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      10-08-2020, 04:51 PM   #243
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Quote:
Originally Posted by Bartledoo View Post
Well, if too soft you will lose grip as well, and have to battle with f'd up tire wear.
Ya, that's why spring rates are always a compromise and why it's difficult to find that 'perfect' setup. I was implying, more generally, that softer = more grip.
Of course there reaches a point where it's detrimental (too soft) and many other factors come into play, like what tire compound you're using, weight of the car, level of aero etc. that change what the optimal spring rate for grip is. And what is optimal for grip isn't necessarily optimal for balance or tire life.
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      10-09-2020, 09:37 AM   #244
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Quote:
Originally Posted by tsk94 View Post
Quote:
Originally Posted by Bartledoo View Post
Well, if too soft you will lose grip as well, and have to battle with f'd up tire wear.
Ya, that's why spring rates are always a compromise and why it's difficult to find that 'perfect' setup. I was implying, more generally, that softer = more grip.
Of course there reaches a point where it's detrimental (too soft) and many other factors come into play, like what tire compound you're using, weight of the car, level of aero etc. that change what the optimal spring rate for grip is. And what is optimal for grip isn't necessarily optimal for balance or tire life.
Isn't the speed and radius also matter in term of front grip.

Meaning a setup for high speed swiping corner may not be the same for slow tight turn.

Adding to the comprised equation. Where do you want the car to have grip
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      10-09-2020, 02:40 PM   #245
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Originally Posted by rhyary View Post
Isn't the speed and radius also matter in term of front grip.

Meaning a setup for high speed swiping corner may not be the same for slow tight turn.

Adding to the comprised equation. Where do you want the car to have grip
If we add aero (downforce) into the equation, then yes it does. If we approach it from a purely mechanical grip standpoint, then we take additional grip from aero out of the equation.

Take a tire for example that can generate 1.5g of peak lateral grip on a skidpad. Therefore, the peak amount of lateral grip through a turn (ignoring additional grip from aero) is 1.5g. So whether the turn is a slow and tight 30mph turn or a fast 100mph sweeper, the peak mechanical grip the tire can generate remains the same. This example assumes a car with no aero and generating no lift.

Adding aero in the equation makes things more complicated, as at higher speeds the additional downforce can create more grip (front and rear). Thus a higher rate spring is needed to support the chassis and not overload the tire and thus lose grip. But then the balance is compromised in lower speeds turns where aero plays no effect.

This is why optimal spring rates are so difficult to determine in the real world, as there are so many factors and the end result will always compromise in some area.
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      10-13-2020, 08:41 PM   #246
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Well race season is over - it was short and sweet but now on to the offseason.
Going to have one or two more track days here shortly, but no more competing until 2021. So naturally time to change things up on the car again

We still have a bit left to finish - the main things being the conversion to wide body and the relocation of the oil & trans coolers. For the widebody work we had been planning on giving that a shot ourselves - but the guys at M-Technik made a good call and talked me in to going with a kit from DTM Fiberwerkz instead. Free time to put towards that is already hard to come by and will get even worse while I'm down for awhile here soon.

The kit is here and looks great. Very well built & although just mocking it up right now the fit looks promising. We will have to adapt it a bit to fit within the specs of the classes we will race in next year - but overall looks like a great product so far. Also fits perfectly with the 12" wheels & 330mm tires on the front.

Also making progress on the tuning front. By this time next week should have a tune to account for the cams & headers







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      10-13-2020, 09:04 PM   #247
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Quote:
Originally Posted by OG Shark View Post
Well race season is over - it was short and sweet but now on to the offseason.
Going to have one or two more track days here shortly, but no more competing until 2021. So naturally time to change things up on the car again

We still have a bit left to finish - the main things being the conversion to wide body and the relocation of the oil & trans coolers. For the widebody work we had been planning on giving that a shot ourselves - but the guys at M-Technik made a good call and talked me in to going with a kit from DTM Fiberwerkz instead. Free time to put towards that is already hard to come by and will get even worse while I'm down for awhile here soon.

