Date: Fri, 7 Feb 2014 12:12:05 -0800
Reply-To: Don Hanson <dhanson928@GMAIL.COM>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: Don Hanson <dhanson928@GMAIL.COM>
Subject: Re: Exhaust Bushing Inner Weave Premature Failure
In-Reply-To: <CAB2RwfjXq2OyLW9isaOQAxV9oPH73T3Cr-SFW9pnx3xqb9nQLg@mail.gmail.com>
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Welding something can induce stress and misalignment. I was shown
this....pretty large movements were apparent as the welder worked. On
something as long and obviously vulnerable to stress as the exhaust systems
on in lines seem to be, I'm guessing that it is common to screw up the
exhaust with careless welding and leave it with welded-in stresses that
lead to fairly quick cracking in a lot of cases. Muffler guys are often
not the most careful craftsmen. The diesel vanagon exhaust mounts, they
are not very forgiving. most exhaust systems have some give..some flex.
Ours have to be correct, or as you tighten them into place you are
stressing something... and those flex joints are the weak link.
Careful skillfully welded should be ok.
On Feb 7, 2014 11:51 AM, "Neil N" <musomuso@gmail.com> wrote:
> Hi Don.
>
> As per Dennis' comment and your's, I may try that.
>
> A previous design had the cat along the back inline with muffler but
> NO flex joint. I used 2 mounts off block. 1 to ~ midpoint of cat, 1 ~
> to midpoint of muffler. The cat outlet cracked very quickly. (this cat
> was "free" so worthy of experimentation) images starting at downpipe:
>
>
> https://lh3.googleusercontent.com/-qPxITHW-rcQ/UPdqA2CUqpI/AAAAAAAAGl8/DwuXF6x4VTE/s720/ABA%2520New%2520Exhaust%25202.jpg
>
>
> https://lh5.googleusercontent.com/-sy9mzTj2VF8/UPdqARcIqkI/AAAAAAAAGlw/Xsv6e99OZZA/s720/ABA%2520New%2520Exhaust%25203.jpg
>
>
> https://lh3.googleusercontent.com/-MJreG5edr1s/UPdqBqFR5aI/AAAAAAAAGmI/mG6zk-GmG88/s720/ABA%2520New%2520Exhaust%25205.jpg
>
> One can see how/why I fudged the angles to make the bushing fit. This
> was not good work!
>
> @ the list. I know this topic has been beaten to death, in no small
> part by me, but I'm doing my best to contribute. Though not many would
> mount their engine at 15º, my errors may help others!
>
> Neil.
>
> On 2/7/14, Don Hanson <dhanson928@gmail.com> wrote:
>
> > Neil try one without the flex section. I've been told that is the way
> to
> > go. Mine cracked so I had a "splint" welded to bridge my bellows flex
> > joint...."temporarily" about 30k miles ago...no further cracks have
> > showed. .....
>
> >> On 2/6/14, Dennis Haynes <d23haynes57@hotmail.com> wrote:
>
> >> > .... I would
> >> > suggest welding that part on the pipe in line with the cat, not the
> >> > down pipe.
>
>
>
> --
> Neil n
>
> Blog: tubaneil.blogspot.ca
>
> '88 Westy http://tinyurl.com/c8rlw6p
>
> '81 VanaJetta 2.0 "Jaco" http://tubaneil.googlepages.com/
>
> Vanagon VAG *Gas* inline-VR Engine Swap Group:
>
> http://tinyurl.com/d7gd5ej
>
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