[mcsweeto]

I need to do all four on my 435xi. On the car are the 340 Msport front calipers- I'm mainly looking for the best stopping, most durable replacements for that setup.

I'm running MHD stage 2 with FBO with plans to go to 2+ when I'm comfortable with log collection and the assessing the state of other internals. However, I am not tracking nor am I dogging my car every chance I get. I appreciate the need for upgraded stopping power, but I'm not sure I'm a candidate for a big brake kit.

Talk me out of a Powerstop Z26 brake service kit?

[Logicoeur]

Pads and fluid. Some will come in here and hawk the Hawk HPS 5.0 (lol) but I have had good bite and wear from the Ferodo DS2500 on the same calipers. Both would be an upgrade from stock as far as initial bite.

For fluid a dot4 shpuld be good. motul 5.1, 600 and some others. Not sure that you need or would notice braided lines so those are up to you really. They look nice when you are in the wheel well.

[Itogliano]

When you say best stopping, do you mean a one time hard braking shortest stopping distance or you want the brakes to be able to hold up to repeated hard braking?

If the former, tires are going to be the variable you want to change, as any stock braking setup has enough clamping force to lock your wheels/trigger ABS.

If the latter, you'll want pads and fluid that can hold up to higher heat (rotors aren't as important but I would say you would at least want vented rotors. Although I think you'd have to go out of your way to get solid rotors for a BMW nowadays). Logicoeur gave you some good starting information. You'll find a lot of different pads that work in a higher temp range with different CoF values (mu) which will affect how the pad feels (e.g. a pad with a high mu will feel like it has a more aggressive bite). Mu values come down to personal preference and how you want the brakes to feel, they don't really affect (effect? I hate this language) performance.

You say you're not tracking or dogging the car but do you occasionally hit some mountain/canyon roads pretty aggressively? If so, and you start to experience brake fade, the first thing to do is upgrade pads and fluid. If you do that and still are getting brake fade, then it would be time to think about a BBK. This is from a performance point of view, you can also upgrade to a BBK for no other reason than liking how it looks, which a lot of people do.

[johnung]

Originally Posted by mcsweeto

I need to do all four on my 435xi. On the car are the 340 Msport front calipers- I'm mainly looking for the best stopping, most durable replacements for that setup.

I'm running MHD stage 2 with FBO with plans to go to 2+ when I'm comfortable with log collection and the assessing the state of other internals. However, I am not tracking nor am I dogging my car every chance I get. I appreciate the need for upgraded stopping power, but I'm not sure I'm a candidate for a big brake kit.

Talk me out of a Powerstop Z26 brake service kit?

Powerstop are cheap Asian metallurgy and garbage pads. Crap!

Do you have actual blue M Sport calipers, or M Sport bumpers with grey brake calipers?

Big brake improvement with Hawk 5.0 pads, StopTech crossdrilled rotors and stainless steel brake lines. If have the blue calipers and you want the best front rotors with amazing bite, see photo!

[mcsweeto]

Originally Posted by johnung

Powerstop are cheap Asian metallurgy and garbage pads. Crap!

Do you have actual blue M Sport calipers, or M Sport bumpers with grey brake calipers?

Big brake improvement with Hawk 5.0 pads, StopTech crossdrilled rotors and stainless steel brake lines. If have the blue calipers and you want the best front rotors with amazing bite, see photo!

The unfortunate gray M Sport combo- 340 in front.

[johnung]

Originally Posted by mcsweeto

The unfortunate gray M Sport combo- 340 in front.

Okay. My F30 335ix began its life with those exact grey Front340mm/Rear 330mm brakes. I've done several brake upgrades so I can tell you exactly what's needed and what improvement you will feel.

First, get Hawk 5.0 pads. Best bite, instant warm up, low/light dust. Best street pad. See photo for part numbers.

The fronts do most of the stopping so you can even do it in front and rear stages.

FRONT BRAKES with Brembo 340 Calipers:

Hawk 5.0 pads
StopTech crossdrilled 340x30 rotors
StopTech Stainless Steel Brake Lines (eliminates mush, makes brake pedal firmer)
Only $110/set of four. See photo.

