AP Racing, Freaky Parts, 996, Cooling? School me on BBK to help pad consumption

[mrgizmo04]

Pistons popping or pads themselves falling out/jamming. The horns that hold the pad in the caliper are made to fit around a wider rotor. Backing plates are around 4mm, remember also as the pad wears, the rotor wears, and that creates more space. I posted a lot of info on similar subject when people were looking at AMG/Cayenne/etc caliper which are made for like x32-x36 rotors and were mating them with CSL x28 or e9x x30 rotors. What fun. Like I said before, people will do crazy things for bbk bling, compromising safety.

To add to what Jae said, one thing that stays constant on st40 caliper is the pad. I can run the same pad on my s2k st40 328x28 as I did on the m3 355x32. The hats/bells are different on different cars to offset the rotor, the mounting brackets for the caliper are also different to mate to each car's knuckle and account for rotor diameter, etc. That said, could you find st40 calipers off whatever car that is made for x32 width and 42/38 piston sizes (m3 spec). Yes. You will need to get the mounting brackets for m3, rotor hats, etc that adds up.

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[bigjae46]

Stoptech question: is an ST40 caliper always an ST40 caliper? Eg. If I got a used ST40 kit made for another car, would I just need brackets, lines, and rotors for my car and be good to go?

Nope. Some calipers are designed for 28mm and 35mm rotor thickness in addition to the 32mm rotor spec'd for the M3. Also the pistons are tuned to the cars OE bias.

IMO, buying a used BBK is a waste because the cost to replace the wear parts is majority of the cost of a new kit.

[Pklauser]

That's good intel on running the rears too thin with 996 calipers, I hadn't heard that. Is there enough space that you risk actually popping the piston out?

Stoptech question: is an ST40 caliper always an ST40 caliper? Eg. If I got a used ST40 kit made for another car, would I just need brackets, lines, and rotors for my car and be good to go?

[mrgizmo04]

Thanks for the thoughtful response, I have thought (and over thought) about this whole subject a lot and at a certain point, I need to just get the car out there with some setup, try it, see how it does, and then change as needed. FWIW I have a set of stock calipers with brass pins and PFC08 pads that I can put on there if these retrofits turn out to be a nightmare. Yes I do want it to look cool though, Brembos are cooler looking than stock calipers, I'm not denying that part. I'm a highly visual person and I do not try to pretend otherwise lol.

Here's my thought process on the brake setup I've landed on as a starting point, please let me know if I'm off here or missing some big points. My understanding is that stock for stock, early cars have a more rearward bias than later cars, due to a different master cyl. So I looked at the brake bias numbers various people have come up with for later cars using Megane front calipers with 345mm rotors and 996 rear calipers, which seems to be a happy starting point, and ballparked that the DB9 front calipers with the slightly larger 44/40 pistons and 345mm rotors should kind of counteract the early car rear bias created by the master cyl. Maybe I'm wrong and TBH I am not an equations kind of guy, so if anyone would be willing to run these numbers and see where it actually falls, that would be very interesting and helpful to the greater knowledge bank.

This is my first time building an e46 for track but not my first rodeo with track cars in general, so I know it's not as easy as just throwing parts at the car. Weight wise, I removed the rear seats and gutted the trunk carpet, but I'm adding a rear brace and roll bar, so it's probably going to be a wash. I'm running off the shelf KW Clubsport 2 way adjustables so yes, I will have to test and tune and see how this whole system works together. I'm aware that might not be the ideal damper and spring but it's what I have, so I'm going to run them for now. I also have a GT4 style rear wing and front lip which I will also run because, not gonna lie, they look cool and I want that just as much as actual performance benefits. I'm running 18x10ET25 wheels with NT01 used spares, and I'll end up likely on a 265 200tw tire after those are done. I will also likely end up doing a MK60 retrofit in the not so distant future. But again right now, all of that stuff is just sitting in my garage because I have no time to dedicate to the car.

Nate, I can tell you that I see some serious track guys running some serious times with me in advanced groups with stock calipers and just upgraded pads/fluids/cooling ducts on stock rotors. That said, their cars are fully gutted, so that setup has enough heat capacity for them and works. For the full pig that our cars are at 3500+ lbs (with driver), that setup might not be ideal.

Having been through various combinations of stock f/r, st40 f/r, 996 f/r, I can tell you that the rear 996 kit is a solid upgrade for our cars. Caliper is not modern, but it is radially mounted, much stiffer than stock, retains same rotor size but pad size increase is rather significant for heat capacity. It also works really well if you trim the dust shield to let the heat radiate to cool the rotor, given the rear has the parking brake surface so cooling is limited. You just need to watch that pads don't make it down to the backing plates, since 996 rotors are x24, while ours are x20.

