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?
Porsche was always making upgrades and small changes. Thank you for showing the small differences. Most of us would never get a chance to see 907,908 calipers with the quick change application.
Eric,
I got a whole box of those calipers. I bought them at a yard sale about three years ago.
OK, not really.
I have had this caliper for about 20 years, and knew from the start that it was something special. It was acquired from a driver that had a 914/6 GT (9140430033) and had raced other Porsche cars. Part of the deal also included titanium con-rod bolts. I was never able to determine the exact use of this caliper though.
The 908 caliper was wider internally for thicker pads, and the quick release mechanism was totally different. It also used shorter pistons, and I believe still used the knock-back mechanism.
Bernie Buschen provided me with this page from the 910 Driver's Manual:
Note that the text says Dunlop disc brake system, they could also be known as Girling calipers. The quick release is identical to my caliper.
Here are some photos of the 910 caliper I found. Perhaps this might be an earlier version since the back cover is completely different:
More photos show that this is an ATE caliper and the back end looks to be the same a pictured in the 910 manual:
and
Just when you think that there is no way to shut-up those that are convinced they
know it all, Eric comes up with another brain bomb. Great info that could come in
handy at a porsche swapmeet. Thanks.
Damn, I get such an education from reading these posts! While this information will probably never directly impact me or my 914, knowing the history of these cars makes them even more fun to drive.
I guess the next time I'm at a cocktail party being really bored, I can bring up the Eric Shea S-Caliper 914 brake story! On second thought, probably not the right audience for this story...
Which brings up a question; Do you notice the more you know about your teener, the fewer people you have to talk to about this information? Do you notice the "deer in the headlights" look from people around you when you bring up incredibly interesting, fascinating, and exciting 914 historical parts discussions?
Maybe it's just me...
Thanks E.
One more measurement from this AM:
There was 3mm (1/8th of an inch) shaved in radius off the tops.
Seriously interesting stuff...
I am amazed at what people have laying around. I have a freind back in Minneapolis who has been buying up "crap" for the last 30 years. Mostly Porsche, Datsun, and Mini. I wonder what he has in his boxes... Last I talked to him he had just bought the entire fleet of Mini Mokes off of Catalina Island. I am sure he has some interesting Porsche parts among his stash. I am going to give him a call today...
Eric, Jeff, your knowledge of Porsche history and brakes enriches us all...
A. Serrano has extensive documentation of the 908 caliper on his website:
http://www.pbase.com/9146gt/gt_alloy_calipers
Note the photo purporting to show the 908 caliper on the 907?
Since I don't see the release pin on the top of the caliper, and see a dark shape on the side, I wonder if it shows the 910 caliper instead? They are very closely related.
Jeff, your photos do show the 910 caliper and a 908 caliper. My caliper appears to be somewhere in between. In fact there may be two 910 calipers or even three. The first would be one with the round rear cover, and the regular pins. The second would be the one shown in the 910 manual with the round rear cover and the quick release U-pin. Perhaps mine is the third variety with the four bolt rear plate, and the U-pin. My caliper does not have the Knock-back pins in the caliper as does the 908 caliper.
Were's that jaw-drop smiley?
Jeff, I think we need to talk some more. It is difficult to track exactly what calipers were used on the race cars. I believe that the 904 used calipers that were essentially the same as the 1967 911S; cast iron with bridge lines. I'm not sure what was done to accommodate the 'S' caliper since they used the wider mount spacing. I'm sure this was a conversion done years after the car was delivered.
I'm pretty sure the 917 introduced the use of 4 piston calipers, some were Girling, some were ATE. The ATE calipers morphed into the 4 piston RSR calipers. Bridge widths varied according to rotor thickness and pad thickness. Endurance calipers were wider to permit the thicker pads and rotors.
So these brakes were at home on these cars???
Attached image(s)
I like that quick change feature for the pad pins... Any chance PMB will manufacture something to convert the more common 4 cylinder brakes and M calipers to a quick change feature. Great for track days...
!!!
I am going the 908 route. After digging thru books and hunting around my first conclusion is brakes were a hodge podge in the race department except on the top tier cars. Different cars, different wheels. What worked at the time were installed. We all know if something didn't fit they made it fit by whatever means necessary. Over the years as cars may have been parted out or upgraded parts ended up on other cars as they were passed down unto other hands. Throw in that ATE, Girling, AP were all players in the stopping business.
I do think this caliper of yours is a unique specimen. The V stamp still has me thinking. Porsche used a V for "Versuch" on many parts meaning experimental. If it was a pre-production unit without a cast part number the V would normally be found. The other alternative to V would be "Verderachse" meaning front axle. A werks 908 weight sheet signed off by Hans Metzger in 1968 confirms both the V designations were used.
Attached image(s)
Now for some brake caliper fun. Digging around many variants were used front and rear. I have tagged them as they were found. Enjoy!