You will feel an immediate improvement with much better bite and stopping power, with a more responsive brake pedal. Also much better braking in the rain since water can't trap between pad and rotor surfaces.

REAR BRAKES:
You have two choices:
1) Do the same as above with the rear 330mm calipers, Hawk 5.0 pads, StopTech crossdrilled 330x20 rotors and SS brake lines.

The combination of Front 340/Rear 330 brakes is very good. It's downside is that during very heavy braking the weaker rear brakes tends to cause the car to nose dive. The way to eliminate nose dive is to upgrade the rear brake calipers to the Brembo 2-piston over 345x24 rotors.

2) Used 345mm calipers typically cost about $450-$550 per pair. They have their own part number for Hawk 5.0 pads and StopTech crossdrilled rotors.

So the cost is roughly the same in Option #1 or Option #2 for the pads, rotors and SS lines. It's just a question of if it's worth it to you to upgrade your rear brakes at the cost of the rear Brembo calipers.

Like I said, you don't even have to decide all at once. You can do the front brakes first and the rear brakes later. (Have them install SS lines at all four wheels with the front brake installation since they have to replace fluid and bleed the brakes anyway.

Hope this helps!

[johnung]

Originally Posted by mcsweeto

The unfortunate gray M Sport combo- 340 in front.

People often ask what the difference is between the F30 Front 370mm/Rear 345mm brake combination and the Front 340mm/Rear 345mm combination.

From a pure step on the brakes and what happens standpoint, the braking power is essentially identical. That's because the front calipers are almost identical. They have the same four 40mm brake pistons, same piston seals, caps, pins, clips and even identical brake pads. The only difference in the calipers is that the 370's caliper casting is stretched out by a 15mm radius which permits the rotor with 30mm more diameter.

Guys like the look of the bigger caliper and assume that it provides more stopping power. But it doesn't. Both the 340 & 370 calipers apply roughly the same force. The one performance advantage of the 370mm brakes is that the larger rotor has more mass so it can dissipate more heat. So the 370's are less susceptible to fade under repeated hard braking.

A used set of Front 370 Brembo calipers typically cost $500-$600. As before the pads, rotors and SS lines are roughly the same cost.

One caveat with the front 370's is that they will fit the full floating StopTech crossdrilled 370x30 rotors that I posted a photo of earlier in this thread. They are almost identical to full floating crossdrilled rotors used in the BremboGT big brake kits. They have amazing bite with the Hawk 5.0 pads. They are expensive, but not too expensive when compared to the price of the BremboGT BBK. This setup bridges the gap between the largest F30 370/345 brakes and aftermarket BremboGT BBK.

Hope this helps!

[mcsweeto]

Originally Posted by johnung

People often ask what the difference is between the F30 Front 370mm/Rear 345mm brake combination and the Front 340mm/Rear 345mm combination.

From a pure step on the brakes and what happens standpoint, the braking power is essentially identical. That's because the front calipers are almost identical. They have the same four 40mm brake pistons, same piston seals, caps, pins, clips and even identical brake pads. The only difference in the calipers is that the 370's caliper casting is stretched out by a 15mm radius which permits the rotor with 30mm more diameter.

Guys like the look of the bigger caliper and assume that it provides more stopping power. But it doesn't. Both the 340 & 370 calipers apply roughly the same force. The one performance advantage of the 370mm brakes is that the larger rotor has more mass so it can dissipate more heat. So the 370's are less susceptible to fade under repeated hard braking.

A used set of Front 370 Brembo calipers typically cost $500-$600. As before the pads, rotors and SS lines are roughly the same cost.

One caveat with the front 370's is that they will fit the full floating StopTech crossdrilled 370x30 rotors that I posted a photo of earlier in this thread. They are almost identical to full floating crossdrilled rotors used in the BremboGT big brake kits. They have amazing bite with the Hawk 5.0 pads. They are expensive, but not too expensive when compared to the price of the BremboGT BBK. This setup bridges the gap between the largest F30 370/345 brakes and aftermarket BremboGT BBK.

Hope this helps!

