Help identifying my front brake calipers - potential Boxter upgrade?

[Jeffreypang911]

Car is a 1974 911, but keep in mind this car has parts changed from many other years. No booster.

Going through my build, I noticed that the previous owner had replaced the driver side caliper that is different than the passenger side. Also noticed that the previous owner installed drilled rotors but one side the holes are going the wrong way. All this coupled with a seized rear left caliper means a full brake system overhaul.





Can anyone identify the calipers on this car? all rotors on the car are 20mm.

I am thinking about rebuilding the rear calipers and leave them stock. Then run Boxter (986) front brakes, and upgrade to 24mm Carrera rotors. Would this setup work fine with my stock '74 non boosted master cylinder? I keep reading about people switching to the 930 master cylinder but I would like to avoid it if possible. Anyone who has done this before - I would love your input.

Thanks.

[Porboynz]

LHS looks like an S alloy caliper and the RHS looks like an M or A type cast iron caliper. Measure the distance between the caliper mounting bolts to be sure

[Jeffreypang911]

Originally Posted by Porboynz

LHS looks like an S alloy caliper and the RHS looks like an M or A type cast iron caliper. Measure the distance between the caliper mounting bolts to be sure

Would the S calipers measure out different than the cast iron ones? I know theres 3 inch and 3.5 inch ear spacing just not sure which calipers have which.

[Bill Verburg]

Originally Posted by Jeffreypang911

Car is a 1974 911, but keep in mind this car has parts changed from many other years. No booster.

Going through my build, I noticed that the previous owner had replaced the driver side caliper that is different than the passenger side. Also noticed that the previous owner installed drilled rotors but one side the holes are going the wrong way. All this coupled with a seized rear left caliper means a full brake system overhaul.





Can anyone identify the calipers on this car? all rotors on the car are 20mm.

I am thinking about rebuilding the rear calipers and leave them stock. Then run Boxter (986) front brakes, and upgrade to 24mm Carrera rotors. Would this setup work fine with my stock '74 non boosted master cylinder? I keep reading about people switching to the 930 master cylinder but I would like to avoid it if possible. Anyone who has done this before - I would love your input.

Thanks.

Not a good pic but probably an A


Definitely an S


Both A & S have 3.5 mounts

If it was my car i'd buy another to match one of those

If you use Boxster fronts then you want 3.2 Carrera rear, no p/v

[Jeffreypang911]

Originally Posted by Bill Verburg

Not a good pic but probably an A

Definitely an S

Both A & S have 3.5 mounts

If it was my car i'd buy another to match one of those

If you use Boxster fronts then you want 3.2 Carrera rear, no p/v

Thank you for your reply - exactly what I was looking for.

Since the S is newer I will likely try and look for an S brake for the passenger side. Boxter caliper is more for cool factor but I am unsure if its worth the headache for marginal performance in a street car.

[Porboynz]

Originally Posted by Jeffreypang911

Would the S calipers measure out different than the cast iron ones? I know theres 3 inch and 3.5 inch ear spacing just not sure which calipers have which.

Both S and A calipers have 3.5 inch spacing and M calipers are 3 inch. You will find it easier to replace the A caliper if that's what it is. I would measure the mount bolt spacing to be sure because whoever fitted the odd caliper has already proven they are short a few spanners in the mechanical department and may have swapped in an entire strut and M caliper. (but it does look like an A caliper, the pads are larger and are the same size in the S and the A caliper, the M pads are smaller.)

[Jeffreypang911]

Cool. Looks like they are both 3.5 inches.

All the callipers need a rebuild anyway - so my plan is to replace the fronts with the late model Carrera 3.2 front callipers (I think they are referred to as "Wide A"?) and corrosponding 24mm thick rotors. From what I have read that -should- just bolt up and work with my current setup and offer slightly more heat dissipation. Then just rebuild the rears. I can find these late model callipers easily at the local parts places. Not so much for the original S calipers.

[JJ 911SC]

Originally Posted by Jeffreypang911

... Also noticed that the previous owner installed drilled rotors but one side the holes are going the wrong way.

Kind of the norm.

All the one that PP sell are the same disk for the left or right event Sebro Pair package got the same pattern on both disks.

I think that one I came across a supplier that had one part # for the left and a different one for the right. I would think if Porsche had some on the Turbo, it would have mirror patter on them. Maybe Bill can shed some light on this.

[tdw28210]

Curious what others think about a Carrera brake upgrade with no booster. I am thinking the same route for my current build and also thinking you may want to upgrade the master cylinder to the bigger bore version.

Bill V or anyone else care to chime in?

[Jeffreypang911]

Originally Posted by tdw28210

Curious what others think about a Carrera brake upgrade with no booster. I am thinking the same route for my current build and also thinking you may want to upgrade the master cylinder to the bigger bore version.

Bill V or anyone else care to chime in?

From my research it would bolt up and just work. Carrera calipers have the same piston size but just use 24mm thick rotors. If I end up going this route I'll let you know if it works out.