2400 rear brake calliper tutorial
Posted: Sun Apr 07, 2019 9:04 pm
There have been many posts regarding how to refurbish the rear brake callipers on the 2400 Dino. The difficulty is that these callipers incorporate a floating two-piston setup that also serves for the handbrake. Often (like me, the first time), one takes it appart and only changes the front piston seal and boots. Unfortunately, this will not correct a sticky handbrake problem.
To fix the handbrake, you need to disassemble the rear piston and lever mechanism, which is a bit of a PITA. Since I had done mine, and a friend asked to help with his, I though I could document the process while it's fresh in my head. Here goes:
Remove the calliper from the car, disconnect the handbrake cable and use a soft mallet to drive out the piston assembly from the curved housing:
Then, remove the rubber boot protecting the piston
You will notice that the notch on the piston is pointing up (or maybe horizontal). You will need to turn it 45° so that it is diagonal. This allows the teeth from the piston insert to disengage. NB: I have heard of new pistons that were manufactured with an incorrect position of the insert, so beware!
Then, you can use compressed air to push out the piston. You might be able to get it out with pliers, but be careful not to damage it. Here it is, badly scored near the rim. It did not leak, but it might be a good idea to replace it.
Here is the piston from behind, you can see the notched shaft that is used by the handbrake mechanism to push the piston forward when engaged. It is a ratchet mechanism, meaning that the pad wear is progressively taken up as the pedal is pressed.
Now for the rear piston. Start by removing the circlip and return spring.
Then the nylon spacer and round plug to expose the circlip and washer that holds the lever mechanism in place. It is still held in place by a short pushrod inside the piston, so don't try to force it out. You should see what is left of the first (9mm o-ring).
You have two possibilities: the first is that if it is not stuck, you can push it out with a wood drift which makes disassembly easier.
The piston will come out the back:
To fix the handbrake, you need to disassemble the rear piston and lever mechanism, which is a bit of a PITA. Since I had done mine, and a friend asked to help with his, I though I could document the process while it's fresh in my head. Here goes:
Remove the calliper from the car, disconnect the handbrake cable and use a soft mallet to drive out the piston assembly from the curved housing:
Then, remove the rubber boot protecting the piston
You will notice that the notch on the piston is pointing up (or maybe horizontal). You will need to turn it 45° so that it is diagonal. This allows the teeth from the piston insert to disengage. NB: I have heard of new pistons that were manufactured with an incorrect position of the insert, so beware!
Then, you can use compressed air to push out the piston. You might be able to get it out with pliers, but be careful not to damage it. Here it is, badly scored near the rim. It did not leak, but it might be a good idea to replace it.
Here is the piston from behind, you can see the notched shaft that is used by the handbrake mechanism to push the piston forward when engaged. It is a ratchet mechanism, meaning that the pad wear is progressively taken up as the pedal is pressed.
Now for the rear piston. Start by removing the circlip and return spring.
Then the nylon spacer and round plug to expose the circlip and washer that holds the lever mechanism in place. It is still held in place by a short pushrod inside the piston, so don't try to force it out. You should see what is left of the first (9mm o-ring).
You have two possibilities: the first is that if it is not stuck, you can push it out with a wood drift which makes disassembly easier.
The piston will come out the back: