Front end crumple zone design

[raygreenwood]

Ok….while working the undercoating….I finally took a long look at the “crumple zones”.

Particularly…. because the bottom, outside cross member at the bottom of the footwell firewall…. on my car…has rust holes in it. The reason why it rusted so much is that its VERY lightly welded in. It has openings at each corner.

It’s MADE to shear loose as the front sheet metal compacts rearward. It’s made to take the rear most mounting point of the front suspension subframe…downward …away from the chassis…..as the subframe gets pushed rearward.

The left and right forward mounting point…are on angled arms or pendulums…that are designed to crumple…back and downward.
The fuel tank….is mounted at two small 6mm corner points on the bottom and a clamp/clip at the top…. angled forward and downward. So, the fuel tank will shear loose …hinged at the top…..and gets squeezed downward and forward.

So…some orientation pictures:

This is the right-hand side…… of the welded crossmember. See the fuel filter mount for orientation ….and the fuel return line at the left of the picture. See the rust holes?

Here it I looking along the cross-member towards the right-hand side. The rear most mounting point for the sub-frame is at the top of the picture. See the rust holes?

See these holes? They are in each end. The weld that holds this crossmember in…is very light. Its designed to shear loose. After I plug the rust holes….I will flood this member with Ospho and then seal these holes.

OK….the red circles are the three mounting point for the suspension subframe. The green circle in the right-hand lower corner is the 6mm stud for the right-hand corner of the gas tank. The yellow dotted lines are the gas tank space.

The two big red arrows…. are the upper BEND POINTS of the crumple zone.

Just some thoughts. Ray

[Abelclasico]

Ray, these tutorials will come in handy when I deal with the underneath of my 411. I am actually saving all your tips and advice for the near future. Thanks for taking the time to explain these things to us,
cheers,
Abel