Attached image(s)
continued
Attached image(s)
for comparison and historical fun here are the big boys which could never be mistaken for an S caliper.
Attached image(s)
OK... now we're really mix'n it up here in brake-land.
The ones marked 911 S, ST (in your first picture post) seem to be the 910 calipers.
The 911ST Caliper is the same as my early S-Caliper (no round indents with the x and notice the cutouts around the bleeder and compensating lines on the inside. This appears to be the exact same caliper I have.
VERY INTERESTING on the 908 caliper grouping as I see two things that I've never seen before with a 908 caliper. While the pad spring is all 908, the nose of the caliper falls more in line with your picture of the later S-Caliper (more on that in a sec.). I've never seen that bull nose pre-1972.5 caliper. I've also never seen the dichromate finish pre 1972.5 either. Very cool pictures which raise big questions for me.
The S picture shows a glass bead blasted S-Caliper that should have the dichromate finish. It has the round indents with the "x" which denote it as post 1970.
Wow... cool stuff.
Rob, I will be making a batch of 12 (possibly more) of the 910 style quick change assemblies. We have a pair of early style S-Calipers coming to perform the mod on. I think it will be fun. It will only be for S-Calipers though...
In the "continued" post.
1. 1972.5 and on Dichromate S-Caliper
2. Early 1969-70 S-Caliper
The rest of that stuff makes me dizzy.
The calipers marked 'early 917 late 908' are the Girling caliper.
The calipers marked '908 914GT 911ST' are very weird. Bull-nose, no pin holes, appear to be genuine 908 construction, but what are the holes in the middle of the lower bridge?
The S caliper progression as I understand it goes:
910 style with a round end cap
standard S caliper with 4 bolt rear cap, no circles on top of bridges
the same as above but with circles
the same as above but with X in the circles
the bull-nose version with X in the circles.
variants:
910 caliper could have two pins, or one U pin
908 caliper had the spring loaded pin
Cool thread. Love the pictures of the calipers. RSR caliper, cooling fins?
I'm fairly certain one set goes on my car...
Jeez, I'll have to remember not to ever get in a tech quiz with youz guys.
No worries mate, I've forgotten 80% of what I once knew.
Here are a couple of shots of the non X 'S' caliper:
fairly typical to have something like a serial # and an operators stamp in an outline
We need to start a list of these marks to see how many varieties there are.
other bridge circle
We'll also have to start trying to get VIN's from the cars these came off of to try and determine a time line of varieties.
That's a weird indent too. Much more angular or pronounced than the others...
Those calipers look gawd awful. Send them up, and I'll pretty them up for you.
BTW, the fellow (Gerhard (Gary) Hirsh) I got the race caliper from did indeed own 9140430033 for a short time, however the last time I saw the car it had the proper 908 calipers on it. I suspect the race caliper came on some other, earlier, race car however I don't recall all the cars he drove.
Is he around?
Somewhere near Toronto I understand.
We should try to look him up (unless you still owe him money) It would be nice to see if he has any recollection of the caliper. It may help us find it's mate.
I'm fairly certain we've narrowed this down to a 908 caliper. I would say it's a fairly rare 908 caliper as well. All of the logo markings are in the exact locations for 908 and the shaved top says 908 as well. The only thing that doesn't is that 910 style pin and "most" of the 910 calipers I've seen now don't even have an endurance pin.
908 being the predecessor to the production S-Caliper (virtually one in the same), I think this is one of the first from this casting but... that is PURE speculation based upon the pin vs. the spring loaded pad mechanism.
Thoughts?
here is an interesting thread I came across in my research:
http://forums.pelicanparts.com/showthread.php?t=169568
I have a few emails out to the fellows involved trying to learn more.
It would appear that the caliper evolved from the 910 style with the round back cover to the more familiar S caliper.
Varieties of the caliper were made to suit particular applications.
The most familiar 908 variety with the bottom pins and plate was an endurance caliper with thicker pads. However the single pin for pad release seems to stick out quite a bit, and may not be suitable for rims less than 15" diameter. My caliper is shaved down and would fit smaller rims better. Therefore I think we need to look at cars that used the smaller rims.
910 - 1967
907 - 1967-1968
908 - 1968-1969
S-Caliper - 1969
I'm not sure about the shaved thing Jeff. I agree totally however, all of the 908 calipers I've seen have the shaved top.
I'm going to call this one of the very first 908 calipers. As the 910 caliper (and it's endurance pin mechanism) evolved, the 908 caliper came to be. I'm going on a limb and saying; this 908 caliper, as one of the very first, received the 910 pin assembly. Subsequent 908 calipers had the single pull pin spring.
When you look at the time line above and the pictures from the 910 manual... it starts to become obvious. Dave is on possion of one if the very first 908 calipers ever made. Want to bring the thread full circle? This is one of the very first S-Calipers ever made, as 908 calipers are really nothing more than an S-Caliper. Amazing history when you consider the success of the 908 Caliper and the S-Caliper.
