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Bfranklyn86

Stoptechs vs AP racing 4 pot BBKs

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Hi,

Just after some opinions if that's ok. I am about to pull the trigger on some front BBKs to fit under stock wheels.

I daily drive my supercharged 86 but will be doing 2-4 track days a year too. The stock brakes arnt up to it at all!

ive had a good price offered for the stoptech 328mm kit, but I'm also considering the AP racing 332m for about 1/3 more money.

im going bbk instead of just pads/disk to future proof it incase I forge the engine internals, and also because of 'cool'.

which would you chose?

thanks,

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I'm guessing here but I'd imagine both BBK will have problems with the stock wheels without spacers, diameter is fine, it's the face of the calipers that might foul the spokes. As for which is better, no idea, Adrian at Fensport run them on his race car and does very well with them, AP racing ones are good enough for Cosworth to stick their name on them.

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Adrian has the Cosworth AP Brakes (356mmx32mm disc) on his car which wont fit under a 17" wheel. 

 

The AP kit formula is a 332x26mm disc and uses a narrow version of their popular CP6600 calipers so that it will fit behind the stock wheels. 

The stopteck is a large bulky caliper and uses a 328x28mm disc but wont fit behind the stock wheels. 

As far as consumables:

Stoptech

Pads DS2500 £190 a set, 

Disc ~£600 a pair

 

AP Racing

Pads DS2500 £100 a set

Discs J hook ~ £600 a pair

 

Not a lot in it to be honest. I would go with the AP kit because it fits under the stock wheels and seems to have cheaper pads, oh and its British :)

 

 

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From a slightly different perspective, I would argue that stock brakes with uprated pads, discs, lines and fluid will be more than sufficient enough.

Adding power doesn't add a significant enough weight penalty that a huge upgrade in brakes is needed, and it's the weight you need to stop at the end of the day. The 86 is still a very light car, so BBK's in my opinion are just completely unnecessary unless you're building a purely track spec car.

If you have the money, do it, it's a great upgrade I have no doubt. If it were my money, I'd spend 30% of the money of a BBK on a set of upgraded stock size parts, with the knowledge that I've saved enough money to completely renew the brakes another 2 times before I've spent the money of a BBK.

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Well technically it is kinetic energy you need to dissipate to stop, and it goes up with the square of the speed, so doubling speed quadruples the amount of energy required to stop. 

With 50% more power you are entering the braking zones faster.

Here is a good comparison.

At Snetterton down bentley supercharged I was hitting 125mph so thats 2.1 Mega Joules

Stock I was hitting 112mph so thats 1.7 Mega Joules

That's 25% more heat alone, but on top of that because you are going faster, there is less time for the discs to cool between braking zones.

Okay so thats the theory but heres a bit of practical. I took mine to bedford with race pads. Stock car apart from the coswroth sc and Ohlins coilovers. I was doing 20-30min sessions and went through two tanks of fuel ~200 miles. When I stripped the calipers down I found the dust boots were all crumbled and falling apart and 1 of the pistons was not sliding smoothly. I went through 1/4th of the disc and pad life too. 

so lets say you have to change the discs and pads every 4 track days. That's about £400 in disc and pads + labour if you dont do it yourself.

After 3 trackdays my current brakes have lost about 20% of their usable life. Its staggering. They just dont get very hot by comparison.

I'm not saying stock sized brakes cant work, because people have and do make it work, it just depends on how you drive and how hard and long you push at the track as to how long and reliable they will be. Everyone is different on the brakes and I think im a bit hard to be honest.

 

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Luckily our stockers are rather good "for stock". And if one keeps track session length to reasonable 10 minutes, imho at least for NA power one often can get by just fine with track pads & fluid change only (at least judging by brake fade) unlike stock brakes of .. almost majority of cars excluding exotics & sporty cars of higher price level. Airducts may add even more life in stockers (strongly considering Velox's kit purchase).

I'd still be happy to upgrade to Essex's AP Sprint kit to save on wearables and prolong sessions (though >15minutes subjectively makes me too tired/loosing concentration), but unfortunately local latvian street-legality technical rules are too strict and i don't want kit to bolt off back to stockers prior inspection each year and then back :/

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A-level physics teaches us many things Ade, unfortunately I must have missed the lesson where we were shown how kinetic energy calculations meant that a big brake kit on a GT86 is significantly better than uprated parts. Curse my poor attendance.

On a more serious note, one extremely vague example doesn't even come close to proving your point. You almost certainly didn't use the same brake pad compound on both stock size and BBK for a starter. You are also comparing a solid disc to a grooved disc with much more effective heat dissipation, which even at the same size disc would cause a huge impact on pad wear.