The kit is here and looks great. Very well built & although just mocking it up right now the fit looks promising. We will have to adapt it a bit to fit within the specs of the classes we will race in next year - but overall looks like a great product so far. Also fits perfectly with the 12" wheels & 330mm tires on the front.

Also making progress on the tuning front. By this time next week should have a tune to account for the cams & headers







Nice

What kind of power are you expecting to make with a finalized tune? I thought 417 was pretty good already. Was that on race or pump gas?
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      10-14-2020, 08:33 PM   #248
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Originally Posted by tsk94 View Post
Nice

What kind of power are you expecting to make with a finalized tune? I thought 417 was pretty good already. Was that on race or pump gas?
Hoping for a bit more - but not really expecting much over what we have already seen. 101
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      10-23-2020, 11:10 PM   #249
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I see. The higher rear rate will definitely make the car have less understeer bias in the steady-state. But overall grip, specifically in the front, is unaffected by the higher rear rate. You'll need a bigger or stickier tire to get more grip, or soften the spring rates (if they are too high already) to maximize mechanical grip.
Quote:
Originally Posted by Bartledoo View Post
Well, if too soft you will lose grip as well, and have to battle with f'd up tire wear.
This actually isn't entirely true (what I said).

Roll stiffness, specifically roll couple distribution, is what ultimately determines the handling balance in the steady state. The first step you, or someone, should always take to improve grip is going to a stickier tire. If that's out of the question, perhaps for due to rules mandating you run a particular tire, then the next step is to play with the roll couple distribution and wheel rates. This is amount of roll stiffness the front of the car has, relative to the rear. Increasing the rear roll stiffness (relative to the front) is what will get rid of understeer in the steady state. This can be down by softening the front springs or bars or stiffening the rear springs or bars. There is actually some published research indicating that stiffening the rear (via spring rate), relative to front, results in improved lateral acceleration - holding the setup on the car otherwise unchanged.

With that being said wheel rates and frequencies are also very important to consider as well. For the most part, almost everyone on the E9X chassis is running VERY front-biased spring rates. This leads to wheel rates and frequencies that are much higher in the front compared to the rear. In short, the effect of this is a car with the tendency to understeer more, a lot more, in the steady state. Now obviously there are other elements of suspension and alignment setup that can help mitigate this problem, but starting with the proper spring rates seems to be the best starting point.

Of most M3 track cars/builds I've seen on this forum, it seems like OG Shark is one of the few that's running spring rates that are even remotely close to being 'balanced' in terms of wheel rates and frequencies. Most, including myself, are severely front-biased - leading to a natural steady state handling balance of understeer.

This post is getting a bit long-winded so I'll cut it here, I mainly wanted to clarify my post from earlier to prevent misinformation from being spread. I'm in the process of completely reworking my spring rates (and thus wheel rates and frequencies) for next season to test this for myself and plan to start a thread outlining the mechanics in more detail and begin a more in-depth discussions.
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      10-23-2020, 11:38 PM   #250
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Very nice OG! Now all we need is to get you a proper set of brakes!
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      10-23-2020, 11:44 PM   #251
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Very nice OG! Now all we need is to get you a proper set of brakes!
How can he get a proper set of brakes when the don't even make them for this car anymore?!
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      10-24-2020, 02:12 AM   #252
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Quote:
Originally Posted by tsk94 View Post
This actually isn't entirely true (what I said).

Roll stiffness, specifically roll couple distribution, is what ultimately determines the handling balance in the steady state. The first step you, or someone, should always take to improve grip is going to a stickier tire. If that's out of the question, perhaps for due to rules mandating you run a particular tire, then the next step is to play with the roll couple distribution and wheel rates. This is amount of roll stiffness the front of the car has, relative to the rear. Increasing the rear roll stiffness (relative to the front) is what will get rid of understeer in the steady state. This can be down by softening the front springs or bars or stiffening the rear springs or bars. There is actually some published research indicating that stiffening the rear (via spring rate), relative to front, results in improved lateral acceleration - holding the setup on the car otherwise unchanged.

