Early brake question

[304065]

Are the wide M calipers used on the REAR of a 1971 911 the same as the wide M calipers used on the FRONT of the 1967 911S?

[304065]

I am thinking that rear calipers were originally 35mm pistons, then bumped to 38mm and stayed there through 1983. . . whereas the fronts were never smaller than 48mm. . .

[chris_seven]

I think the early barkes with the 35mm piston is designated as an L Caliper. They had an external compensation line and were a very small mounting centre not the 3" used on the front.

The 38mm M Type was the same body as the front unit with a smaller piston at 38mm.

[davep]

No, front and rear calipers on the 911 are quite different castings. The 911 front M have 48mm pistons while the rear M has 38mm pistons. The "M" designation has more to do with the pad size than the caliper itself. Note that the fluid inlet locations are also quite different. The 914 also uses M calipers on the front, but these are different again and have 42mm pistons.