Date: Mon, 30 Sep 2002 20:58:03 EDT
Reply-To: FrankGRUN@AOL.COM
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: Frank Grunthaner <FrankGRUN@AOL.COM>
Subject: Re: On I4 and TIICO Exhaust Fixes
Content-Type: text/plain; charset="US-ASCII"
In a message dated 9/30/02 2:22:19 PM, Willolyn99@AOL.COM writes:
<< How much movement do these muffler mounts need to do the job?
The Tiico mounts are as soft as bubble gum. Recently, my exhaust was not
welded together, and I bounced the muffler around freely. You can put your
foot on the muffler and bounce it up and down a few inches. That is
excessive travel to me. When the whole exhaust system is bolted/welded up,
the rigidity of the system reduces the distance the muffler will bounce.
What that tells me is that the weight of the muffler is being held up by the
rest of the exhaust system, not by the mounts.
I can see where a small amount of vibrational movement would be beneficial,
but these mounts, I think, go beyond that. Maybe a rubber washer or grommet
would do. What do you think, Frank?
(And do you still have the counterweight on your header?)
>>
Bill,
I was quite surprised with your observations of a bubble gum mounting system!
The free movement of your system is beyond anything I have seen. Following
your question, I measured the motion in my system. I use the 4 to 2 manifold
(6 bolt flange), then go to the VW bellows, then a tight radius around to a 2
to 1 collector, then cat then oval muffler, then resonator and out. This
system will be obsolete before Xmas if I have my way. The hangers are at the
muffler inlet and the resonator inlet. Both mount off the original muffler
mounting points (driver's side motor mount and the edge of the oil pan). The
hangers are mounted with the width of the strap perpendicular to the
longitudinal axis of the muffler. The assembly pivots easily at a rivet joint
holding the top of the flexible strap to the hanger bar. The pivot point is
at the aligned center point of the muffler tube axis. The system is designed
for easy motion to and fro along the axis of the muffler (in other words it
supports expansion and contraction from thermal effects. The system is
rather rigid otherwise. The rubber is sufficiently stiff that the unit can be
mover upward by about 0.125 inches at the end pipe with a healthy pull (I'd
estimate 20 foot pounds). A similar deflection to the right or left (looking
down the muffler axis) is possible with similar resistance. There is
effectively no downward motion possible. Upon startup, the system deflects
about 0.25 inches and full deflection from full (low load) throttle to idle
is right about 0.375 inches.
So as I tried to say before, the muffler and exhaust are firmly held but
permit compliance. The total deflection (thermal elongation) of the end of
the muffler from cold idle startup to hot operation at full load (hill climb,
Palmdale road, full throttle, 85 degree ambient, 1450 F EGT) is nearly half
an inch (as I recall).
Your numbers are far too large suggesting easy pass through of undampened low
frequency resonances. Tighten er up, but don't weld it up rigid-like!
Hope this helps. Oh yeh, what counterweight?
Frank Grunthaner
| 