With that being said wheel rates and frequencies are also very important to consider as well. For the most part, almost everyone on the E9X chassis is running VERY front-biased spring rates. This leads to wheel rates and frequencies that are much higher in the front compared to the rear. In short, the effect of this is a car with the tendency to understeer more, a lot more, in the steady state. Now obviously there are other elements of suspension and alignment setup that can help mitigate this problem, but starting with the proper spring rates seems to be the best starting point.

Of most M3 track cars/builds I've seen on this forum, it seems like OG Shark is one of the few that's running spring rates that are even remotely close to being 'balanced' in terms of wheel rates and frequencies. Most, including myself, are severely front-biased - leading to a natural steady state handling balance of understeer.

This post is getting a bit long-winded so I'll cut it here, I mainly wanted to clarify my post from earlier to prevent misinformation from being spread. I'm in the process of completely reworking my spring rates (and thus wheel rates and frequencies) for next season to test this for myself and plan to start a thread outlining the mechanics in more detail and begin a more in-depth discussions.
Yea, this is where I'm at as well. Cheers for spending the time to put it all into words!
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      10-24-2020, 02:55 AM   #253
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Quote:
Originally Posted by tsk94 View Post
Quote:
Originally Posted by tsk94 View Post
I see. The higher rear rate will definitely make the car have less understeer bias in the steady-state. But overall grip, specifically in the front, is unaffected by the higher rear rate. You'll need a bigger or stickier tire to get more grip, or soften the spring rates (if they are too high already) to maximize mechanical grip.
Quote:
Originally Posted by Bartledoo View Post
Well, if too soft you will lose grip as well, and have to battle with f'd up tire wear.
This actually isn't entirely true (what I said).

Roll stiffness, specifically roll couple distribution, is what ultimately determines the handling balance in the steady state. The first step you, or someone, should always take to improve grip is going to a stickier tire. If that's out of the question, perhaps for due to rules mandating you run a particular tire, then the next step is to play with the roll couple distribution and wheel rates. This is amount of roll stiffness the front of the car has, relative to the rear. Increasing the rear roll stiffness (relative to the front) is what will get rid of understeer in the steady state. This can be down by softening the front springs or bars or stiffening the rear springs or bars. There is actually some published research indicating that stiffening the rear (via spring rate), relative to front, results in improved lateral acceleration - holding the setup on the car otherwise unchanged.

With that being said wheel rates and frequencies are also very important to consider as well. For the most part, almost everyone on the E9X chassis is running VERY front-biased spring rates. This leads to wheel rates and frequencies that are much higher in the front compared to the rear. In short, the effect of this is a car with the tendency to understeer more, a lot more, in the steady state. Now obviously there are other elements of suspension and alignment setup that can help mitigate this problem, but starting with the proper spring rates seems to be the best starting point.

Of most M3 track cars/builds I've seen on this forum, it seems like OG Shark is one of the few that's running spring rates that are even remotely close to being 'balanced' in terms of wheel rates and frequencies. Most, including myself, are severely front-biased - leading to a natural steady state handling balance of understeer.

This post is getting a bit long-winded so I'll cut it here, I mainly wanted to clarify my post from earlier to prevent misinformation from being spread. I'm in the process of completely reworking my spring rates (and thus wheel rates and frequencies) for next season to test this for myself and plan to start a thread outlining the mechanics in more detail and begin a more in-depth discussions.
Please do start the thread, I really enjoy and appreciate the ease at which you explain tough concepts!
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      10-24-2020, 05:53 AM   #254
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Quote:
Originally Posted by DRLane View Post
Quote:
Originally Posted by tsk94 View Post
Quote:
Originally Posted by tsk94 View Post
I see. The higher rear rate will definitely make the car have less understeer bias in the steady-state. But overall grip, specifically in the front, is unaffected by the higher rear rate. You'll need a bigger or stickier tire to get more grip, or soften the spring rates (if they are too high already) to maximize mechanical grip.
Quote:
Originally Posted by Bartledoo View Post
Well, if too soft you will lose grip as well, and have to battle with f'd up tire wear.
This actually isn't entirely true (what I said).

