Big brake kit time?

[VAD17 479]

On related topic

I had KSports kit now for over 1.5yrs, 10k road miles, dozen or so track days (plus carlimits, pistonheads at Silverstone and even an action day). Used ECB Yellowstuff pads, now on Bluestuff.

After replacing pads before the last track day at Brands ended up with fairly noticeable vibration under heavy braking (particularly into the Paddock Hill bend from 115+ mph). Probably have not bedded pads properly so now a bit of pad material residue on the disks that does not come off (tried couple times on the m-way to re-bed), so the disks need to be skimmed.

The disks themselves show decent amount of wear, probably more than I would expect, but then I do overbrake so for others they could last longer. This said I expect they should last at least another year, which would take them to 15+k miles and about 20 track days in total.

I had a quick look at price for new 356mm disks  - Raylands (J-hook style) would do them for £295, MTEC replacement (grooved) will be £290, KSports original disks from GSM Performance (grooved) £387.

I also don't think pads prices are materially different, I have previously confirmed that the pad size is the same as for one of AP calipers and then doing quick google compare it was not that much of a difference. I did like Yellowstuff, although the way I drive they last about 6-7 track days, but they are quiet and very good from cold, not too dusty either. I am yet to form my opinion of Bluestuff but they are certainly better when hot, ok from cold, but dustier, and I expect they would be wearing disks faster as well.

[Lauren 2259]

I've had my AP four pots on with Reyland grooved discs and DS2500 pads on for over a year and a half now. Done nearly 30K miles on them, about five or six track days, about ten sprints. The pads still have a good amount of meat on them and the discs look hardly worn. Amazing really. Feels like they'll last forever, but reckon I'll get another 10K miles out of them pretty easily. I should add though that my pads tend to last a lot longer than average as I am pretty easy on the brakes. Obviously on track I do use them to their full capacity, especially so on sprints where every hundredth of a second counts, so there's no early braking at all. On the road I brake as little as possible, which probably helps me get great mileage out of them. On stock pads and discs I would get around 37K miles out of them. 

[will300 812]

To echo @Lauren's comment, I've had my Reyland AP kit on for two and a half years now and probably done a about 10 track days since and about 25k road miles, without any concerning issues (I've had some debris scratch the disc's and hats & boiled brake fluid - but both will happen with any brake (OEM or BBK) setup). I'm still on my original AP disc's, which have lasted incredibly well, I'm sure if I ran a  more aggressive pad compound they'd get used up alot quicker. I also changed my brake pads around 9 months ago, purely to try a slightly different compound to the previous pads, Ferrodo's DS2500 as provided with the kit. The Ferrodo's still have a good amount of meat left on them and I'll be switching back to them in a couple of weeks for several upcoming track days. 

The Reyland big brake kit has been my joint best mod to the car, with the exhaust manifold being the other.

[VAD17 479]

I should probably add that I noticed substantial increase in pads wear after getting FI (TD turbo kit). My Yellowstuff has reasonably low wear initially, but then 3 track days (Castle Combe, Brands and Bedford) and couple sessions at other events and they were gone...


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[Adi 40]

@VAD17 Not just with FI, but even on NA, once your driving improves  same will happen.

Once I started  instruction, I went through pads much faster. 3-4 track days on DS2500, EBC Yellows, Stoptech Sports. (I've got the Stoptech BBK  and Velox brake ducts but otherwise completely stock power). I will try Pagid RS29 next. They are supposed to last longer and still be very good.

Or just drive slow : P 

.

[Deacon 1357]

1 hour ago, Tubbytommy said:

Oem brakes are for those who cant drive

You'll have to share your trackday videos so we can all learn then

[gavin_t 184]

On 7/5/2019 at 10:01 AM, Luke said:

That's a shame about k-sport not being in stock. Did they have a lead time for UK stock? 

