Are these GTS calipers or late S4/GT? Please help identify brakes
03-22-2008, 02:19 PM
#31
Rennlist Member
how about measureing from the brake fluid filler to the bottom brake fluid line.
those measurememts are painful to look at with that tape! I dont know what you are measuring. you are short on the length and i dont know where you end up.
So, do we have a verdict??? sure looks like newer S4 calipers now based on the pics.
mk
those measurememts are painful to look at with that tape! I dont know what you are measuring. you are short on the length and i dont know where you end up.
So, do we have a verdict??? sure looks like newer S4 calipers now based on the pics.
mk
03-22-2008, 02:27 PM
#32
Nordschleife Master
Thread Starter
Mark,
Here are the pics side by side, how do you think they look like S4 calipers. Look at the size of the lettering on my calipers?
Also something more telling to me is that like i said the S4 pads in my calipers arent tall enough to get any pressure from the spring. A taller GTS pad would no doubt cure this. Look at the pad side of the calipers and you can see how deep my S4 pads are in this caliper compared with the pictures of the updated S4/GT caliper.
Is it just me, but they look pretty different to me. Also the arrow is different (read different casting) and the bolt locations seem to be different in relation to where the pistons are (well maybe not) . See below for side by side.
I guess in the pic you cant see the arrow design, but my calipers have a very short tail on the arrow. The directional Arrow actually is right above the "H" in "PORSCHE" you can see they are different, so the casting is clearly different. Could it still be an S4 sized caliper with a different casting arrow, sure but its unlikely considering where the pad size issues and the rotor wear issues ive previously mentioned.
Here are the pics side by side, how do you think they look like S4 calipers. Look at the size of the lettering on my calipers?
Also something more telling to me is that like i said the S4 pads in my calipers arent tall enough to get any pressure from the spring. A taller GTS pad would no doubt cure this. Look at the pad side of the calipers and you can see how deep my S4 pads are in this caliper compared with the pictures of the updated S4/GT caliper.
Is it just me, but they look pretty different to me. Also the arrow is different (read different casting) and the bolt locations seem to be different in relation to where the pistons are (well maybe not) . See below for side by side.
I guess in the pic you cant see the arrow design, but my calipers have a very short tail on the arrow. The directional Arrow actually is right above the "H" in "PORSCHE" you can see they are different, so the casting is clearly different. Could it still be an S4 sized caliper with a different casting arrow, sure but its unlikely considering where the pad size issues and the rotor wear issues ive previously mentioned.
03-22-2008, 02:39 PM
#33
Nordschleife Master
Thread Starter
how about measureing from the brake fluid filler to the bottom brake fluid line.
those measurememts are painful to look at with that tape! I dont know what you are measuring. you are short on the length and i dont know where you end up.
So, do we have a verdict??? sure looks like newer S4 calipers now based on the pics.
mk
those measurememts are painful to look at with that tape! I dont know what you are measuring. you are short on the length and i dont know where you end up.
So, do we have a verdict??? sure looks like newer S4 calipers now based on the pics.
mk
Ryan, measure the distance from the casting land where the brake bleeder port mounts to the same location where the crossover tube mounts. The GTS/Big Red caliper is 7 5/8" from edge to edge. That's the only way I've ever been able to tell. The casting numbers have never been a help to me and there isn't a P/N on them that I've ever found.
03-22-2008, 02:44 PM
#34
Rennlist Member
yes they are different. Now we just need a measurement at points someone else can replicate.
the spring doesnt press on the pads, but it does barely touch. your measurement of the pads is real quirky. I dont understand. do you have two sets of pads., ones thougt to be GTS pads and the other S4? i see the ridge that the pad was cut by the rotor. I think the GTS pad is much bigger from what i imagine. should be night and day, after all, they are BIG REDS!!
so, the length of the caliper might be a good indication, if you can give us a measurement that can be duplicated by others. AND, there is always a possibility that other porsche brakes were used. as i said, maybe they are off another 911 front. dont think they are GTS brakes, as that means 911 turbo brakes, and i do remember those being REAL big.
what ever they are, they are nicer than the S4 brakes and certainly different castings than the newer S4 brakes .
the spring doesnt press on the pads, but it does barely touch. your measurement of the pads is real quirky. I dont understand. do you have two sets of pads., ones thougt to be GTS pads and the other S4? i see the ridge that the pad was cut by the rotor. I think the GTS pad is much bigger from what i imagine. should be night and day, after all, they are BIG REDS!!
so, the length of the caliper might be a good indication, if you can give us a measurement that can be duplicated by others. AND, there is always a possibility that other porsche brakes were used. as i said, maybe they are off another 911 front. dont think they are GTS brakes, as that means 911 turbo brakes, and i do remember those being REAL big.
what ever they are, they are nicer than the S4 brakes and certainly different castings than the newer S4 brakes .
