[tpoddar]

Hey guys,
I own a b48 320i LCI luxury line with 300x22mm rotors up front and 300x20mm rotors at the back. The rotors have been paired with EBC yellowstuff brake pads as recommended to maximize brake bite and minimize fade. Im also running Pirelli Cinturato P7 RFT tires (size - 225/50 R17). Pads and brake rotors (Brembo standard) were installed 5000 kms ago and brakes were bled by the dealer as recommended.

Despite performing all these steps, the braking performance of my car is poor to say the least. All the other cars we own (Audi A6,Q5 and Merc. ML) have much superior braking performance in terms of brake grab when the the pedal is initially pressed and overall brake feel. While I haven't compared stopping distances, I know that my Q5 can stop much faster than my 320i can from the same speed.

While the EBC yellowstuff pads have completely eliminated any brake fade issues, there is still a huge lack of bite and I feel that all the braking ability of the car is in the last 20% of the brake pedal. These issues have really become a huge pain ever since I've started to run a bootmod3 stage 2 tune since the car is unable to cope with the added power.

I do not wish to spend thousands over a brake upgrade unless absolutely necessary and stainless steel brake lines are the only remaining upgrade I can think of. I have also seen a video that claims in an improvement in brake feel by recalibrating the DSC pump, do you think that would help? I appreciate any suggestions I can get for this problem as it is the only problem that's plaguing my otherwise perfect driving experience.

[Walker_CW]

Originally Posted by tpoddar

Hey guys,
I own a b48 320i LCI luxury line with 300x22mm rotors up front and 300x20mm rotors at the back. The rotors have been paired with EBC yellowstuff brake pads as recommended to maximize brake bite and minimize fade. Im also running Pirelli Cinturato P7 RFT tires (size - 225/50 R17). Pads and brake rotors (Brembo standard) were installed 5000 kms ago and brakes were bled by the dealer as recommended.

Despite performing all these steps, the braking performance of my car is poor to say the least. All the other cars we own (Audi A6,Q5 and Merc. ML) have much superior braking performance in terms of brake grab when the the pedal is initially pressed and overall brake feel. While I haven't compared stopping distances, I know that my Q5 can stop much faster than my 320i can from the same speed.

While the EBC yellowstuff pads have completely eliminated any brake fade issues, there is still a huge lack of bite and I feel that all the braking ability of the car is in the last 20% of the brake pedal. These issues have really become a huge pain ever since I've started to run a bootmod3 stage 2 tune since the car is unable to cope with the added power.

I do not wish to spend thousands over a brake upgrade unless absolutely necessary and stainless steel brake lines are the only remaining upgrade I can think of. I have also seen a video that claims in an improvement in brake feel by recalibrating the DSC pump, do you think that would help? I appreciate any suggestions I can get for this problem as it is the only problem that's plaguing my otherwise perfect driving experience.

My 2018 330xi has 312mm rotors, and I would describe my issue as the same as yours. They work fine, just underpowered.

I believe I'm going to get StopTech Sport pads, but I'll look in to the EBC YellowStuff as well.

Any suggestions anyone would have, stainless lines or recalibrating DSC pump would be great!

[djacinto]

For my setup, it was the tires that made things very different. Yes, pads and rotors do as well but I noticed the biggest difference when I swapped to my winter wheels, 225/50/17 pirelli p7 cinturato run flats.

I did a full brake refresh in may 2021 and swapped wheels in November 2021. Immediately noticed the difference in braking distance because my other tires, conti dws 06's are much much grippier.

If you want to keep your parts since you've already purchased them, which I would probably do anyways, get new tires. The stock rft suck and are not great for anything other than peace of mind for those not able to swap their tires.

Non run flat all seasons are so much better and you will immediately feel the difference in all those aspects.

[cfm56d7b]

This is a very common issue: the brake pad is not soft enough to provide a more aggressive initial bite.

[tpoddar]

Originally Posted by cfm56d7b

This is a very common issue: the brake pad is not soft enough to provide a more aggressive initial bite.

