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Buckle in if you want to read about brake upgrades and possibly have a say in what is produced for the Volvo SPA chassis. I am aware this is a tiny percentage of even the people reading this post. That's cool because a few people could guide me in bringing the right product to market. The rest maybe you are bored and need entertainment, that's cool too ;-) This post represents over a year of work for me. So it will be long, I condensed down as much as I can. If you aren't interested, click another post you won't hurt my feelings at all. I am going to gloss over all sorts of technical stuff, otherwise this could take days, but feel free to ask any questions you have, I may even know the answer.

About 18 months ago I started thinking…gee I really like my Volvo, and I love driving it, I'd like a fixed caliper brake on this car. That would be nice looking of course and a subjective improvement. Nothing feels like fixed caliper brakes under the foot. It all started with a couple OEM calipers and trying to adapt them to the SPA chassis. That didn't work for a variety of reasons. I spent a lot of time at home in a pandemic, and it all ended up snowballing into where I am today.

The OEM brake system is pretty good, but then why do enthusiasts want to modify their cars…because better! It's a nice driving car, why shouldn't it have nice brakes? Having done a couple custom brake setups before, I knew about matching piston sizes, and mechanical leverage. I knew about heat capacity of rotors and the effects on performance. Over the last year I have learned a whole lot more.

What always bothered me about aftermarket parts is you have two sort of varieties of mfr: The established world-class players, and the off-brand competition. And none of them offers any objective proof of their product. The big players in brakes Brembo, AP, Wilwood don't share because they don't have to. The off-brands Rotora, K-Sport and a million others, they don't have any data to share. All the marketing is about "lightweight" and "forged" this and "aerospace" that. Frankly it's a bunch of crap. So when I started trying a few track nights with my S60, I installed a thermocouple to my rotor. Then I installed one on my caliper. I collected data on the OEM brake system, how it performs, what are the limits. I read research papers and masters theses' on brake systems. Somehow I ended up with a pile of calipers and an SPA suspension upright in my basement.

So there are already kits out there, very few though. I looked at the Rotora, a fine gentleman here provided me with all of the specs and measurements from his kit since Rotora doesn't publish anything. And I found a whole lot of problems with it:
  • On the edge of too much torque added up front through leverage, this means not very compatible with the complex Mk100 ABS controls in the SPA chassis.
  • The 380 rotor has less heat capacity than the OEM rotor
  • The 355 option has way less heat capacity than OEM, really should not be offered
  • The rear kit is needed to bring brake bias (the front rear balance) into line
  • BUT the rear kit has so much more leverage than the OEM brakes it will really mess with the ABS programming, it's a safety issue
  • Splash shield must be removed, which subjects the lower ball joint, tie-rod end and the ABS sensor directly to heat from the rotor and no solution provided
  • Requires wheel spacers, potentially pretty big ones
  • Typical limited availability of service parts
  • Questionable coatings and treatments for long term durability
  • They seem to be sold for "off-road" use only in fine print
  • There is more but the remaining issues are debatable

Let me not belabor the point, the OEM brake system will walk all over the Rotora kit. Out of all the driving one might do, there is maybe 2% of situations that the Rotora can outperform it. I've been to the track, I've put my dad car up in the rear view mirror of some nice machines with the stockers.

I am not trying to dump on Rotora. They are a brake manufacturer. People want brakes. They make them. People buy them. The marketing is what it is. Most of their customers will never use the product to it's limits, they buy them as jewelry behind the wheels. Personally I don't think that's worth over $3k. I figured I could deliver something that is an actual upgrade for less. I figured Volvo people don't want safety compromises.

