Seized pad retaining pins nightmare.

[roadster]

Well it had to be done sooner or later so I decided to change the rear pads knowing that the retaining pin internal hexagons would give way when I tried to unscrew them. Sure enough they wouldn't budge and I couldn't try too much heat because it would damage the hydraulic seals. These callipers are a horrible design. The pads cannot be changed with the calliper in-situ and the M10 threads on the pins would normally warrant a far larger allen key than can be used within the pin diameter.

It doesn't help that the calliper casting is an awkward shape that cannot be clamped firmly in a vice. Even drilling out the pins was not simple because an ordinary HSS bit wouldn't bite in the hardened outer layer. I managed to grind enough away with a burr to make a start with a cobalt bit and eventually got through to where I could break the pin off from the head. With a fair bit of further drilling and fiddling the outer pad could be removed then with a lot more messing about finally the remaining ends of the pins were withdrawn through the holes drilled through the heads.

This just left the heads still seized solidly in the casting and not at all loosened by having their centres removed. So with a junior hacksaw blade inserted through the centre and held in my fingers I cut a pair of slots all the way through on opposite side and finally chiselled out the remaining halves of each one. I then needed a pair of M10 X 1.0 ( metric fine) taps to refinish and clean the threads before it was all ready to reassemble with new pins and new pads.

There is no amount of money that would persuade me to do this job again and its going to take a week for me to recover from spending nearly two days kneeling on the garage floor!

[allen m]

Hi.
Make sure you put everything back with 'copperslip' or some similar compound to prevent things seizing again.
Regards
Allen Morgan

[Dave Milnes]

Could you not have welded a hexagon to the head of the new pins before refitting, a nut or something?

[Mike H]

This is why I removed all the calipers of my *BRAND NEW* X10 and removed and copper-slipped these screws, and smeared Brembo grease around the edge of each of the pistons, as I had these seizing up on my 2 yrs old blue one. The pads were so hard on it was impossible to rotate a wheel by hand! This I only found out one day quite by chance by trying to rotate the front wheel just to get access to the tyre valve. Solid. Jacked it off the floor, still solid... WTF...

[spannerman]

 You can't shift the pins using normal allen keys, so before starting, buy a long extension 10mm to 5mm socket. You can then get at them in-situ (on the Beverly). The factory uses some strong thread lock.

[roadster]

Could you not have welded a hexagon to the head of the new pins before refitting, a nut or something?

I though about this but the heads are recessed when tightened. I also thought about welding in a hex key stub which would at least have removed the problem that is caused by the cap expanding out as the standard key bears on the internal flanks. I think this is what stops the pins coming out. The more force you apply the more the cap expands in the hole and just locks solid. In the end I settled for not overtightening the pins, I used a standard allen key and only applied hand force. I'm going to keep a close eye on them and recheck tightness fairly frequently but I don't see any reason they would loosen.

Other suggestions are all valid and believe me when I say that every possible tool was tried to no avail. The front callipers are the same but I did take these apart when new exactly as Mike H says. I wonder if the blue compound which is pre-applied to the thread actually cooks hard when the brakes get hot so even after a few thousand miles its too late to shift them.

[polecat]

been there got the tshirt i ended up drilling all 4 pins out and remaking them from a 10mm threaded rod on the lathe and just sloting them for a large screwdriver and refitting them with plenty of grease i guess that tin piaggio had has run out by now all the same faults over and over again all the time
polecat

[Techno]

Got this very issue on my 350, the bike is 12 model low mileage at 7500.

Got the left side pins out ok with a little heat but the right now way both have now rounded off

I'm going to try using bearing fit, this is one of the strongest engineering adhesive, it will be much stronger then the stud lock that's been used on the thread.  

It may work has in the past fingers crossed will again, falling that it's drilling  

I'll get either a new or used caliper as I can't be without the bike for more than a day plus the front left and rear are the same, if the rear goes the same way I'll have a spare I can then sell on which ever once repaired.