'73 Vega GT All Aluminum Wildcat 355 Project

Contents:
Page 1: Engine Block prep
Page 2: Head mods
Page 3: Induction/Exhaust
Page 4: Engine Assembly
Page 5: Front Suspension Mods
Page 6: Rear Suspension/Weight Transfer Mods
Page 7: Rust Repair and Undercarriage prep
Page 8: Frame Rail fabrication/Unibody support
Page 9: Body Mods
Page 10: Transmission Mods
Page 11: T5 Rebuild
Page 12: BMW Radiator Swap

Frame Rail Fabrication

There is a bunch of minor stuff I've been doing to the project. Mostly search and identify on rust or hidden problems. On the up shot I've only located two areas of rot. There is a bit of surface rust on parts as well. A big chunk of it was in the uni-body frame supports for the rear suspension. I've cut out those supports now so I can treat the rusty areas and seal them.

ANYWAY! On to the frame rails:

The biggest problem for my Vega project was what the stock Buick 215 torque did to my stock Vega rear suspension. The stock 215 is no powerhouse but it does put out about 220 lb/ft of torque. This caused my Vega's weak unibody construction some nasty damage. The biggest problem was the left rear trailing arm support. It buckled under normal use! In the end the rear left was pushed far enough forward that it was tracking to the right! Not good... SO I've known for a long time that I was going to have to fabricate some frame rails to fix it. Lucky for me the unibody is not twisted or bent in any way. Not sure how I made it out of that one. Probably because the frame support buckled before bending everything else.

So I spent a couple years researching what to do. I went through a crap-load of ideas. Some a lot more extensive than others. I finally desided on a simpler approach mostly because of a friend on my V8 Vega list named Reid. He built a non invasive frame rail for his Monza project. I got his plans and used his measurements to come up with my own solution.

I decided that I wasn't concerned with cutting up a small portion of the car because it was designed wrong in the first place. So that is what I did. I ended up cutting a notch through the rear frame support and designing some simple, straight frame rails that will hardly show from the side. Here is the hole:
In this shot you can see that I cut out the indented section where the trailing arm bolts hook up because the square tube I chose would interfere. The inside width of the square tubing is just about right for the trailing arm bolts. I removed as little existing metal as I could. Here's a shot of the inside hole:

I will be able to bolt the seats up directly to the new frame rails. You can see from the shot above of the inside where the hole ends.

Next I used what I learned from the inside of the support to fabricate these simple frame rails:
Here's some detail shots. I welded the rear so the sheetmetal would be sealed with the weld.
I started (from the rear forward) with 3x3x1/8 inch square tube and necked down to 2x3 rectangle. Then I cut the hole so that the height of the top of the new rail was even with the rear seat mounts.
The top then intersectes with the unibody support that the transmission crossmember is hooked up to. You can see the part I cut out here...
Then I used my angle grinder to form the end of the new frame rail to match the curve of the unibody as it mates up with the front frame rails in the engine compartment...

I will have shots of the rails welded in next... I bought a sheetmetal beader and I'm going to fabricate new floor pans for behind the seats. I'm not planing on having back seats so I will not need deep floor pans. I will also be able to use that extra space for mufflers.

I've made it a bit farther! I welded in the new frame rails. I welded the pinch seam to the rail all along the outer edge of the frame rail. I highlighted the seam in red here...

It looks really straight on the bottom. It took quite a while to weld that far but it was worth it.

Here's a couple shots of the rear suspension support in situ. You can see by the highlighted area how the frame rail was welded in. What I have left to do is weld a plate on the inside part of the frame rail so it matches the floor pan to seal everything up. I will prime and chassis black before the next shots so it's easier to see the results. I will also be removing the tabs I retained at the bottom of the rails for the welding ground clamp...

Moving on to the front reinforcing:
I wanted to remove the unibody brace for the LCA to make more room for headers so I cut it out and started fabricating a solution for it... Here's what I have so far:

Highlighted in red is where the support was. You can see the supports I fabricated over to the left. Also a good shot of my good luck charm.

The bracing is made of yhe same steel stock as the frame rails so it would match up well. Highlighted in red is where the old brace was. In blue is where I've welded some 1/8" steel reinforcing I've added to the LCA mounts. This will make for nice flat surfaces for the crossmember fabrication.

Here's another shot of the brace looking up toward the front slightly. This is the left side of the car. All I have left is a small angled support that will go between this support and the plates I welded on the LCA mounts (highlighted with white). You can see how much real estate I gained for the headers. The collectors will run right between the transmission mount and this brace. COOL! I'm pretty happy with the results. I can already tell the chassis is more sound. (The door slam test. I know it's psychosomatic) I think I've really made a difference.

More to come...