It turned out to be waaaay more work and time to do this than I ever thought! But hey I had fun and learned a ton. I was committed to doing this whether there is any commercial potential or not. I just wanted to do it. And I did it. I built a front brake upgrade that truly upgrades over the OEM system, and will put any off-brand brake kit on the trailer. But now stuff is getting real! There is more work to do: sorting out the coatings and cosmetics, finishing the heat shield, and getting production parts in. And some other stuff probably, there is always more to do ha. You can see the development parts I have been running on the car, excuse the appearance it's not production parts…

Tire Wheel Vehicle Automotive tire Motor vehicle
The features:
  • Fit behind ET42 19" stock wheels, sorry CC wheels there is no room;-(
  • Matches the torque output of the OEM front brakes to maintain all performance and safety brake functions
  • Better brake feel, firmer pedal, all the subjective stuff
  • Better heat capacity than OEM brakes
  • Saves weight (~25lbs) where possible (but no "lightweight" downgrades)
  • Replacement heat shield to protect critical parts while opening up air flow for cooling
  • Production based 4-piston caliper, long service intervals like OEM
  • Caliper bracket has high safety factor and fatigue life, FEA tested design, similar strength to OEM iron bracket, because Volvo, we don't compromise safety
  • All easy to find service parts, pads are super common made by most every pad brand
  • 370mm (14.6") two-piece rotor, all the trimmings floating, aerospace aluminum ;-), hard anodized and GEOMET coated for year round usage. Made by a proven mfr, these guys are awesome they have been super helpful to me.
  • Stainless DOT hoses of course, made to preserve OEM functions, fitment and mounting.
  • I'm working out the remaining coatings, this will be year round, slush and salt durability.
  • OEM expectations for inspections and service intervals, no fine print in the manual "you have to check the calipers every time you drive…"
  • No off-road disclaimers, designed for street use.
Now I am at a crossroads. I'm getting the parts to make a very small run of these. For the custom parts I designed it doesn't cost much more than one-offs anyways. But I do have my doubts about if this is something people want. I could be way early as the second and third owners will want this stuff. The two-piece rotor is the biggest expense adder. I probably can't talk costs and I don't know that I am there anyways, but it's something with a 2 on the front. I tried all sorts of creative ideas to use an existing iron rotor. They are so cheap! But the fact is you just won't get a true upgrade without it. And the custom rotor was essential in the very careful work I did to make this fit the OEM package with the wheel and not need a spacer. Rather than ramble I will offer some options I didn't follow up and why I did not. I'm open to feedback, this is an opportunity for anyone that is interested in this sort of thing to maybe cause me to revisit one of these other approaches. Believe me, if there is a possibility, I have looked at it ha. These are the alternatives in order of my own thoughts on usefulness:
  • Fixed caliper on the OEM 366mm rotor from T8 XC models - would require spacers, 19" wheels. I could easily put the caliper from my current design on this with a bracket change. The 366 rotor isn't much of an upgrade in my testing, it does have a little more heat capacity though and it is cheap! Would cut the upgrade price way down.
  • Stop playing around, go baller - I have a fantastic OEM based caliper off a high-end sports car. Could put it on a big rotor, 380 but 34mm wide. Definitely need spacers. May not even fit 19s. This would be the baller option for world class street brakes on a Volvo. It might cost barely more than my "fits OEM wheels" design. I didn't think there would be the interest in a monster like that but of course I could be wrong!
  • Fixed caliper on the OEM 345mm rotor - would require wheel spacers, have yet to identify a caliper that can perfectly match the torque output but that is likely doable, would fit 18" wheels. Keep your same rotors though and much lower cost.
  • Fixed caliper on various Ford/Jaguar rotors - There are a number of rotors that mount on our hubs from Ford, Jag and Land Rover. Probably a relic from Ford ownership. Nothing spectacular and fitment issues would need to be worked out. There are always more possibilities.

Well thanks for reading! I'll take any feedback, and answer any questions you have about the technical stuff I glossed over.
 

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That's alot to digest, . But kudos to you for putting in the effort, money, time etc.. I feel the same way about the exhaust for these cars.. I really wish Volvo would consider these performance enhancement options, not only for ride quality.. But aesthetics as well. I definitely will be following your progress!

Sent from my SM-G998U using Tapatalk
 

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Anyone got the cliffnotes?
 

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Just curious, would it have been possible to retrofit the front Brembos from the P3 Polestar or SPA Polestar Engineered cars? You'd probably still need to get different wheels or use spacers, but at least it's OEM quality and from a reputable company that makes performance brakee.
 

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Wow, thank you for the time and effort you've invested thus far!

