Rear Disc Brake Caliper Repair [1/2]
Rear disc brakes of my 505 Turbo Injection were working otherwise fine but the hand brake (parking brake) was ineffective. Finally the left side hand brake locked up always when I used it. The only way to release it was to crawl underneath the car and hit the lever with a small hammer... First I tried to adjust the cable properly, cleaned parts from the rust and lubricated the lever but it still didn't help. Luckily I had a set of rear brakes from a parts car.
These are the old rear brake assemblies of the car. The same type of Girling rear disc brakes can be found in almost all 505's (and in some 504 and 604 too, I'm not sure about ABS fitted cars) if drum brakes are not used. The hand brake mechanism of drum brakes is superior to the one used in disc brake cylinder when it comes to reliability and durability. However, with regular maintenance and correct repair procedures you can enjoy a working hand brake in a rear disc brake equipped car too.
Click a picture to see a larger copy of it
These are the rear brakes from a 1981 505 STI parts car. They were quite dirty and rusted but at least they were working when the parts car was still in use. It's also possible to buy a set of factory repaired brake calipers (about 110 e each).
First I removed most of the rust with an angle grinder and after that sand blasting removed the rust that was left.
One brake caliper is already sand blasted while the other is still waiting.
I painted all sand blasted parts with rust-preventive primer. Finally I sprayed two-pack epoxy paint to achieve extremely strong surface against dirt and salt. The paint should also be heat resistant enough (at least for rear brakes).
Walls of the cylinders had some dirt. If there are some serious corrosion or wear, you might have to buy a new brake caliper (brake cylinders are usually not sold separately). All signs of corrosion were removed by carefully smoothing the surface with a very fine water sandpaper.
Here you can see the two halves of the piston and the hand brake self-adjusting mechanism. If the ratchet teeth are broken the hand brake self-adjusting mechanism won't work. These shown in the picture are OK. You can also buy new pistons but they are only available as Peugeot OEM parts and one piston will cost more than two full factory repaired brake calipers!
Make sure that the ratchet teeth are aligned with the piston grooves before engaging the pistons. If they are not properly aligned and you force the halves together, the ratchet teeth will get broken. When the piston halves are completely together and entered into the cylinder, turn the piston 1/8th of a turn (45 degrees) to engage the ratchet teeth. Remember this also when changing brake pads (turn the piston 1/8th turn to disengage the ratchet teeth before trying to press it inwards to make some clearance)! Here is a repair kit with new rubber seals.