[M3SQRD]

Still looking for piston sizes or caliper piston total area so the G8x single-piston sliding-caliper area and your 4p fixed-caliper piston area can be compared (or verified if you provide your area calculations), and F-R brake bias changes checked (or verified if you provide your calculations).

What manufacturer(s)/model(s) has/have used this caliper?

[dentprotony@gmail.com]

Originally Posted by M3SQRD

If the pad outer radius is currently 2 mm larger than the iron disc radius and you shift the caliper down 3.5 mm to minimize the pad and rotor inner radius issue, doesn’t that now create a 1.5 mm mismatch of pad and rotor outer radius? This would force you into always having to change rear rotors every time you change pads due to the 1.5 mm lip that’s formed on the OD of the rotor. Capturing the rotor OD should be more important plus you’re losing braking performance, albeit small, by not using the full rotor at its OD vs. its ID. This happens on every brake caliper retrofit kit. I’d prefer to have the pad and rotor OR match, not minimize the pad rotor IR mismatch, even if it creates an ugly rusted ring at the rotor ID. People need to understand this difference when purchasing this kit?

No both op and myself mentioned several times, total disc surface area is about 2-3mm larger thanthe pad, kit in the picture is a test version, I needed to confirm overall fit, brake line length, bolt length, because typically it would require additional machine work hence why it os not painted. Pad/caliper will be moved in and would have 1mm of the rotor showing on the outer and 2mm inner. I will not offer a kit that has pad overhanging the rotor. I know a little better than that. And again I wanted to make it clear, set up pictured is a test version to confirm/adjust fit , it will be adjusted next week, be on standby for the finished set

[dentprotony@gmail.com]

Originally Posted by M3SQRD

Still looking for piston sizes or caliper piston total area so the G8x single-piston sliding-caliper area and your 4p fixed-caliper piston area can be compared (or verified if you provide your area calculations), and F-R brake bias changes checked (or verified if you provide your calculations).

What manufacturer(s)/model(s) has/have used this caliper?

I replied to you about which vehicles use this caliper and responded to another member with piston area calculations, are you upset with something that all the communication you offer is in the form of interrogation? I hope you would have a better day today

[M3SQRD]

Originally Posted by dentprotony@gmail.com

I replied to you about which vehicles use this caliper and responded to another member with piston area calculations, are you upset with something that all the communication you offer is in the form of interrogation? I hope you would have a better day today

Not at all. Just asking direct questions and providing facts about CCB systems that have been around for almost a decade now for BMWs. I read your response but somehow I glossed over the Porsche Panamera - sorry about that! I missed the other post with the caliper information you provided. Every generation of M3/M4 has people putting together retrofit kits, some successful but most are not. Most refuse to provide piston areas and brake bias calculations. Thanks for providing it

[dentprotony@gmail.com]

Originally Posted by M3SQRD

Not at all. Just asking direct questions and providing facts about CCB systems that have been around for almost a decade now for BMWs. I read your response but somehow I glossed over the Porsche Panamera - sorry about that! I missed the other post with the caliper information you provided. Every generation of M3/M4 has people putting together retrofit kits, some successful but most are not. Most refuse to provide piston areas and brake bias calculations. Thanks for providing it

Yes sir i have been using this caliper for years, between pad selection, piston area, availability, and structural rigidity it makes it a no brainer unless a wider caliper needs to be used due to rotor thickness

[mike@x-ph.com]

Originally Posted by dentprotony@gmail.com

I should have Jimmys kit out of paint with proper adjustments by the end of next week hopefully. Machine shop been crazy busy unfortunately

[ginohhh]

any updates on these? Especially with track season around the corner, I’d love to see a review on how they perform for spirited driving and track use 👍

[TopJimmy]

Originally Posted by ginohhh

any updates on these? Especially with track season around the corner, I’d love to see a review on how they perform for spirited driving and track use 👍

My set is almost finished. Tony is doing a custom powder coat job for me with red hydraulic calipers but a black EPBs.

[dentprotony@gmail.com]

Originally Posted by ginohhh

any updates on these? Especially with track season around the corner, I’d love to see a review on how they perform for spirited driving and track use 👍

I am working on Jimmys set today, calipers are milled to final spec, painted, and brackets are adjusted as well. Hopefully will be able to ship out tomorrow via fast shipping, then depending on Jimmys schedule he will get them on and report back 👍👍👍

[ginohhh]

Originally Posted by dentprotony@gmail.com

I am working on Jimmys set today, calipers are milled to final spec, painted, and brackets are adjusted as well. Hopefully will be able to ship out tomorrow via fast shipping, then depending on Jimmys schedule he will get them on and report back 👍👍👍

Sweet! Can’t wait guys!!!