Fronts are trickier. Depending on your philosophy of running same pads front to rear vs split mu, you will have to play around with your driving style. I've settled to make the 996 kit work on my car even though the fronts are a bit subpar in terms of bite (smaller piston sizes), and pad size increase is minimal vs stock for additional heat capacity. I trick the less bite part with the higher mu front pad (3 variables that impact amount of f vs r bite are rotor diameter, piston sizes, pad mu). Also where the titanium shims come in and Vorshlag cooling deflectors.

If you are going to do mk60, I say do it first so you don't have to run through finding the setup that works for you with mk20 and then again mk60. DB9 on stock 325 rotor will move your bias forward more than Megane on 345 (as you note 44/40 vs 40/40 piston sizes). You will have to see how that feels to you and what you like.

Having run flat ride coming down to 350 spring, I didn't want to go lower given the weight xfer forward with more rear bias of 996 setup.

I like tinkering (although less so in past year or so, time not permitting with family/etc), and am a fan of "upgrades" as needed, but that path is not for everyone.

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[bigjae46]

Appreciate that perspective bigjae46. Cost not-withstanding, sure going with something like an AP kit makes sense, but even then I still don't feel that I KNOW it will work. Maybe on track, but will no dust boots bite me on the street? I know your StopTechs have boots, but like you said it may not make sense to buy StopTech right now with their supply issues. Not to mention that if I don't spend money that I didn't need to spend, that's money that can go to those same costs you mentioned: registration, hotels, fuel, etc. Right now with the stock brakes I don't feel that I'm at risk of ending a weekend early. Travel with spare pads an rotors and I'm good to go.

I think there's value in exploring lower-cost solutions. I understand that it's not for everyone, and there's a chance I end up with a pricier kit in the end, but with kits like your StopTech seeing such significant price increases in the last year or so, along with FCP's lifetime replacement pads/rotors, the economics have changed and I like exploring the options 😄

I really don't understand the whole not having dust boot on track thing. IMO, its marketing and only makes you look cool to other guys in the paddock to say that you don't run dust boots on your calipers. A simple titanium shim with deal with a potential issue. You have to do something like....run the pad to the backing plate to cause an issue.

The OE dust boot is massive - if that hasn't caught fire yet then I think a BBK with the dust boots will be fine.

A day at the track is worth at least $500, maybe more depending on how far and which track. I instructed a guy in a Jaguar F-Type at COTA. He literally drove 1 session because his brakes were vibrating like crazy - cost him $1000 just for the track fee.

[Pklauser]

You will get taper with sliding calipers, no matter what.

You are waaaaayyyyyyy over analyzing this. Its pretty simple.

If you casually track 3-4 days per year and do it for fun then a BBK might not be worth it.

But this is the way I look at it. Brakes can easily end your weekend. A weekend you spent a lot of time and effort prepping the car, getting to the track, and all of the costs like registration, hotels, fuel, etc. I'd spend the $$$ on a BBK purely for reliability - to know that brakes won't be the cause of ending the weekend early. I go 10/10ths otherwise what's the point? What sucks is having to manage brakes because they fade or you know there's not a lot of pad left.

You can cobble a kit together with parts from other cars or keep throwing all of these parts at your stock brakes that aren't all that great. I'd go with something that you KNOW will work and won't have to F with at the track. Been there...changing out hot brake pads so I don't miss my next session in a paddock where the concrete is 120 degrees, can't even kneel down on it because you'll get a 3rd degree burn.

Just a thought from someone who has been doing this for over 15 years - seen a lot over that time. Seen a lot of students go home early because they ran out of brakes.

Appreciate that perspective bigjae46. Cost not-withstanding, sure going with something like an AP kit makes sense, but even then I still don't feel that I KNOW it will work. Maybe on track, but will no dust boots bite me on the street? I know your StopTechs have boots, but like you said it may not make sense to buy StopTech right now with their supply issues. Not to mention that if I don't spend money that I didn't need to spend, that's money that can go to those same costs you mentioned: registration, hotels, fuel, etc. Right now with the stock brakes I don't feel that I'm at risk of ending a weekend early. Travel with spare pads an rotors and I'm good to go.