Roll stiffness, specifically roll couple distribution, is what ultimately determines the handling balance in the steady state. The first step you, or someone, should always take to improve grip is going to a stickier tire. If that's out of the question, perhaps for due to rules mandating you run a particular tire, then the next step is to play with the roll couple distribution and wheel rates. This is amount of roll stiffness the front of the car has, relative to the rear. Increasing the rear roll stiffness (relative to the front) is what will get rid of understeer in the steady state. This can be down by softening the front springs or bars or stiffening the rear springs or bars. There is actually some published research indicating that stiffening the rear (via spring rate), relative to front, results in improved lateral acceleration - holding the setup on the car otherwise unchanged.

With that being said wheel rates and frequencies are also very important to consider as well. For the most part, almost everyone on the E9X chassis is running VERY front-biased spring rates. This leads to wheel rates and frequencies that are much higher in the front compared to the rear. In short, the effect of this is a car with the tendency to understeer more, a lot more, in the steady state. Now obviously there are other elements of suspension and alignment setup that can help mitigate this problem, but starting with the proper spring rates seems to be the best starting point.

Of most M3 track cars/builds I've seen on this forum, it seems like OG Shark is one of the few that's running spring rates that are even remotely close to being 'balanced' in terms of wheel rates and frequencies. Most, including myself, are severely front-biased - leading to a natural steady state handling balance of understeer.

This post is getting a bit long-winded so I'll cut it here, I mainly wanted to clarify my post from earlier to prevent misinformation from being spread. I'm in the process of completely reworking my spring rates (and thus wheel rates and frequencies) for next season to test this for myself and plan to start a thread outlining the mechanics in more detail and begin a more in-depth discussions.
Please do start the thread, I really enjoy and appreciate the ease at which you explain tough concepts!
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      10-24-2020, 05:58 AM   #255
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Quote:
Originally Posted by tsk94 View Post
How can he get a proper set of brakes when the don't even make them for this car anymore?!
Fortunately we now have the Alcons which have the most demented rotors you have ever seen. And you can get real (PFC) pads for them
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      10-24-2020, 09:06 AM   #256
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Quote:
Originally Posted by tsk94 View Post
...
I'm in the process of completely reworking my spring rates (and thus wheel rates and frequencies) for next season to test this for myself and plan to start a thread outlining the mechanics in more detail and begin a more in-depth discussions.
I'm always interested in this topic and making similar changes to my car for next season so will await your thread with anticipation!
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      10-24-2020, 10:47 AM   #257
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Quote:
Originally Posted by tsk94 View Post
This actually isn't entirely true (what I said).

Roll stiffness, specifically roll couple distribution, is what ultimately determines the handling balance in the steady state. The first step you, or someone, should always take to improve grip is going to a stickier tire. If that's out of the question, perhaps for due to rules mandating you run a particular tire, then the next step is to play with the roll couple distribution and wheel rates. This is amount of roll stiffness the front of the car has, relative to the rear. Increasing the rear roll stiffness (relative to the front) is what will get rid of understeer in the steady state. This can be down by softening the front springs or bars or stiffening the rear springs or bars. There is actually some published research indicating that stiffening the rear (via spring rate), relative to front, results in improved lateral acceleration - holding the setup on the car otherwise unchanged.

With that being said wheel rates and frequencies are also very important to consider as well. For the most part, almost everyone on the E9X chassis is running VERY front-biased spring rates. This leads to wheel rates and frequencies that are much higher in the front compared to the rear. In short, the effect of this is a car with the tendency to understeer more, a lot more, in the steady state. Now obviously there are other elements of suspension and alignment setup that can help mitigate this problem, but starting with the proper spring rates seems to be the best starting point.

Of most M3 track cars/builds I've seen on this forum, it seems like OG Shark is one of the few that's running spring rates that are even remotely close to being 'balanced' in terms of wheel rates and frequencies. Most, including myself, are severely front-biased - leading to a natural steady state handling balance of understeer.