I like the current development kit you're running, especially if I can run 19's but do you have to run spacers?

Would this change in brakes affect warranty?
 

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Just curious, would it have been possible to retrofit the front Brembos from the P3 Polestar or SPA Polestar Engineered cars? You'd probably still need to get different wheels or use spacers, but at least it's OEM quality and from a reputable company that makes performance brakee.
my feeling is not because the P*2 and XC40 are on a completely different platform
 

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Awesome writeup, despite the poor balance, the Rotora's look fantastic! If you decide to keep them, you may solve the heat shield problem by using Polestar heat shields, though these calipers look smaller, so it may not be a perfect fit. FWIW, I don't run dust shields on my other car that I race and drive regularly, and it hasn't been an issue.
 

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my feeling is not because the P*2 and XC40 are on a completely different platform
P3 Polestar = the previous gen S/V60 Polestar cars, not the CMA-based Polestar (brand) cars. And even if it's a platform issue, the SPA S/V60 Polestar Engineered cars are on the same platform.
 

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Buckle in if you want to read about brake upgrades and possibly have a say in what is produced for the Volvo SPA chassis. I am aware this is a tiny percentage of even the people reading this post. That's cool because a few people could guide me in bringing the right product to market. The rest maybe you are bored and need entertainment, that's cool too ;-) This post represents over a year of work for me. So it will be long, I condensed down as much as I can. If you aren't interested, click another post you won't hurt my feelings at all. I am going to gloss over all sorts of technical stuff, otherwise this could take days, but feel free to ask any questions you have, I may even know the answer.

About 18 months ago I started thinking…gee I really like my Volvo, and I love driving it, I'd like a fixed caliper brake on this car. That would be nice looking of course and a subjective improvement. Nothing feels like fixed caliper brakes under the foot. It all started with a couple OEM calipers and trying to adapt them to the SPA chassis. That didn't work for a variety of reasons. I spent a lot of time at home in a pandemic, and it all ended up snowballing into where I am today.

The OEM brake system is pretty good, but then why do enthusiasts want to modify their cars…because better! It's a nice driving car, why shouldn't it have nice brakes? Having done a couple custom brake setups before, I knew about matching piston sizes, and mechanical leverage. I knew about heat capacity of rotors and the effects on performance. Over the last year I have learned a whole lot more.

What always bothered me about aftermarket parts is you have two sort of varieties of mfr: The established world-class players, and the off-brand competition. And none of them offers any objective proof of their product. The big players in brakes Brembo, AP, Wilwood don't share because they don't have to. The off-brands Rotora, K-Sport and a million others, they don't have any data to share. All the marketing is about "lightweight" and "forged" this and "aerospace" that. Frankly it's a bunch of crap. So when I started trying a few track nights with my S60, I installed a thermocouple to my rotor. Then I installed one on my caliper. I collected data on the OEM brake system, how it performs, what are the limits. I read research papers and masters theses' on brake systems. Somehow I ended up with a pile of calipers and an SPA suspension upright in my basement.

So there are already kits out there, very few though. I looked at the Rotora, a fine gentleman here provided me with all of the specs and measurements from his kit since Rotora doesn't publish anything. And I found a whole lot of problems with it:
  • On the edge of too much torque added up front through leverage, this means not very compatible with the complex Mk100 ABS controls in the SPA chassis.
  • The 380 rotor has less heat capacity than the OEM rotor
  • The 355 option has way less heat capacity than OEM, really should not be offered
  • The rear kit is needed to bring brake bias (the front rear balance) into line
  • BUT the rear kit has so much more leverage than the OEM brakes it will really mess with the ABS programming, it's a safety issue
  • Splash shield must be removed, which subjects the lower ball joint, tie-rod end and the ABS sensor directly to heat from the rotor and no solution provided
  • Requires wheel spacers, potentially pretty big ones
  • Typical limited availability of service parts
  • Questionable coatings and treatments for long term durability
  • They seem to be sold for "off-road" use only in fine print
  • There is more but the remaining issues are debatable

Let me not belabor the point, the OEM brake system will walk all over the Rotora kit. Out of all the driving one might do, there is maybe 2% of situations that the Rotora can outperform it. I've been to the track, I've put my dad car up in the rear view mirror of some nice machines with the stockers.