[TopJimmy]

Originally Posted by dentprotony@gmail.com

I am working on Jimmys set today, calipers are milled to final spec, painted, and brackets are adjusted as well. Hopefully will be able to ship out tomorrow via fast shipping, then depending on Jimmys schedule he will get them on and report back 👍👍👍

Hi Tony, can you measure piston size for the viewers? A few want to calculate the increase over stock.

[dentprotony@gmail.com]

Originally Posted by TopJimmy

Hi Tony, can you measure piston size for the viewers? A few want to calculate the increase over stock.

I’ve mentioned this in the prior discussion, at 31mm (see attached picture) , so overall piston area increase will be minimal

[TopJimmy]

Originally Posted by dentprotony@gmail.com

I’ve mentioned this in the prior discussion, at 31mm (see attached picture) , so overall piston area increase will be minimal

Thank you. Am I right that multiple pistons spread the brake force across the pad better than a single piston pushing only from the middle?

[dentprotony@gmail.com]

Originally Posted by TopJimmy

Thank you. Am I right that multiple pistons spread the brake force across the pad better than a single piston pushing only from the middle?

That is correct, not ‘better’ but more evenly. Monoblock design of the caliper makes all the difference in how predictable/‘square’ would the brake application feel/perform. Floating caliper has more moving/sliding parts/pins in it

[vasillalov]

Its also about pad wear and heat management. Single piston calipers tend to wear one of the pads faster than the other and as a result of that they heat up one face of the rotor more than the other.

[vasillalov]

Originally Posted by dentprotony@gmail.com

Thanks man, appreciate your support, this caliper has all 4 equal diameter pistons (30mm vs 51mm stock) so it is non-directional and can be mounted in lead position or however it is necessary (it comes towards front on touaregs and sits in the back on Porsche Panamera), unsprung weight is more referred to a moving parts like wheels, brake rotors, flywheels, but we are keeping your stock rotor. As on brake bias, total piston areas compare at 180 vs 160 which adds to minimal (about 11-13%) increase in piston area. Given that rear brakes do only 30% of work this difference is negligible.
All this is definitely something to upgrade and install at your own risk, i am not a mechanic, i just get lucky sometimes

I believe your math is incorrect.

A single 51mm piston has 2,041.785mm area.
A single 30mm piston has 706.5mm area
Four 30mm pistons have 2,826mm area

The difference is 28% change, which can be very significant.

If the rear pad compund was the same between the two calipers, you would most definitely feel a significant change in brake bias. In medium to hard braking, you would feel the car squatting first before the front brakes bite. This can be good on the track in the hands of a good driver but I caution anyone who is not ready for something like this.

Of course the increased rear bias can be mitigated with a softer rear pad or a pad with lower initial friction coefficient.

[vasillalov]

..to elaborate further: I believe this is definitely an interesting solution and it has merit. In my view, most BMWs that I've driven could definitely use more rear brake bias! It's just not something that the average commuter is used to and will require some practice.

[dentprotony@gmail.com]

Originally Posted by vasillalov

I believe your math is incorrect.

A single 51mm piston has 2,041.785mm area.
A single 30mm piston has 706.5mm area
Four 30mm pistons have 2,826mm area

The difference is 28% change, which can be very significant.

If the rear pad compund was the same between the two calipers, you would most definitely feel a significant change in brake bias. In medium to hard braking, you would feel the car squatting first before the front brakes bite. This can be good on the track in the hands of a good driver but I caution anyone who is not ready for something like this.

Of course the increased rear bias can be mitigated with a softer rear pad or a pad with lower initial friction coefficient.

