Why Not K-Sport Big Brakes?

[Takumi788]

Originally Posted by wparsons

He wants beefy 8 piston calipers and a flashy color, nothing else.

Huh, maybe I messed up my brake threads. I could have swore that comment was in this thread tho.

[wparsons]

Originally Posted by SubyRS1

I am searching for a big brake set up for my FRS-One.
All I see here on 86 Club are negative comments on K-Sport brakes.
I was all set to order some K-Sport 8-pot front (13") and 4-pot rear (13") set ups in orange, drilled with street pads, but wanted to research further before pushing the button.
First, I want BBK's for "bling" purposes only and my car will never see more than the occasional JR supercharged stop light to stop light sprint on Sunday morning coffee runs to Javatinis : ) My FRS is not a daily driver or commuter car. It's a fun car that replaces riding a motorcycle (for now). It has 5K miles since new in 2015.

Originally Posted by Takumi788

Huh, maybe I messed up my brake threads. I could have swore that comment was in this thread tho.

Someone else may have chimed in looking for more performance usage, but the OP definitely just wants the bling.

[TRS]

Late answer, but maybe I can report some more 1st hand feedback from the german forum without guesswork. I'm still concerned that my decission might have been wrong, but I also decided to order a set K Sport brakes vor my V8 swap. No dedicated racecar, but still meant to expierience some pretty spirited driving, drift events and a few track days.

After reading through miles of reports I was speaking about that with some guys in the German forum which use D2/K Sport BBK and visit track days pretty often. The concense of them is, that the BBK is for sure not the upper end race product, but still not a bad choice as long as you know about some downsides an how to get arround them.

All of them confirmed that the k sport provided pads are crap. They make the kit looking pretty bad. But this changes when using a reasonable pad like Pagid or Ferrodo. The discs are not the best design in matters of weight to size and cooling capacity, but they hold up. For sure, some higher priced BBKs can take a similar punshment with a smaler and light er disc. But as I said, they are not high end. Thats clear.

Most of them are meanwhile running on the 3rd and up rotor set and 6th set of pads. Many different pads were used, but besides the k sport oem pads All of them perfomrmed reasonable with the rotor and caliper. Non of the guys in the German forum reported issues with leaking calipers. The only real quality issue which was complained about is, that the steel brake lines have corrosion issues when used during salty German winter.

Whats absolutely true, the brake bias is front shifted when only the front kit is used. But this is acceptabel in my book since I anyway plan to get a rear kit also. A further pro in my case is, that getting an approval for AP racing or Wilwood, or, or... can be very difficult to impossible in Germany. Sounds wiered, isnt it? K sport is one of the very few manufacturers providing documents for the German TÜV approval. This for sure is no proof for high quality (unfortunately) but a necessity for German road use (unfortunately).

In matters of engineering, the argument of the monoblock caliper is no killer argument in my book since Im sure a two piece caliper can be as strong or even stronger if it is well designed. A 10mm steel bolt can be stronger then 15 by 30mm solid aluminium. Anyway, there is no proof that the K sport calipers fail to take the necessary force to compress the rotor to a full stop even with sticky tires without (reasonable) deformation. At least I didn't find any reports about that.

The design of the rotors isnt optimal. They could be lighter while providing more vanes, meaning more cooling surface. I make the conclusion, that this is the core point why other BBK are able to take more punishment (or heat) while beeing lighter and smaler. But there is one guy in the German forum who already requested company Tarox to manufacture rotors to his specifications, meaning rotors, which will match the k sport bbk. This means, also the rotors for this BBK can be upgraded.

The rotors are two piece and, if ordered, floating. So this Design feature is fine in my book.

Not optimal is the design of the brake pistons. A big downside is, that the rear brakes are not sealed with a rectangular ring but with a simple o ring, what means that the pull back of the pads after braking is missing and therefore they keep touching the rotor.
While there are brakes which have additional springs behind the pistons to make them slightly touch the rotor all the time to have maximum bite and constant pressure point under race use. But for road use this "Feature" truely can be a "Bug".
Another point is that alluminum pistons are the only available option. I would prefer a vented and/or stainless steel piston. Titanium would be overkill for my case, but also something one could offer. But Im already thinking about crafting my own vented stainless steel pistons once I have the BBK in hands.

