[s-cars] another Stromung failure

[Theodore Chen]

it's not surprising that the pipe cracked right along the edge of the
weld.  welding makes the metal brittle, and the failure point would be
in the thinnest area, which is at the edge of the weld.

looking at the pictures, i agree that it is probably a design issue.
the welds look clean and there appears to have been sufficient weld
penetration.  the problem, i think, is that the welds are being loaded
in tension, which you should never do.  probably has something to do
with the way the exhaust is being stressed while mounted on the car.
the angled tube looks like it was being pulled away from the main tube,
and that puts large bending loads on the site of the weld.  i think the
failure of the main tube welds was secondary to the failure of the
joint between the angled tube and main tube.

slip fit tubes and gussets would help a great deal.  probably welding a
strap between the angled tube and main tube would be enough to prevent
the problem from recurring.

steve, assuming you don't particularly enjoy having to R&R the exhaust,
i'd ask stromung what they're doing to relieve the bending load on the
weld.  if you get the same exhaust, you might ask a muffler shop to weld
a couple of fairly long (say 6") gussets between the tubes.

-teddy


--- Steve Powers <sbpowers at gmail.com> wrote:

> My Stromung downpipe has failed pretty much catastrophically.It
> started when I noticed this crack in the expansion bellows.
> 
> http://spowers.smugmug.com/photos/11150181-M.jpg
> http://spowers.smugmug.com/photos/11150180-M.jpg
> 
> After I removed the bellows, I noticed that the wastegate exhaust tube
> was loose. I figured I'd weld it back together myself, so I removed
> the entire downpipe. Here's what I found.
> 
> http://spowers.smugmug.com/photos/11150184-M.jpg
> http://spowers.smugmug.com/photos/11150178-M.jpg
> http://spowers.smugmug.com/photos/11150173-M.jpg
> http://spowers.smugmug.com/photos/11150175-M.jpg
> 
> This looks like either a welding and/or a design issue. Every joint in
> that transition area is cracked. This is beyond what I want to tackle.
> I plan to get this welded and reinforced here by an exhaust fabricator
> (www.stansheaders.com) as the car is not driveable.
> 
> My call to Stromung met with an answering machine. I left a message.
> My email to Stromung met with a "full mailbox" error. I also have an
> email into Jeff.
> 
> Needless to say, I'm less than impressed at this failure just a year
> since I installed it.
> 
> Steve Powers
> _______________________________________________
> S-CAR-List mailing list
> S-CAR-List at audifans.com
> http://www.audifans.com/mailman/listinfo/s-car-list
> 



		
__________________________________ 
Do you Yahoo!? 
Check out the new Yahoo! Front Page. 
www.yahoo.com