911 M front caliper piston sizes, Same as 914-4 caliper pistons? Options

[phantom914]

I know that the M calipers allow the use of a vented rotor, but are the piston sizes any different than the 914-4 caliper? (speaking of front calipers)


Andrew

[davep]

I have discussed this at length in other threads on brakes.

The 914 rear is 33mm, the 914/6 rear and 911 up to about 77 were 38mm. Later 911 got the 42mm rears.
The 911 rear and the 914 front are very similar since they are all "M" type parts.
The 911 front is a larger casting than the 914 part, but they will interchange. The 911"S", 911"A" and the 911"M" calipers all had 48mm pistons. The "A" and the "S" had bigger pads than the "M". One could almost say the designations were more in reference to the pad sizes than the caliper sizes.

The 914 and 911 fronts had different piston sizes but the same pads.