@johnung Thank you so much for taking the time to put all this together. There is a lot here I'm looking forward to reading through again. Needless to say, I've gotten the Power Stop idea out of my head.

I need to do some window shopping and look at the budget. I'm excited to do that now armed with some solid recs.

[Tommi_Mav]

Originally Posted by johnung

People often ask what the difference is between the F30 Front 370mm/Rear 345mm brake combination and the Front 340mm/Rear 345mm combination.

The one performance advantage of the 370mm brakes is that the larger rotor has more mass so it can dissipate more heat. So the 370's are less susceptible to fade under repeated hard braking.

And a performance disadvantage of the 370's is the higher weight resulting in increase of the unsprung mass, affecting acceleration, steering feel, etc.

I don't know the prices of Hawk 5.0 and Ferodo DS2500 in US, but for DD you will have very good results for the price even with the Ferodo Premier Eco Friction Series pads.

My 2 cents is that you should think on what you try to achieve based on Itogliano's points.

[johnung]

Originally Posted by Tommi_Mav

And a performance disadvantage of the 370's is the higher weight resulting in increase of the unsprung mass, affecting acceleration, steering feel, etc.

I don't know the prices of Hawk 5.0 and Ferodo DS2500 in US, but for DD you will have very good results for the price even with the Ferodo Premier Eco Friction Series pads.

My 2 cents is that you should think on what you try to achieve based on Itogliano's points.

Theoretically what you say is true as far as unsprung weight. When I first got my car four years ago and began researching possible brake upgrades, I heard all of the theoretical arguments. But when parts start being swapped in and out, you find out quickly which theories are true in practicality and which are in a range that just don't have an effect- don't matter.

I heard this a lot from guys who had hands on experience like builders/guys who worked in race shops. Unsprung weight is further down on the priority list, something not really considered until you've accomplished the more important handling or braking goals.

Unsprung weight becomes a factor when you really need that advantage and you have gobs of money to throw at the issue. High end race teams use materials like titanium to accomplish their goals.

My current BMW road wheels (18" 400M) cost me $150 each. I can significantly reduce the unsprung weight of my wheels, but the ones that I'd choose (19" 763M) are $1,000 each. The same thing goes for switching from steel wheel bolts to titanium. Big bucks!

Often race teams choose wheels and tires that negatively effect unsprung weight, but the handling advantage far outweighs the unsprung weight issue.

If unsprung weight was my primary concern with my brake calipers then I would get AP Racing brakes. But the cost would be $8,000.

From a practical standpoint, the extra mass of the front 370 rotors is a very noticeable improvement in less brake fade over the front 340 rotors. Any unsprung weight difference just isn't noticeable in daily driving, even aggressive street performance driving. But 340 brake fade is absolutely noticeable and very undesirable.

Hope this helps!

[Logicoeur]

Originally Posted by johnung

Theoretically what you say is true as far as unsprung weight. When I first got my car four years ago and began researching possible brake upgrades, I heard all of the theoretical arguments. But when parts start being swapped in and out, you find out quickly which theories are true in practicality and which are in a range that just don't have an effect- don't matter.

I heard this a lot from guys who had hands on experience like builders/guys who worked in race shops. Unsprung weight is further down on the priority list, something not really considered until you've accomplished the more important handling or braking goals.

Unsprung weight becomes a factor when you really need that advantage and you have gobs of money to throw at the issue. High end race teams use materials like titanium to accomplish their goals.

My current BMW road wheels (18" 400M) cost me $150 each. I can significantly reduce the unsprung weight of my wheels, but the ones that I'd choose (19" 763M) are $1,000 each. The same thing goes for switching from steel wheel bolts to titanium. Big bucks!

Often race teams choose wheels and tires that negatively effect unsprung weight, but the handling advantage far outweighs the unsprung weight issue.

If unsprung weight was my primary concern with my brake calipers then I would get AP Racing brakes. But the cost would be $8,000.

From a practical standpoint, the extra mass of the front 370 rotors is a very noticeable improvement in less brake fade over the front 340 rotors. Any unsprung weight difference just isn't noticeable in daily driving, even aggressive street performance driving. But 340 brake fade is absolutely noticeable and very undesirable.

Hope this helps!

