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

[ConeDodger]

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...

[Johny Blackstain]

(IMG:style_emoticons/default/popcorn[1].gif)!!!

[Jeff Hail]

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.

[Jeff Hail]

Now for some brake caliper fun. Digging around many variants were used front and rear. I have tagged them as they were found. Enjoy!

[Jeff Hail]

continued

[Jeff Hail]

for comparison and historical fun here are the big boys which could never be mistaken for an S caliper.

[Eric_Shea]

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...

[Eric_Shea]

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.

[Jeff Hail]

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[size=7].

Yup and a headache! Trying to find the pic of a 6 pot used on the 917 30 that is a beast.

[davep]

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

[Eric_Shea]

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.

I wouldn't include the 910 caliper as an S-Caliper... way too different. I would include your caliper and the 908 caliper as in every basic mold from those, they are exactly like the S-Caliper. I'll modify your text to what I'm thinking:

908 Caliper w/910 pad pins. (your caliper, kinda what I was eluding to in the thread title)
908 Caliper Spring loaded and solid bottom load.
________________________________________This ends the racing protoypes of this caliper.

1969 - Standard S caliper with 4 bolt rear cap, no circles on top of bridges. Clear anodizing (I believe your caliper was anodized with some areas recently scratched off for cleaning etc.)

1971 - The same as above but with circles with X. This denotes a new style piston and was used from that point forward. I've never heard of the circular indent without the "X".

1972.5 - The bull-nose version with X in the circles and dichromate sealant.

(IMG:http://www.914world.com/bbs2/uploads/post-1110-1208034010.jpg)

[championgt1]

Cool thread. Love the pictures of the calipers. RSR caliper, cooling fins?

[davep]

1971 - The same as above but with circles with X. This denotes a new style piston and was used from that point forward. I've never heard of the circular indent without the "X".

You will shortly since that set will be the ones destined for modification.

some info on the 917 calipers:
http://forums.pelicanparts.com/showthread.php?t=87025

[Eric_Shea]

You will shortly since that set will be the ones destined for modification.

LOL... this is getting crazy! I love it. Makes sense though. The "X" was to denote a piston change. I'l bet they used up the old ones then started the "X" sequence with the first new piston set.

That's another odd-ball caliper. You must hang a pork chop around your neck and they all flock to you. (IMG:style_emoticons/default/lol3.gif)

[Jeff Hail]

You will shortly since that set will be the ones destined for modification.

LOL... this is getting crazy! I love it. Makes sense though. The "X" was to denote a piston change. I'l bet they used up the old ones then started the "X" sequence with the first new piston set.

That's another odd-ball caliper. You must hang a pork chop around your neck and they all flock to you. (IMG:style_emoticons/default/lol3.gif)

Maybe Daves caliper goes with these?........and I have two sets! (IMG:style_emoticons/default/blink.gif)

[Eric_Shea]

I'm fairly certain one set goes on my car... (IMG:style_emoticons/default/idea.gif) (IMG:style_emoticons/default/biggrin.gif) (IMG:style_emoticons/default/wub.gif)

[1970 Neun vierzehn]

Jeez, I'll have to remember not to ever get in a tech quiz with youz guys. (IMG:style_emoticons/default/unsure.gif)

[davep]

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.

[Eric_Shea]

That's a weird indent too. Much more angular or pronounced than the others... (IMG:style_emoticons/default/idea.gif)

[Eric_Shea]

The 67 911S had a very early version of the M-Caliper. It had funny wings on it and it did not have compensating lines on the front… only on the rear. I have a pair in the shop now so I'll try to grab some quick pictures. The rears on the 67 911S are Wide L-Calipers

Here's the very early 911S M-Caliper with the spacers. For edification; they are posted sided by side with a more common M-Caliper:


Full on top view. See the "wings" front and rear?:


Here they are from the side. I would say they add structural rigidity and possibly cooling?:


And the back:


And the Wide L-Caliper. These are very difficult to build as there are no kits for them any more and in many ways (not all though) they are simply bored out L-Calipers. This makes the dust cover mounting area very fragile. If the pistons are rusted in... it can be lights out for a very rare caliper:


With the unique dog-bone spacers used to center the caliper over the newly vented rear rotor: