2013 Ferrari FF
Discussion
BOR said:
I really doubt that M6 bolts will affect the overall balance when you think of the mass of the wheel and tyre a lot further out than the disc bolt PCD.
Secondly, there are companies that refurbish ceramic disks, Rebrake is one, Surface Transorm is another. They would definitely have the necessary new bolts.
Edit:
The material typically used for the bolts is AISI 316Ti :
"AISI 316Ti is a stainless, austenitic titanium stabilized chromium-nickel-molybdenum steel.
Titanium stabilization makes the AISI 316Ti more susceptible to pitting corrosion and has less resistance to chloride-induced stress corrosion cracking. The maximum application temperature can be increased with the titanium alloy".
Which really makes you wonder if it is such a great material choice for brake discs?
Ouch. Where did the engineers think these cars would be driven?Secondly, there are companies that refurbish ceramic disks, Rebrake is one, Surface Transorm is another. They would definitely have the necessary new bolts.
Edit:
The material typically used for the bolts is AISI 316Ti :
"AISI 316Ti is a stainless, austenitic titanium stabilized chromium-nickel-molybdenum steel.
Titanium stabilization makes the AISI 316Ti more susceptible to pitting corrosion and has less resistance to chloride-induced stress corrosion cracking. The maximum application temperature can be increased with the titanium alloy".
Which really makes you wonder if it is such a great material choice for brake discs?
Edited by BOR on Tuesday 1st August 10:24
Rough101 said:
Isn’t this meant to be a balanced assembly on completion, therefore you aren’t supposed to just swap bolts?
I think this is what Audi are referring to in my post above, but I suspect if you mark the centre hub and the disc when you strip it so that it goes back together the same it’s very likely to be ok.
Thanks again for all the comments, particularly those offering help on identifying the materials for the fixings. I'll be in touch once the investigation properly kicks off. Frankly we're still at the stage of hoping that a mole within Brembo just steps up and helps us out with direct swaps 
With regards to the 'balanced assembly' thing. It's not that I deny the fact that these are indeed balanced assemblies from the factory, but more that I'm sceptical that this is a reason for the fixings to be unavailable on the market. There's clearly evidence of the friction material being balanced, but providing it's orientated on the bell the same way, I can't see the swapping of identical fasteners being an issue - and even if it did throw balance out, we're talking minute amounts at the centre of rotation - so will be far less influential than even a pebble being picked up by the tyre tread... for instance. Swapping friction material independently of the hub I can see being a problem in this context, but swapping out fixings that are on the path towards falling apart anyway... less so.
Each brake is actually individually stamped with the exact weight and therefor tolerance for disk wear (it has another measurement for thickness too) which is pretty convenient.
I weighed my fronts, both are 6.7kg according to my uber accurate bathroom scales. I always suspected they overread when I'm weighing myself on them, but suddenly I've felt myself agreeing with them.
After the drama of inspecting the fixings on the passenger side, I decided to leave the driver side the hell alone for now... but couldn't live with rusty nuts, so I masked off and blobbed a bit of Bilt Hamber Deox on them.
24hrs later that brought them up a treat.
I've got some ceramic coating left over from my Lotus calipers from when they went on. It's heat resistance to a decent level so I'll probably blob some of that on these nuts in a vain attempt to stop them re-rusting in the future.
Looking much better, and ready to go back on the car.
In terms of figuring out what the fixings are made out of, one of the spare discs that Enso had used some bolts that were slightly shorter than what we needed - but had some markings on their heads. The ones in "my size" had no markings, but the markings on the smaller ones read "SD-58" and "FS". No idea if that helps or not, but it's info for the investigation.
With regards to the 'balanced assembly' thing. It's not that I deny the fact that these are indeed balanced assemblies from the factory, but more that I'm sceptical that this is a reason for the fixings to be unavailable on the market. There's clearly evidence of the friction material being balanced, but providing it's orientated on the bell the same way, I can't see the swapping of identical fasteners being an issue - and even if it did throw balance out, we're talking minute amounts at the centre of rotation - so will be far less influential than even a pebble being picked up by the tyre tread... for instance. Swapping friction material independently of the hub I can see being a problem in this context, but swapping out fixings that are on the path towards falling apart anyway... less so.
Each brake is actually individually stamped with the exact weight and therefor tolerance for disk wear (it has another measurement for thickness too) which is pretty convenient.
