front brake piston seized

[ush1000]

Hi - one of my pistons is seized, a bit strange as I have had the bike 3 years and reckon it has been seized all the time. Bike gets used very little so I guess I have got used to slightly rotten brakes. I have never fiddled with callipers before, apart from changing pads and bleeding. I propose to remove the calliper from the bike, tie back the 3 good pistons to prevent them from moving, soak the offending piston for about a week with wd40 or similar, then try to wiggle the piston free using molegrips, being careful not to damage the piston or calliper. Any thoughts? Will this work do you think?

[gstallons]

NO petroleum products of any kind are to be used around brake hydraulic parts. Block the 3 free pistons in the retracted position and use the hydraulic pressure of the brake lever to push the piston out. You can use Scotchbrite pad to clean the caliper piston , then remove the dirt with a brakekleen spray and reassemble with a brake assembly lube.

[dave]

Hi - one of my pistons is seized, a bit strange as I have had the bike 3 years and reckon it has been seized all the time. Bike gets used very little so I guess I have got used to slightly rotten brakes. I have never fiddled with callipers before, apart from changing pads and bleeding. I propose to remove the calliper from the bike, tie back the 3 good pistons to prevent them from moving, soak the offending piston for about a week with wd40 or similar, then try to wiggle the piston free using molegrips, being careful not to damage the piston or calliper. Any thoughts? Will this work do you think?

 

I had a very similar problem that caused one of the pistons to not be seized but nor would it completely release. After much exterior cleaning with no luck and even considering a replacement, I went ahead and split the caliper, removed the pistons and flushed the thing multiple times... far less work than one might expect. The pistons have a non-stick corrosion inhibiting coating worth protecting. The unit works fine now. I did check for a rebuild kit at the time, but found none available for this model brembo. Annoying since it was used on many of my favorite machines! Lesson: always clean the outside of the thing before retracting the pistons to change pads.

 

Good luck!

[Guzzirider]

You can now get overhaul kits http://www.gutsibits.co.uk/pr/TheShop/index.php?q=BRA19723&f=d&Model=0&search=SEARCH

[ush1000]

You can now get overhaul kits http://www.gutsibits.co.uk/pr/TheShop/index.php?q=BRA19723&f=d&Model=0&search=SEARCH

Thanks Guzzirider, when I have the overhaul kit, is the method of removal of the seized piston as I described, albeit with some other releasing agent? Also loving the look of your cafe racer!!!!!

[dave]

You can now get overhaul kits http://www.gutsibits...0&search=SEARCH

Thanks Guzzirider, when I have the overhaul kit, is the method of removal of the seized piston as I described, albeit with some other releasing agent? Also loving the look of your cafe racer!!!!!

 

I am no expert, but I would recommend pushing it out from the back or take measures to not scratch the cylinder finish.

[Dimples]

These calipers are not supposed to be rebuilt-- there's no authentic Brembo kit. You can't get anything from Moto Guzzi either.

 

I posted to this forum when I had this same problem and received similar advice. I tried to rebuild mine anyway with an after-market kit from MG Cycle. The seals (large) were not a correct fit and failed. I've rebuilt calipers in the past and it's simple with actual Brembo labeled parts. If you do decide to disassemble the caliper and see that corrosion has penetrated the piston's anodized surface, you should probably replace the caliper. To clean the pistons, I wouldn't recommend anything as abrasive as Scotchbrite which can remove the anodizing, but you might gently scour the surface with something comparable to "Bar Keepers Friend".

 

In conclusion, if you want to save yourself a lot of messy trouble and have reliable brakes, buy a new caliper. They're about $277. from a dealer. On a related subject, how's your rotor? If you've been riding around with a seized caliper it may have warped the rotor-- you will feel a "pulsing" sensation under light braking.

 

DD

[Baldini]

These calipers are not supposed to be rebuilt-- there's no authentic Brembo kit. You can't get anything from Moto Guzzi either.....

 

 

The link Guzzirider posted aove shows Brembo branded kit from a reputable dealer.

 

Dunno about "not supposed to be rebuilt" ? Kits didn't used to be available but apparently they are now.

 

KB

[gstallons]

There are different "grits" of Scotchbrite pads. You can use the mildest to clean up the piston surface. Any pitting or scoring means it's time to replace it. When you have cleaned the piston , clean the caliper bore with a fine bristle wire brush to get all dirt , debris , etc. out of it . Clean everything up with Brakekleen and use a brake asembly fluid to put it back together. A firm thumb pressure will be needed to bottom out the piston. Reassemble and bleed.