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Lauren

Brake upgrades - discs/pads?

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48 minutes ago, will300 said:

I'm on Cosworth street masters for the rears. They feel like a very similar compound to the DS2500 on the front so they work really well, probably abit more street biased. 

I'd suggest you look for a similar compound to the DS2500. The main thing I was concerned about was brake bias, the AP kit is one of the closest to keeping the stock balance, so you don't want an overly aggressive rear pad. 

 

 

Yes fair point. I was wondering whether you went for the Stoptech rears as they'd probably be similar too. Maybe I should just email Lucas and say 'I'll have what Will had'! ;)

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I'd advocate what Lauren said too, to use same compound in all corners. Unless something really thowing off grip balance is in car setup and needs to be workarounded, like massive aero bits with extra downforce only in front or only in rear, or if one has went for staggered wheel width, or if one has installed brake controller that can allow fine-tune bias on the fly and so on. Toyobaru engineers did many tests to find optimum brake bias for shortest braking distance, lessening chance of one end locking up while another is still underbraked, and also designed safety nannies working with specific grip balance in mind (eg. TC/VSC/ABS). Yes, front pads will wear much more and need more frequent replacement, but still, i wouldn't try to outsmart manufacturer vendors, even more so that most top aftermarket BBK vendors that actually throw some R&D behind their kits, try to keep that brake bias balance too.

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1 hour ago, Lauren said:

@will300, I've noticed you can get matching Ferodo DS2500 rears for our car. £125. Any reason why you didn't go for these to match the fronts? 

Simply because I fitted the StreetMasters a couple of months before hand, I therefore thought it best to try the BBK out first before making any decisions about the rears. As it turned out the balance is spot on, so I left it as is.

 

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Ah I see. I've still got the old Project Mu's on the rear, but I can't tell anything about the balance of braking till I get on the track of course and I will need to change my rear discs and pads before I venture out next at Oulton.  I think I will go for the DS2500's on the rear as well as it's the obvious option to go for really. 

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Actually pad choice options are not 100% obvious. When i thought about it deeper - many, especially track pads, have rather different Mu at different temps (eg, 0.3 at 100C, 0.6 at 400C). So one thing is less usage of rear brakes and rear pads purely from wear viewpoint .. another is - if rears heat up less during heavy braking on track, what Mu fronts/rears, what bias car brakes will have at different brake temps. When with square pad setup i had front rotors glowing red, rears were much cooler. Of course, having staggered pad choice will make it even harder to think out resulting brake impact, as each pad has different curve depending on temps, so compounds may have same Mu only at some specific temperature and one bias below it, opposite bias above it. Square pads can have same brakeing bias cold, and more and more divergence as brakes get hotter/with more brake abuse. Extra points for pads, whose compounds have more consistent/linear temp-dependent Mu curves, it at least can ease to find out what behaviour to expect. I guess that consistency over wide temp range that is sometimes mentioned for DS2500, might be another good point about them.

Weren't it so that in current german touring car championship, were cars used installed brake bias adjustment to get heat in them during first lap after start and then adjusted them differently for rest of race?

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Thanks for your input, Church, but I CBA to think about it that much. Having the same compound front and rear will be fine of course, so obvious enough to me. My car is a road car 99.9 of the time which is far more important than track use.  I already have AP four pots on the front of course, I'm trusting that will be more than adequate for the track.

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6 hours ago, Church said:

I guess that consistency over wide temp range that is sometimes mentioned for DS2500, might be another good point about them.

@Lauren I hope you have a better experience with DS2500's than I did. Always lovely when you're flying into a corner and you nearly end up in the back of a £100k Lotus Exige :lol:

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2 hours ago, TTR said:

@Lauren I hope you have a better experience with DS2500's than I did. Always lovely when you're flying into a corner and you nearly end up in the back of a £100k Lotus Exige :lol:

That happened quite a lot with the stock setup with Project Mu's, the Stoptechs and the stock pads on a fair number of occasions. Hopefully I will fare better with the new front brakes. 

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16 hours ago, Lauren said:

That happened quite a lot with the stock setup with Project Mu's, the Stoptechs and the stock pads on a fair number of occasions. Hopefully I will fare better with the new front brakes. 

I never had an issue with the Project Mu Clubracers (Next pad up from the HC800) in 25/30 minute sessions, even when being lazy and using the ABS instead of threshold braking. I know Adrian had some fade issues with the HC800 as well. The thing I personally really love about the Mu's is the feel, but I guess that's a really subjective thing. 

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Cool. Depending on the pad, I have DS2500's I ran them in in around 20 minutes. Just accelerate hard and brake harder and harder typically braking from 100mph down to 60 or so and repeat 30 odd times. Find a quiet dual carriageway at night. Once you can smell them, you're done. :)

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Didn't want to start a new thread for the same thing. 86 is due disks and pads and I've never found them overly impressive, only OK. Disks and pads are probably the originals. Can't afford a BBK yet so tempted to go from something like this. https://www.tarmacsportz.co.uk/stoptech-toyota-gt86-subaru-brz-13-15-subaru-impreza-wrx-08-14-front-and-rear-slotted-sport-kit.html I did see it was cheaper a while ago but still seems a good all in option. I've never used stoptech before but have heard of them. Do many here run them?

