JHowell37

From one of the the few people who has actually cut a 928 shell into about 8 pieces I'll tell you that I was quite impressed with just how over the top the designers went with these things. The little divits made by the spot welders are less then a 1/4 inch but required a 3/8 inch drill bit or larger to completely drill out the spot welds. There are thousands of them throughout the car. Many of the body seams after being spot welded have some sort of structural adhesive/seam sealer applied. Cut out a complete cross-section of a rocker panel and you will find 3 layers of steel and in some places, 4 layers. Currently, my car has a quarter panel removed and a cross-section of the rocker panel removed. It's sitting on the ground with no special braces or anything and the doors open and close just fine. In other words, you can remove a lot of structural support, but because each part is made so well, they have some ability to compensate for parts that are compromised.

In addition to the countless spot welds, multiple layers of heavy gauge steel, and structural glue/seam sealer, all of that stuff they spray in the car for sound deadening adds yet another layer of material providing structural rigidity.

Honestly though, one doesn't need to chop up a car to realize how tough it is. Just pay attention when you get in it. It feels like you're sitting down in a chair that's been bolted to a concrete slab. Can your Honda Accord give you that feeling?

I was flipping through my 911 Buyer's Guide from Motorbooks, and it mentioned the structural rigidity of the 911. It basically stated that Porsche advised body shops to replace the front subframe if it was bent in a collision because it was so strong that it was next to impossible to properly straighten.

JHowell37

Well obviously newer sports cars will probably surpass the 928 in structural rigidity based on the evolution of engineering and technology. If you look at how the car is designed the majority of the structure runs from front to back, not side to side. There is no cross bar in the rear because the floor from the firewall back is a structural member that holds the two sides of the car together. The area forward of the jack pads is a subframe which needs extra support since it carries the weight of the engine and everything else that's crammed under the hood.

rhys

I tried that, and as soon as I get out of this full-body cast, I plan to write a review of the out-of-body, near-death experience.

rhys

I believe a better term for what the OP was asking would be "rigid", or "torsional rigidity" rather than "strong"

worf928

I drag out this old quote from around 1990 whenever this subject comes up:

That is all I need to know

DonS

The way I heard it was they were looking for a car that could land on it's roof without crushing or hurting the occupants and the 928 was the only one they could find that was capable of such a stunt.

Jim M.

I lost my 89GT to an accident. To make a long story short, I crashed into a previous accident at about 45 MPH. The front of my car was pushed back to the front of the engine. That's about 18" of Porsche stuff compressed and disintigrated to nothing all against the front of the block and water pump. Well both doors opened and closed normally. The windshield didn't even crack. To me they are VERY strong.

Jim Mayzurk
93 GTS 5-spd

Jim bailey - 928 International

Yes Jim BUT the door gap is a little off ! The crush zone worked very well which we see all the time with the HUNDREDS of cars we have taken apart.

DonS

Jim, as professional disassemblers where do you guys draw the line as 'non-recoverable'? When the block moved?

jpitman2

I think you are looking for a measure called torsional rigidty, measured in ft/lbs per degree of twist produced, or Nm/degree. Most frequently quoted by makers when they increase the stiffness of a model....dont know it for any specific makes, but it should be findable.
A couple of times when I have had all 4 corners on stands I have found one corner not really sitting on its stand, just being held up by the other 3.
jp 83 Euro S AT 50k.

IcemanG17

Another way at looking at how strong the 928 frames are is how well they hold up over time-mileage....look at how many 928's are on the road with well over 100K miles and not a single squeek-rattle......that speaks volumes about strength.....I've driven 1 year old cars that squeek-rattle 1000% more than my 928!

Peter F

Thia has happend to me as well, I thought it was more due to that the floor was not level.
Either way the car did not settle down after days in the air on the fourth corner.
(had to add a thin pcs of wood to compensate)

/Peter

Jim bailey - 928 International

The front end is the weakest link BY DESIGN in a big shunt the engine gets pushed down under the car. The motor mount ears on the block shear off ,the bell housing breaks and the engine starts going under the car. When we buy a car at a salvage auction it comes with a branded salvage title and maybe 1 out of 100 will get "saved". We are in the parts business and that is what we do best ! We do not fix cars do not service cars we sell parts ! and lots of them If you jack up the car using the front suspension front bracket on the frame and put jack stands under the forward jack points,what you find is that when you release the jack then pump it back up there is some flex as you start to lift from the suspension the body does not come off the jack stands until you raise the jack a bit. Almost nothing in life is "solid"/ rigid there is always some degree of flex. Late model 911s (996/997) hard the ONLY option is to buy a new body shell and transfer ALL the parts because the force of the impact bends the entire chassis ! Porsche engineered the 928 to be stiff enough to do the intended task any stiffer would have needed to be HEAVIER and weight is the enemy ! The A shaped door opening and flying buttress rear panels creates a Very strong roof and I have never seen a roof crushed on a 928 even when someone was creative enough to get one upside down !

Vilhuer

IIRR 928 body was designed to withstand three times its own weight while upside down without roof collapsing.