Date: Tue, 17 Sep 2002 09:28:22 -0400
Reply-To: Bill Knight <bill.knight@USA.NET>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: Bill Knight <bill.knight@USA.NET>
Subject: Re: A Vibration Free TIICO Exhaust System - A Sucessful Work in
Progress
In-Reply-To: <3D86A420.4010509@bellsouth.net>
Content-Type: text/plain; charset="us-ascii"
As the person who has ridden with Ed in his TIICO bus, I can
concur that the changes have made a significant difference
in vibration. The modifications are simple and, for the
most part, bolt-on. I am planning to do the same with my
exhaust system, as soon as I find the time. I'm very
impressed with the improvement! I'm also very impressed
with Ed's other work, such as the conversion from automatic
transmission to manual, as well as his "behind the glove
box" air conditioning system that he installed to compliment
the rear A/C in the Westy. Nice work Ed...
Bill Knight
Raleigh, NC
-----Original Message-----
From: Vanagon Mailing List
[mailto:vanagon@gerry.vanagon.com]On Behalf
Of Ed McLean
Sent: Monday, September 16, 2002 11:40 PM
To: vanagon@GERRY.VANAGON.COM
Subject: A Vibration Free TIICO Exhaust System - A Sucessful
Work in
Progress
Several in the "headers are headed south (TIICO)" thread
have referred
to the "steel mesh section" in the TIICO header. Actually,
this is a
steel bellows flexible section that has a braided steel
protective outer
layer. This section will flex in a bending mode but it will
not twist.
These are available from Exhaust Productions Inc. (
http://www.epiflex.com/ ) or the same item from JC Whitney
for about
half price (~$22).
It seem that several people are having serious problems with
the exhaust
system on the I-4 conversions. I feel I have made
significant progress
in addressing the problems with the TIICO exhaust system and
I would
like to share my observations with the list.
Although the TIICO header has a flexible section, this
section is
located in the wrong place to do any good in reducing the
vibration. As
a result of its location, the flexible section is asked to
twist to
adsorb the flex when the muffler moves up and down in the
rubber
mountings. The flexible section will not twist at all and
the motion is
taken up by bending the exhaust header pipes. This
consequently makes a
nice vibrational harmonic oscillator using the spring of the
header pipe
as the force and the muffler as the mass. The resonant
frequency
happens to correspond to the ~3600 to 4200 rpm range of the
I-4 engine.
It is this vibration that is breaking the header pipes.
I have built an bolt on exhaust system to address this
problem. The
only welding required is the attachment of a 3-bolt flange
to the
flexible exhaust section and the total cost is about $80.
While it is
not a perfect solution at the moment, I find it totally
acceptable in
reducing the vibration and noise of the TIICO exhaust. I
think there
still is a little more improvement available so I am not
really ready to
recommend this to others. However, if I am not able to do
any better, I
will still be totally satisfied with the results. I really
don't know
how to describe the reduction in vibration except to say at
all engine
speeds the stock speaker grills in the front doors vibrate
more from
music than the gearshift lever does from the engine. At 70
mph there is
no vibration from the gearshift lever. One other
contributor to the
list has ridden in the bus and I would invite him to share
his comments
with the community on the reduction in vibrations.
I assembled the exhaust system using a 5" exhaust clamp and
a piece of
1.5" angle iron to solidly mount the catalytic converter to
its shock
mounting. This fits neatly around the stock converter and
attaches to
the TIICO original bracket, replacing the wasserboxer
muffler bracket
that never actually fit the converter. Attached to the
converter is a
6" flexible exhaust section followed with a 4"x9" oval
muffler 18" long.
The outlet end of the muffler is attached to the right
frame rail with
a traditional muffler hanger. The exhaust hanger attached
to the oil
pan is removed entirely. This system eliminates the vast
majority of
the vibration and noise from the exhaust system by allowing
the engine
and the converter to move while the muffler remains
essentially
motionless, isolated from the vibration by the 6" flexible
section. I
currently have about 2000 miles on the system with zero
problems and no
change in vibration or sound.
I still have a little investigation of the system to
complete.
Specifically, I find the shock mounting of the converter
allows a
little too much motion and, under some temperature and rpm
conditions, a
small harmonic oscillation can develop. I plan to modify my
original
design to allow the converter to be mounted solidly to the
left motor
mount to reduce it's motion. I have the necessary angle
iron cut and I
only need time to make the modifications. I also want to
investigate
the addition of the updated 1 piece left engine carrier and
some less
compliant motor mounts. When I've investigated these
options, I'll
provide to all some pictures and diagrams with a parts list
and assembly
instructions.
If anyone wishes to correspond by p-mail, I'll be glad to
supply a few
pictures and diagrams of the work in progress.
Ed McLean