B-Body - Body Bushing Installation Description (From Scott Mueller)
There are a total of 7 of
these body mounts on each side of the frame, or 14 total for the vehicle. They
are numbered from the front to the rear, with the first #1 mount being located
right behind and inboard of the front wheels below the cowl. Mount #2 is about
6" outboard of the first mount, and mount #3 is a foot or so further down
the frame, below the B-pillar area. Mount #4 is directly in front of the rear
wheels, where the frame starts to curve inward. Mount #5 is at the top of the
frame next to each rear wheel, and is unique in that there is no bolt running
through it. The #5 upper cushion merely snaps into a hole in the frame, and the
weight of the body holds it in place. Mount numbers 6 and 7 are along the rear
part of the frame, with #7 at the far rear just in front of the bumper
supports.
Now, being the type of
person I am (who can leave nothing alone) I re-examined the newly installed
mounts, and studied the rest of the mounts on the vehicle more closely as well.
What I found is that the bolts bottom out in the threaded holes in the body,
with the head of the bolt resting up to an inch below the frame. Since the
standard lower body mounts are only 5/8" thick (compressed), several of
the lower mounts were NOT touching the frame, meaning the body could lift up
from 1/8" to 1/2" or so before the lower body cushion would make
contact. Also when examining one of the standard factory lower cushions, I felt
that they were constructed of a very low durometer (soft) rubber, and thought
that something a little firmer would be in order.
So I set out to find if
there were different lower body mounts available from other vehicle
applications, which I might be able to use on the B-car to close these gaps and
further tighten the body to the frame. After ordering a variety of different
mount cushion part numbers (all I could find), and trial fitting them, I can
now finally announce the ultimate upgrade for the lower body mounts! The great
thing is that a complete set of upgraded mounts cost only $62.58 and can be installed
in minutes with the simplest of tools.
This upgrade applies even
to the 9C1 cars, as well as the '93 and older B-cars which apparently had all
of the lower body mounts factory installed. Of course it is MOST noticeable on
the '94-'96 non-9C1 B-cars which are missing the front three mounts completely.
The applicable lower body mounts are as follows:
|
P/N |
Description |
Cost
(ea.) |
|
377801 |
Stock
5/8" thick soft rubber (Black) |
$7.16 |
|
457917 |
New
3/4" thick firm rubber (Dark Green) |
$4.24 |
|
457915 |
New
7/8" thick firm rubber (Pink) |
$5.41 |
Note that the thicker cushions are color coded with paint, which makes them easier to identify. For this upgrade you will want to remove and replace all of the missing cushions as well as the existing soft 5/8" cushions with the thicker 7/8" (pink) versions, EXCEPT the number 7 mount, which I found works better with the 3/4" thick (dk green) cushion. Note that mount number 5 does not use a bolt, and thus requires no lower cushion at all. The upgrade would therefore consist of the following 12 new lower body mounts:
|
P/N |
Usage |
Net |
Qty. |
Amount |
|
457915 |
Position
1, 2, 3, 4, and 6 |
$5.41 |
10 |
$54.10 |
|
457917 |
Position
7 |
$4.24 |
2 |
$8.48 |
|
|
|
|
Total: |
$62.58 |
You will want to install the 7/8" (pink) lower body mount cushions at locations 1, 2, 3, 4, and 6, replacing the flat washers or existing 5/8" soft cushions. Finally you will also want to install 3/4" thick (dk green) cushions at the number 7 locations. Again note that location 5 uses no lower mount whatsoever.
** Remember, prices are subject to change!!
B-Body - Body Bushing Installation Description
Here are the installation instructions:
1.) While this CAN be done without even jacking up the car, it will be easier (especially if you are doing this for the first time) if you raise the car and put it on jackstands.
2.) Using a 15mm socket and 6" extension on a standard 3/8" or 1/2" ratchet, remove the #1 (front) body mount bolts and large washers (or existing soft cushion w/integral washer) from both sides of the frame. They are accessed through a large 2-1/8" hole in the bottom of the frame.
3.) Slide the new cushions over the bolts, and insert each bolt and cushion up through the hole in the frame and into the threaded hole in the body. Tighten the bolts to 30 ft-lbs.
Note that the Factory Service Manual calls for 52 ft-lbs, but I have found that the threaded holes in the body like to strip(!), and 30 ft-lbs. works extremely well with far less of a chance of stripping out the hole. If you do strip the threads in the hole, you will likely have to use an oversized bolt, as it is difficult to repair those threads.
4.) Repeat the procedure for the next location on both sides of the frame. Work your way down from mount #1 through #7, doing both sides each time. This will prevent any possible body movement or misalignment during the procedure. Remember that the pair of thinner 3/4" (dk green) cushions are to be used in the #7 position, all other positions work best with the thicker 7/8" (pink) cushions.
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This Page Last revised: Dezember 05, 2006 gem and fmw