Brake Caliper Type ??
12-28-2001, 07:19 PM
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Brake Caliper Type ??
I am about to order rebuild kits for my front calipers. The markings on them are ATE 44 G.
Are these A-type calipers ???
The car is a 1970 911T
Are these A-type calipers ???
The car is a 1970 911T
12-28-2001, 08:30 PM
#2
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Originally posted by JimNB:
<STRONG>I am about to order rebuild kits for my front calipers. The markings on them are ATE 44 G.
Are these A-type calipers ???
The car is a 1970 911T</STRONG>
<STRONG>I am about to order rebuild kits for my front calipers. The markings on them are ATE 44 G.
Are these A-type calipers ???
The car is a 1970 911T</STRONG>
Those are likely "M" calipers.
01-02-2002, 12:28 AM
#5
An easy method to tell the difference between 'M', 'A', and 'S' calipers is to measure the mounting bolt spacing. 'M' has 3" OC, 'A' and 'S' have 3.5" OC. The 'A' is a 2 piece ferrous casting which a magnet will stick to, the 'S' is a 1 piece aluminum piece.
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texas_maverick (11-27-2020)
01-02-2002, 05:32 PM
#6
Rennlist Member
As would be expected, Bill is correct again. He does alright for a guy with only 4 Stars. 
I will send the original poster a portion of an article I wrote on 911 brakes, sheer genius, if I don'r say so myself.
Martin
I will send the original poster a portion of an article I wrote on 911 brakes, sheer genius, if I don'r say so myself.
Martin
01-02-2002, 05:38 PM
#7
Rennlist Member
Commencing with the "B" Series in late 1968, Porsche delivered their highest performing 1969 models, the 911E and the 911S, with aluminum front calipers developed specifically for Porsche by the Ate Company. These new aluminum "S" calipers, designated as "S" originating from the German word "schwer" meaning heavy (heavy duty), are one piece in design and weigh considerably less, lighter by 3.44 Lbs. each, compared to the cast iron "A" caliper.
"S" calipers were standard on the high performance 911E and 911S through 1973. In 1974, the "S" calipers were found on the 911 S and the Carrera with the heavier, three piece, cast iron "M" calipers mounted on the standard 911.
In 1975, the "S" caliper could be found only on the US Carrera and the R.o.W (Rest of World) Turbo. 1976 saw the "S" caliper on the US and R.o.W. Turbo, but dropped from the Carrera (Not sold in the US) which acquired the new "A" cast iron calipers.
The Turbo introduced to the R.o.W. in 1975 and the US in 1976, incorporated the "S" calipers until the introduction of the 1978 model when the 917 style alloy brakes became standard. 1977 saw the "S" caliper limited to the Turbo only, with the 3.0 Carrera equipped with "A" front calipers, and "M" calipers to the rear.
The "S" caliper was also delivered on some 1978 SCs only to disappear entirely on the 1979 model line, replaced by the cast iron "A" caliper. From the "I" series through the SC model run, "A" calipers brakes are found at the front with "M" calipers to the rear.
Advantages of the "S" front calipers over cast iron: In addition to the obvious reduced weight factor (Less unsprung weight with resulting better suspension response), aluminum "S" calipers conduct heat away better than cast iron, some say they provide improved pedal feel, and the "S" calipers utilize a thicker 13 millimeter brake pad, contrasted to the 10 millimeter pad of the "A" caliper.
On the down side, some drivers report the "S" brakes tend to flex under extremely hard usage. And being constructed of aluminum, they are subject to the forces of corrosion. I used these brakes and never experienced this flex effect.
Availability: Porsche "S" calipers are difficult to find and will cost at least $400 per pair, used and rebuilt, probably more, plus installation. New "S" calipers are available but are extremely expensive. Stoddard's 1987 catalogue lists new "S" calipers at $1,136.90 each.
Under the "update-backdate" provision of the PCA and POC GCRs, because the "S" caliper appeared on some models of the 1978 911SC, this allows for a "S" caliper update of "A" calipers equipped cars for the 1978-1983SC's model run. The update is a relatively simple bolt in operation.
The "S" caliper update does not apply to 1984 and later cars. These model years were delivered with a redesigned, wider, "A" style cast iron calipers to accommodate a more efficient 24mm rotor, possessing better heat dissipation characteristics than the previous 20mm rotor, electronic wear indicators designed into the brake pads providing dashboard warning for needed brake pad replacement, larger rear brake cylinder bores, a larger brake servo, an engine driven vacuum pump and a brake pressure limiting proportioning device.