03-22-2008, 02:50 PM
#35
Burning Brakes
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03-22-2008, 02:51 PM
#36
Nordschleife Master
Thread Starter
Mark,
To clarify the pad issue. Follow me here, When i bought the car it had the pagid's which measure the same as yours do. But they had a crazy edge because the spring wasn't holding the pads in place. (because larger pads were required and the rotor wasnt big enough)
The other pads i put side by side to it which had a smaller measurement of 54.5 are the performance friction carbon metallic pad's from autozone with lifetime warranty (my reason for buying them from autozone) They appear to be even a little bit smaller then the S4 pagid's. (I had thought the pagids were larger but based on your measurements they are the same as the S4 pads, safe to assume they are S4's now.)
So I would like to see the same measurement for a GTS pad and see how much bigger those really are. The GTS pad is taller, which would obviously fit my calipers because i can fit a taller pad maybe as much as 8mm and the spring will do its job and hold the pads in place as its supposed to.
Combined with new 965 cast hole rotors and i would then have a complete GTS brake setup, as it stands now i have a mish-mash of parts that i am less then happy with, but i am glad i have the most expensive bits of the GTS upgrade, the calipers.
To clarify the pad issue. Follow me here, When i bought the car it had the pagid's which measure the same as yours do. But they had a crazy edge because the spring wasn't holding the pads in place. (because larger pads were required and the rotor wasnt big enough)
The other pads i put side by side to it which had a smaller measurement of 54.5 are the performance friction carbon metallic pad's from autozone with lifetime warranty (my reason for buying them from autozone) They appear to be even a little bit smaller then the S4 pagid's. (I had thought the pagids were larger but based on your measurements they are the same as the S4 pads, safe to assume they are S4's now.)
So I would like to see the same measurement for a GTS pad and see how much bigger those really are. The GTS pad is taller, which would obviously fit my calipers because i can fit a taller pad maybe as much as 8mm and the spring will do its job and hold the pads in place as its supposed to.
Combined with new 965 cast hole rotors and i would then have a complete GTS brake setup, as it stands now i have a mish-mash of parts that i am less then happy with, but i am glad i have the most expensive bits of the GTS upgrade, the calipers.
03-22-2008, 02:53 PM
#37
Nordschleife Master
Thread Starter
Bert,
Thanks for finding that, that shows the big reds with the same casting marks for the directional arrows as mine. I think that confirms it.
So what did we learn, dimensionally GT and GTS calipers look the same with no size reference, but a quick indicator is the directional arrow. A full length arrow is S4, a smaller arrow inside a small circle is big black or big red.
That should be the new way of identifying what calipers you have.
Thanks for finding that, that shows the big reds with the same casting marks for the directional arrows as mine. I think that confirms it.
So what did we learn, dimensionally GT and GTS calipers look the same with no size reference, but a quick indicator is the directional arrow. A full length arrow is S4, a smaller arrow inside a small circle is big black or big red.
That should be the new way of identifying what calipers you have.
03-22-2008, 06:04 PM
#38
Rennlist Member
so, why not get a spacer for the S4 caliper and use the GTS rotors for a little more braking force?
sounds like the S4 caliper is not much smaller, if any than the GTS caliper, aside from the 8mm taller pad. is that where we are at ?
mk
sounds like the S4 caliper is not much smaller, if any than the GTS caliper, aside from the 8mm taller pad. is that where we are at ?
mk
03-22-2008, 06:12 PM
#39
Nordschleife Master
Thread Starter
It sounds like it.
I liken the S4 / GTS front brakes to be like the 965 3.3L / 965 3.6L. I believe the 3.3L uses the S4 brakes but with a 322mm rotor and the smaller pads. The 3.6L uses the larger calipers, different 322mm rotors (not sure in which way) and the larger or taller pads.
Actually come to think of it, you couldnt take advantage of the larger disc even if it could be fit inside the S4 caliper. The pads would still contact the rotor in the same spot so you wouldnt get anymore leverage out of it.
Late S4 and GTS calipers have the same pistons, so can you assume they put out the same clamping torque on the rotor. If you can get a 322mm rotor to fit on an S4 caliper (I guess with a small spacer bracket) You would still be using the smaller pads and i think the surface area of the pads is probably where the largest gain is in the performance in going from S4 to GTS.
Interesting idea though. I wouldnt be surprised if you can get the 322mm rotor in the S4 caliper there maybe room when you mount it as the factory did. But the pad would contact the same area so there would be no benefit and mostly just a weight gain.
The benefit of the GTS brake upgrade is 2 fold i guess, a larger caliper which allows for a larger disc and larger pads over the S4
I liken the S4 / GTS front brakes to be like the 965 3.3L / 965 3.6L. I believe the 3.3L uses the S4 brakes but with a 322mm rotor and the smaller pads. The 3.6L uses the larger calipers, different 322mm rotors (not sure in which way) and the larger or taller pads.
