Just another forward firewall

[Mountain-Metalworks]

Nothing really special here, just another relatively easy firewall forward mod. I'm interested in a clean engine-side firewall so I'll be putting the entire heater assembly inside while still having a glovebox(new FFR molded dash). I'm going to try using either dual marine wipers synched together or fab up something similar to a Jeep, which will also be inside. I picked up several sheets of .050" 6061 that were a "Fire Sale" at the local Speedy Metals. A company had ordered 50 sheets of 24" X 48" and then rejected the order so they had them CHEAP. Win for me.

I couldn't make a bend as wide as the whole firewall so I took one sheet to the local HVAC shop and we made a bend 5" from the bottom. Their brake makes super sharp radius bends in thin sheet steel so we first cut a 2" sacrificial strip and bent it. This clearly cracked the .050" aluminum as expected. Cut another 2" strip and loaded them both in the brake which now produced a larger radius in the second strip, though a slight crack as well. Finally loaded the real piece with both sacrificial pieces to produce a nice rounded radius. We didn't re-adjust their bend-bar offset so even on a massive brake it took lots of muscle to essentially cram .150" of aluminum(3 sheets of .050") into a spot made for .030" of sheet metal ducting. It worked beautifully....

Once bent, I traced my original firewall onto the new piece and cut it using a band saw and 4.5" cutoff wheel. It mounts under the 2" cross tube creating a trough that will be used for the heater setup. I'll be sandwiching the original .040" dash with the new .050" one to create a nice sturdy .090" dash similar to the FFMetal offering.

That's the easy part. The more challenging issue is modifying the upper and inner DS side footbox panels. Lots of compound angles which make it a measure 15 times, cut once type of ordeal. Worked well though and finished up using my new new Harbor Freight brake press. Best sub-$50 tool I may have bought for this build so far(see write-up here).







I'm pretty happy with everything so far, we'll see how well the original arch works once the body goes back on for a test fit. I'm sure it'll need some minor adjusting.

-TJ

[Makgecko2017]

Looking Great!

[wareaglescott]

Nice work. Really smart process using the sacrificial pieces to make your desired bend!
What kind of motor is that? Would there be any issues getting it in or out with the forward firewall in position?

[Mountain-Metalworks]

Nice work. Really smart process using the sacrificial pieces to make your desired bend!
What kind of motor is that? Would there be any issues getting it in or out with the forward firewall in position?

Motor is a 6.2L LS3 with an ASA cam, should have plenty of go-power when you tap the skinny pedal. Good call, with the relatively large T56 Magnum it's gonna be challenging to get the motor/tranny combo in and out easily. I'm not going to permanently attach the firewall for a while yet, hopefully after the last time the engine goes in. I actually installed the tranny from the bottom and mated it to the engine with no flywheel or clutch at the moment. I may just keep doing that since it worked pretty well working by myself but we'll see.

-TJ

[NAZ]

jeepurz, I suspect your 6061 had a T-6 heat treatment and that stuff just does not want to bend 90-deg even as thin as .050". If you use a large enough radius (like you did) it works OK but is tough to bend. When I need to increase the radius I use pre-bent strips to fit over the fingers that way I'm still only bending one sheet. Since I have a pan brake with individual fingers the strip also improves the bend quality. There are bending radius charts you can refer to. Or if you don't need the T-6 strength you can pick up 6061 in T-4 or O (annealed) treatment and it's much easier to bend and work with in general. Also much less expensive. For future panels consider 3003-O temper -- it's even easier to work with, has better corrosion resistance properties, and way less expensive that 6061 T-6. 6061 T-6 is heat treated structural aluminum with much higher tensile strength making it hard to work with when forming shapes. I enjoy seeing guys take the uncharted path and putting their personal touch on their builds. Looks like you have fabrication experience and not afraid to modify things to suit your needs. Good work!

[PeteH]

Nice work! That extra room will be nice to work with. Mine is crammed with duct hose now, even though I made up a small heater box mounted to the engine side of the firewall, and the only protrusions inside are three 1 3/4" snouts to attaché hoses to. If you're installing wipers later, I suspect the tube and wheel boxes will now be behind the firewall between the firewall and dash, keep that in mind for clearance. Remember that you'll need access to the windshield frame holes that are now behind the dash on passengers side, although it might be easier than the standard setup.