American Expedition Vehicles Tummy Tucker – TJ Wrangler NON-Rubicon - Manual (Page 10)

Installation Instructions:Tummy Tucker™ – TJ Wrangler NON-Rubicon
Nth30115 v4.doc page 10 of 11 Download @ www.nthdegreemobility.com
to 4 mild ‘thumps’ during a hard launch from standing still that seem to come from right under the driver’s
seat, you need more clearance at the dimple from step 4.
Issue: Vibration while Idling. If you notice significantly more vibration while sitting still with the engine
running, the issue is most likely that there is contact somewhere between the powertrain and the body
floor or TT. These should have been caught and corrected in step 12, but something may have been
overlooked or too hidden to detect visually.
Solution Suggestions: Thoroughly inspect the area above the TT for any contact between parts that
was missed previously. On 4 speed automatics, especially check the clearance above the bellhousing
as mentioned in step 4a.
Also check the t-case linkage relay rod and confirm that it is not bound up or plunged to the point
where it is contacting the tunnel though the tunnel-end bracket. If the linkage is not close to horizontal, it
may be binding and the vibration is then transmitted to the interior through the rod. You can try
disconnecting the relay rod to test if it is the ‘noise path’.
Another possibility is wrong or incorrectly installed isolators. Make sure that the isolators are sitting
flat on the TT and have a uniform, slightly conical shape. If they appear distorted to one side, front, or
back, or are otherwise unevenly shaped, there is an unnatural preload on them that should not be
present – check for crooked/misinstalled/bent brackets, bad motor mounts or motor mount spacing, etc.
If their appearance is okay, verify their height while they are supporting the powertrain with the engine
off. They should be about 1.0” to 1-1/16” tall from the surface of the TT to their tops (not counting any
shims above them) – if the height is more (about 1-1/8”), you may have isolators that are too stiff
(standard TT isolators are marked with one paint dot on their undersides, but stiffer isolators for custom
installations exist and have multiple paint dots).
Issue: Exhaust is too high over rear axle and at tailpipe and the hangers at muffler and tailpipe
are not ‘hanging’ and/or exhaust is touching heat shield over rear axle. Since the TT installation
does slightly elevate the center portion of the exhaust relative to the floor, the rear portion may require
adjustment to keep it in its proper place. If this did not happen ‘naturally’ via some ‘sag’ at the joint
between the catalytic converter and the muffler, you may need to make this adjustment deliberately.
Solution: On newer TJ’s there is a joint in the system made up of two large flanges that are held
together with two bolts. This connection is above the right-rear portion of the TT ahead of the muffler.
By loosening the two bolts, the exhaust should drop back into place, then retighten the bolts. If the
hanger at the back of the muffler is still not fully ‘hanging’, bend the rod that is welded to the exhaust pipe
slightly forward. The exhaust grows in length when it warms up, so the hanger will swing into position
during operation.
If your factory exhaust system has a ‘slip joint’ and a muffler clamp ahead of the muffler, you have
two options: 1) If the clamp can be loosened and there is not too much ‘crimp’ in the tube (indentation
from the clamp), you should be able to adjust the angle of the muffler and retighten the clamp. 2) You
may be able to simply bend the muffler/tailpipe down by prying/hanging on it to get the joint to shift. This
may not be a desirable method if your system is old and/or rusty as it may weaken the pipes and lead to
exhaust system failures.
If your exhaust system is custom, you may or may not have a joint ahead of the muffler and it may be
necessary to visit a muffler shop to do a proper adjustment.
Issue: Engine Fan is touching fan shroud (static), or fan can be heard touching shroud while
driving over bumps, etc. Wrangler front-end sheetmetal is only supported by one body mount forward
of the firewall, consequently, there can be major variation (up to an inch!) in the position of the grille
along with the radiator and fan shroud. Normal TT installations tip the powertrain ‘flatter’ to the point
where the engine fan may touch the bottom lip of the fan shroud if the sheetmetal on your Jeep happens
to be ‘high’. You need at least ¼” clearance between the tips of the blades and the shroud, though more
is desirable - if you have less, you need to fix it.
Solution: The easiest solution is to lower the fan shroud. Remove the shroud from the radiator and slip
it over the fan (you may have to unbolt the fan to do this). Use a small round file or similar to ‘router’ the