Actually come to think of it, you couldnt take advantage of the larger disc even if it could be fit inside the S4 caliper. The pads would still contact the rotor in the same spot so you wouldnt get anymore leverage out of it.
Late S4 and GTS calipers have the same pistons, so can you assume they put out the same clamping torque on the rotor. If you can get a 322mm rotor to fit on an S4 caliper (I guess with a small spacer bracket) You would still be using the smaller pads and i think the surface area of the pads is probably where the largest gain is in the performance in going from S4 to GTS.
Interesting idea though. I wouldnt be surprised if you can get the 322mm rotor in the S4 caliper there maybe room when you mount it as the factory did. But the pad would contact the same area so there would be no benefit and mostly just a weight gain.
The benefit of the GTS brake upgrade is 2 fold i guess, a larger caliper which allows for a larger disc and larger pads over the S4
03-22-2008, 09:07 PM
#40
Race Car
Er... so the way I understand this now is that there are two types of S4 calipers, an older one (so-called "medium" S4) and a newer one. The older one is pretty substantially smaller in length than GTS, and the newer one is the same length but not as wide. It looks like my GT's brakes are the later S4 style since they measure the same length as GTS, but have long arrows instead of short ones. Interesting.
Dan
'91 928GT S/C
'86 928S 5-spd w/LSD *sale pending*
Dan
'91 928GT S/C
'86 928S 5-spd w/LSD *sale pending*
03-22-2008, 09:15 PM
#41
Nordschleife Master
Thread Starter
All S4 Calipers are commonly referred to as "MEDIUM" opposed to "BIG BLACK's" or "BIG RED's"
There are 2 S4 calipers. They changed in 89 or mid 89.
Original S4 calipers have the raised "PORSCHE" lettering as an easy identifier. The pistons are smaller (Correct me if i am wrong and i will edit it) at 42mm and 36mm
Newer S4 calipers appeared in 89 or mid 89 with 44mm and 36mm pistons. Identifying marker is that they "PORSCHE" lettering is now a stick on type emblem and is smooth with the rest of the caliper.
GTS Calipers at a glance look like late S4 calipers, but they are larger to fit the larger pad's and rotors. The identifying marker i believe to be either the length measurement as Jim Mentioned on page 1, or as I noticed but cant confirm as the arrow casting. The GTS caliper has a small arrow in a circle about the "H" in Porsche. It maybe above another letter on the other side, I wold imagine this to be the case. Either way, the arrow is inside a small circle opposed to the large arrow on the early and late S4's
There are 2 S4 calipers. They changed in 89 or mid 89.
Original S4 calipers have the raised "PORSCHE" lettering as an easy identifier. The pistons are smaller (Correct me if i am wrong and i will edit it) at 42mm and 36mm
Newer S4 calipers appeared in 89 or mid 89 with 44mm and 36mm pistons. Identifying marker is that they "PORSCHE" lettering is now a stick on type emblem and is smooth with the rest of the caliper.
GTS Calipers at a glance look like late S4 calipers, but they are larger to fit the larger pad's and rotors. The identifying marker i believe to be either the length measurement as Jim Mentioned on page 1, or as I noticed but cant confirm as the arrow casting. The GTS caliper has a small arrow in a circle about the "H" in Porsche. It maybe above another letter on the other side, I wold imagine this to be the case. Either way, the arrow is inside a small circle opposed to the large arrow on the early and late S4's
03-22-2008, 09:25 PM
#42
Race Car
This quote by cobalt in the first post of the thread linked here in a previous post:
"I have seen 90 GT's and some S4's with brakes that look almost Identical to the big blacks used on the GTS. The differences are smaller rotors and slightly smaller size of the caliper. I believe the length was the same but the width is different."
reinforces my measurements of my calipers. They are 7 5/8", just like GTS calipers are. However, they have the long directional arrow, and I bet if I measured their width they would be narrower than GTS calipers.
Dan
'91 928GT S/C
'86 928S 5-spd w/LSD *sale pending*
"I have seen 90 GT's and some S4's with brakes that look almost Identical to the big blacks used on the GTS. The differences are smaller rotors and slightly smaller size of the caliper. I believe the length was the same but the width is different."
reinforces my measurements of my calipers. They are 7 5/8", just like GTS calipers are. However, they have the long directional arrow, and I bet if I measured their width they would be narrower than GTS calipers.
Dan
'91 928GT S/C
'86 928S 5-spd w/LSD *sale pending*
03-22-2008, 09:29 PM
#43
Nordschleife Master
Thread Starter
could be right,
It really is quite a controversy.
Maybe the arrow should be the indicator if your duplicating my measurements and getting the same 7 5/8" then the measurement isnt the best way to identify.
