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      05-14-2018, 07:39 AM   #1
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Brake upgrade for my 120d F21

Hey there !

My f21 needs a discs and pads replacement so I've been thinking to put something better without spending loads.

Ive been reading a lot but Im not so sure if the brakes setup are the same in the E8x generation.

I know the best way would be to get the m performance kit, but tbh I dont want to spend that much. With stock brakes, the car aint bad at all.

What about to install 123d brakes? If I am not wrong I can fit 330mm discs and pads with the stock calipers.

Other option can be to get a 335i brakes but Im not sure if I can get em here (Im in Croatia)

Atm the car has 18" rims and Im planning to get a 17" winter set .

Thanks a bunch!
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      05-14-2018, 10:06 AM   #2
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Don't go cheap. Don't play with safety systems.

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Originally Posted by Chocolatero€ View Post
What about to install 123d brakes? If I am not wrong I can fit 330mm discs and pads with the stock calipers.
What about the deployment effort? You should squeeze'em tight as well, perhaps.

Brakes recreation doesn't look really cheap, incidentally (unless you intend well-used parts ). With no money excess you'll unlikely want to go beyond.

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Originally Posted by Chocolatero€ View Post
Atm the car has 18" rims and Im planning to get a 17" winter set .
You can't use 17" rims with M-Performance brakes enhancement. Plan responsibly.
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      05-14-2018, 10:20 AM   #3
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Thanks for your reply mate. M performance brakes are out from my budget, plus you r saying it would not fit with 17"....

I could go for stock size discs and better pads, but because I have to do it in the period of 10k km I though it would be a good idea to get something better.
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      05-14-2018, 10:54 AM   #4
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I have to do it in the period of 10k km
Why so? Don't trust the computer estimate!
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      05-14-2018, 12:08 PM   #5
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I dont trust it (the idrive says 15000km) but when you physicaly check em, you can estimate how much do you have. I also used to change the oil and filters every 12/13k km instead 30k (what bmw says).
Anyways, thoughts?
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      05-14-2018, 01:10 PM   #6
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Quote:
Originally Posted by Chocolatero€ View Post
Anyways, thoughts?
Here are some already shared (in case of lack of replies here):

116i Sport brake pad upgrade

Retrofit M Sport Brake help.

Blue M Sport Brakes

2011 F20 118d brake upgrade options?.

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      05-14-2018, 02:30 PM   #7
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Im gonna take a look! cheers mate!
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      05-14-2018, 02:39 PM   #8
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I read those threads before, not helping much, cuz the m performance option isnt an option.

What I would like to know if the brake systems are the same in F20/21 and E8x series
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      05-14-2018, 02:58 PM   #9
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Do you realize the difference between M-Performance and M-Sport discussed in those threads? M-Sport is not intended for retrofitting but someone in those threads admitted he had had them retrofitted. They are 17'' rims compatible (OEM rims: minimal clearance, offset is important). Retrofit cost unknown. Breaking force I mentioned is really an issue to take care of at least programmatically.

No, F and E series brakes don't look compatible, at least here: www.realoem.com.

Last edited by No one; 05-14-2018 at 03:11 PM.. Reason: Added a detail on 17'' rims compatibility.
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      05-14-2018, 03:54 PM   #10
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Yes yes, I know, but still confused about the differences between Fxx and E8x series. Though you can fit a e90 brakes (i.e 335i ) or 123d brakes on F20 (at least you can if you have a E8x series)

Maybe the best solution would be get new stock discs and better brake pads.
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      05-14-2018, 04:12 PM   #11
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What issues do you currently have with the brakes? My pre facelift 116i had standard brakes with cooling ducts from the front bumpers. The braking performance was impressive, but the brake pedal became low and soft after track weekends due to overheated front pads.

Now I have M-Sport brakes with no cooling ducts (they somehow got lost on the facelift front). I can feel the extra weight of the brakes, but the brake pedal is just fine after track weekends. Maybe they are slightly overkill on a 118i. I think the standard brakes with more dedicated brake pads would have done the job.
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      05-14-2018, 04:25 PM   #12
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Quote:
Originally Posted by ovekvam View Post
What issues do you currently have with the brakes? My pre facelift 116i had standard brakes with cooling ducts from the front bumpers. The braking performance was impressive, but the brake pedal became low and soft after track weekends due to overheated front pads.

Now I have M-Sport brakes with no cooling ducts (they somehow got lost on the facelift front). I can feel the extra weight of the brakes, but the brake pedal is just fine after track weekends. Maybe they are slightly overkill on a 118i. I think the standard brakes with more dedicated brake pads would have done the job.
I have no problem, but since Im going to replace discs and pads I thought it would be the right time to make also an upgrade.
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      05-14-2018, 04:40 PM   #13
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Quote:
Originally Posted by ovekvam View Post
I can feel the extra weight of the brakes
I just can't help suggesting it's engine weight reduction (by 1 cylinder) in fact.
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      05-14-2018, 11:27 PM   #14
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I just can't help suggesting it's engine weight reduction (by 1 cylinder) in fact.
That is possible, but I meant unsprung weight. Lighter wheels go over bumps in a different way, and the rotational inertia is smaller. That means they respond quicker to acceleration and braking.
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      05-15-2018, 09:30 AM   #15
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I am going to ask to my local dealer about the M sports one , if not I would go for good pads and stock discs
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      05-15-2018, 10:30 AM   #16
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Quote:
Originally Posted by ovekvam View Post
Lighter wheels go over bumps in a different way, and the rotational inertia is smaller. That means they respond quicker to acceleration and braking.
Yet, on the other hand, shouldn't that unsprung weight add to the grip (reducing sprung shift effect)? Bumps can be handled by suspension and tires while inertia is a subject for engine/brakes power.