I weighed my fronts, both are 6.7kg according to my uber accurate bathroom scales. I always suspected they overread when I'm weighing myself on them, but suddenly I've felt myself agreeing with them.
After the drama of inspecting the fixings on the passenger side, I decided to leave the driver side the hell alone for now... but couldn't live with rusty nuts, so I masked off and blobbed a bit of Bilt Hamber Deox on them.
24hrs later that brought them up a treat.
I've got some ceramic coating left over from my Lotus calipers from when they went on. It's heat resistance to a decent level so I'll probably blob some of that on these nuts in a vain attempt to stop them re-rusting in the future.
Looking much better, and ready to go back on the car.
In terms of figuring out what the fixings are made out of, one of the spare discs that Enso had used some bolts that were slightly shorter than what we needed - but had some markings on their heads. The ones in "my size" had no markings, but the markings on the smaller ones read "SD-58" and "FS". No idea if that helps or not, but it's info for the investigation.
GCCP said:
1) very interested to follow the progress
2) What is the procedure for taking the discs off without removing the calipers
thanks!
2) Calipers need to come off, but there's enough play in the brake line to just sort of angle the disc out. Taking the pads out would make it even easier.
Julian Thompson said:
I think this is what Audi are referring to in my post above, but I suspect if you mark the centre hub and the disc when you strip it so that it goes back together the same it’s very likely to be ok.
That's my take. Keep the bell and disc orientated as they came out of the factory and anything else you touch is going to easily be within tolerance of a bit of dirt sticking to the inside of the bell...nfcf said:
Fonzey said:
Thanks all for the suggestions, links, recommendations etc.
I'm not sure I buy the 'balanced assembly' theory purely on the basis that there's no machined balancing marks or telltales. At least not that I can find. So if the disc and bell are both perfectly balanced in isolation, then providing identical hardware is used... it shouldn't really matter, right?
You can achieve something approximating a balanced assembly without machining by selectively installing the parts to improve the overall balance of the final assembly so in theory they could check the balance of the 2 parts individually and assemble them to improve the overall balance.I'm not sure I buy the 'balanced assembly' theory purely on the basis that there's no machined balancing marks or telltales. At least not that I can find. So if the disc and bell are both perfectly balanced in isolation, then providing identical hardware is used... it shouldn't really matter, right?
It is (was?) a method used to help balance the turbine on a jet engine (each blade is weighted before starting assembly and a computer works out the best installation order on to the disc).
It's of course done now, but weight difference should be negligible across such small bolts. If you know anyone that works in Engineering and has access to material testing they can xrf the bolts you have and they'll give you an idea what they are.
10nm is nothing to cheese off at, but I would surmise the fasteners were to be used once as they will have seen lots of heat.
Julian Thompson said:
Mucho interesting. I am working on adding some S8 CCB’s to my old D3 Audi, and I’ve come up against Audi documentation that forbids touching those bolts that hold the rotor to the centre hub. Intrigued and armed with a knackered old disc I stripped the hub off and inspected it all.
Other than a specific arrangement of conical washers I can find absolutely no reason for the warning. Everything centres up automatically on assembly. No idea why they’re so insistent about it.
Here is what I'm guessing and this applies to all BMW/AUDI/Ferrari/Porsche who use this design of Brembro disc.Other than a specific arrangement of conical washers I can find absolutely no reason for the warning. Everything centres up automatically on assembly. No idea why they’re so insistent about it.
These are probably stretch bolts that are being tightened using torque+angle to put the bolt into plastic deformation.
This is done to maintain the clamping load on the disc as the bolt shortens and lengthens as the temperature hits it.
You can imagine the ceramic has a really low coefficient of thermal expansion and the bolt, despite the added titanium, will expand a lot more. In an extreme case, the bolt could expand so much, that there is no longer any clamping force on the disc.
Putting the bolt into plastic deformation should mean that the clamping force changes much less as the temperature changes, as the force now moves back and forth on the flat part of the curve.
You won't be able to do this with your Halfords torque wrench.
My first thoughts were that these bolts should be treated as consumables and regularly replaced, but I now think it is not quite so simple as I initially thought.
Of course, I could have this completely back-to-front.
BOR said:
Julian Thompson said:
Mucho interesting. I am working on adding some S8 CCB’s to my old D3 Audi, and I’ve come up against Audi documentation that forbids touching those bolts that hold the rotor to the centre hub. Intrigued and armed with a knackered old disc I stripped the hub off and inspected it all.
