Tibo

iTrader: (15)

I'm in the process of restoring/customizing a 91 Z/28 convertible with no rust or structural issues and has never been in a (reported) accident. I plan on covering up the battery tray(s) on either side and all of the holes on the firewall with patch panels. The core support bar running from fender to fender I'll weld smooth too. I'll also be welding all of the sharp seams like the strut tower caps and idler arm bracket.

There are a few areas or patches of metal that appear to have no real structural value and are only used as a divider/aesthetic purposes/grounding purposes. The first one in question is the metal that is parallel to the sides of the radiator. The part from above the frame rail up seems like it serves no structural purpose.

The next area is the metal panel directly behind the headlights. Removing that 18 or 20 gauge metal panel would be nice. Being as thin as it is with many holes already in it I wouldn't think this would not be structural.

This would lead to a more obvious question of is the radiator core support providing any more support than to keep the front of the fenders from caving in? It appears that the actual bumper or impact bar would provide the real structural support and the core support's function is only to hold the radiator and a few other items. I'm not really wanting to make my own tubular core support but I would like to know what I can cut away at before I need to start making additional braces.

haps

iTrader: (4)

From an engineering point of view, I would think that every member in a unibody car was put there for a reason. I would also argue that every member supports a load. Auto manufacturers typically don't install support members that have no structural value...it's cost prohibitive.

RedLeader289

iTrader: (2)

I'd leave it. unless someone had a stress/strain model for the car and those pieces were found to be zero force members then I wouldn't trust taking them out.

92RS_Ttop

iTrader: (3)

I would tend to agree that all of the metal in a unibody car is there to provide at least some structural support.

I will start by saying I'm not that great on physics or car suspensions, and certainly no structural engineer, so I may be way off base here, but here is how I look at those areas.

The strut towers are attached to the top fender rails on either side. Now we know for sure that the strut towers flex towards each other and away from each other in corners. This is evidenced by the fact that strut tower braces provide a noticeable difference in handling. It's also easily seen when you think about how the struts move. The front control arm is essentially a hinge where it attaches the front subframe. The end of the arm pushes up or pulls down on the strut body when driving. Because of the hinge effect of the control arm mounting, the strut will not move in a perfectly linear line up and down. It will have some lateral movement due to that "hinge", although the balljoints do act to lessen this effect somewhat. This movement will move the top of the struts and therefore the strut towers, trying to push them together or pull them apart.

Now, if you remove the metal from the proposed areas, the radiator/core support becomes essentially a large rectangular box that the strut towers are attached to. Think of a cardboard box for an analogy. If you open both ends of the box and lay it on its side so you can see through it from end to end, and then try moving the top corners left and right, what happens? The box flexes easily and can easily be folded on itself as the top side collapses. Next take the 2 side flaps closest to you and close them. Now try moving the top of the box side to side and you'll see it's much harder to get it to move. The flaps have become the sheet metal behind the headlights. Now take this same flaps and fold them at their middle into the box to a 90* angle to represent the side supports for the radiator. You'll find the box is even harder to shift side to side at the top. So in this example, adding the "behind the headlights" and "side radiator supports" strengthens the overall rigidity significantly. The same principle should be in play in the front of our cars.

Sorry for the long post, and as I said I may be completely off my rocker here so if someone can explain it better(right or wrong) I won't be offended.

Tibo

iTrader: (15)

Well, I went ahead and removed the metal. After I really got to looking at it it just doesn't seem that it would provide structural support. At the top of the radiator side support(s) it's only held on by two spot welds on one side and three spot welds on the other. I could grab that sheet of metal and flex it easily. I measured the thickness with the paint on and it came to 0.036 which corresponds to about 20 gauge metal. The sheet metal behind the headlights may have provided a small amount of support but I think the metal rods crossing in front of the radiator provide more support to resist twisting.

However because I don't know with certainty if they really are structurally needed I'll weld some 14 gauge angle iron over the top of the core support and a flat piece of 16 over the side of the radiator support. That would serve two fold, smoothing and adding strength.




I'll post the pictures in a while when I am ready to weld it in. I think welding in the 14 and 16 gauge will strengthen it more than it was stock.

Scorpner

iTrader: (4)

My guess is even if it isn't structural it may be there to help cushion impact during an accident. It is in the crumple zone.
I agree that they wouldn't include any extra metal unless it was necessary. This was one of the first computer designed vehicles and from what I understand they did everything they could to save weight while providing strength where it was needed. Some of the strength is from compound curves, or the way the metal is shaped. (Edit: I forgot, one other thing could be for manufacturing purposes during the build process.)
Either way, if it is there for impact, I wouldn't make it stronger than it was.