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Introduction
The front lower control arms on the Saab 9000 are mounted on the front subframe
by means of two rubber bushes, one front and one rear. The front bush seldom
gives trouble, but the rear bush takes most of the force of dragging the car
along under acceleration, dragging it back under deceleration and dragging it
sideways during cornering. Unsurprisingly, it eventually wears out. When this
happens, steering can become less precise and eventually there is enough movement
to cause the suspension to "clonk" on occasion.
It is also not uncommon to replace the standard rubber rear bushes with after-market
polyurethane bushes. These give longer life and are generally stiffer, giving
more precise handling, arguably at the expense of some ride quality. I have
not seen polyurethane replacements for the front bushes offered for sale.
This procedure documents what I did to replace the front and rear bushes on
the front control arms on my 1996 9000 Aero. Unfortunately, I don't have a digital
camera, so there aren't any photographs. I'll have to use the proverbial "thousand
words" in lieu of each picture.
Note
I considered two methods of tightening up the rear bush retaining nut: out
of the car where I could get a torque wrench on it, and in the car with the
wheels on the ground. The former makes it easy to get the correct torque setting,
while the latter makes it easy to get the bush fixed in the correct position,
so that there is no torsion on it in its rest position, but at the expense of
having to guess the torque setting with a spanner. I chose the latter, but of
course you are free to make your own choice.
A similar procedure was also carried out independently by Matt Sullivan,
who has kindly allowed me to link to the photographs
he took.
Time required
Naturally, this will vary with both the individual and what they find when
they get there. However, excluding removal/replacement of the front bushes,
this took less than an hour per side. The front bushes took an hour or more
each by themselves. I'm sure this would be much quicker had I had access to
a proper press or had I made my tool from metal
rather than plastic pipe. Since the front bush rarely gives trouble, I would
leave it alone in future, unless I suspected a problem or wanted to replace
it with polyurethane (if I could find some).
Tools required
I assume some basic tools here, such as a jack, axle stands, socket set, etc.
However I do not assume you will already have all the necessary metric socket
and spanner sizes, especially if you are in the USA. Here is a list so you can
make sure you have all the necessary sizes before you start.
Spanners
- 13mm
- 16mm (x2 possibly, see text)
- 18mm
Sockets
Other
If replacing the front bushes, and not using a press to remove/replace them,
see the instructions for making a home-made tool.
Procedure
- Jack up the front of the car and place it on axle stands. If you are not
sure where you can safely place the jack and axle stands on a 9000, go here
for more information.
- Remove the roadwheel.
- Remove the three nuts/bolts holding the lower ball joint to the control
arm (13mm). The middle bolt can be tricky to get a spanner on - just push
the hub around on the steering until you get the right angle.
Photo by Matt Sulllivan
- Remove the 16mm nut holding the anti-roll bar drop link to the control arm
(underneath). remove the lower rubber bush and washer as well.
 
Photos by Matt Sullivan
- Slacken the 18mm nut holding the drop-link to the anti-roll bar to allow
rotation. There is no need to remove this nut completely unless you are replacing
the drop-link. I was replacing these as well.
- Pull the hub assembly clear of the control arm and press the arm down to
free the end of the drop-link. Sounds easier than it is - I had to place my
foot on the end of the control arm and put some weight on it, and while doing
one side of the car I also had to simultaneously apply sideways pressure to
the drop-link to stop it catching in the hole in the control arm. You're supposed
to be careful not to flex the bushes too much at this point, but I see no
alternative. However, it wasn't terribly difficult. Swing the drop-link up
and out of the way.
- Remove the two 16mm nuts holding the front bush to the subframe. These are
screwed onto two bolts (also 16mm) that go right through the subframe. The
front one is fairly easy - you can get a socket onto the nut and a spanner
on the bolt. The rear one, however, is partly obscured by the control arm.