I am not trying to dump on Rotora. They are a brake manufacturer. People want brakes. They make them. People buy them. The marketing is what it is. Most of their customers will never use the product to it's limits, they buy them as jewelry behind the wheels. Personally I don't think that's worth over $3k. I figured I could deliver something that is an actual upgrade for less. I figured Volvo people don't want safety compromises.

It turned out to be waaaay more work and time to do this than I ever thought! But hey I had fun and learned a ton. I was committed to doing this whether there is any commercial potential or not. I just wanted to do it. And I did it. I built a front brake upgrade that truly upgrades over the OEM system, and will put any off-brand brake kit on the trailer. But now stuff is getting real! There is more work to do: sorting out the coatings and cosmetics, finishing the heat shield, and getting production parts in. And some other stuff probably, there is always more to do ha. You can see the development parts I have been running on the car, excuse the appearance it's not production parts…

View attachment 128083
The features:
  • Fit behind ET42 19" stock wheels, sorry CC wheels there is no room;-(
  • Matches the torque output of the OEM front brakes to maintain all performance and safety brake functions
  • Better brake feel, firmer pedal, all the subjective stuff
  • Better heat capacity than OEM brakes
  • Saves weight (~25lbs) where possible (but no "lightweight" downgrades)
  • Replacement heat shield to protect critical parts while opening up air flow for cooling
  • Production based 4-piston caliper, long service intervals like OEM
  • Caliper bracket has high safety factor and fatigue life, FEA tested design, similar strength to OEM iron bracket, because Volvo, we don't compromise safety
  • All easy to find service parts, pads are super common made by most every pad brand
  • 370mm (14.6") two-piece rotor, all the trimmings floating, aerospace aluminum ;-), hard anodized and GEOMET coated for year round usage. Made by a proven mfr, these guys are awesome they have been super helpful to me.
  • Stainless DOT hoses of course, made to preserve OEM functions, fitment and mounting.
  • I'm working out the remaining coatings, this will be year round, slush and salt durability.
  • OEM expectations for inspections and service intervals, no fine print in the manual "you have to check the calipers every time you drive…"
  • No off-road disclaimers, designed for street use.
Now I am at a crossroads. I'm getting the parts to make a very small run of these. For the custom parts I designed it doesn't cost much more than one-offs anyways. But I do have my doubts about if this is something people want. I could be way early as the second and third owners will want this stuff. The two-piece rotor is the biggest expense adder. I probably can't talk costs and I don't know that I am there anyways, but it's something with a 2 on the front. I tried all sorts of creative ideas to use an existing iron rotor. They are so cheap! But the fact is you just won't get a true upgrade without it. And the custom rotor was essential in the very careful work I did to make this fit the OEM package with the wheel and not need a spacer. Rather than ramble I will offer some options I didn't follow up and why I did not. I'm open to feedback, this is an opportunity for anyone that is interested in this sort of thing to maybe cause me to revisit one of these other approaches. Believe me, if there is a possibility, I have looked at it ha. These are the alternatives in order of my own thoughts on usefulness:
  • Fixed caliper on the OEM 366mm rotor from T8 XC models - would require spacers, 19" wheels. I could easily put the caliper from my current design on this with a bracket change. The 366 rotor isn't much of an upgrade in my testing, it does have a little more heat capacity though and it is cheap! Would cut the upgrade price way down.
  • Stop playing around, go baller - I have a fantastic OEM based caliper off a high-end sports car. Could put it on a big rotor, 380 but 34mm wide. Definitely need spacers. May not even fit 19s. This would be the baller option for world class street brakes on a Volvo. It might cost barely more than my "fits OEM wheels" design. I didn't think there would be the interest in a monster like that but of course I could be wrong!
  • Fixed caliper on the OEM 345mm rotor - would require wheel spacers, have yet to identify a caliper that can perfectly match the torque output but that is likely doable, would fit 18" wheels. Keep your same rotors though and much lower cost.
  • Fixed caliper on various Ford/Jaguar rotors - There are a number of rotors that mount on our hubs from Ford, Jag and Land Rover. Probably a relic from Ford ownership. Nothing spectacular and fitment issues would need to be worked out. There are always more possibilities.

