Hot early 911 parts - pics + quiz

[hesaputz]

Found these while I was rooting around in the junk bin last weekend. Anybody know what they are?



Answer tomorrow evening.

[BURN-BROS]

908 calipers?

[BURN-BROS]

Look like you can pull the pads without removing the caliper. Very cool if they are. And what my prize for playing anyhow?

[hesaputz]

No prize, just an attaboy and the satisfaction of knowing that YOU are the sharpest parts and racing historian on the board this PM.

[}{arlequin]

can you use them on a 911?

[Early_S_Man]

You can always change the pads on 'S' caliper without pulling the caliper or breaking the fluid circuit ... but those aren't production 'S' calipers!

Probably early racing calipers circa 1967/68 for 907/910/908 ... as the holes aren't even present for the locating pins used on the race cars and production calipers from 1969! Frere shows a similar caliper as used on a 907 around 1967, I believe. By the time cross-drilled rotors were experimented with at Le Mans with 'S' caliper on a 908 ... it was indistinguishable from production 'S' calipers!

[Zeke]

Well, given Grady's history with the 914, I'm gonna take a WAG and say some special calipers for a 914/6 GT Le Mans car from 1970.

Edit: Sorry, I confused Grady Clay with hesapuzt. Sorry to both! both have a long history with Porsches. Anyway, maybe Grady knows the answer. I'll bet he's seen them before somewhere.

[BURN-BROS]

Woo Hoo! I would like to thank all the little people that I stepped on to get where I am today.

Warren, as usual your noodle stores an impressive amount of information.

[CarreraS2]

Can't you pull the pads on most production porsches (and most other cars, too) without removing the caliper or breaking open the fluid lines?

All my garden-variety 914s and 911s (and most BMWs and MBs) have been that way.

[BURN-BROS]

Yes you can, the difference as Warren pointed out was that they did not use locating pins like ours. They used a plate and the retainer on top to hold the pads in.When you needed to replace the front pads You simply flipped the retainer up and pulled the pads out with pliers quickly.

[masraum]

Generally you have to remove the calipers, but not break the fluid lines. Most cars, however, do not allow you to change pads without at least removing the caliper from the rotor.

[CarreraS2]

Originally posted by masraum
Generally you have to remove the calipers, but not break the fluid lines. Most cars, however, do not allow you to change pads without at least removing the caliper from the rotor.

Burn - I see what you're saying.

Masraum, I don't think that is correct, I think on most cars (including almost all, if not all, Porsche disc brake cars) you DON'T need to remove calipers to swap brake pads.

Like this:

http://www.pelicanparts.com/techarticles/911_brake_pads/911_brake_pads.htm

[BURN-BROS]

Most of the cars that I have done brakes on required at least the caliper to rotate on one mounting bolt in order to get pads out. Single piston designs mostly require the pad to be pulled down. The multiple piston designs especially with small pads allowed access from the top of the caliper.

[CarreraS2]

Hmm, I guess different people can have difference experiences even when working on (presumably) the same cars or parts.

I've changed so many Porsche and BMW brake pads I couldn't even begin to count, including during the time I worked summers in a shop.

I've never in 25 years had to pull a caliper to swap out pads in those cars.

[BURN-BROS]

No argument here. The comment was towards cars in general. Your experiences are different than mine. I'm used to domestics.

[Grady Clay]

Guys,
You caught me napping, literally. The Speed coverage of Rennsport Reunion was so limited I fell asleep.

I don’t think they are 908 because the release pin would contact the inside of the smaller rim. I had four of the 908 sets with the ~15 mm larger rotors.
This photo is the same 908 brake but on a 907.
I recall seeing a sorta homade "Factory" tool that was like a small claw hammer on one end and on the other end had a pair on pins to pull the hot pads. The claw pulled the release pin and the hammer smacked the retaining spring back in place. You used the pin end to push the piston back.
"

"
(C) 1973 Paul Frere, First Edition

I made aluminum brackets to radially space the calipers out to clear the rotors. I drilled the clearance holes for 911 wheel studs in the rear and normal mounting holes in front. I left the 908 pin drive holes in place.



I have seen a fair number of these calipers over the years. They fit the standard 911S rotor and ears on the struts. The release clears a 15” wheel.

I will speculate they were from the 914-6GT parts kits that Porsche tried to homologate as 914-6GT “cars.” They are probably the same as ’70-’71 911SGT.

You can check and see if the caliper fits the outside diameter of a 911 rotor or does it fit larger?

Is the piston diameter the same as 911?

Interesting, Bruce Anderson doesn’t show this brake.

Best,
Grady

[Grady Clay]

Burn, Steve,
I agree with Brian. I have never seen a Porsche disc brake that you can’t get the pads out without removing (or loosening) the caliper. I’m sure there are some so neglected and rusted that all sorts of unusual means are necessary.

To every situation there is an exception. The “Porsche patent” anular disc brake on a ’62-’63 356B 2000GS required extraordinary effort to change pads. This was Porsche’s effort to not pay Dunlop royalties. Dunlop won out in the end with the 356C Ate brakes under license from the Brits.


The interesting part of this thread is the extent Porsche goes to in order to make brakes serviceable in the heat of a race.

The standard “S” calipers are a chore to change pads, even between race sessions. BTW, I like to use the springs because the taper slightly helps retract the pad so there is less brake drag.

The calipers in the original post are the “trick” racing calipers just prior to, and contemporary with, the 4-piston magnesium calipers used on the 917.

Best,
Grady

[Zeke]

So, I win. How 'bout it, David?

[Bill Verburg]

Ate S prototypes? or the 904 Le Mans calipers?
One of the really unique things is the latch mechanism for the spring plates that hold the pads in, never seen that before. Even the 906 used regular pin held pads in the S calipers

The other oddity is the pad positioning buses

[Grady Clay]

Bill,
Of course they could be Ate S prototypes. However they are new, most protypes would have been run into the ground. I have seen others like them in the Porsche racing parts system.

I don’t think there is much possibility they are anything 904. Even the 906 had assembled calipers, all iron that I ever saw. I had the one piece forged aluminum S calipers on the front of my RS-60 in 1969 but they came out of the street parts system and that doesn’t count.

Yes, that pad latch system was contemporary with those calipers and 917. It is a really cool design for fast changing of pads under race conditions. The 917 and later systems had the large wire spring type. The early 917 type still had the release pin. Soon they changed to the configuration where you used pliers to grab and release the spring retainer and the same pliers to grab the pad. The current GT3-RSR uses a similar set-up. Most are designed so if the latch comes loose and the spring retainer is free to move, the pads still can’t move much out of position. A BIG issue in the hustle of flawed pit stops.

The two pins and the bolt-on plate serve to prevent the pads from moving in toward the spindle. No removable pins are necessary. As I recall the two pins and the plate were usually titanium. In these photos the pins appear to be titanium and the plate aluminum. The bolts for the plate appear to be steel and not plated.

What are they?

Zeke gets my vote.


Best,
Grady