I think there's value in exploring lower-cost solutions. I understand that it's not for everyone, and there's a chance I end up with a pricier kit in the end, but with kits like your StopTech seeing such significant price increases in the last year or so, along with FCP's lifetime replacement pads/rotors, the economics have changed and I like exploring the options 😄

[bigjae46]

I present to y'all, the ECS bronze bushings: https://youtube.com/shorts/GdIRm2POlG8

Will this help with taper? We'll see. I just picked up two (yep) sets of rear 996 calipers for a song off marketplace. It's likely I'll pair one of them with a set of Megane fronts at some point, but I'm hoping these ECS bushings at least improve things for the next couple of months of DEs.

You will get taper with sliding calipers, no matter what.

You are waaaaayyyyyyy over analyzing this. Its pretty simple.

If you casually track 3-4 days per year and do it for fun then a BBK might not be worth it.

But this is the way I look at it. Brakes can easily end your weekend. A weekend you spent a lot of time and effort prepping the car, getting to the track, and all of the costs like registration, hotels, fuel, etc. I'd spend the $$$ on a BBK purely for reliability - to know that brakes won't be the cause of ending the weekend early. I go 10/10ths otherwise what's the point? What sucks is having to manage brakes because they fade or you know there's not a lot of pad left.

You can cobble a kit together with parts from other cars or keep throwing all of these parts at your stock brakes that aren't all that great. I'd go with something that you KNOW will work and won't have to F with at the track. Been there...changing out hot brake pads so I don't miss my next session in a paddock where the concrete is 120 degrees, can't even kneel down on it because you'll get a 3rd degree burn.

Just a thought from someone who has been doing this for over 15 years - seen a lot over that time. Seen a lot of students go home early because they ran out of brakes.

[Pklauser]

I present to y'all, the ECS bronze bushings: https://youtube.com/shorts/GdIRm2POlG8

Will this help with taper? We'll see. I just picked up two (yep) sets of rear 996 calipers for a song off marketplace. It's likely I'll pair one of them with a set of Megane fronts at some point, but I'm hoping these ECS bushings at least improve things for the next couple of months of DEs.

[bigjae46]

So I’d check tires and suspension first. Bad tires can work the brakes harder. You’re on the brakes for a longer period to get the car slowed down. Also a poor suspension setup can extend braking distances - more heat.

My car is pretty light - 2630lbs without driver and fuel.

I run the ST40 front and rear BBK. The calipers have dust seals, haven’t been a problem thus far.

I started out with PF01s and then switched to Stoptech SR34s which were PF01 clones but $200 instead of $350 for the PFCs. With cooling, front pads lasted about 10-12 days. The pads were the same front to rear. I kept new pads on the rear and just swap them when the fronts get low.

Also the rotor discs were the same. Over 100 track days, my front rotors are 12 days in and the rear rotors were originally on the front.

I bleed my brakes once a year or if a tech inspection requires one within 6 months. Ive used OEM BMW brake fluid and Motul RBF600.

Never had an issue - 12 years. No brake fade, knock back, or performance issue. The kit has been reliable, low maintenance and low cost. My pad life has increased by about 1-2 days since I’ve installed the roll cage and lightened the car.

I believe Stoptech is having some issues…so I’d be advised before proceeding. It’s been a great balance of performance and cost.

[Nate047]

Nate, it depends what you are building for and how your car is set up and how you want it to behave. It is a system and everything impacts everything.

For example, if your car is gutted from midpoint rearward, your weight distribution will be closer to 52-54% front (similarly if you want to run flat ride with "softly" sprung front where you xfer a tonne of weight forward under heavy braking). You probably don't want a brake setup that shifts brake bias rearward ala 996 kit (which I keep reminding people comes from mid/rear engines car) or ZCP/CSL kit. Unless you adjust the rake (more negative) and run rear lower to give rear end more weight distribution and add some rear grip under braking. But then you might understeer coming out of the corners on early throttle application. Or maybe you have a wing which adds dynamic force and grip to the rear, then a brake setup that moves bias rearward makes sense. Or maybe you have different spring rates or adjustment knobs to play with.

That unsprung weight difference will be noticeable chucking it into corners. I am not saying lighter setup is better necessarily.

I've had to play around quite a bit with brakes and suspension and when changing either, or removing weight from the car it impacts the other. Everything is dynamic. Pi r^2 on caliper pistons, rotor diameters, pad mu variables are good to ballpark on paper to see directionally what might change, but application to your setup and you as a driver will feel different the first time you come to a hard braking zone that is downward sloping and things get surprisingly loose. You can adjust your driving style or you can go back to the equations and crunch what suspension or brake setup changes (or maybe removing all that weight in the rear was not a good idea) to give you directionality on what to try changing next in your setup.

