[johnung]

Originally Posted by Alarbus

This is true. The BMW instructions are only for the calipers, pads, and rotors. (And coding)

However, after having a local shop bleed my 440, it's still shy of the feeling from my 335, so I started looking at parts numbers. If the car comes with 2NHA, at least for the 335, it'll have the master cylinder and brake booster that would come on the M3/M4. If you retrofit SPBR, it will be different, and the pedal will feel different, even with a pro bleeding it with much fancier brake fluid.

I know this because I have the two cars parked next to each other, and I had just refreshed the 335s pads and rotors with OEM, and put all new on the 440, and can drive them side by side. The 440 is probably 95% of the way there, but I didn't feel like chasing the last 5% for a daily driver by swapper the MC and booster. But they are different.

I have a 2015 335i XDrive that came from the factory with the P337A standard brakes of Front Brembo 340’s and Rear Bosch 330’s. I have since upgraded to what would have been factory code S2NHA with F370/R345. I did not code them because two different expert BMW techs told me that both configurations come from the factory with the same code. My brake performance with the aftermarket rotors, pads and stainless steel lines that I chose has been fantastic.

I tried to verify your statement about their being a different master cylinder and brake servo on the F-335i depending on which of the two brake packages are on the car from the factory.

When there are different part options for a car model, then realoem shows them. For example realoem shows the different calipers, rotors and pads for the two factory brake configurations that I mentioned. But for the master cylinder and brake servo, realoem only shows one part number for each for my model. (34336851095, 34336851098)

So my F-335ix would receive the same master cylinder and brake servo regardless of whether it came from the factory with standard brakes or the factory option M Sport Brake package.

I also looked up on Realoem an F80 M3 built the same month as my car. It has completely different part numbers for master cylinder and brake servo. (34337849878, 34337849876)

Note: Sometimes different model cars use different part numbers because one is more heavy duty or an improvement. But that doesn’t mean that they are interchangeable. It is important not to automatically make that assumption. Just as often there is a completely different reason for a different part number like a different parts supplier, a clearance issue or some compatibility issue that may not be obvious.

The most common reason for brakes not performing 100% after brake component replacement is that a full fluid replacement with a brake bleed following the BMW ISTA procedure was not done. Air bubbles cling to the inside walls of the brake system, using ISTA is the only way to shake them loose, to then bleed them out. See FaRKle! video below.

https://youtu.be/o7XsCMqZXw0?si=jndNITBrmeb4H-iZ

[casualDIYer]

Originally Posted by johnung

I have a 2015 335i XDrive that came from the factory with the P337A standard brakes of Front Brembo 340’s and Rear Bosch 330’s. I have since upgraded to what would have been factory code S2NHA with F370/R345. I did not code them because two different expert BMW techs told me that both configurations come from the factory with the same code.

So you did not VO(FA) code SPBR into the car? I believe this adds "SPBR_18_ZOLL_SPORTBRAKE" added to the Vehicle Profile under "aftermarket retrofit"

I am currently on the 340/345 combo and wonder if I should VO code SPBR into the car, as some coders have reported a more linear and immediate brake effect.

[johnung]

Originally Posted by casualDIYer

So you did not VO(FA) code SPBR into the car? I believe this adds "SPBR_18_ZOLL_SPORTBRAKE" added to the Vehicle Profile under "aftermarket retrofit"

I am currently on the 340/345 combo and wonder if I should VO code SPBR into the car, as some coders have reported a more linear and immediate brake effect.

My car came from the factory with F340/R330. I upgraded first to F340/R345, and later F370/F345. I never changed the factory coding because two different experienced BMW techs advised that there was no reason to. They both said that those three brake combinations come coded with the same factory setting so there is nothing to change.

My brakes are so responsive that I don’t want to mess up a good thing by playing around with coding them. It’s a BMW. I always have a list of things to do!

[Junaed08]

Originally Posted by Alarbus

This is true. The BMW instructions are only for the calipers, pads, and rotors. (And coding)

However, after having a local shop bleed my 440, it's still shy of the feeling from my 335, so I started looking at parts numbers. If the car comes with 2NHA, at least for the 335, it'll have the master cylinder and brake booster that would come on the M3/M4. If you retrofit SPBR, it will be different, and the pedal will feel different, even with a pro bleeding it with much fancier brake fluid.

I know this because I have the two cars parked next to each other, and I had just refreshed the 335s pads and rotors with OEM, and put all new on the 440, and can drive them side by side. The 440 is probably 95% of the way there, but I didn't feel like chasing the last 5% for a daily driver by swapper the MC and booster. But they are different.

i've just got hold of master cylinder from an M4. Hopefully this should sort it. I was checking the posts on here and someone upgraded their brakes to the m-sport ones, however, they needed to change their master cylinder too as non m-sport models have different ones.

[rlesko]

Originally Posted by Junaed08

i've just got hold of master cylinder from an M4. Hopefully this should sort it. I was checking the posts on here and someone upgraded their brakes to the m-sport ones, however, they needed to change their master cylinder too as non m-sport models have different ones.