At the same time, those rear calipers are one point which made me go with this kit, since they offer a Option for dual fuel rear calipers, what makes a additional hydraulic flyoff possible on a german road legal car. The mandatory mechanical parking brake stays functional and also the ABS and VSC system keeps untouched since the Flyoff is working in separates fluid circuit.

Last but not least, the k sport brakes was teste by a big German sports car magazin. They tested K-sport, Brembo, StopTech, AP racing and some more. I believe 6 overall. While K-sport was on the second last place, they achieved the second best stopping distances for all situations. (cold, warm, hot for 100-0, 200-0, and 250-0) The argument which was given for the still pretty bad rating was that the rotor was not running balanced and the price to performance was bad. I understand the first point, but when not going through a test, having one physical set available, I would call the seller and make them send a replacement. As well, I had more than one rotor from more than one manufacturer running out of balance right out the box. The second point concerning price to performance is hard to understand when second best results was achieved.
In this test Brembo (as a well known and popular Brand) was far of with a much higher priced BBK since the stopping distances were in some tests about 10% longer then the best result. Im not absolutely sure, but if I remember correctly, the k sport was always less than1% away from the best result.
Shortest stopping distance was achieved by StopTech and AP racing (in different tests). Stoptech won this comparrison, but it was also stated that in the former tests stoptech was always one of the worst BBKs, what kind of reflects a former post in this thread. What also should be mentioned, that the K-sport was running with Pagid pads in this test.

Well, what makes the difference on a BBK?

-1 (up and above everything) the pad
-2 design of the rotor
-3 material of the rotor in matters of stability and compatibility with (a good) pad
-4 a rigid caliper design
-5 heat reduction features like vented pistons

Those are the functional aspects I would say. Of course, the system size and weight is very important but hard to place in this row. In an Ideal world, each point would be perfect. But unfortunately this will not happen as with most things.

Ok, let me summarize what I expect from this BBK:

-1 OK, since I ordered my kit with DS2500 pads
-2&3 not optimal, but acceptabel from what I know from first hand reports and anyway there is the option to upgrade by using custom Tarox discs (BTW I was told the added price is 125bucks for the first set of rotors, after that the price is identical to a standard Tarox rotor)
-4 should be OK from I know for now. Maybe the rotor is a little heavy compared to others. But I dont have knowledge jet if the higher weight compared to the competitiors is caused by the caliper, the rotor or both of them.
-5 NOK. Not optimal at all. But functional and as I said, I expect that I should be able to craft some on my own. For sure not an option for each customer. As well for sure not necessary for each one.

Since Im personally not searching for the last 10th of second on the track and my build is primary for road and drift use, I can life with the higher weight. Otherwise I would not carry a sound system in my car. But still I want my biuld beeing able to take the stress of some spirited laps on a race track. Maybe not endurance like, but in the duration of a sprint race would be fine. If I lose some 10th of second per round because the brake is 3 or 4kg heavier then it could be, I could live with that. Even if unlikely, I have the hope that with a later change to Tarox rotors even this issue could be reduced a little. But thats realy just guesswork.

But as I said, Im still waiting on delivery. Do to the pandemic since more then 10 month now. But I hope it will be delivered soon and I will definately report here once I have road and track tested this brake.

[vagthomas]

Originally Posted by TRS

Late answer, but maybe I can report some more 1st hand feedback from the german forum without guesswork. I'm still concerned that my decission might have been wrong, but I also decided to order a set K Sport brakes vor my V8 swap. No dedicated racecar, but still meant to expierience some pretty spirited driving, drift events and a few track days.

After reading through miles of reports I was speaking about that with some guys in the German forum which use D2/K Sport BBK and visit track days pretty often. The concense of them is, that the BBK is for sure not the upper end race product, but still not a bad choice as long as you know about some downsides an how to get arround them.

