The Very First S-Caliper?, an interesting look at one of DaveP's calipers Options

[Eric_Shea]

Dave Pateman sent some S-Calipers down for a dichromate re-do (not these in the thread, a later pair off a 73+ car) and he graciously sent an odd-ball caliper he had laying around for me to have a look at.

It sure proved interesting and, I have my "theory(s)" as to what it is and how it, and the following S-Caliper lineage came to be. The theory goes like this:

Porsche has been well documented in proving a concept at the track and then positioning that concept on their production line vehicles. I believe that ATE was commissioned to make a lighter caliper for their racing vehicles. I believe what we're about to see is one of the first basic S-Calipers to exist.

On with a tale of two S-Calipers:



Mine's on the left. It's a reconditioned, very early (69-70) S-Caliper that I will be using on my GT car. Dave's one-off is on the right. The first glaringly obvious difference is the endurance pad pin assembly. Any car that is going to go through S-Caliper pads in a single race is probably going at it for 24 hours.



Upon further inspection, this caliper was finish machined slightly different as well. The tops were flattened but only by a small amount. Various logos and markings are not in the usual production locations and there's a few "niceties" that would be missing. I'll try to cover it all herein.

First let's look at the bottom side logos. Both are "basically" in the same place but, the casting lines from the production caliper (red arrow) is missing and the logo is centered (refinishers buffed the other logo a tad much):




The flute around the pad cavity is slightly different. These calipers are nearly identical with the exception of some of these things which lead me to believe a later production model was molded off the same casting. The later flute is slightly deeper:




Again, markings and castings are slightly different. I do not believe the 68 represents a year. Mine have similar markings elsewhere on the caliper and they're something like 33. I would guess a finisher stamp??




Here's one of the convenience things or "niceties" I found. It's a pain in the @$$ to get S-Caliper lines and bleeders off. These must have been a bear. Note how the later production model caliper differs:




This stamping on the machined top tells me this was no afterthought to make it fit a certain wheel. The race dept. probably worked closely with ATE for these specs.:



Here's the two side by side. Again, proportionately these calipers are identical. You can see how they finished the top on this caliper:



On the side of the nose of the caliper there's an odd bump, possibly denoting the back of the piston chamber. The production model bump is more pronounced:




Here's a little more detail on the quick-change endurance pad pin. While this was a rather crude adaptation to the original caliper, I do believe it falls right in line with a factory race look and feel. I'm fairly certain this was an original mod.:






Pistons are different. The one-off has a very deep piston top. The standard S-Caliper piston is pictured in-hand:




The pin assembly itself is rather crude and not even but again I think this is a factory manifestation. I've seen these pins on one other set of calipers but without the latch mechanism. All in all, it was an interesting afternoon (for me anyway). Here's a full-on shot of both calipers (pay no attention to the two pair of original GT calipers in the background!):




What are your thoughts?

[ME733]

..........ERIC....add to the mix of wheel sizes, and possable caliper clearance (shaving) of O.E.M. brake installations.....The early 911,s 1965-thru at least 1967.....had as an option OR furnished on the car....J-14 X 5.5 inch FUCHs forged wheels....AND as another piece of history......."back in the Day" around 1977, when VINTAGE racing had just started, there were many older guys that showed up (in the paddock, pits) who actually owned or drove some of the famous racecars of the 1950,s and 1960,s...WELL my point is, EVERY guy I ever talked too who drove a 550 spyder/or derivitive.....said that those cars were a" handful , twichy and " treacherous " to drive near the limit, and under braking.....now bearing in mind those cars had drum brakes, larger and highly refined drum brakes.....POINT IS... those cars did not have a "Emergency pressure regulator" to provide braking stability....and of course as compaired to the 914 , they had a shorter wheelbase and smaller track.(and approximately 700 pounds less weight).....So once again we can see PORSCHE utilized racing feedback,to refine....In our case....the 914...the GRANDSON of the 550/718 et al, series of mid engine racecars.........murray.