A lot of variables at play here...328 vs 335, M Sport trim, S2NHA option (not always present on M sport), etc... Based off realOEM the F8x brake booster is not present on any F3x chassis in any capacity. However, it does seem true based on realOEM that a 328 with S2NHA would get a 335 brake booster. Let us know how it goes, but I have a bad feeling you are just throwing money at the problem.

[Junaed08]

Originally Posted by rlesko

A lot of variables at play here...328 vs 335, M Sport trim, S2NHA option (not always present on M sport), etc... Based off realOEM the F8x brake booster is not present on any F3x chassis in any capacity. However, it does seem true based on realOEM that a 328 with S2NHA would get a 335 brake booster. Let us know how it goes, but I have a bad feeling you are just throwing money at the problem.

I had the car coded to S2NHA and SPBR. Made a slight difference but still got a spongy pedal. My last hope is the Brake Master Cylinder. I was checking on auto doc for the brake master cylinder and it does show if the parts are compatible with cars fitted with m-sport brakes or not. Had a few mechanics say it's definitely the master cylinder.

Fingers crossed it's sorted now. Just waiting to take it in.

[rlesko]

Originally Posted by Junaed08

I had the car coded to S2NHA and SPBR. Made a slight difference but still got a spongy pedal. My last hope is the Brake Master Cylinder. I was checking on auto doc for the brake master cylinder and it does show if the parts are compatible with cars fitted with m-sport brakes or not. Had a few mechanics say it's definitely the master cylinder.

Fingers crossed it's sorted now. Just waiting to take it in.

You're not supposed to code both, I hope thats not what you did.

[Junaed08]

Originally Posted by rlesko

You're not supposed to code both, I hope thats not what you did.

My coder put in both. Which one should i take out?

[rlesko]

Originally Posted by Junaed08

My coder put in both. Which one should i take out?

SPBR = proper coding if you've only retrofitted calipers

2NH = if you swapped master cylinder. technically I believe S2NHA comes with reinforced brake lines as well from factory.

So you should probably KEEP SPBR and REMOVE 2NH

[Junaed08]

Originally Posted by rlesko

SPBR = proper coding if you've only retrofitted calipers

2NH = if you swapped master cylinder. technically I believe S2NHA comes with reinforced brake lines as well from factory.

So you should probably KEEP SPBR and REMOVE 2NH

I've had stainless steel brake lines put in. will take out S2NHA and keep SPBR only and let you know how it goes.

Thank you

[rlesko]

Originally Posted by Junaed08

I've had stainless steel brake lines put in. will take out S2NHA and keep SPBR only and let you know how it goes.

Thank you

No problem.

I coded SPBR with the following set up: stoptech SS brake lines, stock 4 piston brembo up front (340mm rotors), retrofitting 2 piston rembo in rear (345mm rotors). The car feels good and performs even better.

[Junaed08]

Originally Posted by rlesko

No problem.

I coded SPBR with the following set up: stoptech SS brake lines, stock 4 piston brembo up front (340mm rotors), retrofitting 2 piston rembo in rear (345mm rotors). The car feels good and performs even better.

Had the master cylinder replaced with one compatible with M-Performance brakes. Coded out 2NHA and only left SPBR on. Still nothings changed

[rlesko]

Originally Posted by rlesko

Unless you leave the brake lines open for extended period of time, the The ISTA procedure shouldn't be necessary (albeit can't hurt if done properly). The real reason the procedure exists is for master cylinder replacement.

I clamped off my plastic brake lines while I painted my calipers and installed stainless steel braided cables once my calipers were ready and I don't have any spongy-ness. Obviously I immediately bled both sides of the caliper on installation.

Also, no new DSC should be needed for the brake kit.

Originally Posted by Junaed08

Had the master cylinder replaced with one compatible with M-Performance brakes. Coded out 2NHA and only left SPBR on. Still nothings changed

It was a bad idea IMO to change the master cylinder. Now you've introduced a ton of air into the system and you need to run the ISTA brake bleed procedure. Did you do that?

[Junaed08]

Will try again with ISTA. This is becoming a bit of a headache now

[rlesko]

Originally Posted by Junaed08

Will try again with ISTA. This is becoming a bit of a headache now

Yes sir, did you try out how it feels with the factory master cylinder and only SPBR coded (removing 2NH)?

In any case, the path forward is to run the ISTA brake bleeding procedure and ensure only one of SPBR and 2NH is coded.

[WDE82]

I tried to skim this but I think there is a lot of misinformation or misunderstanding of how these brake systems work.

If you increased the volume of the pistons compared to your original brakes (you did) then your pedal travel will be longer no matter what you do. You're having to move a higher volume of fluid to achieve similar piston position/force. A lot of people assume the M perf brakes MUST improve brake feel because "performance!". But that's no the case. They are higher volume with more pistons/surface area and thus have a "looser" feel.