In addition, the head of the bolt is close to the gearbox on the left side
of the car and the engine mounting on the right. Unless you have a very
shallow socket (shallower than I've ever come across), you'll have to do these
with two spanners. I did find that a 5/8" spanner was a very good fit,
being just slightly smaller than 16mm.
When you've got the nuts off, push the bolts back a bit - it'll make it easier
to get the control arm off in a minute. The bolts won't go back very far,
as there are engine/transmission bits in the way.
Photo by Matt Sullivan
- Remove the two 13mm bolts from under the rear bush. The Haynes
manual says to remove the other two bolts holding the reinforcing
plate and remove the plate, but I didn't need to. Note that at this
point, the rear bush is all that is supporting the arm. It
isn't very heavy, but if you're under it, don't pull it about yet,
as you probably don't want it landing on your face.
Photo by Matt Sullivan
- Slide the arm forwards and outwards to remove it.
- Replacing the rear bush
- If you wish to torque the rear bush retaining nut with the arm out of
the car, mark the position of the rear bush on the arm. This assumes,
of course, that the existing bush was fitted correctly.
- Remove the 18mm nut and the large washer, followed by the bush.
- Fit the new bush, followed by the large washer and the 18mm nut.
- If you'd rather torque the bush with a torque wrench, line it up with
the marks you made previously and tighten the nut to 50Nm
(37lbft). Otherwise leave it loose enough for the bush to rotate
with resistance.
- Replacing the front bush (optional)
- Remove the aluminium brackets from either end of the bush.
- Mark the position of the old bush so the new bush can be fitted in the
same position.
- Using either a press or the home-made tool,
press out the old bush. This was relatively easy with my home-made tool.
- I found some crud stuck to the inside of the bush housing. I there is
any, clean it up gently with some fine abrasive paper.
- Lubricate the bush and the housing. I used engine oil (5w30 synthetic,
if you're really interested - feel free to use non-synthetic!).
- Press the new bush into the housing, again using either a press or the
home-made tool. I had problems pressing mine in with the home-made tool.
The plastic pipe wasn't really strong enough. Metal pipe would certainly
have been. I'm convinced that one of the reasons was that the new bushes
(made by Scantech in Sweden) were larger in diameter than the old ones.
Perhaps the old ones just hardened in compression and didn't spring back
all the way.
Make sure you line the new bush up with the position marks you made earlier.
- Refit the aluminium brackets to either end of the bush. You might find
it easier to fit the rearmost one before the bush is fully pressed into
position.
- Refit the control arm to the car by sliding the rear bush into place in
the subframe. Don't fit the bolts yet.
- Offer up the front bush to the mounting bolts and push the bolts through.
Refit the nuts and tighten to 50Nm (37lbft).You'll
probably have to guess at the torque on the rear nut/bolt, as it's unlikely
you'll be able to get a torque wrench on it.
- Refit the bolts on the rear bush and torque them to
50Nm (37lbft).
- Refit the drop-link along with its rubber bush, washer and nut. I had to
lever it back into the hole in the control arm. Torque the nut to 25Nm
(18lbft).
- Retighten the nut on the end of the anti-roll bar. Torque it to 30Nm
(22lbft).
- Secure the lower ball joint to the control arm with the three nuts/bolts.
Torque to 30Nm (22lbft).
- Refit the roadwheel.
- Lower the car.
- Torque the roadwheel bolts to 115Nm (85lbft).
- If you decided to torque the rear bush retaining nut with the car on the
ground, you may find it easier if you drive it onto ramps. I borrowed some
ramps for this purpose, but my Aero is too low at the front to drive onto
ramps (at least those ones) without scuffing the front spoiler. I found I
had enough room without the ramps anyway. Using an 18mm open-ended spanner
(I couldn't get a ring spanner on the nut) tighten the nut - you're trying
to approximate 65Nm (48lbft). I just pulled it
as tight as I could manage with the length of the spanner and the available
space.
- As always after suspension work, have the front wheel alignment checked
as soon as possible.
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