A tip for those of you re-building your Brakes

[86 911]

I just finished rebuilding my front calipers on my '76 911. In the process I found out that I have the aluminum "S" calipers (they run over $2700 per caliper new on Pelican ). Anyway, I got the rebuild kit and have been warned that the dust boot is hard to get on. I noticed that there is a circular metal clip inside the rubber dust boot that goes between the piston and the caliper. At first, I tried putting the boot in, but it gave me a hard time and felt like it was too big for the groove. Knowing that metal shrinks when cold, I put the dust boots in the freezer for half an hour, took them out, and inserted them into the groove. It was still a tight fit, but at least you could now push the dust boot in the groove with your thumbs! That's just my trick to it. It works pretty much for any other metal application.

[Evans, Marv]

Thanks Matt. For some reason I've never had a problem getting the dust boots in. But, if I do, I'll try your trick.

[vash]

that aint the only thing that shrinks in the cold. good job matt.

[azasadny]

Shrinkage! (Seinfeld reference)! Thanks for the pointer.

[juanbenae]

that ring you describe is to retain the dust boot. i dont know for sure in your case, but if i recall my rebuild kit came with new retainer rings. did yours? did you have the ring all the way out, install the dust boot, and then reinstall the frozen retainer?

i interpreted your post as trying to stuff the boot "flange" under the ring while in place. clearify...

[lateapex911]

The flipside to the "Freeze technique is the heat method to expand stuff.

Some times you freeze one part while baking the other.

Slips in like butter, but won't budge once things equalize. An engineering buddy refers to that as a "Negative tolerance fit".

[vash]

toby, his calipers (s-caliper?) are different from ours. those are alot harder to do. my 75 had them, it was a cuss fest.

[juanbenae]

cliff, you dont seem like the type that would cuss at inanimimate objects. i only would expect beautiful songs to emanate from that pretty mouth of your.

T$

[Dan in Pasadena]

Originally posted by 86 911
I just finished rebuilding my front calipers on my '76 911. In the process I found out that I have the aluminum "S" calipers (they run over $2700 per caliper new on Pelican ).....

I have a '76S and my understanding is that I may or may not have the aluminum S calipers. Does anyone know the change over point or why some '76's do/don' have them?

I ask because I have rebuilt Carrera calipers for the front and have not installed them yet as discussed in another post.

I have not examined my calipers closely and I've heard there is a dimensional difference in the S and non S steel caliper mounting bolt holes. If I understand it correctly, 3" for one and 3-1/2" +/- for the other...not sure which?

I have been assuming I did NOT have aluminum S calipers since mine show some very minor surface rust about 1-1/2" square on the surface of the caliper body visible through the wheel openings. But maybe that is rust from metallic particles that came off pads in the past? Is it possible I DO have the S calipers (in which case I'll obviously stay with them!) Anyone?

[Zeke]

No such thing as S and steel S calipers. 3.5" steel cals are known as A. 3.0 are M. Then you go to Carrera cals (also at 3.5 spacing) which take a thicker rotor. Search bill Verburg's charts for further info.

AFA the rubber in the freezer, it might make it stiffer and easier to shove in the groove. It's been awhile, but I think the ring goes in after. Could be mistaken on that.

[Dan in Pasadena]

milt, I didn't write "steel S calipers" I wrote "non S steel calipers". I assumed everyone knew the early S calipers are aluminum, perhaps I presumed too much. I have since searched and realize the non S are cast iron, not truly steel.

My basic question is still: when/where was the cutoff point for the aluminum S calipers. Might I have them on my '76?

[juanbenae]

i think young mat's car is a 76 with a widebody kit, and 3.0L SC motor. so take that for what it's worth.

[Dan in Pasadena]

Toby,
Thanks but the kit and the 3.0 didn't come from the factory. At least the kit didn't. I suppose it could be a Carrera 3.o of that era...but I don't know enough to know if they came with the early S aluminum calipers or what? I suppose I should drop Bill Verbug a line. Thanks for he input, Dan

[86 911]

Dan, the "S" calipers are aluminum and as a pelican told me, about a third of the weight of a steel caliper. The "S" calipers also have 3.5 inch spacing from bolt centers and come on cars built from '74 to '77. Your car may have them.

[randywebb]

can also use brake paste to lube these

[klaucke]

As far as I know (arguably not that much), only the Carrera's came w/ the aluminum S calipers. The 911 Normal and S from 74-77 came w/ cast iron M front (as stated above, 3" spacing) and cast iron M rear calipers. Matt's S calipers are probably an upgrade done to the car.

And as an aside, while the S calipers are light and valuable, the A caliper is dimensionally similar and actually has a better feel due to less flex. The S calipers are a good period correct upgrade for an early car, but there are definately better, or at least more cost effective, upgrades out there.

[Dan in Pasadena]

Thank you Klaucke. THAT is what I was trying to find out!

[Zeke]

My '77 had aluminum calipers as ordered from the dealer by the PO. Koni struts too. That was the upgrade AFAIK. It was not a Carrera. It was a normal 2.7

Dan, thanks for righting me. I did indeed misread your words. The point is Bill Verburg has all this info. I believe the "S" AL caliper came in 2 casting designs (very slight difference) as I had both versions at one time. And the S caliper was made well into the late '70's according to what I know.

[aturboman]

The early aluminum front caliper commonly referred to as "S" calipers were used on several models. All "S" cars from 69-74 had them. These were also fitted to E models with the comfort package and all Turbo Carrera 3.0 models. They were also fitted to most "S" cars and Carrera models from 1975-1977.
A freind even has an all original early Euro SC that also has these on it. I think it was a case of Porche using up what was left in inventory as the M caliper was phased in. Short answer is that there never seems to be a clear start and stop date for anything with Porsche's early models. That is part of their charm.

[JP911]

My 76S did not have them. FYI, the easiest test if you're unsure as to whether or not you have S calipers is to hold a magnet up to the calipers. If it sticks you're not an S man (or woman), but if it doesn't stick you are indeed in possession of the sometimes-coveted S calipers.