Now, most of this is actually controlled by the takeup cylinder within the mastercylinder assembly. This is a cylinder that is relatively large and it's valved so it "takes up" the dead zone rapidly by moving a lot of fluid. Then when the pads start making contact and pressure builds, the actual master cylinders are used which are significantly smaller diameter. That gives you hydraulic leverage to apply more force to the pad for the same pedal force.



Additionally, pads can have different feels relative to eachother with some feeling softer than others. And new pads that aren't bedded will also feel softer still.

New lines don't contribute much to the feel. Those are mostly bullshit and I'd recommend just sticking with the stock lines.

If you truly don't like the feel still, then I recommend you get a new master cylinder from an M3 or M4. I haven't done the research for the F chassis cars but on E90/82s the 1M/M3 cylinders are a direct swap and have a pretty big takeup cylinder that feels great.

Originally Posted by Junaed08

Had the master cylinder replaced with one compatible with M-Performance brakes. Coded out 2NHA and only left SPBR on. Still nothings changed

The real question is what master cylinder did you swap in? Unless it had a larger takeup then you're still going to have shit feel.

[Junaed08]

I’ve put in a master cylinder from a BMW M4 Competition. I know the m performance brakes have a bit more travel but this sinks to the floor!

[rlesko]

Originally Posted by Junaed08

I’ve put in a master cylinder from a BMW M4 Competition. I know the m performance brakes have a bit more travel but this sinks to the floor!

Yea thats definitely not right. Are you doing this work yourself or having a shop do it?

[WDE82]

Originally Posted by Junaed08

I’ve put in a master cylinder from a BMW M4 Competition. I know the m performance brakes have a bit more travel but this sinks to the floor!

Ok in this case you likely have not filled the system properly. I would do a couple cycles of INPA bleed then traditional bleed with full liter of fluid. Maybe do this a couple times and go through 2L. It's overkill, but there's no way air remains after this.


use something decent like this


https://www.amazon.com/ATE-706202-Or..._t1_B07338GQM8

Also are you bleeding both sides of the brakes? The performance brakes each caliper has 2 bleed screws. And the screws must be on TOP. If they are not on top, the calipers are on the wrong side (not even sure this is possible to fuck up).

[johnung]

What are the last 7 digits of your VIN? I looked up a generic 428i on realoem and got the exact same master cylinder as my 2015 335ix which is part# 34336851095. There was no difference in master cylinder if your car came with M Sport factory brakes or not. I need the VIN to verify this for your exact car.

The F8x and F3x are different models. Although a small number of parts are used on both and sometimes mounting holes line up, it doesn’t mean that F8x parts will work on an F3x. And it doesn’t mean that F8x parts are an upgrade for F8x parts.

Factory rubber brake hoses will balloon slightly with brake fluid when the brake pedal is initially applied. This causes a slight delay before pressure is actually applied to brake pads. As rubber hoses age they tend to balloon more which causes more brake pedal delay.

The stainless steel outer sheath on a brake line both protects it from road debris and prevents any ballooning. So there is no delay and pedal application goes immediately towards activating the pads.

I’ve always used StopTech stainless steel lines but any high quality brand will work. Besides StopTech there are also F3x lines by Turner, ECS and European brand Goodridge. If one is out of stock you should be able to find another. See photos for some part numbers.

Please post last seven digits of your VIN?

[Watsey]

Originally Posted by WDE82

Ok in this case you likely have not filled the system properly. I would do a couple cycles of INPA bleed then traditional bleed with full liter of fluid. Maybe do this a couple times and go through 2L. It's overkill, but there's no way air remains after this.


use something decent like this


https://www.amazon.com/ATE-706202-Or..._t1_B07338GQM8

Also are you bleeding both sides of the brakes? The performance brakes each caliper has 2 bleed screws. And the screws must be on TOP. If they are not on top, the calipers are on the wrong side (not even sure this is possible to fuck up).

That ATE is good fluid - I've been using it for several years, daily driving and on track, and have never had any problems with it.

To answer your question "not even sure this is possible to fuck up", yes it is. I've seen photos posted on the UK Sub-Forum of BMW M Sport calibers which were installed upside down by a 'shop. Bleed nipples at the bottom of calibers is obviously going to make calibers very tricky to bleed.

[danb1979]

Originally Posted by Watsey

That ATE is good fluid - I've been using it for several years, daily driving and on track, and have never had any problems with it.

To answer your question "not even sure this is possible to fuck up", yes it is. I've seen photos posted on the UK Sub-Forum of BMW M Sport calibers which were installed upside down by a 'shop. Bleed nipples at the bottom of calibers is obviously going to make calibers very tricky to bleed.

FFS

My pal had this in his shop the other day; someone had their ITR DC5 fitted with the K24 engine and all new brakes all round (some sort of concoction of Porshe calipers rather than sticking with the OEM ones) and kept having issues

Had it trailered up to my pal and that was the first thing they saw when they took the wheels off in readiness to drop the engine etc...

All 4 corners with the lines in to the top, bleed nipples at the bottom...