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ECS tuning agreed to strongly consider making 380mm replacements if there was enough interest. They already have a 380x38 front rotor but the bolt pattern is only for Audi.
Someone should start a thread with a poll and send the ECS guys the link to the thread so they can monitor it and see the level of interest. I don't know anyone over there but just did something similar with the Rennline guys for a different product idea.
Whether you are looking for OE rotor replacement (iron or CCB) or upgrading to CCB (from iron), there is no brake company offers more choices than RacingBrake.
This caliper is also known as 19Z (fits 19" wheels) made to fit 380x36mm rotor. Below is the image of the caliper and pad:
We will take some measurement on this caliper and determine how big the rotor it can fit in or whether 410mm rotor requires a new caliper or not.
I considered this before purchasing a complete PCCB 958 setup to retrofit to my 957. What concerned me is that the OEM caliper is designed to work with a 380x38 mm rotor on the '09 Turbo S (not a 36mm rotor) and that rotor has a minimum wear threshold of 36mm. These offerings start at 36mm so I don't know what happens once you get into a worn pad situation where you lose that thickness, along with some rotor wear, and then add to that the 2mm thinner starting rotor thickness - you may end up where the pistons inside the calipers have to travel too far and bind or leak fluid. Maybe not, but I wasn't willing to risk it..
With that unknown, I went with the safer bet of a very lightly used full OEM Porsche PCCB setup which included all 4 rotors, all 4 calipers, all the pads, and all the caliper hardware for less than just the 4 CCB rotors were going to cost based on the prices quoted here.
That's a good alternative, I would do the same if I were you.
Just to clarify the rotor thickness and calipers pad gap. In general we reduced the rotor thickness by 2mm so the rotor is not excessively over-weighted as we convert from CCB to Iron. However if a rotor thickness is 36mm (when new) the minimum thickness is 34mm, it's different from original 38mm worn down to 36mm (@discard thickness).
As to the caliper design, Porsche 991 GT3 Yellow calipers are made for pccb 36mm thickness (410x36), but it's exactly the same as standard brake's RED calipers for 34mm thickness iron rotor (380x34) in body/size except with shorter legs for smaller rotors, although the total rotor thickness difference is 2mm, but the extra piston advancement per side is only 1mm which is quite acceptable in a caliper design, in fact it's better than a tight fit of 36mm for better air circulation.
Multiple sets of iron rotors (36mm) were shipped to domestic and European customers w/o any issue.
I considered this before purchasing a complete PCCB 958 setup to retrofit to my 957. What concerned me is that the OEM caliper is designed to work with a 380x38 mm rotor on the '09 Turbo S (not a 36mm rotor) and that rotor has a minimum wear threshold of 36mm. These offerings start at 36mm so I don't know what happens once you get into a worn pad situation where you lose that thickness, along with some rotor wear, and then add to that the 2mm thinner starting rotor thickness - you may end up where the pistons inside the calipers have to travel too far and bind or leak fluid. Maybe not, but I wasn't willing to risk it..
With that unknown, I went with the safer bet of a very lightly used full OEM Porsche PCCB setup which included all 4 rotors, all 4 calipers, all the pads, and all the caliper hardware for less than just the 4 CCB rotors were going to cost based on the prices quoted here.
Reviving an old thread here...
Based upon what our friend from Racing Brake said about European customers running a 36mm disc in caliper designed for 38mm and the assertion that the 410MM disc would fit in a caliper specced for a 380mm, couldn't one use the newer 2011 CTT and CTTS rotors (95835140350, etc) on a 2009 CTTS like yours and mine with no issues? I assume the bolt pattern (disc mounting, not wheel) is the same, not sure about the offset... I certainly understand your concern about overtravel on the caliper pistons, but 1mm per side additional would seem to be okay based on the length of the pistons, which are quite long.
I have also thought about changing to the newer calipers to accommodate the newer rotors, but I can't find any info on the performance and number of pistons. The 2009 CTTS has the Brembo 19Z calipers.