The simple answer is always very clear, everyone should run AP kit, "the best". The complicated answer that everyone hates, is it depends. You start doing track, and jam on the brake pedal at every turn and think you are booking it and you need a bbk because your pads burn up. Upgrade pads and cooling. You will also learn as you develop as a driver that whereas at beginning you used to jam the brakes at every turn, now you are more advanced and only need to brake on 3 turns instead of 10, you can tap on others to xfer weight and help with rotation, etc. Things start lasting longer naturally. Those huge upgrades you thought you needed, you can now maybe even downgrade.

Obviously for upgrades for bling factor over function, like all my posts, my post can be ignored.

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Thanks for the thoughtful response, I have thought (and over thought) about this whole subject a lot and at a certain point, I need to just get the car out there with some setup, try it, see how it does, and then change as needed. FWIW I have a set of stock calipers with brass pins and PFC08 pads that I can put on there if these retrofits turn out to be a nightmare. Yes I do want it to look cool though, Brembos are cooler looking than stock calipers, I'm not denying that part. I'm a highly visual person and I do not try to pretend otherwise lol.

Here's my thought process on the brake setup I've landed on as a starting point, please let me know if I'm off here or missing some big points. My understanding is that stock for stock, early cars have a more rearward bias than later cars, due to a different master cyl. So I looked at the brake bias numbers various people have come up with for later cars using Megane front calipers with 345mm rotors and 996 rear calipers, which seems to be a happy starting point, and ballparked that the DB9 front calipers with the slightly larger 44/40 pistons and 345mm rotors should kind of counteract the early car rear bias created by the master cyl. Maybe I'm wrong and TBH I am not an equations kind of guy, so if anyone would be willing to run these numbers and see where it actually falls, that would be very interesting and helpful to the greater knowledge bank.

This is my first time building an e46 for track but not my first rodeo with track cars in general, so I know it's not as easy as just throwing parts at the car. Weight wise, I removed the rear seats and gutted the trunk carpet, but I'm adding a rear brace and roll bar, so it's probably going to be a wash. I'm running off the shelf KW Clubsport 2 way adjustables so yes, I will have to test and tune and see how this whole system works together. I'm aware that might not be the ideal damper and spring but it's what I have, so I'm going to run them for now. I also have a GT4 style rear wing and front lip which I will also run because, not gonna lie, they look cool and I want that just as much as actual performance benefits. I'm running 18x10ET25 wheels with NT01 used spares, and I'll end up likely on a 265 200tw tire after those are done. I will also likely end up doing a MK60 retrofit in the not so distant future. But again right now, all of that stuff is just sitting in my garage because I have no time to dedicate to the car.

[mrgizmo04]

Nate, it depends what you are building for and how your car is set up and how you want it to behave. It is a system and everything impacts everything.

For example, if your car is gutted from midpoint rearward, your weight distribution will be closer to 52-54% front (similarly if you want to run flat ride with "softly" sprung front where you xfer a tonne of weight forward under heavy braking). You probably don't want a brake setup that shifts brake bias rearward ala 996 kit (which I keep reminding people comes from mid/rear engines car) or ZCP/CSL kit. Unless you adjust the rake (more negative) and run rear lower to give rear end more weight distribution and add some rear grip under braking. But then you might understeer coming out of the corners on early throttle application. Or maybe you have a wing which adds dynamic force and grip to the rear, then a brake setup that moves bias rearward makes sense. Or maybe you have different spring rates or adjustment knobs to play with.

That unsprung weight difference will be noticeable chucking it into corners. I am not saying lighter setup is better necessarily.

I've had to play around quite a bit with brakes and suspension and when changing either, or removing weight from the car it impacts the other. Everything is dynamic. Pi r^2 on caliper pistons, rotor diameters, pad mu variables are good to ballpark on paper to see directionally what might change, but application to your setup and you as a driver will feel different the first time you come to a hard braking zone that is downward sloping and things get surprisingly loose. You can adjust your driving style or you can go back to the equations and crunch what suspension or brake setup changes (or maybe removing all that weight in the rear was not a good idea) to give you directionality on what to try changing next in your setup.

The simple answer is always very clear, everyone should run AP kit, "the best". The complicated answer that everyone hates, is it depends. You start doing track, and jam on the brake pedal at every turn and think you are booking it and you need a bbk because your pads burn up. Upgrade pads and cooling. You will also learn as you develop as a driver that whereas at beginning you used to jam the brakes at every turn, now you are more advanced and only need to brake on 3 turns instead of 10, you can tap on others to xfer weight and help with rotation, etc. Things start lasting longer naturally. Those huge upgrades you thought you needed, you can now maybe even downgrade.