I spoke with Mike at TD. By now I assume they will be back on the shelf as that was a couple of months ago

[Burtie178 3]

Sorry to hijack, has anyone on here fitted the Impreza Brembo’s to the front. Just looked like a good alternative?

Cheers

[Deacon 1357]

1 hour ago, Burtie178 said:

Sorry to hijack, has anyone on here fitted the Impreza Brembo’s to the front. Just looked like a good alternative?

Cheers

This is a good read - https://www.pointmeby.com/2016/09/24/which-big-brake-kit-bbk-should-you-get-for-the-brz-frs-gt86-86/

The issue with the Sti brakes is how much they shift the bias forwards. 

[Burtie178 3]

Thanks both and that’s an interesting read Deacon on how it upsets the brake bias, especially as I plan on having a go in the TSS 👍

[Church 209]

Bias is important enough though for anybody actually caring for actual brake performance and safety. After all, bias too off on one end of spectrum means longer braking distances due one end underbraked, and on other end of spectrum - also longer braking distances if with nannies like ABS on, and downright unsafe/unstable, if without. And i don't think that "i never track my car" may serve as excuse if one couldn't avoid accident/crash due brake "upgrade" being done with just two goals in mind - visual bling by getting painted calipers with known branding and to spend as little as possible, even if it meant actually compromise braking.

If it looks and budget that matters most, why not just paint calipers? At least one will know that braking won't be worse then. And keep ability to use stock wearables like rotors/pads, possibly also cheaper. Better brake wheel clearance, allowing to use even smaller wheels (for eg. winter). Win-win i'd say.

[Luke 193]

The sti brembo conversion sends the bias to the front by roughly 7% doesn't it. I can't imagine many drivers being able to feel that sort of change in the cars handling characteristics. Let alone have it affect braking performance in such a negative way that it makes it dangerous in a heavy braking situation on the public road.

Every big brake kit that I've seen for sale has never mentioned that it moves the bias forwards or backwards at all. Surely the load proportioning valves and the cars ABS/ EBFD systems will be able to adjust to these small bias changes. 

Otherwise no manufacturer would recommend a front big brake kit without a rear setup also?

[Luke 193]

I've done a few track days and agree the factory brakes are good for 1 or 2 hot laps before the heat fade ruins all the pedal feel. Several owners have done the sti brembo upgrade and zero have reported that they can really notice the bias change. Neither Ap racing or k sport list the bias percentage change but I reckon its a very similar case of bias will shift to the front. Can anyone confirm that they haven't crashed their car because of the bias shift? 

[Deacon 1357]

Still looking forward to seeing those videos 👍

[Deacon 1357]

3 hours ago, Luke said:

The sti brembo conversion sends the bias to the front by roughly 7% doesn't it. I can't imagine many drivers being able to feel that sort of change in the cars handling characteristics. Let alone have it affect braking performance in such a negative way that it makes it dangerous in a heavy braking situation on the public road.

Every big brake kit that I've seen for sale has never mentioned that it moves the bias forwards or backwards at all. Surely the load proportioning valves and the cars ABS/ EBFD systems will be able to adjust to these small bias changes. 

Otherwise no manufacturer would recommend a front big brake kit without a rear setup also?

This is worth a read for more info on bias:-

https://www.brakes-shop.com/brakepedia/general/brake-bias-and-performance

In 'normal' use (probably 95%+ of the braking people regularly do) you won't really notice any difference in braking. In 'extreme' use (a proper emergency stop, hard use on track, etc) if the bias has been shifted forwards you will see an increase in stopping distance. 

The big thing many people seem to forget is the effect of tyres as they're what really do the braking. If you're running a tyre with poor grip (something like a Toyo T1R for instance) your braking is going to be more limited by the tyres than anything else in your brake system. A grippy tyre (like a Yoko A052 say) will be able to handle much more braking force being applied to it before locking up. A good rule of thumb I saw is that if you can trigger the ABS you're tyre limited not brake limited for stopping. 