My thinking is that one, the OEM replacements on the 2006 and 2008 CTTS are expensive and the fitment unique, making it harder to find them in the future and possibly even more expensive. Also, the delta in the cost between the stock 380 X38MM rotors and the 390 X 36mm rotors would go a long way to changing the calipers to newer ones. I love my brakes, so the if the newer calipers are lesser in terms of performance, I certainly wouldn't consider that route.
As an example on 991 GT3; Pccb (Yellow) calipers (body and construction) are the same exact calipers as Standard (Red) calipers - Front and rear.
The only difference is the offset - varied to fit different rotor thickness (36 vs. 34mm) and leg length (410 vs. 380mm). We didn't make it up to convince you to believe, we simply follow what OE does which no one will question that.
You can count on the brake data presented here and elsewhere in the forum. We post only objective data/numbers, that's how our brake components and system are designed.
We have OE caliper samples in house and their dimensions are measured and recorded in our database. See our complete caliper listing with all piston size details - The most comprehensive brake store for Porsche. https://www.racingbrake.com/category-s/7185.htm
Bump... I am trying to ascertain whether or not the 958 CTT front rotors at 390/ 36 MM would fit an OEM 380/38MM application. It appears that there wouldn't be enough clearance without spacing the calipers outboard slightly from the hub.
Tom, I had typed you a nice long response yesterday while waiting at the school to pick up my son, then took a phone call and when I reopoened the page it was all gone - damnit and my thumbs didn't have it in me to start over on my phone. In the future I'm going submit the partial responses with a note at the bottom that they'll be edited and finished later, as that happens far too often.
Anyway, after living through the 928 Ceramic Brake upgrade project on my TTS I can provides some first had knowledge that will answer some of your questions.
Here's a picture of calipers mounted on a motorcycle so you understand what I'm talking about with radially and axially mounting methods.
You cannot just purchase 958 calipers to go along with 958 rotors and bolt them onto your 957.
First problem is that the 958 Calipers mount radially (bolts through the top into the wheel carrier) whereas the 957 calipers mount axially (bolted in through the side). The 957 calipers actually do have radial bolts that secure them to the axial adapter, but Porsche doesn't sell this piece separately, only as part of a complete caliper
The above creates a problem with the concept of running a larger rotor in the stock braking setup as with the axially mounted caliper on the 957 there is not a simple way to just space it out higher. Maybe you could take out the radial bolts that attach the caliper to the axially mounted portion and space that out using longer axial bolts - I don't know.
Second problem is that the axial bolt spacing is different between the 2 models of caliper. I can only tell you about my personal measurements comparing a 958 PCCB caliper with a 957 Turbo S steel caliper - it's possible that the 957 PCCB caliper and the 958 PCCB caliper or that the 957 TTS and 958 Turbo Steel calipers do share the same spacing, however I doubt it as that would mean Porsche would have to use different wheel carriers for a steel braked Turbo Cayenne vs a PCCB braked Turbo Cayenne instead of just attaching the specified caliper and rotor to the same wheel carrier.
If the complete 958 wheel carrier will bolt into a 957, and you did this, then you could just buy 958 parts and they should all attached correctly.
On the front brakes, the radial bolt center to center spacing is different enough from the 957 axial bolt center to center spacing where the bolts coming in from both directions don't actually interfere with each other so you could make an axial to radial mounting adapter. The problem I ran into is that the standoffs on the PCCB calipers were so long that there wasn't enough spacing to make the adapter robust enough (it would have been too thin). So I had to machine down the mounting posts of the PCCB caliper so I could make the adapter thick enough to have the large bolts go into and through it from both orientations and it be substantial.
See how the axial mounting post of this front caliper goes down too far to the radial mounting hole in the wheel carrier. The spacer guys said they needed at least 15mm of clearance to be comfortable manufacturing the spacer, so I had to mill those caliper mounting posts down.
What you see comparing the above pictures to the below pictures is that I took the total front caliper mounting depth from 107.6mm down to 93.05 and this allowed for enough thickness where the custom adapter was 26mm thick.
Custom adapters look like this. I used the 958 radial mounting holes with custom length Titanium fasteners that thread into the custom adapter, then the adapter bolts to the 957 wheel carrier just like the axially mounted 957 calipers did before.