All of them confirmed that the k sport provided pads are crap. They make the kit looking pretty bad. But this changes when using a reasonable pad like Pagid or Ferrodo. The discs are not the best design in matters of weight to size and cooling capacity, but they hold up. For sure, some higher priced BBKs can take a similar punshment with a smaler and light er disc. But as I said, they are not high end. Thats clear.

Most of them are meanwhile running on the 3rd and up rotor set and 6th set of pads. Many different pads were used, but besides the k sport oem pads All of them perfomrmed reasonable with the rotor and caliper. Non of the guys in the German forum reported issues with leaking calipers. The only real quality issue which was complained about is, that the steel brake lines have corrosion issues when used during salty German winter.

Whats absolutely true, the brake bias is front shifted when only the front kit is used. But this is acceptabel in my book since I anyway plan to get a rear kit also. A further pro in my case is, that getting an approval for AP racing or Wilwood, or, or... can be very difficult to impossible in Germany. Sounds wiered, isnt it? K sport is one of the very few manufacturers providing documents for the German TÜV approval. This for sure is no proof for high quality (unfortunately) but a necessity for German road use (unfortunately).

In matters of engineering, the argument of the monoblock caliper is no killer argument in my book since Im sure a two piece caliper can be as strong or even stronger if it is well designed. A 10mm steel bolt can be stronger then 15 by 30mm solid aluminium. Anyway, there is no proof that the K sport calipers fail to take the necessary force to compress the rotor to a full stop even with sticky tires without (reasonable) deformation. At least I didn't find any reports about that.

The design of the rotors isnt optimal. They could be lighter while providing more vanes, meaning more cooling surface. I make the conclusion, that this is the core point why other BBK are able to take more punishment (or heat) while beeing lighter and smaler. But there is one guy in the German forum who already requested company Tarox to manufacture rotors to his specifications, meaning rotors, which will match the k sport bbk. This means, also the rotors for this BBK can be upgraded.

The rotors are two piece and, if ordered, floating. So this Design feature is fine in my book.

Not optimal is the design of the brake pistons. A big downside is, that the rear brakes are not sealed with a rectangular ring but with a simple o ring, what means that the pull back of the pads after braking is missing and therefore they keep touching the rotor.
While there are brakes which have additional springs behind the pistons to make them slightly touch the rotor all the time to have maximum bite and constant pressure point under race use. But for road use this "Feature" truely can be a "Bug".
Another point is that alluminum pistons are the only available option. I would prefer a vented and/or stainless steel piston. Titanium would be overkill for my case, but also something one could offer. But Im already thinking about crafting my own vented stainless steel pistons once I have the BBK in hands.

At the same time, those rear calipers are one point which made me go with this kit, since they offer a Option for dual fuel rear calipers, what makes a additional hydraulic flyoff possible on a german road legal car. The mandatory mechanical parking brake stays functional and also the ABS and VSC system keeps untouched since the Flyoff is working in separates fluid circuit.

Last but not least, the k sport brakes was teste by a big German sports car magazin. They tested K-sport, Brembo, StopTech, AP racing and some more. I believe 6 overall. While K-sport was on the second last place, they achieved the second best stopping distances for all situations. (cold, warm, hot for 100-0, 200-0, and 250-0) The argument which was given for the still pretty bad rating was that the rotor was not running balanced and the price to performance was bad. I understand the first point, but when not going through a test, having one physical set available, I would call the seller and make them send a replacement. As well, I had more than one rotor from more than one manufacturer running out of balance right out the box. The second point concerning price to performance is hard to understand when second best results was achieved.
In this test Brembo (as a well known and popular Brand) was far of with a much higher priced BBK since the stopping distances were in some tests about 10% longer then the best result. Im not absolutely sure, but if I remember correctly, the k sport was always less than1% away from the best result.
Shortest stopping distance was achieved by StopTech and AP racing (in different tests). Stoptech won this comparrison, but it was also stated that in the former tests stoptech was always one of the worst BBKs, what kind of reflects a former post in this thread. What also should be mentioned, that the K-sport was running with Pagid pads in this test.

Well, what makes the difference on a BBK?