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That Stoptech package is quite pricey. Just doing pads alone will improve matters, many run the Stoptech pads and are seen as a fast road/mild track compound. Slotted discs increase wear, on a road car I would always advise standard blank discs.

Unless the discs are worn, you could just replace the pads. I've just managed to source OEM quality (Bosch) rear discs for £45 for the pair, but that was the last on their website. MTEC do discs that come well recommended and do C hook (AP J Hook style) discs for £82 a pair of fronts, or £65ish for slotted. You can get hold of Bosch/Brembo/ATE blank front discs for around £80 a pair on many car part sites. These are OEM quality without paying quite the Toyota premium. Compare that to a Stoptech disc that's £120+ per disc...... The Stoptech may be better for hard track use, but I bet there's not much in it.

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I wouldn't normally go slotted either for road use, more to show that package as an option. What started off as a search for pads ended up being disks, then braided hoses, then bigger setups. The disks have quite a lip on them so I'd change them while I'm there. The only pad I won't consider is EBC as I run them a few years ago on another car, didn't seem any better than stock, didn't last long and got far too much brake dust.

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What would be turnoff for me for this set, no mention for what car kit is designed, and "work perfectly great sti wrx or classic upgrade" makes me even more sure that it's not twins native kit, thus very possibly changing brake bias. Cheapness is not worth compromising something as important as brakes.

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48 minutes ago, Church said:

What would be turnoff for me for this set, no mention for what car kit is designed, and "work perfectly great sti wrx or classic upgrade" makes me even more sure that it's not twins native kit, thus very possibly changing brake bias. Cheapness is not worth compromising something as important as brakes.

I definitely wouldn't recommend it unless you've done your research. However @Ade is running this exact setup, also @smudge has the same calipers with 360mm discs. 

For those that want a 355mm kit, its good value.

Worst case it'll need a refurb and new brackets made up, this will still be alot cheaper than a brand new AP Racing kit. 

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That is the exact kit I have and should fit straight on with the exception that the bleeders/crossover tubes will need to be swapped as its a trailing caliper on the WRX vs the 86.

It's the same kit as the cosworth one as well.

If that's not enough the pistons sizes are exactly the same as the official AP kit using a 350mm diameter disc. So bias will be approx the same as that.

It does move bias forward a little bit but I really don't think it's a worry. You can always run a more aggressive pad the back if you want to move it back a bit.

Sent from my SM-G935F using Tapatalk

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Ade: except there was no info if that's the same kit, what piston sizes and so on .. make decision by mentioned rotor size only and some pics seems depending on luck too much. After all, there might be several kits using same caliper line and look almost same but a bit different piston sizes and moving bias to unknown side at unknown rate, resulting in easy to lock rears while fronts are underworked in one case or unstable car under heavy braking with rear tendency to swing in other. Maker, rotor size and caliper line is not the only variable that may change. Often BBKs are used for track use. That's last place i'd wish to see braking compromised. (leaving aside customers, that get BBKs "to fill wheels" and "to have painted calipers with # branding", and which probably can get by with rather large changes, if never pushing when daily driving and if driving with nannies on).

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8 hours ago, will300 said:

I definitely wouldn't recommend it unless you've done your research. However @Ade is running this exact setup, also @smudge has the same calipers with 360mm discs. 

For those that want a 355mm kit, its good value.

Worst case it'll need a refurb and new brackets made up, this will still be alot cheaper than a brand new AP Racing kit. 

362mm, thank you! ;)

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On 4/14/2018 at 8:39 AM, Church said:

Ade: except there was no info if that's the same kit, what piston sizes and so on .. make decision by mentioned rotor size only and some pics seems depending on luck too much. After all, there might be several kits using same caliper line and look almost same but a bit different piston sizes and moving bias to unknown side at unknown rate, resulting in easy to lock rears while fronts are underworked in one case or unstable car under heavy braking with rear tendency to swing in other. Maker, rotor size and caliper line is not the only variable that may change. Often BBKs are used for track use. That's last place i'd wish to see braking compromised. (leaving aside customers, that get BBKs "to fill wheels" and "to have painted calipers with # branding", and which probably can get by with rather large changes, if never pushing when daily driving and if driving with nannies on).

Stop being pedantic. The front brakes on our car are pilfered from the WRX anyway.

Its the AP racing kit for the Subaru WRX STI. AP only made one kit with that size disc and using the CP7040 caliper.

https://www.apracing.com/product_details/performance_upgrades/factory_big_brake_kits/subaru/new_age_shape_and_n14_(01-2014)-front_6_piston_kit_cp7040-1001-information_only.aspx

I have a spreadsheet with all the brake bias calculations as well comparing this to the "official" AP kits for the GT86 and the "unofficial" Essex kits as well as others.... The Official AP kit with 350x32mm disc uses the direct replacement to the CP7040; the CP9040 forged caliper. Its has exactly the same size pistons and therefore bias. 

 

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