What calipers do I have? 1974 911

[Hoegenauer]

I need to order rebuild kit from our host and there are several offered.

From a '74 911 (I cannot be sure they are even the original but I assume so)

Rear calipers; single piston

The only numbers on the castings are:
88 on outside half 18 on inside half
48 on outside half 17 on inside half

Thanks for the help.

[fanaudical]

Pictures?

[djpateman]

The casting mold #'s tell us nothing. I've never seen single piston rear calipers on a 911, always two opposed pistons. A photo would help.
Generally though, a 74 911 should have M calipers with 38mm pistons in the rear.

[Charles Freeborn]

If your '74 is an "S" it could have the aluminum "S" calipers on the front. If they're cast iron they're probably M's. Rear will be M's too. Fronts interchange with "a" calipers (as I have done), so it's possible that they've been upgraded to those. PMB performance will have all the info about your brakes on their website. They also do top notch re-building. My car has PMB re-builts on all 4 corners. Stops like a champ, especially after stepping up to a street / race pad (Fedoro's).
-C

[Hoegenauer]

Sorry for late reply. Traveling lately and no time for the car.

Below are the rear calipers. I hope they are clear enough to identify.







Thanks for your replies.

[moneymanager]

Put a magnet on them. If steel, they are probably M's front and rear. If aluminum, you have an S caliper. Your rears look like M's to me.

[Tidybuoy]

My '74 has "M" calipers in the rear - here's what they look like for comparison:



A standard '74 will have slightly larger "M" calipers in the front or if it's an S, then you will have the aluminum S brakes. One way to tell on the front is the bolt spacing that holds the caliper on. The Front M caliper will have 3" bolt spacing (center to center) and the S will be 3.5".

Here is my front caliper on my '74 but I have upgraded to the SC "A" caliper and it has 3.5" bolt spacing. The "A" caliper has the brake line entering the caliper in the middle on the inside side, whereas the "M" caliper has the brake line connecting on one end of the caliper.



Your caliper looks like an "M" caliper to me.

[Matt Monson]

Brakes

[djpateman]

Those appear to be M type rear vented calipers; note the inlet location and the spacer for the vented rotor:


On the front you might have M-type with 3" spacing the same as the rears:

or A-type with 3.5" mount spacing (note inlet location):

or aluminum S-type with 3.5" mount spacing (note one piece forging with rear cap):

[Hoegenauer]

Thanks to All!

Have a great weekend.