However, to humour you, let's talk numbers, and continue where you started.

Stock brakes last 4 track days @ £400 per renewal of parts.

BBK last 12-15 track days @ approx £600 per renewal of parts (purely a guess, but I would say this is quite a reasonable assumption).

So, every 12 track days (to keep the maths a little easier) someone with stock brakes spends £1200 to your £600 with a BBK. Unfortunately, we've not yet factored in the initial purchase price of a BBK, at £1200 (another nice round number). 

So, if you're making a £600 saving every 12 track days, you would need to do 36 track days to break even with someone on stock brakes. If we assume that this person does one track day a month, every month, it will take you 3 years of ownership for your point about cost to become relevant. Even if the replacement pads/discs on your BBK are the same price as stock, that's still 2 years before you make back your money, so really, I think we can ignore that point :)

Also, just to refer back to my initial response. For someone with a solely track focused car (which is where your argument carries a little more weight) I said that a BBK makes sense, but in this case OP is talking about 4 track days a year, maximum, then all road driving. Going back to our old friend the "numbers", he would need to own his car for 9 years in order for a BBK to make sense from a purely financial standpoint. 

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5 minutes ago, S18 RSG said:

You are also comparing a solid disc to a grooved disc with much more effective heat dissipation, which even at the same size disc would cause a huge impact on pad wear.

I'm not sure grooved discs are actually an upgrade with regards to heat dissipation, they really just help bite and lessen pad life. You have more disc mass on solid discs ;)

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13 minutes ago, knightryder said:

I'm not sure grooved discs are actually an upgrade with regards to heat dissipation, they really just help bite and lessen pad life. You have more disc mass on solid discs ;)

The more effective heat dissipation was more to do with the thickness of the discs and therefore size of the vents, which would make a big difference even on same size discs, grooved discs was just an observation of the difference. Just read through it myself and realise that I didn't really write what I meant. 

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3 hours ago, S18 RSG said:

From a slightly different perspective, I would argue that stock brakes with uprated pads, discs, lines and fluid will be more than sufficient enough.

Adding power doesn't add a significant enough weight penalty that a huge upgrade in brakes is needed, and it's the weight you need to stop at the end of the day. The 86 is still a very light car, so BBK's in my opinion are just completely unnecessary unless you're building a purely track spec car.

If you have the money, do it, it's a great upgrade I have no doubt. If it were my money, I'd spend 30% of the money of a BBK on a set of upgraded stock size parts, with the knowledge that I've saved enough money to completely renew the brakes another 2 times before I've spent the money of a BBK.

I always appreciate a different perspective!

I wasn't aware that forging the internals would be too much extra weight, it was more that I would be going faster (320ish wheel HP vs 240 currently)

this has been prompted by the fact that on NA power my stock brakes were by far the limiting factor on track (that and my ability obvs). Cooked after 3-4 laps. And since the SC has gone I've found myself needig a harder more 'unfadable' bite even for B road driving, because the speeds I'm hitting are much higher.

i was last on track with a mate who's Cayman R brakes completely put mine to shame (as expected, but still, now I'm up there with power I want to be up there with braking too)

thanks for all your responses so far.

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Just now, Bfranklyn86 said:

I always appreciate a different perspective!

I wasn't aware that forging the internals would be too much extra weight, it was more that I would be going faster (320ish wheel HP vs 240 currently)

this has been prompted by the fact that on NA power my stock brakes were by far the limiting factor on track (that and my ability obvs). Cooked after 3-4 laps. And since the SC has gone I've found myself needig a harder more 'unfadable' bite even for B road driving, because the speeds I'm hitting are much higher.

i was last on track with a mate who's Cayman R brakes completely put mine to shame (as expected, but still, now I'm up there with power I want to be up there with braking too)

thanks for all your responses so far.

Reason for the different perspective, contrary to what you may believe, wasn't to shit on BBK's, but more to make you aware that you don't NEED to spend that much money to get good improvements. 

Upgrading lines, fluid, discs and pads is already a huge upgrade and should see a marked improvement in the length of time you can spend on track. Because the car is so light, you don't necessarily need 6 or 8 pistons clamping on the disc for you to slow down. If you have a 2 ton Bentley, then yes, you do, but not a 1.2 ton sports car doing half the speed :P

At the end of the day, it's your money. A BBK will obviously be better, but that's where your money goes. If you want to save some money, you can get probably 80-90% of the benefits for less than 50% of the cost :)

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2 hours ago, Ade said:

 

I'm not saying stock sized brakes cant work, because people have and do make it work, it just depends on how you drive and how hard and long you push at the track as to how long and reliable they will be. Everyone is different on the brakes and I think im a bit hard to be honest.