Other than a specific arrangement of conical washers I can find absolutely no reason for the warning. Everything centres up automatically on assembly. No idea why they’re so insistent about it.
Here is what I'm guessing and this applies to all BMW/AUDI/Ferrari/Porsche who use this design of Brembro disc.Other than a specific arrangement of conical washers I can find absolutely no reason for the warning. Everything centres up automatically on assembly. No idea why they’re so insistent about it.
These are probably stretch bolts that are being tightened using torque+angle to put the bolt into plastic deformation.
This is done to maintain the clamping load on the disc as the bolt shortens and lengthens as the temperature hits it.
You can imagine the ceramic has a really low coefficient of thermal expansion and the bolt, despite the added titanium, will expand a lot more. In an extreme case, the bolt could expand so much, that there is no longer any clamping force on the disc.
Putting the bolt into plastic deformation should mean that the clamping force changes much less as the temperature changes, as the force now moves back and forth on the flat part of the curve.
You won't be able to do this with your Halfords torque wrench.
My first thoughts were that these bolts should be treated as consumables and regularly replaced, but I now think it is not quite so simple as I initially thought.
Of course, I could have this completely back-to-front.
pre-loading the fasteners to a set torque is to protect them from fatigue loading normally??
Thanks again for all the input. It's not falling on deaf ears, and I'm taking all on board. That said, I am trying not to overthink this too much for a couple of reasons:
1. I've heard from unofficial channels that even under Ferrari inspection/warranty, they weren't that bothered until more than three(!) individual fixings failed on a car. So there's clearly plenty of redundancy engineered in, and I'll get plenty of warning if my fixings are not up to a second rodeo.
2. The Bobbins are doing most of the heavy lifting anyway, right? The shear forces from the caliper resisting the rotation are all going into the aluminium bobbins - the bolts are "just" pinning everything together. All of the failures I've seen examples of seem to be corrosion related, and the 10 bolts that I now have in the disc are visually clear of any/all corrosion.
Ultimately though Brembo are the experts, and I'd love their thoughts on it. Second to that I do have a dialogue open with a few specialists who put together brake kits for a living, and nobody is particularly scared about reusing hardware providing it can hold the torque.
One of the companies I've talked to make their own hardware for their CCB assemblies and they're very similar - their heads are 3.3mm thick up from 2.0mm on these brembos, so bigger but still will give clearance (I think), but they have an allen hex in them for tightening rather than the flats. They're 10.9 grade steel I believe and could be an option for me if I can validate the clearances.
AP in their off the shelf kits use 12.9 with some anti-corrosion coating - so nothing exotic there, but they use big torx heads that I just don't have clearance for.
For now, based on no engineering expertise at all I'm comfortable with the rebuilt disc, I'll keep an eye on it and will continue the hunt for an appropriate new set of hardware to get this all bolted back together again in the future.
In other news, I got a CTEK Ferrari adapter.
Not sure the actual name of it, or if it's Ferrari specific - but it does send a signal to the car to let it know it's plugged in.
This also prevents you from firing up the engine I believe.
This was then connected to a space MXS 5.0 I had lying around. I believe it came in a bag of freebies/spares when I bought the 2-Eleven and it's sat dormant since I already have a trickle charger mounted to the wall near where the Lotus gets parked up.
Brakes are bolted back to the car now, calipers torqued to spec and all the bolts looking nice and shiny, for now. Really hoping to get wheels back before the weekend and figure out if the car now drives OK. If it doesn't, the elasticity of my brake bolts will be the least of my concerns...
1. I've heard from unofficial channels that even under Ferrari inspection/warranty, they weren't that bothered until more than three(!) individual fixings failed on a car. So there's clearly plenty of redundancy engineered in, and I'll get plenty of warning if my fixings are not up to a second rodeo.
2. The Bobbins are doing most of the heavy lifting anyway, right? The shear forces from the caliper resisting the rotation are all going into the aluminium bobbins - the bolts are "just" pinning everything together. All of the failures I've seen examples of seem to be corrosion related, and the 10 bolts that I now have in the disc are visually clear of any/all corrosion.
Ultimately though Brembo are the experts, and I'd love their thoughts on it. Second to that I do have a dialogue open with a few specialists who put together brake kits for a living, and nobody is particularly scared about reusing hardware providing it can hold the torque.
danwebster said:
Epic car!
Have you looked at NAS bolts for the bells? Definitely up to the job if you can get the right size to suit your application. Generally they're imperial sizes but a 1/4 bolt will be very close to your M6's. My carbon brakes use them.