This post is getting a bit long-winded so I'll cut it here, I mainly wanted to clarify my post from earlier to prevent misinformation from being spread. I'm in the process of completely reworking my spring rates (and thus wheel rates and frequencies) for next season to test this for myself and plan to start a thread outlining the mechanics in more detail and begin a more in-depth discussions.
tsk94 great stuff. More than welcome to have this discussion on this thread but do think it would be better served as a separate thread. Will be much more visible and also hopefully be picked up on better in searches - this is great info that needs to be as visible as possible!


As far as my spring rate choice - a few drivers that lead to 800/800 for us. Right or wrong this is how we got there. Weight balance - we are creeping in on 50/50 - don’t think we will quite get there but should end up pretty close. We are also going to be running a pretty decent aero package at times - this will change a bit though depending on which org we are running in at the time. I also like a neutral car but Also do know their are multiple ways of getting there besides matching spring rates - just felt like a good starting point.

I do also have quite a bit of grip in the rear that so far has played nice with the spring rates. Between the diff, balance, and sticky tires we have not had to make adjustments to add grip in the rear yet. This should only get better too as we better the weight balance, add more tire to the rear, and add the front aero we’ve been missing allowing us to dial in some more rear aero.

So far the car has been very neutral. Hint of exit oversteer which is very manageable. Expect it to possibly change a bit with the upgrades coming - but anticipate it being close to where I want it. That being said we will be extensively testing both lower and higher rates. Absolutely want to see if there are any improvements to be had.
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      10-24-2020, 10:49 AM   #258
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I second that. I like complex
Understatement of the year right there!!!
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      11-04-2020, 12:58 PM   #259
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Originally Posted by SYT_Shadow View Post
Fortunately we now have the Alcons which have the most demented rotors you have ever seen. And you can get real (PFC) pads for them
Oooooh, I want to see these. Is this the Bimmerworld kit?

In the same vein, I'm starting to wonder if the E92 kit from Essex is suboptimal. Local guy was ranting to me about how the Essex caliper isn't even a full race version.

I have a feeling the Schirmer guys run an AP Racing kit that's different to Essex, and likely a better option. Someone want to donate to a GoFundMe to find out? :P
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      11-04-2020, 01:40 PM   #260
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Quote:
Originally Posted by LeveragedTiger View Post
Oooooh, I want to see these. Is this the Bimmerworld kit?

In the same vein, I'm starting to wonder if the E92 kit from Essex is suboptimal. Local guy was ranting to me about how the Essex caliper isn't even a full race version.

I have a feeling the Schirmer guys run an AP Racing kit that's different to Essex, and likely a better option. Someone want to donate to a GoFundMe to find out? :P
They are definitely doing something different for sure. Their hats are custom and the rotors look different. Possibly a totally different caliper. I think out back they just have custom brackets to use an AP caliper on the stock rotors.
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      11-04-2020, 02:35 PM   #261
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Quote:
Originally Posted by LeveragedTiger View Post
Oooooh, I want to see these. Is this the Bimmerworld kit?

In the same vein, I'm starting to wonder if the E92 kit from Essex is suboptimal. Local guy was ranting to me about how the Essex caliper isn't even a full race version.

I have a feeling the Schirmer guys run an AP Racing kit that's different to Essex, and likely a better option. Someone want to donate to a GoFundMe to find out? :P
Yes, it's the Bimmerworld kit. PM your email or something and I'll send some pics over.

The AP RadiCal/Essex kit is not worth the money. It's top shelf price but not top shelf performance.

I've seen the M4 GT4's brakes up close and they are branded AP Radical but it is a completely different kit than what we buy.

Obviously it all depends on what you are doing. Someone at the track in an M4 full race built told me they loved their APs. I asked how many pads they had gone through. The answer was zero. So... how could this person know much about the brakes they're running.
I go through a pad in one or at most two weekends. I've used all 3 big boy kits (AP, PFC, Alcon-BW). The AP is not, at all, at the level of the other two.