It really is quite a controversy.
Maybe the arrow should be the indicator if your duplicating my measurements and getting the same 7 5/8" then the measurement isnt the best way to identify.
03-22-2008, 09:54 PM
#44
Rennlist Member
Ryan,
993TT front rotors will not fit with the Porsche hats. You will need the Koklen hats, sold by Lindsey Racing for the 944T. And I believe they are $299 EACH, (I wish it was for the pair) meaning $600.00+ for a set plus the rotors.
If you want one piece rotors you will need to use 965.351.045.00 and 965.351.046.00. These are the cast hole rotors and are a direct bolt on with the correct spacing (I've now done it twice). 
The 968 has the S4 calipers only if equipped with the MO30 option IIRC. They are not the same as big blacks or big reds.
I believe I read somewhere that Porsche had Brembo remove the cast "Porche" on the S4 and the Big Reds due to clearance issues with the new style wheels on the 911.
The only difference between big reds and big blacks is the location of the crossover tube and the bleed ports. This is because the 928 caliper is mounted on the back side of the rotor (Keeps the the CG between the wheels) and the 911 caliper is located on the front side (because of the heavy *** end they needed as much moment arm as possible forward, so it helps move the CG towards the center).
One other way to tell if the calipers are big R/B or S4 is the angle of the bleed port and the cross over tube. On the big calipers they are parallel to each other on the S4 or 944T/968 (with MO30 option) they are at an angle to each other.
993TT front rotors will not fit with the Porsche hats. You will need the Koklen hats, sold by Lindsey Racing for the 944T. And I believe they are $299 EACH, (I wish it was for the pair) meaning $600.00+ for a set plus the rotors.
If you want one piece rotors you will need to use 965.351.045.00 and 965.351.046.00. These are the cast hole rotors and are a direct bolt on with the correct spacing (I've now done it twice). The 968 has the S4 calipers only if equipped with the MO30 option IIRC. They are not the same as big blacks or big reds.
I believe I read somewhere that Porsche had Brembo remove the cast "Porche" on the S4 and the Big Reds due to clearance issues with the new style wheels on the 911.
The only difference between big reds and big blacks is the location of the crossover tube and the bleed ports. This is because the 928 caliper is mounted on the back side of the rotor (Keeps the the CG between the wheels) and the 911 caliper is located on the front side (because of the heavy *** end they needed as much moment arm as possible forward, so it helps move the CG towards the center).
One other way to tell if the calipers are big R/B or S4 is the angle of the bleed port and the cross over tube. On the big calipers they are parallel to each other on the S4 or 944T/968 (with MO30 option) they are at an angle to each other.
03-22-2008, 10:35 PM
#45
Nordschleife Master
Thread Starter
Great Post Jim
Holy crap $600 for the pair! I thought it was $300 for the pair. Even at $300 I decided to go with the 965 rotors you mentioned. They are only $302 per pair! And they are in stock on the shelves. The OE GTS rotors which dont have the holes are more expensive at $380ish per pair, but i much prefer the holed versions, they look real nice. I will also buy the missing wire clip and probably new brake pad wear sensors and probably chub up for the GTS dust shields. I am debating on wether to use the porsche type pad dampener which are 4 individual pads that snap into the pistons, or just go with a single plate to cover both pistons. Which is the preferred method? Has the individual dampener idea been replaced with the single plate method for getting rid of squealing?
I am now trying to decide what to do for pads as i have 2 sets of S4 pads. I may go with the OE Porsche Textar i believe if they are cheaper then the OEM versions of the same thing. I wouldnt be surprised if they are. Or there is Mintex pads for $55 but i havent heard anything good or bad about mintex. I will stay away from Pagid's as i see those really as a track pad. Low dust and noise is my priority.
Holy crap $600 for the pair! I thought it was $300 for the pair. Even at $300 I decided to go with the 965 rotors you mentioned. They are only $302 per pair! And they are in stock on the shelves. The OE GTS rotors which dont have the holes are more expensive at $380ish per pair, but i much prefer the holed versions, they look real nice. I will also buy the missing wire clip and probably new brake pad wear sensors and probably chub up for the GTS dust shields. I am debating on wether to use the porsche type pad dampener which are 4 individual pads that snap into the pistons, or just go with a single plate to cover both pistons. Which is the preferred method? Has the individual dampener idea been replaced with the single plate method for getting rid of squealing?
I am now trying to decide what to do for pads as i have 2 sets of S4 pads. I may go with the OE Porsche Textar i believe if they are cheaper then the OEM versions of the same thing. I wouldnt be surprised if they are. Or there is Mintex pads for $55 but i havent heard anything good or bad about mintex. I will stay away from Pagid's as i see those really as a track pad. Low dust and noise is my priority.