tip provides additional information to the Tech Tip “FIXING YOUR C4 SPORT
SEAT LUMBAR SUPPORT” authored by Bob Thibodeau on 6/15/2001.
An alternative source for material to replace the ruptured diaphragm is a
bicycle inner tube.
It is much thicker than the original
diaphragm, and should provide longer “life”. To prepare the tube, cut a
square about 2″ X 2″. Locate the center of the square by intersecting
the lines from each corner. This will provide the location for the center
screw. If the screw is off center, you will develop a “rolling pulsation”
, which is not as efficient as a “verical pulsation”.
2. Using a
compus placed at the center mark, draw a circle 11/4″ in diameter. Cut
out your circle precisely, and now you have your diaphragm
3. The pump is held in positon by three bolts. The
heads of the bolts are located under the seat, and the nuts are recessed
on the top, which requires removal from the under side of the seat.
4. When reinstalling the pump, it is recommended to replace
the bolts with screws and self locking nuts. Installing the screws from
the top will allow you to use a screw driver for ease of installation. I
found that when using self locking nuts, only two were required to
sufficiently fasten the pump to the seat.
With the “inner tube”
replacement diaphragm, I am able to compare pump production with the
original diaphragm in the passenger seat. The inner tube diaphragm
provides a more rapid inflation of the lumbar bladder.