[BRZ-123 174]

This is worth a read for more info on bias:-
https://www.brakes-shop.com/brakepedia/general/brake-bias-and-performance
In 'normal' use (probably 95%+ of the braking people regularly do) you won't really notice any difference in braking. In 'extreme' use (a proper emergency stop, hard use on track, etc) if the bias has been shifted forwards you will see an increase in stopping distance. 
The big thing many people seem to forget is the effect of tyres as they're what really do the braking. If you're running a tyre with poor grip (something like a Toyo T1R for instance) your braking is going to be more limited by the tyres than anything else in your brake system. A grippy tyre (like a Yoko A052 say) will be able to handle much more braking force being applied to it before locking up. A good rule of thumb I saw is that if you can trigger the ABS you're tyre limited not brake limited for stopping. 

Tyres definitely are the most important but having said that , if you add another variable to it, temperature, the tyres mentioned above will not be as good at reducing braking distance below 4 degrees C as a good set of winter tyres and also most high temp brake compounds work well when warmed up not cold. So brakes + tyres + temperature determines the best stopping distance.

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[Kodename47 446]

10 hours ago, Luke said:

Every big brake kit that I've seen for sale has never mentioned that it moves the bias forwards or backwards at all. 

That's because the well designed kits aren't designed to shift bias. You use piston area and disc size to maintain the balance, a BBK isn't primarily for improved braking distances, it's to get the heat out the system for longevity.

[gavin_t 184]

Ooo my topic has re-appeared

 

The opposite to what has been mentioned here is that now my driving has improved I feel I am less heavy on the brakes and driving quicker.

Feel I am carrying more speed and getting my braking done in a shorter heavier period so less chance of building heat.

Circuits you drive play a big part too with some been a lot heavier on brakes then others.

 

Worth noting that I just use standard Road tyres (Yoko V105) so as @Deacon said the rubber is one of the limiting factors anyway.

 

I summary I still haven't gone BBK. Tried a new setup of Pads and have found them ok. I will get a kit in the future mind as I feel there is still room for improvement even if it is just the feel and confidence in the pedal rather then out right stopping power.

As it stands for me its still either K-sport or Reyland AP. Probably swaying Reyland as there is yet to be a bad word spoken about them.

[Church 209]

gavin_t:Slowing from speed A to speed B is to convert specific amount of kinetic energy into heat via brakes, that amount won't change if you do it quicker or slower over longer distance. And there can be both more heat from braking later/heavier (and thus quicker laptimes due accelerating longer elsewhere and higher speeds to bleed/more kinetic energy (which changes square of speed btw) to brake) but also it can be better cooled off (longer driving without braking, more cooling at higher speeds, better heat dissipation from hotter brakes vs ambient temps). Newbies imho often overheat brakes more because they may drive with nannies like SC/ABS/EBD/ediff, that may add up brake use/wear/heat when trying to correct car behaviour via actuating brakes.

Imho issues with stock brakes for some on track working worse might be like using too sticky tires (or too much aero, also increasing grip) overcoming max brake torque, and using too street oriented pads with little friction Mu, thus due harder pressing brakes needed it robs from fine-control of brakes. Both can be improved/fixed with right pads for specific use (unfortunately compromising daily driveability noise/dust/cold-stops wise). What pads & better brake fluid won't fix - max heat capacity and cooling efficiency. But if one operates within these known limitations, there is nothing wrong with using stock brakes on track. For exampl-NA car (as forced induction = faster speeds/more kinetic energy (square of speed) = much more heat in brakes) on not too sticky tires and track sessions not longer then 10-15min (fine by me. I often start to loose top concentration past 15min tracking anyway). Also brake cooling ducts can be added (or even electric fans. saw such kit made by ausies, engaging according to temp probe readings) to get more from stockers if wished so.