At the rear, it was a completely different story where the radial and axial 957 mounting holes and the radial 958 caliper holes were too close together and actually interfering. The other problem at the rear is that the PCCB rotors aren't larger by enough margin to have space for an adapter. I had no choice for the rears but to purchase the correct 957 PCCB calipers, but before doing this checked the PET catalog to confirm that both the 957 and 958 PCCB option package used the same rear rotor part #, and they do - BTW, the front part # is different even though PCCBs on both 957s and 958s are 410mm, which means something is different and that something is probably the rotor hat offset! This likely answers your other question about whether you could install 958 rotors onto a 957 and have them work - I don't think so.
Here's the problem with the 958 caliper and the rear of the 957. See how the hole spacing is too similar so you can't have bolts coming in from two different orientations and not interfere with each other.
Also, earlier in this thread someone didn't understand how going to a larger rotor could lessen the swept pad area so let's look at that for a second. The inside of the caliper is curved where the rotor rides in it. The circumference of the rotor has to clear the two edges of the caliper. As you go to a larger rotor diameter, the outside curve of the caliper becomes straighter, so when you clear the two edges of the caliper, the rotor is less engaged into the pad area of the caliper - think about a hypothetical extreme of a caliper on a 20" rotor so you understand what I'm talking about - virtually none of that rotor would be inside the pad area of the caliper. So when you go to a larger rotor and space the caliper out, there is less swept pad area inside the caliper unless the pads are redesigned to match the new internal curve the rotor takes. Pads need to run just inside the outer circumference of the rotor as you can't have the pad material extending beyond the rotor or as the pad wears, it creates a lip on the pad outside the rotor. So, when RacingBrake said that they looked at the 957 TTS caliper and the largest rotor it could accommodate is 396mm it has to do with the curve of the rotor in the pad area of the caliper and how the stock pads contact the rotor in that area. Going larger, even if you spaced the caliper out further (to lets say a 410mm would not keep the pad contact area completely on the surface of the rotor.
Hope that answers some of your questions.
I love the PCCBs on my Cayenne and have put about 10,000 miles on them since the conversion, to where I finally felt comfortable enough to sell off the complete Turbo S brake system I removed, which I did this past weekend.
The PCCBs work fantastic, don't get the wheels dirty, and I haven't had any issues with any of it, but it was a very tedious conversion process because of the way I chose to do it (caliper adapters instead of looking at swapping wheel carriers - if that's possible) and there was the risk that I wouldn't be able to make it work or that the alignment of some two components wouldn't be perfect and I'd have to scrap the whole thing and throw away a few thousand dollars of non standard 958 calipers.
The company that manufactured the adapters from my measurement actually does an interim step where they provide a 3D printed one so you can do a test fitment before they manufacture the galvanized metal ones. Turns out this was necessary as I found a clearance issue with the upright and the adapter and they had to increase the curve in this area from the prototype to the finished one. At a 25.87mm thickness in this area, it wouldn't attach flush. I reworked it and provided another measurement and they made the final versions with 24mm in that area.
Would I do it again knowing what I know about what was required - no, not the way I did it. I'd buy 957 PCCB calipers and try to find a set of used 957 PCCB rotors or just keep the Turbo S red setup and pay the exhorbitant price for new rotors or possibly look at the Racing Brake option.
I know this is an old thread but fantastic work you did there!
Thanks a lot !
Still loving and enjoying the CTTS with the PCCBs, even though it doesn't see a lot of use with both our kids now driving their own cars (Audi Q5 and 944 S2).
Can you do the opposite, i:e convert PCCB 410 mm rotors F and 370 mm R to steel 380 mm F and 340 mm R , using the OE yellow calipers ?
You would have to take some very detailed measurements and know a good machine shop as you'd have to mill the legs of the 958 calipers to be 40mm shorter than stock and I don't think they're that long to start with, so I'm thinking no.
Your best bet would be to switch to the next size down calipers (red versions) that take the smaller rotors - don't know what size those rotors are on a 958. Need to factor in pad shape and rotor swept area as well.
11-24-2016, 08:36 PM