Obviously for upgrades for bling factor over function, like all my posts, my post can be ignored.

Sent from my SM-G950U using Tapatalk

[jet_dogg]

Fair warning, VBT does not ship to the US currently, full stop... I had to ship the parts to my friend in Germany who then turned around and shipped them to me. It was definitely not economical in the long run, but whatever. This car has been one giant financial snowball after another so does it really even matter? Live and learn. I bought some used calipers separately, which also for the record was the wrong choice. In total it will cost me a couple hundred bucks more to rebuild and powdercoat the calipers, including new pins and clips, dust boots, bleeders, and cross over pipes. I should have just bought the full kit including rebuilt calipers from VBT.

I'm doing DB9 fronts with 345mm rotors and 996 rears. My car is an early MK20 ABS car, which also has a different master cylinder, so the stock brake bias is more towards the rear than on later cars.

So according to my ricer math, the early master cyl plus the combo of 996 rears and the DB9 front 40/44mm piston pairing should be a little better than the 40/40mm pistons of the Megane, moving the bias forward and closer to the ballpark of a stock CSL brake bias. And in theory these will be a little better for tapered pad wear also. Still use the same D1001 pads. The DB9 calipers weigh about .5lb more each than the Megane caliper.

I might sell the Freakyparts kit, but I may just keep it and put it on my e36 (I have some adapters from a Polish company called K-System Pro for that application too)

I have PhDs in ricer mathematics and broscience.

[PSUEng]

Fair warning, VBT does not ship to the US currently, full stop... I had to ship the parts to my friend in Germany who then turned around and shipped them to me. It was definitely not economical in the long run, but whatever. This car has been one giant financial snowball after another so does it really even matter? Live and learn. I bought some used calipers separately, which also for the record was the wrong choice. In total it will cost me a couple hundred bucks more to rebuild and powdercoat the calipers, including new pins and clips, dust boots, bleeders, and cross over pipes. I should have just bought the full kit including rebuilt calipers from VBT.

I'm doing DB9 fronts with 345mm rotors and 996 rears. My car is an early MK20 ABS car, which also has a different master cylinder, so the stock brake bias is more towards the rear than on later cars.

So according to my ricer math, the early master cyl plus the combo of 996 rears and the DB9 front 40/44mm piston pairing should be a little better than the 40/40mm pistons of the Megane, moving the bias forward and closer to the ballpark of a stock CSL brake bias. And in theory these will be a little better for tapered pad wear also. Still use the same D1001 pads. The DB9 calipers weigh about .5lb more each than the Megane caliper.

I might sell the Freakyparts kit, but I may just keep it and put it on my e36 (I have some adapters from a Polish company called K-System Pro for that application too)

Good to know, thank you!

[Nate047]

Fair warning, VBT does not ship to the US currently, full stop... I had to ship the parts to my friend in Germany who then turned around and shipped them to me. It was definitely not economical in the long run, but whatever. This car has been one giant financial snowball after another so does it really even matter? Live and learn. I bought some used calipers separately, which also for the record was the wrong choice. In total it will cost me a couple hundred bucks more to rebuild and powdercoat the calipers, including new pins and clips, dust boots, bleeders, and cross over pipes. I should have just bought the full kit including rebuilt calipers from VBT.

I'm doing DB9 fronts with 345mm rotors and 996 rears. My car is an early MK20 ABS car, which also has a different master cylinder, so the stock brake bias is more towards the rear than on later cars.

So according to my ricer math, the early master cyl plus the combo of 996 rears and the DB9 front 40/44mm piston pairing should be a little better than the 40/40mm pistons of the Megane, moving the bias forward and closer to the ballpark of a stock CSL brake bias. And in theory these will be a little better for tapered pad wear also. Still use the same D1001 pads. The DB9 calipers weigh about .5lb more each than the Megane caliper.

I might sell the Freakyparts kit, but I may just keep it and put it on my e36 (I have some adapters from a Polish company called K-System Pro for that application too)

[PSUEng]

Unrelated but kind of related, I recently picked up a set of DB9 calipers and Vagbremtechnic brackets and hoses. Their brackets are a nicer and cleaner looking than the Freakyparts brackets. But material wise I believe they are the same.

I've been looking at this exact same option. Did you do fronts only? What is your rear setup?

I'm looking at the biasing if I were to do FR Aston calipers on 325mm rotors, and either 1) keep stock non-ZCP rear calipers or 2) install my rebuilt stock ZCP rear calipers.

What color did you get?!