Well thanks for reading! I'll take any feedback, and answer any questions you have about the technical stuff I glossed over.

Hi. I like your approach. Here are some questions and feedback.

  • How do you determine brake torque, and in relation to what? Have you measured it with a dyno or what kind of data have you got?
  • How have you determined heat capacity? Is it calculated based on weight and thermal capacity? Or have you done any further FE/numerical analysis? I presume you already understand there is a difference in what these numbers mean between solid and floating rotors because of a couple of reasons. One is the hub and the upright contribute to a higher capacity for solid rotors compared to floating (because of better heat transfer).
  • Again regarding heat capacity and in continuation to above question, have you used the same temperature target when calculating heat capacity for both type of rotors? And what temperature deltas have you looked at? (because since floating rotors can withstand higher temperature delta, they have a higher "heat capacity" because of that for same mass and "thermal capacity")

Personally I firmly believe going fixed calipers with solid rotors is more for show than go because of the vibration/performance/stress problems this configuration might bring when running hard, but just as seems to be the case with Rotora, most potetional brake upgrade customers dont upgrade their brakes to run flat out track pace but rather as a styling upgrade. So in terms of target group and potential customers for your solution, if you plan on offering such, solid rotors might actually be the smartest choice. The most important thing is to choose a caliper with good availability of high quality performance brake pads that fit "premium quality" rotors from renowned third party OE suppliers. Otherwise it is just not worth it over the available genuine volvo polestar brake kit.
 

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Would this transfer over to the XC90 T8 with minimal modification as well? I agree that the floating rotor would still be the best option. I would be interested as the T8s Brakes with regen are powerful but not performance and it is one heavy vehicle.
 

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Discussion Starter · #12 · (Edited)
Thanks for the feedback, even though I am doing this for me, to do it, and I am totally fine with whatever comes of it. I'm putting something out there and it's my baby ha so some of my ego is wrapped up in it. Just part of being a humanoid.

All great questions, I'm a take them one by one so scroll down for your reply ;-)

But kudos to you for putting in the effort, money, time etc.. I feel the same way about the exhaust for these cars.. I really wish Volvo would consider these performance enhancement options, not only for ride quality.. But aesthetics as well. I definitely will be following your progress!
Me too. It's easy to get ahead of myself, but one of the paths I envisioned in figuring out the sourcing, designing and mfr side of this, is perhaps I can make some of these dreams come true. An exhaust that integrates with the OEM flapper valve, and all the other things we might want, that is def something I have thought about...

Anyone got the cliffnotes?
Me want brakey faster. Big brakies no brake good? Me build better brakies.

Just curious, would it have been possible to retrofit the front Brembos from the P3 Polestar or SPA Polestar Engineered cars? You'd probably still need to get different wheels or use spacers, but at least it's OEM quality and from a reputable company that makes performance brake.
This is a possibility I looked at, as why bother when there are OEM parts? So there were the few issues with that avenue: The OEM parts have been about $4k. There would be caliper clearance issues, which Volvo solves with the wheels, but would be spacers to swap them on. And lastly, while the calipers are a hydraulic match (only recently I finally got the info on that), they do not match the existing lesser brake systems on this setup, to maintain the compatibility. That would seem not right since they are OEM on the Volvo...but Volvo engineers don't have our limitations, they control the software programming for the ABS, so they can adjust for a different brake setup. We have to take a different strategy when we are changing the calipers without the software. BTW the P3 chassis and earlier stuff not that different, the hub offset for the brakes changed, but not too much other than that.

Wow, thank you for the time and effort you've invested thus far! I like the current development kit you're running, especially if I can run 19's but do you have to run spacers? Would this change in brakes affect warranty?
Don't you read!! Just kidding!! NO spacers, and let me tell you that was a trick and half to do. Warranty...well that is always the thing with mods, there is much said on that, would be a concern but it's up to the individual how much they care about that.