My use case is not typical, but it is what I consider torture testing. If I buy a rear BBK that is 4.5k it had better perform at that level. It had better be able to chew through pads and give me nice even wear. The rotors had better last a long time, because I have other rotors that last much longer from other kits.
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      11-04-2020, 03:24 PM   #262
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Quote:
Originally Posted by LeveragedTiger View Post
Oooooh, I want to see these. Is this the Bimmerworld kit?

In the same vein, I'm starting to wonder if the E92 kit from Essex is suboptimal. Local guy was ranting to me about how the Essex caliper isn't even a full race version.

I have a feeling the Schirmer guys run an AP Racing kit that's different to Essex, and likely a better option. Someone want to donate to a GoFundMe to find out? :P
Quote:
Originally Posted by //steve\\ View Post
They are definitely doing something different for sure. Their hats are custom and the rotors look different. Possibly a totally different caliper. I think out back they just have custom brackets to use an AP caliper on the stock rotors.
Been running the Essex AP kits on this car & my M2 (which is no slouch either) & haven't found anything suboptimal about them yet. Like to think I push them pretty hard, especially while racing in the M3. Complete confidence in them & feel like braking is probably one of my stronger points on the track. I do not run ducts to the front either, have not experienced any fade to this point. Think I will add some ducts though over the winter to see if they have a positive effect on pad wear.
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      11-04-2020, 03:34 PM   #263
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Quote:
Originally Posted by SYT_Shadow View Post
Yes, it's the Bimmerworld kit. PM your email or something and I'll send some pics over.

The AP RadiCal/Essex kit is not worth the money. It's top shelf price but not top shelf performance.

I've seen the M4 GT4's brakes up close and they are branded AP Radical but it is a completely different kit than what we buy.

Obviously it all depends on what you are doing. Someone at the track in an M4 full race built told me they loved their APs. I asked how many pads they had gone through. The answer was zero. So... how could this person know much about the brakes they're running.
I go through a pad in one or at most two weekends. I've used all 3 big boy kits (AP, PFC, Alcon-BW). The AP is not, at all, at the level of the other two.

My use case is not typical, but it is what I consider torture testing. If I buy a rear BBK that is 4.5k it had better perform at that level. It had better be able to chew through pads and give me nice even wear. The rotors had better last a long time, because I have other rotors that last much longer from other kits.
I do not have a problem chewing through pads... no problem at all

What was your issue with the AP set compared to the others? You say that they are not at all on the same level - how so? Can't just say drop that and not back it up - learn us!!!

And as you know many people who say they love their brakes on the track (or hate others) have not really pushed brakes before. One guy in an M4 that hasn't burned up any pads doesn't really fail the product. You know how it goes with BBKs - if someone says how much better they stop than whatever they had before likely hasn't pushed either to their max.
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      11-05-2020, 12:41 AM   #264
LeveragedTiger
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Quote:
Originally Posted by OG Shark View Post
Been running the Essex AP kits on this car & my M2 (which is no slouch either) & haven't found anything suboptimal about them yet. Like to think I push them pretty hard, especially while racing in the M3. Complete confidence in them & feel like braking is probably one of my stronger points on the track. I do not run ducts to the front either, have not experienced any fade to this point. Think I will add some ducts though over the winter to see if they have a positive effect on pad wear.
I think the main knock against them is uneven pad wear.

The other thing as SYT_Shadow mentioned is that Essex markets their product as a premium product, even though the Pro 5000 R caliper series is actually an "entry-level" product according to AP Racing's website. See for yourself: https://apracing.com/race-car/brake-...o-5000-r-range

There are actually two caliper lines that slot above the 5000 R series: 1) The 5000+ series (EDIT, I can't actually tell if 5000+ slots above the R), or 2) the GT/Touring car line-up.

I have been looking at CP5095 caliper and it would have exactly the same torque as the CP9668 caliper. It's also about a pounder lighter while holding the same size of pad (25mm). Just need someone to fab brackets but that's not exactly rocket science.

https://apracing.com/race-car/brake-...adi-cal-cp5095

//steve\\ - I think Schirmer runs either something from the 5000+ line (CP5270 up front) or the CP5095 from the GT/Touring line.
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Last edited by LeveragedTiger; 11-05-2020 at 12:48 AM..
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