Brembo disk and pad replacement
I know this is a common issue but I need a rant.
Yesterday I took into replacing the front and rear discs and pads on my 159 2.4. I was expecting sticky pins so geared up with a proper punch / drift and hammer before starting. The first pin I punched came out with little or no issues which gave me false hopes for the rest of the job. The 2nd pin would not budge after several attempts to strike it out. Out came the grinder and I chopped the ends of the pins as tight to the caliper as I could to prevent the pin swelling when hit. This allowed the side nearest to the wheel to drift out easily but the side with the steel retaining spring was corroded into the caliper. This took about 30 minutes or so of striking to remove. Still not too bad, it also took me a little while to work out how to push back the 4 pot pistons as my draper windback tool could not be used. After a bit of fiddling it turned out to be very easy to do except at that stage the disk and pads were already off, so on they went again and after loosening the bleed nipples I applied a small lever onto the pads to push them back in. The remainder of that side went smoothly.
Next up was the other front calliper. I was prepared this time so first up was to press the pistons back, no problem. Next was to drift the pins out. No movement on either, so not dicking about I went straight for the grinder. The top pin was removed in about 10 minutes this time which wasn't too bad at all. The bottom pin refused to move. No amount of persuasion would work. Eventually I had to drill a hole through the pin to hopefully weaken it. Still this would not work, I didn't want to apply heat from a torch as the offending part, the steel spring, is located well inside the caliper which would have required a lot of localised heat to the area. I wasn't sure of what damage could have been caused by heating so left that out. There was nothing else for it so out came the mini sledge / heavy hammer and with several hard slaps on the drift out came the remaining piece of the pin. This probably took a whole 1-1.5 hours on this pin alone.
The next issue was removing the grub screw holding on the disk. I tried moving it with an allen key (5mm) but it would not budge so out came the windy gun. All this did was strip the allen head on the screw! Ahhhh! There was nothing for it but to drill out the screw. The problem with that was after using different size drills up to 10mm I still didn't have the head off the screw and the chuck on the cordless is only 10mm. My dad pulled out an old manual powered/ hand wind drill which had a 13mm chuck on it. I didn't think this could work but using a sharp 13mm bit my dad was able to drill the head off the bolt. What a session! In the middle of it all the electric went out leaving us to work with torches for a while as well. The remainder of the work was as straight forward as it should have been. What should have been a 2-3 hr job ended up taking 7 hours!!
On examining the pins it appears the steel spring corrodes with the aluminium on the calliper effectively welding together. I also noticed a lot of pitting on the slide of the callipers where the pads sit. I assume this is again a reaction between steel pads and aluminium slides helped by winter gritting on our roads. Other than a light coat of paint at the factory there is nothing to prevent the galvanic reaction from occuring. I think this is a poor design and some attempt should have been made to prevent this. It really made for a ball breaker of a day yesterday. On the plus side the brakes all ready feel much more positive and they haven't bedded in yet.
I also bled the brake lines a little yesterday but I think they may need bled more. The brakes pump up solid when the car is off but when the car is running, holding a lot of pressure on the pedal will see it gradually move to the floor although this is not felt when driving. The brakes react and feel as they should so I'm not sure if this is normal or not. I have checked all bleed nipples for seeping which there isn't any just in case. If anyone has any ideas on this let me know.