If you are fitting new pads as well, you will also need to look
On the smart car, the brakes discs are 9mm thick when new. The maximum wear
they can have before being replaced is only 1mm. You can measure them with a
caliper gauge, if they are anywhere near 8mm or below you should change them
Fitting The Discs
You will need the following tools:
15mm socket to remove wheel,
13mm ring or open end spanner,
17mm open end spanner,
Clamp to push piston back.
First of all loosen front wheel nuts, jack up the car and place the axle
stand securely. Lower onto the stand. Check for security of car on stand -
you're going to be working on it!
With the wheel removed it will look like this.
You are now going to remove the brake pads prior to removing the brake disks.
Undo the top bolt using the 13mm spanner and hold the lock nut with the 17mm
With the top bolt removed you can swing the brake piston carrier to the rear
but do not
let the weight hang on the brake hose. Keep it supported. You can remove the
pads noting the position that they are fitted in. The rear pad has a metal
prong that will help you see the difference between the two pads.
Now comes a slightly more tricky bit. You need to remove the brake caliper
to have access to remove the brake disk. Rotate the piston back into
(without the pads in place) and lightly do up the bolt to secure it. You
need to identify
the 2 bolts at the rear of the brake assembly that hold the caliper into
can be undone using the E18 socket. The next photo shows the bolt holes on
caliper after removal and will give you a sense of where the bolts are.
Ensure that the caliper is supported in order not to stress the brake hose.
Then remove the small T30 screw holding the disk to the hub.
Once you have removed the disk - it may need a tap with a soft hammer if it
is stuck around the hub centre with rust. It should then look like this. You
can see that I've secured the caliper out of the way. You can also see the 2
bolts holes where the caliper was bolted.
I've included the following photograph as it gives you a better
view of the ABS reluctor ring and sensor.
Clean up around the hub and remove the rust where the disk fits the hub
Refit the new disk and secure it using the T30 screw. Ensure the new disk is
grease free and handle it with clean hands avoiding the braking surface. You
now carefully refit the caliper and its 2 bolts and torque them to 115Nm.
Be sure not to damage the new disk when doing this. Once secured and
undo the 15mm top bolt on the caliper and push the piston carrier to the
You will now need to push the brake piston back into its housing and before
so check that the brake fluid cylinder is not too full. If it is you may
need to remove
some brake fluid to allow the piston to move back without spillage at the
I managed to push my pistons back just using my fingers. If you can't do
a thin piece of wood and a clamp to force the piston back
taking care not to damage
the piston face and its rubber dust sleeve.
You can now refit the old brake pads into position. It is advised to use a
small amount of copper grease on the rear faces of the pads to avoid brake
squeal - be careful not to overdo
this or get it on the face of the pads or disc
Once they are in place you can reposition the piston carrier and reinsert
and tighten the top bolt. The springs on the back of the pads should not
stick through the back of the caliper and the pressure of the spings should
be felt when you reinsert the top bolt.
Clean the entire disc front and back with brake cleaner to remove the
Before refitting the wheel pump the brake pedal to move the piston back
into contact with the pads. Check the brake fluid in the reservoir. Refit
wheel and tighten the bolts to 110 nm (approx 80 lb ft).
Now go and do the other side. Carefully drive the car to settle the pads and
ensure that the brakes are working properly. It will take a while miles to
them in depending on usage so you will need to drive carefully while this