Im using the best available for this rotor size. EBC yellowstuff are widely known for being one of the most aggressive pads available in terms of bite so I don't know what else to try. Hawk 5.0 aren't available for this size.

[cfm56d7b]

Originally Posted by tpoddar

Im using the best available for this rotor size. EBC yellowstuff are widely known for being one of the most aggressive pads available in terms of bite so I don't know what else to try. Hawk 5.0 aren't available for this size.

Did your car have OEM brake pads and then you installed EBC Yellowstuff later?

[tpoddar]

Originally Posted by cfm56d7b

Did your car have OEM brake pads and then you installed EBC Yellowstuff later?

yes.

[Onizukachan]

I have a 328d (320d EU) f31 which came with the 312/300 brake set up from factory.

Had same issues, resulting in my wife rear ending someone in an emergency stop situation when the Japanese econo car ahead of her stopped much shorter than it could, resulting in a low speed collision.

They are simply undersized.

I solved the problem by getting a set of used 340/330 brakes and rotors off someone with a 335/340i who had upgraded to the mperformance 370/345 system. It was about $900 all in plus some caliper paint.

Even With stock (super dusty) Msport pads and factory run flats (still) the brakes are now confidence inspiring instead of dread inspiring.

I would honestly suggest that instead of spending even more funds on trying to improve things further, which you won’t, you simply get brakes adequately sized to your car’s weight and performance and it doesn’t have to cost a lot.

A few hours of your time finding someone who recently upgraded and is looking to recover partial costs by selling their old set up, and a couple more hours swapping parts, and you will be pleased.

[tpoddar]

Originally Posted by Onizukachan

I would honestly suggest that instead of spending even more funds on trying to improve things further, which you won’t, you simply get brakes adequately sized to your car’s weight and performance and it doesn’t have to cost a lot.

A few hours of your time finding someone who recently upgraded and is looking to recover partial costs by selling their old set up, and a couple more hours swapping parts, and you will be pleased.

I have often thought about upgrading to the 340/330mm setup from a 335i but the sad part is that my country never got that model. The only other brake option available in my country was the 312/300mm setup which I know won't be a sufficient upgrade from my current setup. The only options I have are to buy a big brake kit or import a m performance brake kit from abroad which would cost the same as a Big brake kit due to all the duties etc.

[Onizukachan]

Apologies for not knowing that, can you source just the calipers used and buy new discs without being raped on customs duties?

If not hawk 5.0 pads are about the limit of what you will be able to do otherwise. Just not enough mechanical advantage on the small rotors.

[tpoddar]

Originally Posted by Onizukachan

Apologies for not knowing that, can you source just the calipers used and buy new discs without being raped on customs duties?

If not hawk 5.0 pads are about the limit of what you will be able to do otherwise. Just not enough mechanical advantage on the small rotors.

Sourcing used calipers would cost 900 USD including shipping. 4 discs and 2 sets of pads would cost another 1100 so it'll end up being a 2k plus USD job. This is an extremely conservative estimate.

[tpoddar]

Would switching to 330x24 brakes up front from a 330i b48 help with my problem? How much of a difference should I expect? Any opinions

[Onizukachan]

Yes, anything bigger would be loads better. From what you report your front brakes are the size of my original REAR brakes,

[tpoddar]

Just a front brake upgrade from my current setup to the setup from a 330i with EBC yellowstuff pads and ss lines should be about 700USD. Unless I find any other options, I will go ahead with this.

[tpoddar]

As I read more about this upgrade, the more I get confused. I hope experts can chime in to help.

The front brakes on a 330i are 330x24mm with a single piston caliper upfront. This caliper has a 57mm piston in comparison to my car's 54mm single piston caliper. Considering that the piston isn't that much larger than my car's, should i expect an improvement in braking performance? The larger and thicker disc should help with heat dissipation and I would expect that a 10% greater surface area would give the brake pad more area to grab onto but what % improvement of braking performance should I expect?

