Caliper pistons

Please, 
Could you tell me the measurement of the internal diameter of the piston of the caliper (the carved side where is the pad).
Should I buy an extractor tool to pull out the internal piston.
Thank you.
Ciao
Piero

Piero, have a read of this;

https://www.oldbritts.com/caliper_rebuild.html

If you still want the dimensions of the pistons after reading the above article, I can get them but it will be Friday before I can get back to you with this. Let me know if so.

Hi,
I still wish the dimension of the internal carved side of the piston.
I have to buy the extractor tool.
Thank you.
Piero

Read through this a couple times to get the idea.
Seems I recall leaving the outer piston in place and keeping it in place with a piece of flat stock and 2 clamp. All this before unscrewing the plug. Them pump the inner piston out a little via the master cylinder hydrahlic pressure until you can get a grip on it.
Then unscrew the cap and punch the outer piston in just until the seal can be removed. Once the seal is removed, then the outer will come out through where the seal was and with the inner piston, pre loosed and in a position, work it on through.

Put in a new inner piston and inner seal is easy due to the direction of the seal lip, but the outer is a little tricky.
After the new inner piston and seal is in place, put the new outer piston in and just past where the new seal will go in.
With the outer piston in and past the seal groove, put in a new outer seal. The outer piston will then press back in over the seal without damaging the new seal. Reapply the cap and away you go. Cake!

Hi,
thank you.
But someone has the measurement of the internal carved side of the piston, please?
Ciao
Piero

pierodn said:

Hi,
thank you.
But someone has the measurement of the internal carved side of the piston, please?
Ciao
Piero

Click to expand...

Just measured an old original factory piston.
Internal hollowed out diameter 1.500" or 38.1mm
Depth of hollowed out area 0.500" or 12.5mm
There is a radius of between 1 and 2mm between bottom of hollow and sides but the size of that is my best guess as don't have a radius guage handy. (But am fully train turner so its best guess probably 1/16" as rest is imperial)
The hollow is machine tool cut so hopefully they should all be reasonable similar.

Hope that what you need to know. Good luck with it.

toppy said:

pierodn said:

Hi,
thank you.
But someone has the measurement of the internal carved side of the piston, please?
Ciao
Piero

Click to expand...

Just measured an old original factory piston.
Internal hollowed out diameter 1.500" or 38.1mm
Depth of hollowed out area 0.500" or 12.5mm
There is a radius of between 1 and 2mm between bottom of hollow and sides but the size of that is my best guess as don't have a radius guage handy. (But am fully train turner so its best guess probably 1/16" as rest is imperial)
The hollow is machine tool cut so hopefully they should all be reasonable similar.

Hope that what you need to know. Good luck with it.

Click to expand...

Hi Toppy,
Thank you so much.
Ciao
Piero