Note: Before you decide to rush out and upgrade your pre-1976 911 to "S" calipers, please remember they will not fit on struts having the "M" series calipers.
If you are in doubt as to what calipers are on your car, measure the distance between centers on the caliper mounting bolts on the front struts. If the distance measures 3", you have "M" calipers. "S" and "A" caliper mounting bolts are approximately 3 1/2" apart.
In order to install "S" calipers, on a "M" caliper equipped cars, you will first incur the added expense of changing out the old "M" caliper struts to struts accepting the "A" or "S" calipers. Expect to pay approximately $1,000 for the struts alone, add in the cost of shock absorber inserts at about $200, as well as the cost of used and rebuilt "S" calipers at $600 or more, and the required labor. In summary, the total cost for the conversion to "S" calipers could exceed $2,500.
In the long run, for those determined to own a 911 with "S" calipers, it could be less expensive in the long run to acquire a 911 delivered originally with "A", or preferably the "S" calipers, as standard equipment. Caution: for those considering the change from "M" calipers to "S" calipers with the required strut change, you may wish to check your GCRs to see if this is an allowable modification.
Non "S" calipers equipped cars: From the earliest 911 models, the 911S prior to 1969, the 911T's and the 911L, all were equipped with the "M" front calipers which remained as the standard through the "H" production series ending in July 1975. At this point the "M" front caliper was replaced by the by the "A" caliper.
The "A" caliper, also developed by Ate, first integrated into the 1976 models, is similar in size to the "S" caliper and originally developed for Alpha Romeo hence the "A" designation. The "A" caliper is a three piece, cast iron caliper, providing the same 78 sq. cm brake pad area as the "S" caliper, utilizing a 10mm brake pad contrasted to the 13mm pad found on the "S" brakes.
Rear calipers: Ate also designed the "L" (light) caliper, mounted at the rear of the 911 from the first introduction of the car through the "A" production series ending in July 1968. From the "B" series 911 onward, the "M" caliper is found at the rear of the all 911's, with the exception of the 1978 and later Turbo which received 917 style light alloy rear brakes. The long reign of the rear mounted "M" caliper ended with the introduction of the 1984 Carrera.
"S" calipers were standard on the high performance 911E and 911S through 1973. In 1974, the "S" calipers were found on the 911 S and the Carrera with the heavier, three piece, cast iron "M" calipers mounted on the standard 911.
In 1975, the "S" caliper could be found only on the US Carrera and the R.o.W (Rest of World) Turbo. 1976 saw the "S" caliper on the US and R.o.W. Turbo, but dropped from the Carrera (Not sold in the US) which acquired the new "A" cast iron calipers.
The Turbo introduced to the R.o.W. in 1975 and the US in 1976, incorporated the "S" calipers until the introduction of the 1978 model when the 917 style alloy brakes became standard. 1977 saw the "S" caliper limited to the Turbo only, with the 3.0 Carrera equipped with "A" front calipers, and "M" calipers to the rear.
The "S" caliper was also delivered on some 1978 SCs only to disappear entirely on the 1979 model line, replaced by the cast iron "A" caliper. From the "I" series through the SC model run, "A" calipers brakes are found at the front with "M" calipers to the rear.
Advantages of the "S" front calipers over cast iron: In addition to the obvious reduced weight factor (Less unsprung weight with resulting better suspension response), aluminum "S" calipers conduct heat away better than cast iron, some say they provide improved pedal feel, and the "S" calipers utilize a thicker 13 millimeter brake pad, contrasted to the 10 millimeter pad of the "A" caliper.
On the down side, some drivers report the "S" brakes tend to flex under extremely hard usage. And being constructed of aluminum, they are subject to the forces of corrosion. I used these brakes and never experienced this flex effect.
Availability: Porsche "S" calipers are difficult to find and will cost at least $400 per pair, used and rebuilt, probably more, plus installation. New "S" calipers are available but are extremely expensive. Stoddard's 1987 catalogue lists new "S" calipers at $1,136.90 each.