-1 (up and above everything) the pad
-2 design of the rotor
-3 material of the rotor in matters of stability and compatibility with (a good) pad
-4 a rigid caliper design
-5 heat reduction features like vented pistons

Those are the functional aspects I would say. Of course, the system size and weight is very important but hard to place in this row. In an Ideal world, each point would be perfect. But unfortunately this will not happen as with most things.

Ok, let me summarize what I expect from this BBK:

-1 OK, since I ordered my kit with DS2500 pads
-2&3 not optimal, but acceptabel from what I know from first hand reports and anyway there is the option to upgrade by using custom Tarox discs (BTW I was told the added price is 125bucks for the first set of rotors, after that the price is identical to a standard Tarox rotor)
-4 should be OK from I know for now. Maybe the rotor is a little heavy compared to others. But I dont have knowledge jet if the higher weight compared to the competitiors is caused by the caliper, the rotor or both of them.
-5 NOK. Not optimal at all. But functional and as I said, I expect that I should be able to craft some on my own. For sure not an option for each customer. As well for sure not necessary for each one.

Since Im personally not searching for the last 10th of second on the track and my build is primary for road and drift use, I can life with the higher weight. Otherwise I would not carry a sound system in my car. But still I want my biuld beeing able to take the stress of some spirited laps on a race track. Maybe not endurance like, but in the duration of a sprint race would be fine. If I lose some 10th of second per round because the brake is 3 or 4kg heavier then it could be, I could live with that. Even if unlikely, I have the hope that with a later change to Tarox rotors even this issue could be reduced a little. But thats realy just guesswork.

But as I said, Im still waiting on delivery. Do to the pandemic since more then 10 month now. But I hope it will be delivered soon and I will definately report here once I have road and track tested this brake.

Mind be asking for any feedback after 1 year of use?

[TRS]

I wasnt on any track days the last year and also had only very few miles on the car, but what I can say for now:

Pro:
-the brake definately performs much better then stock what I was able to expierience on the Autobahn during multiple 70-140mph Sprints with hard braking back to arround 70. The bite is impressive and there was no fading in around 15 to 20min driving like that. (to be noted: car is LS3 swapped, so reaching the 140mph doesnt take the time required to drink good cup of coffee)
-no vibration (as some other users reported)
-no signs of wear I wouldnt expect until today
-reasonable quality of the components.

Cons:
-definately buy a complete system (front and rear), the effective brake torque is not matching the factory value, what means a front only install will change the brake ratio excessively to the front. In my case (356mm 6pod front, stock rear) this causes also failures in the ABS System, since the control limits are exceeded. The car still brakes well thanks to the intervention of the ABS system, but the heat load on the rear disc is to low compared to the front and as stated, warning lights for the ABS system start to flash. (Im not talking about the yellow ABS/VSC notification, its lighting the red symbol for the E brake, indicating a brake system malfunction)

As side note, while doing a pretty good job, the Ferrodo DS pads throw a pretty disgusting brown dust all over the place. This also is pretty noticable under casual driving and gets extremely extenaive under heavy braking over longer periods. It pretty much looks like someone painted your entire rim and the tire sidewall as well with a dark brown spray paint. Though, the dirt can be removed relatively easy. As well, the pads dont fit the caliper exactly. A little grinding of the base plate is required.

As already said Id judge the overall quality as very acceptable. Though, I doubt that the discs and some caliper components would surfive driving in salty winter conditions without some noticable corrosion. But this is no point of intrest for me since I dont run the car in this kind of conditions.

Im currently in the process of upgrading the rear to a 356mm system also. This will exactly match the factory ratio. Since my LS swapped car is heavier in the front it will cause a slightly tail-heavy ratio, but I want to use this for a more aggressive corner entry behavior on the brake.

As well, I have to note that Im still on factory pads and disc in the rear. A similar aggressive pad as the Ferrodo I use in the front combined with a matching disc might reduce the overly front heavy ratio partialy. But I doubt that it could solve this issue completely, since the effective brake torque is higher foor the Ksport system even if identical pads front and rear are assumed.