 

I want to have the option to be hard on the brakes if I want, on track and occasionally road. I thought that was good driving? - if you arnt accelerating you should be braking hard.

Im not saying I want an absolute track weapon for 30 minute sessions or anything. But when I'm on track I want to be fast.

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16 minutes ago, Bfranklyn86 said:

I want to have the option to be hard on the brakes if I want, on track and occasionally road. I thought that was good driving? - if you arnt accelerating you should be braking hard.

Im not saying I want an absolute track weapon for 30 minute sessions or anything. But when I'm on track I want to be fast.

Actually it's not good driving to be really hard on the brakes. If you jump on your brakes when you are approaching a corner it hugely unsettles the car. Better to squeeze the brakes and load them up in a progressive manner. You can be very quick without melting the brakes. I've only got Stoptech pads. I don't generally have a problem with brakes on track doing 10, maybe 15 minute sessions. Sure they're grumbling towards the end, but they're adequate. I find brakes last me very well, as I dont brake unnecessarily and use them as little as possible. You gain far more on track by your corner entry and exit speeds.

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24 minutes ago, S18 RSG said:

Reason for the different perspective, contrary to what you may believe, wasn't to shit on BBK's, but more to make you aware that you don't NEED to spend that much money to get good improvements. 

Upgrading lines, fluid, discs and pads is already a huge upgrade and should see a marked improvement in the length of time you can spend on track. Because the car is so light, you don't necessarily need 6 or 8 pistons clamping on the disc for you to slow down. If you have a 2 ton Bentley, then yes, you do, but not a 1.2 ton sports car doing half the speed :P

At the end of the day, it's your money. A BBK will obviously be better, but that's where your money goes. If you want to save some money, you can get probably 80-90% of the benefits for less than 50% of the cost :)

I didn't interpret that as shitting on BBKs. Besides, i don't see brown coloured callipers going well with any GT86  (he he).

Pointing out that there are good options for less money is appreciated, because money saved here could go on other mods (e.g. Flex As or exhaust) 

That the Stoptechs don't fit the stock wheels does actually throw the cat amongst the pigeons. I was sure I read that they fit somewhere. I will double check with the supplier tomorrow.

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Very good thread, all be it I am still NA I have done 2 seasons of TSS and 3 rounds of Time Attack together with three track days. All on stock size DBA discs and 2 sets of Hawk Street pads, great value and good enough stopping power for good lap times.

Hope that is another angle for you.

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I agree that Stoptechs won't fit with standard 17" OEM wheels but it's the offset that causes the problem, not the diameter. Can be overcome with Eibach spacers.

I run Stoptechs - having ditched my K-Sports - with 17" rims. DS2500 pads. Brakes are fabulous, on road and track.

And I'm guessing an auto is harder on brakes than a manual.

 

Spec K

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10 hours ago, KevinA said:

Very good thread, all be it I am still NA I have done 2 seasons of TSS and 3 rounds of Time Attack together with three track days. All on stock size DBA discs and 2 sets of Hawk Street pads, great value and good enough stopping power for good lap times.

Hope that is another angle for you.

How long are your track sessions typically Kevin? That's not bad life at all, though sprinting is not as hard on the brakes as trackdays. 

DBA state their Kangaroo paw vane design is up to 20% better cooling than the standard straight vanes so well worth the expense as they probably increase pad life.

 

 

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10 hours ago, knightryder said:

Very few calipers fit beneath the OEM rims.

I cant think of any others than the AP kit. They had to make a thinner version of their CP6600 caliper and use a thinner disc to make it fit. 

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2 hours ago, Ade said:

How long are your track sessions typically Kevin? That's not bad life at all, though sprinting is not as hard on the brakes as trackdays. 

DBA state their Kangaroo paw vane design is up to 20% better cooling than the standard straight vanes so well worth the expense as they probably increase pad life.

 

 

Track days I do 15min sessions and TA is a full 20 mins on it. 

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7 hours ago, Special K said:

I agree that Stoptechs won't fit with standard 17" OEM wheels but it's the offset that causes the problem, not the diameter. Can be overcome with Eibach spacers.

I run Stoptechs - having ditched my K-Sports - with 17" rims. DS2500 pads. Brakes are fabulous, on road and track.

And I'm guessing an auto is harder on brakes than a manual.

 

Spec K

What was wrong with the K-Sports if you don't mind me asking?

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