UberScheitzer

Just found out that our recently purchased 74 911 has Carerra S front aluminum calipers. What is the advantages/disadvantages of having these?

I would assume that they are less weight and might cool faster.

Any help?

Bill Verburg

There are 3 calipers that use the 3.5" mounts, The S, the A , the wide A

• the aluminum S weighs ~6# w/o pads and has a bad rep for flexing under extreme abuse
• the iron A weighs ~7.5# w/o pads , flexes less
• the iron wide A weighs ~8# w/o pads and has the additional advantage of fitting over a wider 24mm rotor

They all use the same size pads, cooling the caliper is not generally the issue

UberScheitzer

Thanks for the info again Bill!

Steve Weiner-Rennsport Systems

Bill is SOOOO right.

Install the 83-89 Carrera front calipers & rotors and you'll have far better brakes than any '74 ever had,...

Jim Richards

Steve, if a person had an early car with M calipers, does the Carrera brake upgrade require replacing the strut assemblies, too? Thanks.

quinnfiske

If you wish to upgrade from "M" calipers to "S" calipers in an early car you must either use "S" struts or modify your current struts. The S cars used Koni insets rather than Boge inserts.

r911

As I recall, Jim Calzia put the rear calipers from a 951 (944T) all the way around on his car. That's the light wt. way to go -- he races it, so must get decent fade resistance.

Someday there will be ceramic rotors for the early cars....

Bill Verburg

That wouldn't work very well Randy. He put a set of 964/944t calipers on his car, the correct 40/36 on the front and 30/28 on the rear. I did the same on mine

Here's the link to his page, he used some Aluminum MM rotors, it would be interesting to learn how they worked, I have heard that there were some difficulties w/ them.

Bill Verburg

You can use any of the later 3.5" ear struts. The difference between the 911 and 930 struts is the inserts, 930 uses an sportier insert. IMHO Bilstein or perhaps the newer SRP/Fox inserts from Smartracing are the way to go

JPhillips-998

I have struggled w/ the S calipers but am stuck due to club race rules. If you are not going to race it, I would look at different options, even the M calipers.

One race weekend I installed/reinstalled/rebuild calipers 8 times over a day and a half! My last experience led me to replace the master cylinder and my test day on the track worked out well. Hopefully that will take care of it but again, if you are not required to go with the S's, I would look at other optioins.

Steve Weiner-Rennsport Systems

Hi Jim:

As Bill indicated above, you'll need different struts with the 3.5" bolt spacing to install ANY larger front brake calipers. I'd use Bilstein's, JRZ, or Moton if it were me. Using adapters to mount larger calipers on 3" struts is not safe.

IMHO, the "A" calipers used on SC's are much better than "S" calipers and its a worthwhile upgrade. The only time we use "S" calipers is on certain vintage race cars that cannot use anything else, per local rules.

Jim Richards

Thanks Steve. I'm going to put that on my project list for this winter. My wife likes the 73E but she is not too high on its brakes.

Mach 5

Wow, this discussion kind of "bums me out". I had M calipers on my 72T and just went through the hassle (and expense) of installing new front Bilstein strut assumblies to put S calipers on. I haven't had a chance to drive it yet (long story, different thread), but I was hoping I would get a lot less fade at DE events with the S calipers.

Bill Verburg

The larger pad area will help a tad, but the real cause of brake fade is rotors that are undersized for extended periods of hard braking, i. e. track use. Generally early 911s are light enough that either A or S calipers w/ stock rotors and a bit of help are fine.

Easy things to do that help are; cooling ducts, quality fluid and track oriented pads

An inexpensve up grade is wider Carrera rotors and calipers. The extra 4mm of rotor thickness helps a lot in a lighter under 225hp car. Check w/ your sanctioning body about this as you may get bumped a class.