1967 Firebird Convertible - Project "LEGACY" - Page 7 - Lateral-g Forums

**WSSix** · #61 05-10-2013, 04:26 PM

Looking good, Jarrod!

zingercustoms · #62 05-10-2013, 06:45 PM

Yeah, lots of hard work but looks great...doing it right. Love the birds...

Firebird-Geek · #63 05-13-2013, 11:23 AM

Quote:

Originally Posted by zingercustoms

Yeah, lots of hard work but looks great...doing it right. Love the birds...

Love what you guys are doing with the 69 you are building... I am following the thread!

Firebird-Geek · #64 05-13-2013, 11:33 AM

Next up... Mini-tubs.

I know they say it usually takes about 40-50 hours to mini-tub a Camaro/Firebird... honestly, I probably have closer to 100 due to wanting to build in more strength into this area.

ISSUE: Convertibles put MUCH more stress into this area than coupes do. This is due to lack of having a roof, the convertibles use the rear seat brace to compensate (plus thicker rockers and extra bracing.) On the sides of the rear seat brace (where it attaches to the inner wheelhouse) there is actually a few layers of steel used here to build up the strength so as to reduce body flex.

Being that I will be running a WAY larger set of rear tires, cutting the frame down for the mini-tubs and adding MUCH more horsepower than the car had originally, I wanted to OVERBUILD this area to compensate. I know some people put in roll cages to handle some of the body flex, but I am building this with my family in mind, and didn't want to deal with the cage being in the way of using the rear seat. So my plan is to BEEF UP this area.
Stay tuned for the PLAN.

Firebird-Geek · #65 05-13-2013, 11:37 AM

Here is where I am starting...

I didn't take as great of pictures on the passenger side (where I started)... so you will see more when I show the drivers side installation.

Will be installing the DSE (Detroit Speed and Engineering) min-tubs...

Firebird-Geek · #66 05-13-2013, 11:43 AM

I will go over the process better on the passenger side (due to better pictures). But you can see here where I marked my cut line about 2.75" inside of where the inner wheelhouse would be mounted

Then with the help of a cutoff wheel / Plasma / and sawzall I removed the necessary metal. (This was the first cut... there is MUCH more trimming and cleaning up done before the tub goes in.)

Here is the passenger side tub being trial fit into it's location.

Firebird-Geek · #67 05-13-2013, 12:15 PM

OK my plan for "Beefing Up" my mini-tub install.

Like I said before, (on the convertibles) GM addressed the loss of rigidity that the roof gives the coupes in a few different ways. One of the major ways it did this was to build in more support between the wheelhouses with a much larger and more structural brace between them (the rear seat brace.)

Here you can see where they used some 20 gauge sheet metal to mount the seat brace to the wheelhouses. (NOTE: this brace is not clamped tight up against the front of the floor... so it is sitting almost an inch forward and low.)

Firebird-Geek · #68 05-13-2013, 12:19 PM

I wanted to use this idea, but make it MUCH stronger... so I started by making a template of GM's design...

Here it is taped into location on the passenger side.

Here you can see how the rear seat brace gets tied inbetween the wheelhouse and trunk floor.

Firebird-Geek · #69 05-13-2013, 12:22 PM

To make room for the larger tubs, you must cut into the frame rails. To compensate for the loss of strength, DSE suggests that a person welds 1/8" steel plate back into the missing portion of the frame rail. For this is MUCH thicker metal than what GM actually used on the frame rails themselves.

Here you can see the missing portion of the frame rail.

My plan was to add to DSE's plan and also incorporate GM's design... but BEEF UP both!

Firebird-Geek · #70 05-13-2013, 12:24 PM

So rather than just close up the frame and patch shut the missing portions in the trunk floor, I would build a plate that would do both. PLUS I would incorporate GM's brace... but not out of 20 gauge sheet metal.

MY PLAN:
If welding the frame back shut with 1/8" steel plate builds strength back into the frame... making this plate twice as high and running it all the way to the front of the trunk would add MUCH more strength into the car.
Here the plan... the transparent red area is where I will be welding in a 1/8" steel plate to not only build back up the missing portion of the frame rail, but also add in a MUCH larger area for the inner wheelhouse to make it's connection to the frame and rear seat brace.

Here you can see how much more of the wheelhouse I will be making contact with and basically doubling the height of the frame rail in this section.