Dave, I found the original owner of that GT as well. Good conversations all around. Thanks guys.
E.
Been busy cloning things...
Very nice. They will look even better in person.
I see you finally have got my calipers done!
Intresting stuff. For what its worth, i believe the "bump" you show is the remnant of the "spru". When metal is cast the spru is central the channel the molten metal is poured into to cast multiple castings in the same mold.( imagine a tree upside down, metal is poured into the trunk and flows out the branches, finally filling the fruit). Then they break off/machine off the tree & branches leaving only the fruit. If it is a spru the variation of the bump (spru) location probably indicated a change from low production moulding/manufacturing techniques to higher volume methods. if their are casting marks, then the calipers were not made using lost wax technique, which is generally one off. So a theory is ate/porsche used wooden pattern plates for the earliest of your calipers, then went to higher pattern cost/production metal plates and possibly changed from horizontal to verticle molding equipment for the "s" calipers once they had committed to multi year application for a production car
I seem to have stumbled upon the missing link today. This is an amazing find. Something I never expected to see.
Another supplier was looking for a 908 caliper and sent me this to find a match:
Notice:
1. It originally had the 910 pad pin mechanism. You can see the cutout for the latching tab on the nose section of this caliper. As suspected, this would place Dave's 908 caliper as the earliest version of such caliper I've yet to see.
2. It now sports the 908 spring and pull pin. This is literally the missing link, showing the progression from Dave's 908 caliper to the more common 908 caliper.
3. It does not have the pad rests at the bottom ala later 908 calipers, it still retains the pins. This shot shows that it has the wrong pins in place (it should have the "U" pin as seen in Dave's caliper).
Wow...
Eric,
Although I have never chimed in as I really have nothing of value to add to this thread, I am completely fascinated and keeping a close eye on your recreations.
To be completely honest, I have been on the hunt for some sets of the early S calipers as well. A couple of sets have come up on eBay recently, went in the mid-$300's. Even a mismatched set went to that level, one early, one 2nd generation.
I think your work on these things looks awesome, and certainly want the "next" one wearing these.
Peter
Thanks Pete!
I just grabbed 3 pair for @ $250 over the weekend so, they're out there. Keep looking. I wouldn't pay any more than that for an S-Caliper as they're all basically "junk".
Let me qualify that statement; the pistons are almost always a throw-away item. New ones will add some coin to the bill. Most compensating lines are bent or broken or break when you attempt to remove them. The finish is usually gone. You can glass bead blast them but, that leaves them unprotected for the future, these are anodized. so... add de-anodizing, polishing and re-anodizing to the bill. If you don't anodize them they'll corrode even faster.
We've sold out of this first run with more on order. I'll keep you posted on the next build. So far there's 3 sets on backorder with 4 cores. I'd be proud to have them on anything you create.
Played around with the "V" (versuch) stampings. I think they came out well!
Oh Happy Days!
Pins and clips are done and back from plating!!
Done! (that was a crazy project)
The first pair are off to a 914-6/GT IMSA car that belongs to one of our 914World "darlings".
Enjoy!
Whoa, those are things of beauty!! Keep up the good work!
...........ERIC, your knowledge of brakes and systems is just great. you are obviously an expert....I found the previous post about 914 brakes, and especially the proporting valve explanation the best of any I have ever read....this post about other calapers and uses is great also.......I would like to know if you have , tracked , compiled ,information reguarding the calaper PUCK/PISTON sizes as well.....if you have it could you post it?......here,s my reason for the question and intrest....FOR going on forever - I have read, and been told by brake experts...that the IDEAL brake proportioning is ...FRONT 60%-----REAR 40%....(without a proporting valve in the mix as on stock 914,s.).....I am curious to know IF the front and rear calapers have different PUCK/PISTON sizes in the various , early A-thru----what ever information you have available-917 etal, carrera etc. etc..... This information would be very informative, especially to provide a basis of fact, and stistics relative to BRAKE BIAS.............great job. thank you Murray Mcafee.
Thanks Murray,
Now on video. John and Dave, your calipers are stars!
Beautiful. You pronounce Versuch incorrectly, but you got the caliper right!
What do you expect from a stupid American...? Fer-ZOOK it is.
Fixed.
Well now it's friggin' perfect. And the calipers are still
Big for undertaking this...
Danke Mark,
The credit goes to Dave Pateman who sent me his very valuable and very early 908 caliper. Without batting an eye and, without EVER asking when it would come back. It's a good feeling to have a project like this come to fruition. It will be a better feeling to get that caliper in a box on it's way back to Dave.
..........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.
Thanks Murray, Here's some video's I did last summer with those 14's (I'm saving a set for my trailer!) Not a problem fitting over stock S-Calipers of either variety.
Powered by Invision Power Board (http://www.invisionboard.com)
© Invision Power Services (http://www.invisionpower.com)