Curious why you went this route instead of throwing a set of oem polestar edition brakes on?
Similar question to above, cost, doesn't fit the wheels without spacers and doesn't match the existing brakes for compatibility with the ABS functions. I do also prefer a 4 piston caliper.

Awesome writeup, despite the poor balance, the Rotora's look fantastic! If you decide to keep them, you may solve the heat shield problem by using Polestar heat shields, though these calipers look smaller, so it may not be a perfect fit. FWIW, I don't run dust shields on my other car that I race and drive regularly, and it hasn't been an issue.
Yeah they do look pretty good, and a zillion different colors and all that. But I do have a bit of a chip on my shoulder for the cost for something that is just sort of slapped together like that. I have seen that the Polestar does have different dust shields. I haven't tried them though, they likely won't fit as making the package work required me to set the rotor back a bit which is what interferes with the OEM dust shield. Removing the dust shield has benefits though, from my testing I've found that at lower temps and speeds, i.e. real world use of street brakes...radiation is a bigger factor than convection cooling, opening up that space has a benefit, while then shielding the sensitive parts from the radiation is the best of both worlds. I have definitely anticipated feedback similar to what you say about running without heat shields. It probably does depend on the car. On the SPA chassis the lower ball joint is very close to the rotor and so is the wheel speed sensor and harness, the tie-rod end less so. The temps they could be subjected to without a shield is above the range for the grease used in these joints. To know if that matters, would be a massive undertaking in failure analysis, i.e. not going to happen. So my philosophy on it is duplicate the OEM function and remove it as a factor.

Since you pointed out the caliper is smaller, yes it is, it's a 4 piston and that is intentional. A 4 piston, given the same design, will always be stiffer than a 6 piston. There is too much made of piston count. Using a 4-piston production based caliper, that is monoblock with a brace over the "window" it's a stiff design given the constraints of OEM cost control. As well the pad is classic d1001 used in tons of Brembos, and the annulus (depth) is bigger than the typical 6 piston and the aftermarket stuff, so I get more swept area over the Polestar, Rotora, and many other brake kits. That allows a rotor with longer cooling vanes and more surface area, all around good stuff for street car performance where we don't want to run a rotor to 1200deg.

Hi. I like your approach. Here are some questions and feedback.

  • How do you determine brake torque, and in relation to what? Have you measured it with a dyno or what kind of data have you got?
  • How have you determined heat capacity? Is it calculated based on weight and thermal capacity? Or have you done any further FE/numerical analysis? I presume you already understand there is a difference in what these numbers mean between solid and floating rotors because of a couple of reasons. One is the hub and the upright contribute to a higher capacity for solid rotors compared to floating (because of better heat transfer).
  • Again regarding heat capacity and in continuation to above question, have you used the same temperature target when calculating heat capacity for both type of rotors? And what temperature deltas have you looked at? (because since floating rotors can withstand higher temperature delta, they have a higher "heat capacity" because of that for same mass and "thermal capacity")

Personally I firmly believe going fixed calipers with solid rotors is more for show than go because of the vibration/performance/stress problems this configuration might bring when running hard, but just as seems to be the case with Rotora, most protentional brake upgrade customers dont upgrade their brakes to run flat out track pace but rather as a styling upgrade. So in terms of target group and potential customers for your solution, if you plan on offering such, solid rotors might actually be the smartest choice. The most important thing is to choose a caliper with good availability of high quality performance brake pads that fit "premium quality" rotors from renowned third party OE suppliers. Otherwise it is just not worth it over the available genuine volvo polestar brake kit.
That is a lot! Now we are getting technical ;-) Gonna try my best here, you are asking some big one!

Brake torque is in relation to the input pressure. The ABS wizardry is all dependent on the input pressure putting out an expected brake torque result at each wheel. It's called the Pt or "pressure-torque relationship" in some industry circles. StopTech has really been the leader in this design philosophy, which has become critical as ABS became stability control and now we have dozens of systems from brake force distribution, torque vectoring, cornering brake control, there are dozens of functions that rely on this and the old school brake mfrs have not all caught up. The goal may be to fit a bigger rotor or different caliper, but preserve that relationship. Most people only get as far as the piston sizes on this. But they forget the leverage of the larger rotor. And if they get that far, they don't realize the effect of pad depth (how tall is the pad) as those all play into the "effective radius" which is, how much leverage you have mechanically, which must be paired with the hydraulic leverage of the caliper, to match Pt of the OEM system. Since this is all static components of the system, we can do math on it. To make it simpler for others to do this math, I have created a calculator to make it easy, you can check it out! Upgrade Advisor - it defaults to the specs of my design but you can use it to evaluate any upgrade.

