A-body frame to firewall bracing?

[Mr. Anderson]

Getting my El Camino up in the air and back down again doing the exhaust and other stuff under the car, I noticed how much flex their is in the frame from the firewall forward. I have jack stands on the frames torsion boxes but keep a jack with pressure under the front crossmember because it makes me nervous. There aren't any fenders bolted on currently.

I've been thinking about some bars going from the frame horns to the firewall.

I would weld some heave threaded plates to the top of the framerails above where the sway bar mounts. Then the feet for the bars would bolt on to those (want to keep it removable). At the firewall, I would use some 3/16" or 1/4" steel to sandwich the firewall, probably all along the top of the body seam. And then tubes in between. See attached picture. The dots indicate bolts.

https://static1.pt-content.com/images/noimg.gif

My concerns are the strength at the firewall. I think mounting it right along the seam puts it at a pretty strong area. What do you think?

[ChevelleNV]

Just my opinion but on a full frame A-body I really don't see the need for it. once the car is all together, there isn't a lot of flexing going on. if you really want to stiffen it up. put a cage in it. this mod would be something I would do on a uni-body (Camaro,Nova)

[Bryce]

Do you have solid body mounts?

I dont know how much stiffness would be added by attaching to the firewall. I doubt there is much structure there since it is a full frame car. A cage that ties into the frame ang goes through the firewall with down bars would be ideal.

[TheJDMan]

I don't think bars going from the frame to the center of the firewall would be a idea. Hotchkis makes a similar bar that attaches to the upper A-arm mount and goes up to the mount for the front fender and is completely bolt in.

[exwestracer]

There is some real structure in the body out at the door posts, but you would have to go through the firewall itself, and I'd recommend putting a cross bar in as well. Starts to get complicated... Along your original line of thinking, can you move the firewall mount down to where the bottom of the heater plenum attaches? That is the strongest point you will find in the center.

[Randy67]

My 67 Elkys firewall was not very substantial, just sheetmetal so I don't know how well it would hold up. Then after cutting the center of the firewall on my 81 Camaro for crossover headers, there really isn't alot to the firewall as far as a strong structure. Putting a cage in it is a better idea, or go with something like the Hotchkis bars mentioned above.

[Mr. Anderson]

Thanks for the input guys! Think I'll scrap this idea and keep moving forward.