (and I was smart enough to raise the camera) and was finally stationary just grinding the wheels into the track (it it finally burned through the fuel lines or ignition wires or something and the engine died so they could approach.


EPETERSON2.JPG


The rules are there because bad things do happen. And you don't always have the opportunity to control the situation,,, give the rules a chance to save your life. Look at what they are trying to accomplish and don't just follow the 'minimum' word of the rule,,, Build it as though your life depended on it.


I remember that crash and it was so surreal seeing it sit on the track with the throttle hung open and rear tires up in smoke

The throttle hung immediately once he launched causing him to impact the l/side wall which knocked him out
 




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