Heat capacity is thermal capacity yes, simple mass of grey iron and putting kinetic energy into it. Again these are static attributes, the weight of the rotor. And you are correct one-piece vs two-piece rotors is not a clear comparison. Many two-piece rotors are touted for their "light weight" but how much is due to the weight savings of the hat, vs removing heat capacity? Well that just remains a mystery because the mfr doesn't talk about it. So I took this on myself. Since density of grey cast iron is known, I took the Volvo rotor and estimated the weight of the "hat" portion via dimensions. It's about 4lbs. The rotor weighs 26 lbs. So the friction ring, the "functional heat capacity" is what I call it, is 22lbs. This allows us to then compare the weights with two-piece. My rotor design is 24lbs, with a 1lb alloy hat. 23lbs of functional heat capacity. It's a slight upgrade. A typical rotor, say the 380 Rotora is 20lbs. We assume a 1lb hat, you have a 19lb functional heat capacity. That's a downgrade. A single stop from 60/80/100mph that rotor will heat up beyond the OEM rotor. It's somewhat typical though. There is a whole other discussion of the far superior convection cooling, which may or may not make up for the loss of capacity. Maybe on the track but not on the street. A two-piece that saves more than 4-5 lbs is removing heat capacity. More rotor mass and superior convection cooling, I have found works awesome it resists heating up, but returns to ambient many times faster than the OEM rotor. To put this philosophy into action, I created a calculator for this as well to recommend a rotor mass for a car given HP and weight. LOTS of assumptions of course but useful I think: Rotor Advisor. I do not think that the hub contributes much to heat capacity, the link to the hat portion on an iron rotor is a small cross section, iron doesn't actually flow heat all that well (most goes into the plates and vanes), and once in the hub other than reducing wheel bearing life there is not far for the heat to go. Research I have read suggests this is true, much of the deformity of the one-piece rotor in extreme usage is due to the delta of the friction surface temp to the hub.

I have compared the performance of course! I'll post a graph below where I have sync'd up two similar sessions AND what happens after with stock and my kit. No cool down laps are given at Track Night, I always run the same cooling lap of the paddock and then park the car. While I did not design this as a track kit, it shows an objective decrease in running temp and importantly the upgrade rotor shed heat after the session so much quicker. This is more important for street use, a hard stop or two can put you up over 500 deg, and the recovery time at slow speed would be important there. I would not agree that "floating rotors can withstand a higher temp delta", well that's technically correct, but in practical, real world use I don't think it becomes relevant for our purposes, the OEM Volvo rotor has stood up to more than a few 1000deg cycles with no apparent permanent deformity, i.e. still smooth as silk in daily driving. BUT at those temps, even the best street/track pads get to their limits, for the Porterfield R4-S it starts to grind the rotors hard over 900F and I can't keep from boiling RBF600 race fluid. On a race car, we solve this by race pads, steel pistons, remove dust boots, Castrol super-expensive fluid, brake ducting etc. But we can't manage it that way in a street car, we need to keep the temps down. More heat capacity (or at least not a loss) and superior cooling is how we can improve performance.

I talked about the caliper above, agreed, using a production based caliper, with easy parts availability was a key for me. The pads are the same as the old Volvo R Brembo, WRX STI, about a million other cars so easy to source from $6 pads to whatever you like ;-)

You get to the heart though, if looks is more the driver, then putting this on the 366 rotor is better solution. But some people consider the two-piece rotors part of the looks too!

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Would this transfer over to the XC90 T8 with minimal modification as well? I agree that the floating rotor would still be the best option. I would be interested as the T8s Brakes with regen are powerful but not performance and it is one heavy vehicle.
Yes sir! The SPA is pretty standard, all the brake mounting is the same. There are some variances in hoses and brackets, but I am accounting for those or can deal with them as we go. It has been a consideration from the start, that if I do this I am creating something that can be used across all the SPA platform vehicles.
 