What I felt driving a new courtesy 3 Series with basic brakes was surprising uncertainty whether it would stop or not. I guess it's floating calliper against fixed support effect.
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      05-15-2018, 01:17 PM   #17
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Quote:
Originally Posted by No one View Post
Yet, on the other hand, shouldn't that unsprung weight add to the grip (reducing sprung shift effect)? Bumps can be handled by suspension and tires while inertia is a subject for engine/brakes power.

What I felt driving a new courtesy 3 Series with basic brakes was surprising uncertainty whether it would stop or not. I guess it's floating calliper against fixed support effect.
The lower the unsprung weight is, the better the wheels will follow the ground, with even load. That will give you the most grip, like formula 1 cars. When the unsprung weight gets too high, the wheels will bounce all over the place, and you need a very stiff suspention to keep it in place. Less grip, like big trucks.

My pre facelift 116i with basic brakes had awesome stopping power, and probably even shorter stopping distance than my newer 118i with M-Sport brakes. The bigger brakes will however cope a lot better with heat, and can handle a series of hard braking without overheating. The basic brakes will eventually overheat on the track. The pads will get soft and slippery, causing a low brake pedal and higher pedal effort to stop the car. No drama, but annoying for the driver if you wanted to drive more.

With racing brake pads, the brakes can get significantly warmer without any fading issues. Those pads do however come with other disadvantages. They cost more, they squeal, they can have lower friction when cold, and the brake dust will melt itself into the clear coat on the wheels and the car paint.
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      05-15-2018, 02:18 PM   #18
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Quote:
Originally Posted by ovekvam View Post
The lower the unsprung weight is, the better the wheels will follow the ground, with even load. That will give you the most grip, like formula 1 cars. When the unsprung weight gets too high, the wheels will bounce all over the place, and you need a very stiff suspention to keep it in place.
With even load, of course. But when the car shifts it's weight due to inertia (when you are braking, in particular) what's there to push the unloaded wheel against the ground except it's own weight? Touching the ground just barely should lead to slipping I'd presume.

AFAIK Formula 1 cars' grip is pretty much all about aerodynamics, they are undrivable at low speeds. And they reportedly have very stiff, rock hard suspension.

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Originally Posted by ovekvam View Post
My pre facelift 116i with basic brakes had awesome stopping power, and probably even shorter stopping distance than my newer 118i with M-Sport brakes.
Could it be more effective engine braking? Have you got rid of runflat tires already?

Last edited by No one; 05-15-2018 at 02:33 PM.. Reason: Spelling correction.
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      05-15-2018, 03:19 PM   #19
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Quote:
Originally Posted by No one View Post
With even load, of course. But when the car shifts it's weight due to inertia (when you are braking, in particular) what's there to push the unloaded wheel against the ground except it's own weight? Touching the ground just barely should lead to slipping I'd presume.

AFAIK Formula 1 cars' grip is pretty much all about aerodynamics, they are undrivable at low speeds. And they reportedly have very stiff, rock hard suspension.
Maybe formula one was a too extreme example. Single seaters without wings are more relevant. They have super light wheels and suspension, not all that stiff springs and dampers, and they have lots of mechanical grip.

When driving over a bump, or just tarmac that isn't super smooth, the wheels will have vertical motion. The lighter they are, the quicker they can move down (pushed by springs) after being forced up by the ground. Heavy wheels can not accelerate quick enough, and will bounce. This causes uneven load on the contact patch to the ground. Lighter wheels will follow the ground with even load, more grip, and less tyre deformation.

This load I talk about is for one wheel isolated. The load changes between different wheels you mention, are the not really affected by unsprung weight. Both cars with low and high unsprung weight can get airborne wheels in very dynamic situations.

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Could it be more effective engine braking? Have you got rid of runflat tires already?
Yes, the summer runflats are gone. I still have the winter runflats. They are actually quite okay.

I think the lower unsprung weight and less intertia is the key to short stopping distance, if you have perfect balance between the front and rear tyres. Bigger brakes is not about shorter braking distance, but ability to brake more often. The whole concept of braking is to convert kinetic energy into heat, and the bigger brakes have more heat capacity.
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      10-30-2018, 08:42 AM   #20
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How did you finally take care of this?
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      11-08-2018, 05:08 AM   #21
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How did you finally take care of this?
Bok Njave !


I got front and read discs from EBC and yellow stuff pads.
Bought it from ebcbrakes.co.uk and was delivered to Zagreb in a 5 days.

I am going to install it next week .

here you have the pics

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      12-05-2019, 01:05 PM   #22
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