01-30-2024, 07:14 AM | #23 |
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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? |
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01-30-2024, 07:21 AM | #24 | |
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01-30-2024, 07:30 AM | #25 | |
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01-30-2024, 08:32 AM | #26 | |
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01-30-2024, 09:36 AM | #27 | |
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01-30-2024, 10:22 AM | #28 |
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02-17-2024, 10:28 AM | #29 |
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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 👍
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02-18-2024, 08:35 AM | #31 |
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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 👍👍👍
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02-18-2024, 08:57 AM | #32 | |
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Sweet! Can’t wait guys!!! |
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02-18-2024, 09:00 AM | #33 |
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Hi Tony, can you measure piston size for the viewers? A few want to calculate the increase over stock.
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02-18-2024, 10:34 AM | #34 |
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I’ve mentioned this in the prior discussion, at 31mm (see attached picture) , so overall piston area increase will be minimal
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02-18-2024, 10:41 AM | #35 |
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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?
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02-18-2024, 10:50 AM | #36 |
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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
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02-18-2024, 09:19 PM | #37 |
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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.
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02-18-2024, 09:31 PM | #38 | |
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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. |
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02-18-2024, 09:36 PM | #39 |
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..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.
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02-18-2024, 10:50 PM | #40 | |
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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 |
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02-19-2024, 06:58 AM | #41 | |
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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. |
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02-19-2024, 08:56 AM | #42 | |
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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 |
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02-19-2024, 09:15 PM | #43 |
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Formula for area of a piston is pi times the radius SQUARED, not doubled.
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02-20-2024, 06:15 PM | #44 |
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