Under the "update-backdate" provision of the PCA and POC GCRs, because the "S" caliper appeared on some models of the 1978 911SC, this allows for a "S" caliper update of "A" calipers equipped cars for the 1978-1983SC's model run. The update is a relatively simple bolt in operation.
The "S" caliper update does not apply to 1984 and later cars. These model years were delivered with a redesigned, wider, "A" style cast iron calipers to accommodate a more efficient 24mm rotor, possessing better heat dissipation characteristics than the previous 20mm rotor, electronic wear indicators designed into the brake pads providing dashboard warning for needed brake pad replacement, larger rear brake cylinder bores, a larger brake servo, an engine driven vacuum pump and a brake pressure limiting proportioning device.
Note: Before you decide to rush out and upgrade your pre-1976 911 to "S" calipers, please remember they will not fit on struts having the "M" series calipers.
If you are in doubt as to what calipers are on your car, measure the distance between centers on the caliper mounting bolts on the front struts. If the distance measures 3", you have "M" calipers. "S" and "A" caliper mounting bolts are approximately 3 1/2" apart.
In order to install "S" calipers, on a "M" caliper equipped cars, you will first incur the added expense of changing out the old "M" caliper struts to struts accepting the "A" or "S" calipers. Expect to pay approximately $1,000 for the struts alone, add in the cost of shock absorber inserts at about $200, as well as the cost of used and rebuilt "S" calipers at $600 or more, and the required labor. In summary, the total cost for the conversion to "S" calipers could exceed $2,500.
In the long run, for those determined to own a 911 with "S" calipers, it could be less expensive in the long run to acquire a 911 delivered originally with "A", or preferably the "S" calipers, as standard equipment. Caution: for those considering the change from "M" calipers to "S" calipers with the required strut change, you may wish to check your GCRs to see if this is an allowable modification.
Non "S" calipers equipped cars: From the earliest 911 models, the 911S prior to 1969, the 911T's and the 911L, all were equipped with the "M" front calipers which remained as the standard through the "H" production series ending in July 1975. At this point the "M" front caliper was replaced by the by the "A" caliper.
The "A" caliper, also developed by Ate, first integrated into the 1976 models, is similar in size to the "S" caliper and originally developed for Alpha Romeo hence the "A" designation. The "A" caliper is a three piece, cast iron caliper, providing the same 78 sq. cm brake pad area as the "S" caliper, utilizing a 10mm brake pad contrasted to the 13mm pad found on the "S" brakes.
Rear calipers: Ate also designed the "L" (light) caliper, mounted at the rear of the 911 from the first introduction of the car through the "A" production series ending in July 1968. From the "B" series 911 onward, the "M" caliper is found at the rear of the all 911's, with the exception of the 1978 and later Turbo which received 917 style light alloy rear brakes. The long reign of the rear mounted "M" caliper ended with the introduction of the 1984 Carrera.
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Max964t36 (09-30-2023)
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02-14-2020, 07:40 PM
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GREAT INFO THANK YOU
Commencing with the "B" Series in late 1968, Porsche delivered their highest performing 1969 models, the 911E and the 911S, with aluminum front calipers developed specifically for Porsche by the Ate Company. These new aluminum "S" calipers, designated as "S" originating from the German word "schwer" meaning heavy (heavy duty), are one piece in design and weigh considerably less, lighter by 3.44 Lbs. each, compared to the cast iron "A" caliper.
"S" calipers were standard on the high performance 911E and 911S through 1973. In 1974, the "S" calipers were found on the 911 S and the Carrera with the heavier, three piece, cast iron "M" calipers mounted on the standard 911.
In 1975, the "S" caliper could be found only on the US Carrera and the R.o.W (Rest of World) Turbo. 1976 saw the "S" caliper on the US and R.o.W. Turbo, but dropped from the Carrera (Not sold in the US) which acquired the new "A" cast iron calipers.
The Turbo introduced to the R.o.W. in 1975 and the US in 1976, incorporated the "S" calipers until the introduction of the 1978 model when the 917 style alloy brakes became standard. 1977 saw the "S" caliper limited to the Turbo only, with the 3.0 Carrera equipped with "A" front calipers, and "M" calipers to the rear.
The "S" caliper was also delivered on some 1978 SCs only to disappear entirely on the 1979 model line, replaced by the cast iron "A" caliper. From the "I" series through the SC model run, "A" calipers brakes are found at the front with "M" calipers to the rear.