That is mostly correct, if i am not mistaken to calculate piston area you multiply by amount of pistons on one side (by 2 in my case), please double check.
I also wanted to mention i dont have experience driving g80 on the track unfortunately, but something to keep in mind, is rear brakes do 25% of actual braking, they do 30% in severe braking conditions (approximately) , to feel a 15% increase in piston area of the system that does 25% of work that would likely be very hard to do. Maybe more of a placebo, or fresh pads/fresh fluid situation would bring a very negligible amount of ‘different’ feel. Again in theory, in a severe braking situation/emergency conditions most drivers are out of control either way because things happen in seconds. They already would not know what to do with stock brakes as is, dsc, abs, tires and other assistants would do most of the work likely. Again I am not an engineer, i am an enthusiast, i have cool quick cars that i drive fast every now and then, i pay attention to mods, how things are built, physics, engineering solutions applied to our vehicles, and try to build cool unique set ups (brakes, heat exchangers, driveshafts) , keeping it fun, safe , classy/badass looking, and affordable.

PS correct me on the calculated piston area please, i would like to learn more , appreciate the conversation and your support

[vasillalov]

Originally Posted by dentprotony@gmail.com

That is mostly correct, if i am not mistaken to calculate piston area you multiply by amount of pistons on one side (by 2 in my case), please double check.
I also wanted to mention i dont have experience driving g80 on the track unfortunately, but something to keep in mind, is rear brakes do 25% of actual braking, they do 30% in severe braking conditions (approximately) , to feel a 15% increase in piston area of the system that does 25% of work that would likely be very hard to do. Maybe more of a placebo, or fresh pads/fresh fluid situation would bring a very negligible amount of ‘different’ feel. Again in theory, in a severe braking situation/emergency conditions most drivers are out of control either way because things happen in seconds. They already would not know what to do with stock brakes as is, dsc, abs, tires and other assistants would do most of the work likely. Again I am not an engineer, i am an enthusiast, i have cool quick cars that i drive fast every now and then, i pay attention to mods, how things are built, physics, engineering solutions applied to our vehicles, and try to build cool unique set ups (brakes, heat exchangers, driveshafts) , keeping it fun, safe , classy/badass looking, and affordable.

PS correct me on the calculated piston area please, i would like to learn more , appreciate the conversation and your support

I already did all of the multiplication for piston area for 1 caliper. You are replacing a single caliper piston with a 4-piston caliper. The math I showed is for one of the calipers being replaced so the % of change in the area for other caliper would be the same.

I agree, the vast majority of braking is provided by the front brakes. The thing is, the rear brakes are used for more than stopping the car. Various controllers may choose to apply braking at various times for various reasons. For an example, during heavy rain, the car will gently squeeze the brakes to ensure the pads are dry in case of emergency braking is needed. Stability control may choose to engage one of the rear brakes during acceleration in hard cornering, etc. The various computer modules do not know that the rear bias will be so different and so you may notice weird behavior. On a track, if you have the same brake compound as oem, you will notice the car squatting first before the front brakes engaging. This can increase driver confidence in straight line braking, but can be quite unnerving during delayed braking and entering a corner.

Like I said, this solution has merit, one just needs to be careful and relearn their car afterwards.

[dentprotony@gmail.com]

Originally Posted by vasillalov

I already did all of the multiplication for piston area for 1 caliper. You are replacing a single caliper piston with a 4-piston caliper. The math I showed is for one of the calipers being replaced so the % of change in the area for other caliper would be the same.

I agree, the vast majority of braking is provided by the front brakes. The thing is, the rear brakes are used for more than stopping the car. Various controllers may choose to apply braking at various times for various reasons. For an example, during heavy rain, the car will gently squeeze the brakes to ensure the pads are dry in case of emergency braking is needed. Stability control may choose to engage one of the rear brakes during acceleration in hard cornering, etc. The various computer modules do not know that the rear bias will be so different and so you may notice weird behavior. On a track, if you have the same brake compound as oem, you will notice the car squatting first before the front brakes engaging. This can increase driver confidence in straight line braking, but can be quite unnerving during delayed braking and entering a corner.

Like I said, this solution has merit, one just needs to be careful and relearn their car afterwards.

Correct, but keep in mind assistants do not slam on brakes, they ‘feel’ out the car/braking/traction and react to it , because there could be water/mud/ice etc. this happens in a fraction of seconds but they do adapt to given conditions , i wanted to confirm if I deducted piston area correctly, its 3.14 times dia times amount of pistons per one side (2). Please let me know if that latter is the correct equation or i been calculating it all wrong

[vasillalov]

Formula for area of a piston is pi times the radius SQUARED, not doubled.

[dentprotony@gmail.com]

Originally Posted by vasillalov

Formula for area of a piston is pi times the radius SQUARED, not doubled.

Gotcha, glad i learned something out of this 👍👍👍.