Griso 1200 4 pot caliper

[fredvv44]

Can anyone tell me the piston diameter on these calipers?
Thanks,
Fred V

[Moto Fugazzi]

If it's the same gold line Brembo as the older Grisos, it should be 34/30 (2 of each) on those. It only takes 2 bolts to remove them, so you might be better of to measure them.

Why do you ask? Having issues with yours? What year bike?
Ken

edit:
After looking at Harper Moto Guzzi website, it may be the Brembo P432 caliper. That might mean 4-32mm pistons. This is for a 2012 Griso 8V:
http://www.harpermoto.com/parts-by-motorcycle/2000-up-moto-guzzi-motorcycles/griso-v-8v-1200-2007-2009/front-brake-caliper-en-griso-8v-1200.html

[fredvv44]

Thanks Ken. I built a replica of a Morgan 3 wheeler using a Cal2 drive train. The front brakes are Wilwood calipers on Guzzi rotors and are inadiquate for the job. They stop OK but need hard pedal force and then the caliper o-rings leak. It looks like the Griso calipers will be a rather easy mount with a new bracket. I looked at putting on the F08 calipers but the mounting would not be as easy nor would the calipers be as strong. Here is a photo showing that and the Wilwood units.
Fred V
http://jzrusa2.blogspot.com/

[fredvv44]

I just ran the piston area numbers ( I see the 30/34 now on Harper's site).
Willwood=2.4"
F08       =3.53"
Griso     =5"
So that would about double the piston area from what I now have. I have a proportioning valve going to the rear caliper and I run it wide open.

Another problem with the Willwood brakes is that they tend to pull one way or the other so I have to correct the steering when I hit the brakes hard; not good.
Fred