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Don't you read!! Just kidding!! NO spacers, and let me tell you that was a trick and half to do. Warranty...well that is always the thing with mods, there is much said on that, would be a concern but it's up to the individual how much they care about that.
Sorry buddy, don't know how I missed that part "Fit behind ET42 19" stock wheels" . Curious to know what caliper you used.
 

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Discussion Starter · #14 ·
Sorry buddy, don't know how I missed that part "Fit behind ET42 19" stock wheels" . Curious to know what caliper you used.
Just messing with you anyways. I expected questions on the caliper...I'm not being dodgy, I am using a well known brand of caliper from another OEM application, I may have even mentioned them ;-) But due to their litigious history with others "trading on their name" that is why I don't mention it.

I have developed a modified hardware to allow the caliper to fit correctly on the rotor and use a super common pad. Other wise it's an OEM caliper. I can get it readily new or used cores and build with new parts. Since they have to be refinished (and the factory paint finishes are not very good anyways), I can do either. I'm considering that option as I go. One of the last things to do is work with coaters to come up with something more durable than what is typical. And shiny of course!
 

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Very nice.

Love the temperature plot. Is that rotor surface temperature via IR sensor? What sort of data acq box do you use?

Embrace your inner nerd, I always say.
 

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Discussion Starter · #16 ·
Love the temperature plot. Is that rotor surface temperature via IR sensor? What sort of data acq box do you use?

Embrace your inner nerd, I always say.
Thanks! It's real simple (i.e. cheap) I have a spring loaded thermocouple mounted to the inside face of the rotor, near the outside edge, to capture max temp right after the rotor comes through the caliper and pads. It's noisy as you may imagine metal on metal to be, so I only set it against the rotor when testing, otherwise its pulled back from the rotor for daily driving! Data logging is just a simple lab grade 4 channel thermocouple logger. I run TrackAddict with Bluetooth OBD dongle and capture dashcam video at the track, so I can sync up all the sources within RaceRender.

IR would be nice, faster sample rate and sense multiple points, but much more costly for data acq equipment.
 

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Discussion Starter · #17 ·
Thanks for the feedback so far all. It has given me plenty to think about. The first phase of this was doing something for myself but now since I have all the work into it, I'd like to make something for the Volvo enthusiasts. So keep your feedback coming no matter how crazy it is ha.
 

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I was wondering to myself prior to seeing this thread if any of the Ford Focus Brembos may in fact be a bolt-on option? I think there are some similar hub dimensions, but not 100%.

I've also noticed looking at wheels that Neuspeed RSE102's come in a Ford/Volvo specific spec (5x108 63.4 hub bore). These are a great wheel if you need additional clearance and want to save a lot of weight--and, if (like me) you're afraid of hub rings.

I'm mostly interested in this thread though because I'm looking to score a set of stock 345mm calipers/brackets/dust shields. I have a slightly used V60 T-5 Momentum on the way, which I'm pretty sure will have the 322 front rotors. As soon as guys with the stock 345's start upgrading that should make a cheaper upgrade path for those T-T FWD owners!
 

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Discussion Starter · #19 ·
The Focus Brembos...small car small brakes! It's a 350mm rotor, 25mm wide, very thin light rotor for our heavy cars. The Focus does share the 5x108 and the center 63.5mm is essentially the same as Volvo.
 

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The Focus Brembos...small car small brakes! It's a 350mm rotor, 25mm wide, very thin light rotor for our heavy cars. The Focus does share the 5x108 and the center 63.5mm is essentially the same as Volvo.
bigger than the 320's that come with my T5 FWD!

If you find yourself getting rid of your 345's at some point, let me know. I think for FWD owners, this is probably the best upgrade path.

FWIW, the 340/30mm rotors on my Golf R saw some pretty hard use, and with good pads it was always more than enough--the tires were always the limiting factory. If the Focus Brembos fit I bet they've be a good option--but somehow I'm betting that the spacing will be off.
 
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