[Jimmert]

Friction force (of the brakes) is determined by the friction coefficient (material property) and the normal force (force applied by the caliper, which is determined by the piston diameter). Just only upgrading disc/pad size isn’t going to increase either the coefficient nor the normal force. Maybe the brake performance will be improved a little tiny bit (because disc stays slightly cooler), but not worth the upgrade imho. I don’t believe you’ll notice any difference. Either do it properly, meaning upgrade both the rotors/pads AND calipers or don’t do it at all. From my experience if you are looking for initial bite, there isn’t much that beat the OEM BMW pads, they are soft, dusty as hell, but yes they bite! Aftermarket solutions like EBC or Hawk can offer better braking performance in general, less fading, less dust, shorter stopping distance on high speed etc.

If you drive ‘normally’, and not often very spirited, stick to OEM.

[tpoddar]

Originally Posted by Jimmert

Friction force (of the brakes) is determined by the friction coefficient (material property) and the normal force (force applied by the caliper, which is determined by the piston diameter). Just only upgrading disc/pad size isn’t going to increase either the coefficient nor the normal force. Maybe the brake performance will be improved a little tiny bit (because disc stays slightly cooler), but not worth the upgrade imho. I don’t believe you’ll notice any difference. Either do it properly, meaning upgrade both the rotors/pads AND calipers or don’t do it at all. From my experience if you are looking for initial bite, there isn’t much that beat the OEM BMW pads, they are soft, dusty as hell, but yes they bite! Aftermarket solutions like EBC or Hawk can offer better braking performance in general, less fading, less dust, shorter stopping distance on high speed etc.

If you drive ‘normally’, and not often very spirited, stick to OEM.

I tend to drive my car in my spirited manner but bite characteristics are much more important than fade for me so I'll stick to BMW oem for pads.

With regards to upgrading the disc and pad, if I switch to the 330mm rotor, I'll also upgrade the caliper. So if i upgrade the caliper, the normal force will increase and I'll get better braking right? Question is by how much, a 10% increase in surface area of contact (considering the bigger disc and pad contact area) with a bigger caliper (3mm piston diameter bigger in comparison) would make how much difference?

[Onizukachan]

Jimmert, you forgot about the increase in the lever arm.

It’s not increased clamping force, greater Mu, nor increased heat sink that makes larger brakes have more braking power.

It’s that they literally have a larger mechanical advantage.

Hypothetically Mount the same caliper and pads on a 300mm disc and a 340 mm disc. The 340 will brake more effectively and stop shorter. It’s simple physics.

That’s also the real world difference between the 340 m sport and 370 m performance brakes. Same caliper and same pads, larger lever.

[Jimmert]

Yes you’re right. What is ‘stopping’ your car is the brake moment around the wheel center, so that is determined by the friction force times the lever (distance friction force center to wheel center). However does that lever length change when you only change the rotor?

Regarding the 340mm vs 370mm setup, you’re not correct, the 370mm has different calipers as well (stamped on the backside). So the pistons of the 370mm variant are also moved outside.

[Onizukachan]

Originally Posted by Jimmert

Yes you’re right. What is ‘stopping’ your car is the brake moment around the wheel center, so that is determined by the friction force times the lever (distance friction force center to wheel center). However does that lever length change when you only change the rotor?

Regarding the 340mm vs 370mm setup, you’re not correct, the 370mm has different calipers as well (stamped on the backside). So the pistons of the 370mm variant are also moved outside.

Same exact caliper, only mounting ears are moved 15 mm longer . Different pn and marked 370/380 because they are otherwise identical to the 340 besides mounting ears.

You can’t only change the rotor size without moving the caliper and thus increasing lever to clear it.

[cfm56d7b]

Brakes are much more complex than just a collection of parts: calipers, pistons, pads, and wear sensors.

Worth reading about the debate about 4 piston calipers vs 6 piston calipers to appreciate how much complex brake technology is.

https://f30.bimmerpost.com/forums/sh....php?t=1834199

My suggestion: try to find M Sport or M Performance brake kit and install it correctly, including proper coding.

[tpoddar]

Does switching from 300mm brakes upfront to 330mm require any sort of coding for the abs or the brake system to work optimally?