If pads fit well to one's use, recall CSG Mike writing: "As a rule of thumb, if you're getting 4 days out of a pad, you're pad is roughly matched to your setup/driving/experience on the FRS/BRZ. If you're getting more, you should stay where you are, or possibly move down a compound, depending on wear. If you're getting less, you need to move up compounds, and/or get a BBK, and/or get ducting."

After all, stock brakes on our cars are not exactly very bad (fronts AFAIK were from wrx, rears - legacy gt), and there are cars with worse stock brakes (eg. heard that S2000 are a bit more underbraked, requiring even more uprated pads). And big bonus of stock brakes - better clearance of small wheels (for eg. winter) and also legality wise (country specific, but eg. in LV to be MOT legal only manufacturer official options can be considered (for example PP brembos), otherwise  - just pads/fluid/ducts and very limited number of homologated brake lines, of course one can twice a year change to aftermarket BBK and back to stockers, but i don't want to consider that as option ).

[Luke 193]

@Deaconthanks for posting that article that made things much clearer. Especially the part about bigger disc diameter being paired with smaller pistons which is what any decent bbk supplier would have done. @Knightrider57 pointed out the same fact.

@gavin_twhat is your current setup that your comfortable with at the moment?

From that article you can swap the rear pad for something more aggressive to balance the bias a bit more.

All of this is a very delicate balance when you're using the car daily on the road of course. 

@church I guess we are lucky enough in the UK to not have the strict MOT laws. 

[Deacon 1357]

Or use decent pads and fluid

[Deacon 1357]

1 hour ago, Luke said:

@Deaconthanks for posting that article that made things much clearer. Especially the part about bigger disc diameter being paired with smaller pistons which is what any decent bbk supplier would have done. @Knightrider57 pointed out the same fact.

@gavin_t

This is where people can compromise braking performance by just bolting on a set of bigger brakes from another car though. 

A good, well done BBK shouldn't have these issues but unless paired with decent tyres will be a little pointless other than for looks and bragging over your extensive and expensive mods. 

[Lauren 2259]

3 minutes ago, Deacon said:

A good, well done BBK shouldn't have these issues but unless paired with decent tyres will be a little pointless other than for looks and bragging over your extensive and expensive mods. 

Depends upon what you mean by 'decent' tyres. Even with decent road tyres you will over come what the stock brakes are capable of after a few laps. It's about sustaining feel and keeping the consistency of it lap after lap. Even in a sprint which is only one lap I get the advantage of a BBK. It inspires confidence and the brakes simply consistent and don't fade. On a sprint I struggle with stock calipers. Uprated pads offer only a slight improvement. 

The other point you and most are missing is that if you trail brake the modulation of pressure and consistency of feel is key to being able to adjust the angle of the car when turning into a corner. I admit these are advanced techniques that I don't expect your average driver to thoroughly grasp, but having  a BBK even using road tyres has possibly been one of the best modifications I've done to my car. 

[Deacon 1357]

Just now, Lauren said:

Depends upon what you mean by 'decent' tyres. Even with decent road tyres you will over come what the stock brakes are capable of after a few laps. It's about sustaining feel and keeping the consistency of it lap after lap. Even in a sprint which is only one lap I get the advantage of a BBK. It inspires confidence and the brakes simply consistent and don't fade. On a sprint I struggle with stock calipers. Uprated pads offer only a slight improvement. 

The other point you and most are missing is that if you trail brake the modulation of pressure and consistency of feel is key to being able to adjust the angle of the car when turning into a corner. I admit these are advanced techniques that I don't expect your average driver to thoroughly grasp, but having  a BBK even using road tyres has possibly been one of the best modifications I've done to my car. 

You never ran any properly capable pads on the stock calipers though did you? Thought Project Mu Hc800+'s were the best you'd run? 

[Lauren 2259]

11 minutes ago, Deacon said:

You never ran any properly capable pads on the stock calipers though did you? Thought Project Mu Hc800+'s were the best you'd run? 

They were, yes. I'm not convinced properly capable pads would have given me the confidence in consistency of braking that I have now though.