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Posted by: rtalich Nov 11 2009, 06:34 PM

Help... Does anyone know if it would possible to cut a 3"x3" hole in the side of the passenger side long with NO effect to the structural integrity?

Thanks,
Rob

Posted by: SirAndy Nov 11 2009, 06:42 PM

No.
But the real question is, just how much will you weaken the structure and if marginal, does it matter?

The factory added holes on the inside of the longs about the same size and plugged them with a chunk of tar.
Obviously, they thought that was OK ...

Andy

Posted by: brer Nov 12 2009, 12:03 PM

stresses in the longs or any beam type contruct are not carried in the center of the vertical plane. Have a look at how a castellated (or cellular) beam is made for reference.





You can hole the long, but i'm not saying a 3" hole in any location won't affect it.

There are areas in the car that are higher stressed than others but I'm not the one who will tell you exactly where those are. I have an idea but i'll leave that to the people who have more experience repairing these chassis.

Posted by: kwales Nov 14 2009, 05:21 PM

Stress flows like water in a river.....

Cut a hole in the beam and it will flow aroud the hole.....

Reduce the flow area with a hole and it will concentrate the stress in the material that is left......

Can we say failure/fold point???

VW used to drill holes along the side of the underside hood reinforcement (Rabbit) to force it to fold like an accordian duriing impact. Can we say energy absorption as it folds durign a crash????

Posted by: brer Nov 15 2009, 02:05 AM

i believe the tension on the bottom of the long is the critical condition. did you see the thread about the cracking long?

tension on the bottom, compression on the top is the rule. The centroid is a zero point, until you dynamically load it .... like in a racecar.

Posted by: sean_v8_914 Nov 15 2009, 02:14 PM

dude, dont go poking speaker holes in your chassis...there, i said it.
...by the way, I weld up cracked 914s for a living