The decrease in unsprung weight is noticeable. I can't recall the different in mass between the 370mm and 340mm rotors, but a drop in 8 lbs at each wheel has been significant in my experience. You will likely spend more money to drop so much via the brake system, but the wheels are a different story. The car definitly felt punchier from a stop, lighter on steering, and I was able to chip tires without much throttle input. This was all before any suspension or power mods.

There are definitely more fun mods than focusing on unsprung weight, but wheels and tires is one avenue you can have both. You don't need a race team or loads of money. But I do agree you will spend more money trying to reduce weight via the brake system for anything significant like the above example 32lbs + ( diff between AS runflats and go flat summer tires)


Edit: posted an excel sheet listing OE weights compared to my go flat + lightweight wheels setup couple posts down

[johnung]

Originally Posted by Logicoeur

The decrease in unsprung weight is noticeable. I can't recall the different in mass between the 370mm and 340mm rotors, but a drop in 5 lbs at each wheel has been significant in my experience. You will likely spend more money to drop so much via the brake system, but the wheels are a different story. The car definitly felt punchier from a stop, lighter on steering, and I was able to chip tires without much throttle input. This was all before any suspension or power mods.

There are definitely more fun mods than focusing on unsprung weight, but wheels and tires is one avenue you can have both. You don't need a race team or loads of money. But I do agree you will spend more money trying to reduce weight via the brake system for anything significant like the above example 20lbs + ( diff between AS runflats and go flat summer tires)

Good points! The difference in weight between 370 and 340 rotor is 5 lbs. But I'd never trade the greater brake fade resistance for unsprung weight reduction.

However, as you pointed out the weight difference between runflats and my summer tires are 6 lbs each. Easy way to gain handling improvement and unsprung weight savings.

[Tommi_Mav]

Originally Posted by johnung

Theoretically what you say is true as far as unsprung weight. When I first got my car four years ago and began researching possible brake upgrades, I heard all of the theoretical arguments. But when parts start being swapped in and out, you find out quickly which theories are true in practicality and which are in a range that just don't have an effect- don't matter.

I heard this a lot from guys who had hands on experience like builders/guys who worked in race shops. Unsprung weight is further down on the priority list, something not really considered until you've accomplished the more important handling or braking goals.

Unsprung weight becomes a factor when you really need that advantage and you have gobs of money to throw at the issue. High end race teams use materials like titanium to accomplish their goals.

My current BMW road wheels (18" 400M) cost me $150 each. I can significantly reduce the unsprung weight of my wheels, but the ones that I'd choose (19" 763M) are $1,000 each. The same thing goes for switching from steel wheel bolts to titanium. Big bucks!

Often race teams choose wheels and tires that negatively effect unsprung weight, but the handling advantage far outweighs the unsprung weight issue.

If unsprung weight was my primary concern with my brake calipers then I would get AP Racing brakes. But the cost would be $8,000.

From a practical standpoint, the extra mass of the front 370 rotors is a very noticeable improvement in less brake fade over the front 340 rotors. Any unsprung weight difference just isn't noticeable in daily driving, even aggressive street performance driving. But 340 brake fade is absolutely noticeable and very undesirable.

Hope this helps!

I will kindly disagree with you that the increase in unsprung mass is not noticeable. Quite the opposite. 5lbs on each wheel, so a total of 10 lbs is quite a lot in unsprung mass. Even when I changed my wheels from 18" 397M to 19" 437M, I managed to save less (3.3 lbs) on each wheel and it still made a noticeable difference.
Taking also into account the OP´s goal, which is mainly DD and not tracking, and as we all agree that there is no advantage for the 370's over the 340's in braking other than brake fade, I think the weight advantage of the 340s overweights the brake fade advantage of the 370s. Personally, I would stay with the 340s and upgrade pads and tires to improve braking for DD.

