993- Replacing Stock Motor Mounts with RS Motor Mounts
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After experiencing some difficulty shifting
the car while under load, my mechanic recommended replacing the motor mounts
as a first step in diagnosing the problem. I decided to replace the stock
motor mounts with RS motor mounts. Surprisingly, they are in the same price
range as the stock motor mounts. Additionally, the mechanic encouraged me
to change them, saying it was really easy. I took his advice and followed
his directions. Here they are.
First of all, make sure you get all the
parts. The stock motor mount is a one piece hydraulic unit, while the RS
comes with several bolts, seats and washers in addition to the actual
mount. You can reuse the bolts that hold the mounts in place in the engine
compartment and the nut on the bottom that holds the bolt to the engine
carrier. I decided to get new ones just in case. Here are the part
12.) 964.375.043.80 Engine Mounts (qty 2)
13.) 901.305.311.00 Seat (qty 4)
14.) 900.082.030.02 Bolt (qty 2)
15.) 999.025.074.02 Washer (qty 4)
16.) 999.025.134.02 Washer (qty 4)
9.) 900.074.134.02 Bolt (qty 4)
10.) 999.084.215.09 Locking Nut (qty 2)
Two 19mm ratchets (one with torque measuring
One 13mm ratchet
One long screwdriver
Put the car up on jack stands. I decided to
only lift the rear end. Place the jack under the engine and apply just
enough pressure to the engine where you see you exhaust tips move slightly.
You dont want to lift it to where it takes any pressure off the jack
stands. Here is what it should look like.
Open the engine lid and locate the motor
mounts. The one on the passenger side is clearly visible, while the one on
the driver side is covered by hoses from the AC compressor. Here is what
they look like
I started off with replacing the passenger
side mount because it looked much easier. First, take a 18mm or 19mm (Not
exactly sure in this case) socket with a long extension and loosen and
remove the nut from the bottom of the car that holds the engine to the
mount. Mine was torqued down pretty good so I did have to use extra force.
After removing the nut, go to the engine bay
and remove the 13mm bolts. At this point you may want to lower the engine
slightly as it helps to slide out the mount bolt. Once the mount is
disconnected, you will notice that the AC compressor is in the way and you
cant easily slide the mount out. I turned it several times and in
different directions until it finally was able to slide out.
Here is what it looks when you remove the
Here is the RS mount.
Here is where it gets a little tricky.
First, raise the engine again to where the carrier is up to the mount
location. Take one washer (999.025.074.02) and one seat (901.305.311.00)
and place them down onto the engine carrier. Make sure you align them to
where you can see the opening. The original mounts had a rectangle notch on
the shaft of the bolt so that aligning them was easy. With the RS mounts,
you have to take your time and make sure they are aligned. Now, take the
mount and place it down in the opening. You will notice that the washer and
seat have moved a little. Take a long screwdriver (something long and
skinny) and adjust the opening so that you can place the bolt through the
hole. Now take another seat and washer and place them on top of the mount.
Take the large bolt (900.082.030.02) and run it down through the mount.
Take the large locking nut (999.084.215.09) and just get the nut to go onto
the bolt to make sure nothing gets out of place. Next, insert the smaller
bolts (900.074.134.02) into each side of the mount and tighten them down to
approximately 40Nm. I dont have the exact torque specs but was told by my
mechanic that 40Nm for the smaller bolts and 95Nm for the larger bolts would
be good a start. Upon further reading, the correct torque setting for the
large bolt is 85Nm but I still havent found the setting for the smaller
Here is where you need a friends
assistance. First jack the engine up just a little more than before. I
actually jacked it up to where my jack stands wiggled just a little. I
wanted to make sure that the engine was at its highest point in the car.
Next, take two 19mm sockets, one with a long extension (bottom) and one with
a medium extension (top) and begin the tightening process. I used my torque
wrench on the bottom since it does have a long extension and had my wife
hold the top of the bolt in place with a medium sized ratchet. (None of my
friends were around, so I asked her for her assistance. If she could hold
in place, so can anyone.) I torqued the nut down to 95Nm (even though the
spec is at 85Nm). The nut is a locking type that requires plenty of force
to get it moving up the bolt. That is it for the passenger side. (Make
sure you re-torque the 13mm bolts when you get the car back on the ground)
Here is what it should look like when you
The driver side is very similar with one
exception; you have to move the AC compressor lines to get access to the
mount. First, take off the bolt (7mm) holding the compressor lines to the
fan housing. Then take the plastic hex bolt (6mm) holding the compressor
lines underneath the wiring harness box. This should give you enough
movement in the lines to get the old mount out and replace it with the new
Here is a picture of the bolt holding the
compressor line to the fan housing.
Here is a picture of the 19mm bolt under the
driver side of the engine carrier.
You follow the same procedure described
above for the driver side mount as you do for the passenger side. Make sure
you let the engine down a little when removing this mount as you have less
room to work with on this side as you try to slide the old mounts out. When
you are done, move the compressor line back in place and tighten them down.
You may want to wait until you have the car down on the ground when you do
this because checking the torque settings on the mount is a little difficult
(not impossible) with the lines in the way.
As a final check, when you get the car back
on the ground you should re-torque the 13mm bolts as a double check. Also,
I was able to torque the large bolt from the top once the car was on the
ground but I thing this should only be done to ensure that you torqued it
properly the first time.
Replacing the mounts was easier than I
thought. I would compare it to replacing mufflers. There is definitely
more noise/vibration in the car but the difference is minimal. If a cup car
is at level of 10 and stock is 1, I would rate the harshness/noise/vibration
of the RS motor mounts as a 2. My initial impressions are that the
transmission does shift a little better and that some of the wiggling I
experienced in the rear end as it shifts its weight has decreased. I would
definitely recommend this upgrade to anyone, even those that arent looking
for increased stiffness. The reason; I noticed that my original motor
mounts were gone (dead). One shaft was longer than the other causing my
engine to be lower on one side as compared to the other. The difference was
only maybe 3 to 5mm but it was enough to make me readjust the exhaust tips.
I guess just like shocks and struts, the hydraulic mounts wear out. Here is
a picture of them side by side. Once you get past the optical illusion of
one being closer to the camera, you will notice that the one further away
(on the right) has a longer shaft.
information update for 993 twin turbo owners
(Oct / 2003)
Contributed by :
(Posted on Rennlist.com 993 turbo forum )
RS Motor Mounts in a TT
Just finished installing my RS motor mounts in
The only problem with our cars is that the
engine carrier is a bit taller than the NA cars, so the normal bolt
specified on Robin's DIY is not long enough.
The correct bolt is a 12mm, 1.5 pitch, GR
10.9, 120mm length bolt. The original bolt in the DIY was a 105mm length, GR
8.8 bolt. The extra 15 mm length leaves about 10mm of threading past the nut
when fully assembled and torqued.
I didn't have time to test out the car yet,
since there are a few other things I want to change "while i'm in there",
but I'll post my impressions when I get the car back together.
I got the bolts from a place called
http://www.metricspecialties.com/ They had great service and prices as
well. Although they usually have a small minimum order. I had to order 6
bolts. So I have 4 extra bolts, so if somebody needs a pair, let me know.
Rennlist members only please... Locals preferred over having to ship.
Here are some pics:
Differences in length of the main bolt.
More differences in length. You can see in the
old bolt ( top ) where it was too short and I stripped it. DOH!
Picture of the old motor mounts. For some
strange reason the right one was pretty rusty...
Installed on the right hand side
Installed on the left hand side
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