Advantages of the "S" front calipers over cast iron: In addition to the obvious reduced weight factor (Less unsprung weight with resulting better suspension response), aluminum "S" calipers conduct heat away better than cast iron, some say they provide improved pedal feel, and the "S" calipers utilize a thicker 13 millimeter brake pad, contrasted to the 10 millimeter pad of the "A" caliper.
On the down side, some drivers report the "S" brakes tend to flex under extremely hard usage. And being constructed of aluminum, they are subject to the forces of corrosion. I used these brakes and never experienced this flex effect.
Availability: Porsche "S" calipers are difficult to find and will cost at least $400 per pair, used and rebuilt, probably more, plus installation. New "S" calipers are available but are extremely expensive. Stoddard's 1987 catalogue lists new "S" calipers at $1,136.90 each.
Under the "update-backdate" provision of the PCA and POC GCRs, because the "S" caliper appeared on some models of the 1978 911SC, this allows for a "S" caliper update of "A" calipers equipped cars for the 1978-1983SC's model run. The update is a relatively simple bolt in operation.
The "S" caliper update does not apply to 1984 and later cars. These model years were delivered with a redesigned, wider, "A" style cast iron calipers to accommodate a more efficient 24mm rotor, possessing better heat dissipation characteristics than the previous 20mm rotor, electronic wear indicators designed into the brake pads providing dashboard warning for needed brake pad replacement, larger rear brake cylinder bores, a larger brake servo, an engine driven vacuum pump and a brake pressure limiting proportioning device.
Note: Before you decide to rush out and upgrade your pre-1976 911 to "S" calipers, please remember they will not fit on struts having the "M" series calipers.
If you are in doubt as to what calipers are on your car, measure the distance between centers on the caliper mounting bolts on the front struts. If the distance measures 3", you have "M" calipers. "S" and "A" caliper mounting bolts are approximately 3 1/2" apart.
In order to install "S" calipers, on a "M" caliper equipped cars, you will first incur the added expense of changing out the old "M" caliper struts to struts accepting the "A" or "S" calipers. Expect to pay approximately $1,000 for the struts alone, add in the cost of shock absorber inserts at about $200, as well as the cost of used and rebuilt "S" calipers at $600 or more, and the required labor. In summary, the total cost for the conversion to "S" calipers could exceed $2,500.
In the long run, for those determined to own a 911 with "S" calipers, it could be less expensive in the long run to acquire a 911 delivered originally with "A", or preferably the "S" calipers, as standard equipment. Caution: for those considering the change from "M" calipers to "S" calipers with the required strut change, you may wish to check your GCRs to see if this is an allowable modification.
Non "S" calipers equipped cars: From the earliest 911 models, the 911S prior to 1969, the 911T's and the 911L, all were equipped with the "M" front calipers which remained as the standard through the "H" production series ending in July 1975. At this point the "M" front caliper was replaced by the by the "A" caliper.
The "A" caliper, also developed by Ate, first integrated into the 1976 models, is similar in size to the "S" caliper and originally developed for Alpha Romeo hence the "A" designation. The "A" caliper is a three piece, cast iron caliper, providing the same 78 sq. cm brake pad area as the "S" caliper, utilizing a 10mm brake pad contrasted to the 13mm pad found on the "S" brakes.
Rear calipers: Ate also designed the "L" (light) caliper, mounted at the rear of the 911 from the first introduction of the car through the "A" production series ending in July 1968. From the "B" series 911 onward, the "M" caliper is found at the rear of the all 911's, with the exception of the 1978 and later Turbo which received 917 style light alloy rear brakes. The long reign of the rear mounted "M" caliper ended with the introduction of the 1984 Carrera.
"S" calipers were standard on the high performance 911E and 911S through 1973. In 1974, the "S" calipers were found on the 911 S and the Carrera with the heavier, three piece, cast iron "M" calipers mounted on the standard 911.
In 1975, the "S" caliper could be found only on the US Carrera and the R.o.W (Rest of World) Turbo. 1976 saw the "S" caliper on the US and R.o.W. Turbo, but dropped from the Carrera (Not sold in the US) which acquired the new "A" cast iron calipers.
The Turbo introduced to the R.o.W. in 1975 and the US in 1976, incorporated the "S" calipers until the introduction of the 1978 model when the 917 style alloy brakes became standard. 1977 saw the "S" caliper limited to the Turbo only, with the 3.0 Carrera equipped with "A" front calipers, and "M" calipers to the rear.