[johnung]

Originally Posted by Tommi_Mav

I will kindly disagree with you that the increase in unsprung mass is not noticeable. Quite the opposite. 5lbs on each wheel, so a total of 10 lbs is quite a lot in unsprung mass. Even when I changed my wheels from 18" 397M to 19" 437M, I managed to save less (3.3 lbs) on each wheel and it still made a noticeable difference.
Taking also into account the OP´s goal, which is mainly DD and not tracking, and as we all agree that there is no advantage for the 370's over the 340's in braking other than brake fade, I think the weight advantage of the 340s overweights the brake fade advantage of the 370s. Personally, I would stay with the 340s and upgrade pads and tires to improve braking for DD.

You are kinda mixing two conversations. I recommended that OP keep Front 340's and, if he upgrades anything, it should be to rear 345 calipers to eliminate nosedive under heavy breaking and to improve overall brake performance.

The difference between Front 340's and Front 370's was just an aside that I added because the question is often asked.

I understand that you believe that you felt a 3.3lb weight savings. I would suggest that the wheel weight was probably not the only variable that changed. Perhaps changes in tire weight, tire size, tire model, tire compound, etc contributed to the improvement that you felt.

[Logicoeur]

I really want to know that the 400m + stock run lats weigh now so I can get an exact change to my current summer setup. I have go flat winters on the stock wheels now

[johnung]

Originally Posted by Logicoeur

I really want to know that the 400m + stock run lats weigh now so I can get an exact change to my current summer setup. I have go flat winters on the stock wheels now

Which weights do you want exactly? I can weigh them

[Logicoeur]

Originally Posted by johnung

Which weights do you want exactly? I can weigh them

Fully dressed 400m with the stock runflat tire

[johnung]

Originally Posted by Logicoeur

Fully dressed 400m with the stock runflat tire

I've got one in my trunk that I use as a full sized spare. I seem to recall wheel and tire each being about 25 lbs each. But I'll get you an exact weight.

[Tommi_Mav]

Originally Posted by Logicoeur

Fully dressed 400m with the stock runflat tire

https://www.carsaddiction.com/en/wheels/bmw/style-400

Hope this helps.

[Tommi_Mav]

Originally Posted by johnung

You are kinda mixing two conversations. I recommended that OP keep Front 340's and, if he upgrades anything, it should be to rear 345 calipers to eliminate nosedive under heavy breaking and to improve overall brake performance.

The difference between Front 340's and Front 370's was just an aside that I added because the question is often asked.

I understand that you believe that you felt a 3.3lb weight savings. I would suggest that the wheel weight was probably not the only variable that changed. Perhaps changes in tire weight, tire size, tire model, tire compound, etc contributed to the improvement that you felt.

I just added to the differences between 340s and 370s that you stated, when you only refered to brake fade whereas unsprung mass is equally important.

Furthermore, my comment was mainly refering to the part where you said

Any unsprung weight difference just isn't noticeable in daily driving, even aggressive street performance driving.

, which I strongly disagree.

Anyway, each driver has his/her own priorities. No hard feelings, just to make things clear.

PS: 3.3 lbs were saved only due to wheels. Going from run-flats to go-flats saved me another 4 lbs on front tires and 2 lbs on rear tires (I changed from square to staggered). So an average of 6.3 lbs was saved on each wheel, which is almost equivalent to the 5 lbs weight difference between 370 and 340 rotors.

[Logicoeur]

Thanks for that link.

Calculated an estimated 13.1-13.6lbs saved at each wheel with my setup from the stock 400m+Bridgestone RFT. That's a 52.4-54.4lbs reduction of rotational mass which explains the significant change in feel and engine response.

This doesn't include lug bolts/studs or tpms. Also can't get hard numbers for the rotors but I believe my 2piece 340mm save around 2-2.5lbs.

[mcsweeto]

Originally Posted by Logicoeur

Thanks for that link.

Calculated an estimated 13.1-13.6lbs saved at each wheel with my setup from the stock 400m+Bridgestone RFT. That's a 52.4-54.4lbs reduction of rotational mass which explains the significant change in feel and engine response.

This doesn't include lug bolts/studs or tpms. Also can't get hard numbers for the rotors but I believe my 2piece 340mm save around 2-2.5lbs.

Wait, not to hijack my own topic, but you're proposing our cars are faster with run flats? Shit, I've got 245/40/18 go-flats on my 400s now and they feel like butter, but maybe they're slowing me down.