Cheers Dan, you were actually on my list of people to ping a phonecall to! I figured you'd have an opinion on it. NAS has come up in my Googling but ultimately I'm limited by clearance on the head sizes.Have you looked at NAS bolts for the bells? Definitely up to the job if you can get the right size to suit your application. Generally they're imperial sizes but a 1/4 bolt will be very close to your M6's. My carbon brakes use them.
One of the companies I've talked to make their own hardware for their CCB assemblies and they're very similar - their heads are 3.3mm thick up from 2.0mm on these brembos, so bigger but still will give clearance (I think), but they have an allen hex in them for tightening rather than the flats. They're 10.9 grade steel I believe and could be an option for me if I can validate the clearances.
AP in their off the shelf kits use 12.9 with some anti-corrosion coating - so nothing exotic there, but they use big torx heads that I just don't have clearance for.
For now, based on no engineering expertise at all I'm comfortable with the rebuilt disc, I'll keep an eye on it and will continue the hunt for an appropriate new set of hardware to get this all bolted back together again in the future.
In other news, I got a CTEK Ferrari adapter.
Not sure the actual name of it, or if it's Ferrari specific - but it does send a signal to the car to let it know it's plugged in.
This also prevents you from firing up the engine I believe.
This was then connected to a space MXS 5.0 I had lying around. I believe it came in a bag of freebies/spares when I bought the 2-Eleven and it's sat dormant since I already have a trickle charger mounted to the wall near where the Lotus gets parked up.
Brakes are bolted back to the car now, calipers torqued to spec and all the bolts looking nice and shiny, for now. Really hoping to get wheels back before the weekend and figure out if the car now drives OK. If it doesn't, the elasticity of my brake bolts will be the least of my concerns...
Fonzey said:
In terms of figuring out what the fixings are made out of, one of the spare discs that Enso had used some bolts that were slightly shorter than what we needed - but had some markings on their heads. The ones in "my size" had no markings, but the markings on the smaller ones read "SD-58" and "FS". No idea if that helps or not, but it's info for the investigation.
Courtesy of the US Fastener Quality Act, every manufacturer selling fastener products in the USA has to register their markings. The US Department of Defense publishes a handbook for fastener manufacturer identification. You can find it here:https://quicksearch.dla.mil/qsDocDetails.aspx?iden...
From this, we find "F S" denotes:
FERRIERE DI STABIO, S.A.
VIA LAVEGGIO 6/A
CH-6855 STABIO
SWITZERLAND
who - amongst many other things - offer "High performance braking system screws"
What about "SD" - for this we turn to Güldner, who decode the abbreviations for us at https://www.gueldner.com/en/gueldner/technik/kennz...
In this case, "SD" is a material abbreviation, meaning X6NiCrTiMoVB25-15-2, an austenitic precipitation hardened stainless steel. It has excellent creep strength and can be used at higher temperatures - up to 700°C - making it ideal for high-performance braking applications.
X6NiCrTiMoVB25-15-2 is commonly known as Grade 660 (or A-286)
What about "58"? For a normal steel bolt, that would usually be the property class, usually expressed with a point, such as "10.9" or "3.6" where the first number is 1/100 of the minimum tensile strength (in N/mm2 = MPa), and the second number is 1/10 of the ratio of the lower yield point (or "0.2% proof stress") to the tensile strength. Unfortunately, for steels and nickel alloys for use at elevated temperatures per DIN EN 10269, there are no standard property classes.
So I'm not immediately sure what "58" refers to at this time of night
But 585 MPa is the 0.2% proof stress of Grade 660.If you want to get a hold of some replacement screws, it might be worth reaching out to Stabio in Switzerland.
Alternatively, in terms of other suppliers, I note ReBrake https://www.rebrake.de/en/minor-repairs-to-ceramic... claim to be able to do so, but only - it seems - if you send them your complete discs and ask for service. But they might be worth talking to also.
For reasons I'll go into in another post, I'm not convinced re-using these fixings is a good idea in the long term.
Excellent post. Also of interest hopefully I shared it with my friend who runs an engineering firm that make bolts/fixings in standard and exotic materials and he's able to make you these in 660 grade and said I can share his direct email address if you like.
He's made himself some studs from the same material for exhaust manifolds previously.
He's in South Yorkshire, drop me a pm if you want his details
He's made himself some studs from the same material for exhaust manifolds previously.
He's in South Yorkshire, drop me a pm if you want his details
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