The "S" caliper was also delivered on some 1978 SCs only to disappear entirely on the 1979 model line, replaced by the cast iron "A" caliper. From the "I" series through the SC model run, "A" calipers brakes are found at the front with "M" calipers to the rear.
Advantages of the "S" front calipers over cast iron: In addition to the obvious reduced weight factor (Less unsprung weight with resulting better suspension response), aluminum "S" calipers conduct heat away better than cast iron, some say they provide improved pedal feel, and the "S" calipers utilize a thicker 13 millimeter brake pad, contrasted to the 10 millimeter pad of the "A" caliper.
On the down side, some drivers report the "S" brakes tend to flex under extremely hard usage. And being constructed of aluminum, they are subject to the forces of corrosion. I used these brakes and never experienced this flex effect.
Availability: Porsche "S" calipers are difficult to find and will cost at least $400 per pair, used and rebuilt, probably more, plus installation. New "S" calipers are available but are extremely expensive. Stoddard's 1987 catalogue lists new "S" calipers at $1,136.90 each.
Under the "update-backdate" provision of the PCA and POC GCRs, because the "S" caliper appeared on some models of the 1978 911SC, this allows for a "S" caliper update of "A" calipers equipped cars for the 1978-1983SC's model run. The update is a relatively simple bolt in operation.
The "S" caliper update does not apply to 1984 and later cars. These model years were delivered with a redesigned, wider, "A" style cast iron calipers to accommodate a more efficient 24mm rotor, possessing better heat dissipation characteristics than the previous 20mm rotor, electronic wear indicators designed into the brake pads providing dashboard warning for needed brake pad replacement, larger rear brake cylinder bores, a larger brake servo, an engine driven vacuum pump and a brake pressure limiting proportioning device.
Note: Before you decide to rush out and upgrade your pre-1976 911 to "S" calipers, please remember they will not fit on struts having the "M" series calipers.
If you are in doubt as to what calipers are on your car, measure the distance between centers on the caliper mounting bolts on the front struts. If the distance measures 3", you have "M" calipers. "S" and "A" caliper mounting bolts are approximately 3 1/2" apart.
In order to install "S" calipers, on a "M" caliper equipped cars, you will first incur the added expense of changing out the old "M" caliper struts to struts accepting the "A" or "S" calipers. Expect to pay approximately $1,000 for the struts alone, add in the cost of shock absorber inserts at about $200, as well as the cost of used and rebuilt "S" calipers at $600 or more, and the required labor. In summary, the total cost for the conversion to "S" calipers could exceed $2,500.
In the long run, for those determined to own a 911 with "S" calipers, it could be less expensive in the long run to acquire a 911 delivered originally with "A", or preferably the "S" calipers, as standard equipment. Caution: for those considering the change from "M" calipers to "S" calipers with the required strut change, you may wish to check your GCRs to see if this is an allowable modification.
Non "S" calipers equipped cars: From the earliest 911 models, the 911S prior to 1969, the 911T's and the 911L, all were equipped with the "M" front calipers which remained as the standard through the "H" production series ending in July 1975. At this point the "M" front caliper was replaced by the by the "A" caliper.
The "A" caliper, also developed by Ate, first integrated into the 1976 models, is similar in size to the "S" caliper and originally developed for Alpha Romeo hence the "A" designation. The "A" caliper is a three piece, cast iron caliper, providing the same 78 sq. cm brake pad area as the "S" caliper, utilizing a 10mm brake pad contrasted to the 13mm pad found on the "S" brakes.
Rear calipers: Ate also designed the "L" (light) caliper, mounted at the rear of the 911 from the first introduction of the car through the "A" production series ending in July 1968. From the "B" series 911 onward, the "M" caliper is found at the rear of the all 911's, with the exception of the 1978 and later Turbo which received 917 style light alloy rear brakes. The long reign of the rear mounted "M" caliper ended with the introduction of the 1984 Carrera.
02-15-2020, 11:05 AM
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S calipers
Well as I said my 75 Silver has S calipers in the front. Found out last year when I was rebuilding the brakes. My assumption is that the S caliper was part of the Silver Anniversary option package like the headlight washer, paint, interior and rear window defroster.
Terry
Terry
