BMW E85/86
Z4 M Coupe Exhaust Removal and
BMS Performance Exhaust
Installation
When I
first brought my M Coupe home, I loved everything about the car but the
silence. To me exhaust sound has always been one more way for me to connect to
the car. Some other manufacturers had some exhausts on the market but I elected
to try the BMS exhaust system (http://www.bmsracecars.com).
Pics of
the exhaust system when it arrived, consisting of a new X-Pipe (sans resonator)
and new mufflers:
NOTE: The following is provided for information only and any use of
this information by you is at your own risk.
The
secondary cats located in front of the X-Pipe do not have to be removed, but
since it was easier to get to the two bolts holding it to the exhaust manifold
than the three bolts for the X-Pipe to secondary cat pipe junction, I elected
to remove the entire center section as a unit and disassemble it when off of
the car. In order to access the components under the car I used a ramp and jack
stand combination. To remove the four bolts I used a size E12 external Torx
socket (also called a reverse Torx) and a 14 mm metric wrench:
Disconnecting
both rear cans makes it a little easier when not using a lift to remove the center
section by itself, this is accomplished using a 13mm box end wrench and a 13mm
socket wrench. There is a seal located between the two flanges and two
nuts/bolts on each side:
To access
the hanger bolts to remove the rear mufflers the plastic plate underneath the
rear section will have to be removed, 8-8mm bolts and 2-12 mm plastic nuts:
One of the
rear braces will need to be removed to allow the center section to be removed,
left or right side does not matter. The brace is held on to the car with a 14mm
bolt at either end and a 10mm hex head screw in the middle brace support:
The front
and rear hanger bolts to the mufflers can be removed with a 13mm wrench; the
nuts on the OE muffler hanger mounts are welded and will not spin. There are
two hangers per muffler:
The next
step was to remove the hex head screws holding the aluminum cover plate to the
center section support brace to access the bolts for the brace. This is done
using an 8mm socket wrench, 5 screws in front/ 1 screw in the middle/ 2 screws
in the back:
Next the
bolts for the support brace can be removed, 4-14 mm bolts and 2-12mm bolts. You
may want to use a jack to support the center exhaust assembly because it will
drop when these bolts are removed from the support. The exhaust is removed by
pulling assembly to the rear to disconnect the front pipes and then moved
forward to clear the remaining rear brace:
The secondary cat section can be separated from the X-Pipe
by removing the 6 nuts and bolts (both 13mm). The gaskets should be carefully
removed for re-use. The X-Pipe can be removed from the center support by
removing the two bolts from the support:
Installation is reverse of above steps. The OE hardware can
be re-used, but the two hanger bolts must be swapped between the front and rear
muffler mounts to allow for fitment of the BMS mufflers. Nuts will also need to
be sourced for these four bolts, future BMS exhaust shipments should include
all necessary hardware. The alignment of the tips for symmetry and centering
may require some fine tuning of the muffler to center pipe clamp bolts:
Some installed pics:
TIS Torque Specs: TIS instructions below with torque
specs-
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