08-11-2023, 02:10 AM | #1 |
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Clarifying the M-Performance Brake Kit - Wheel Size and Master Cylinder/Brake Booster
I've seen a lot of confusion and misinformation in these forums, so lets clarify the requirements for the M-Performance Brake Kit on the G20 3 series!
Backstory I recently installed M Performance Brakes on my North American 330i that used to have the base floating calipers. I learned a lot of things in the process. After the upgrade, I ended up with annoyingly soft/mushy brake feel. Totally fine for daily road use, annoying for backroad driving, and inadequate for track use. The faster you go and the harder you press on the brakes, the softer they feel - not great! And yes, they were coded in properly. How could these brakes feel so mushy? I've driven an M-Sport Brake equipped 330i and an M340i with the same M-Sport brakes - these cars had a consistently firm pedal and near-instant brake bite with minimal pedal travel. How could my car with M-Performance Brakes feel so different? I sought out for a solution. The answers are below. As for why I made the upgrade? 1. They look great. The base floating calipers are a travesty - should be a crime that BMW does not include M-Sport brakes in the M-Sport package (they're a standalone option). 2. I wanted brakes that were capable of light to medium track use. Base floating calipers don't cut it. AP Racing kits or Brembo kits were twice the price of the M-Performance. From this perspective, it made sense. Minimum Wheel Size Requirements for M-Performance Brake Kit The g20 M Performance brakes will fit on SOME 18 inch wheels - that's why the official minimum is 18inch for the kit, but I think some dealers edit the description to 19inch to save themselves the trouble. It all depends on the barrel size and clearance. Supported 18inch wheels (based on what I personally know) BMW 796M - Part of the M-Performance catalog. Offered in Winter Tire packages and Summer Tire packages. APEX VS-5RS 18inch - Check their fitment guide for more information Master Cylinder and Brake Booster Requirements for M-Performance Brake Kit Summary for g20 M Performance Brake Upgrade US 330i with base brakes (grey floating calipers)
US 330i with M-Sport Brakes or M340i? - Direct Fit!
EU/ASIA 320i/330i with base brakes (grey floating calipers)?
Detailed Explanation While US 330i with base brakes don't technically need a brake booster (the m-perf brakes will work, but pedal feel will be soft and mushy), you will benefit from upgrading to the stronger brake booster offered in M-Sport Brake equipped cars (330i with M-Sport brake option or standard on M340i). North American g20 3 series Fortunately, all North American 3 series regardless of brake type have the same Master Cylinder. This may be the reason why BMW NA chose to not sell the M-Perf Brake Kit that comes with the additional Master Cylinder+Brake Booster part - because NA vehicles are already equipped with the better Master Cylinder. BUT, 330i with base brakes are equipped with the weaker brake booster and will suffer from an annoyingly soft/mushy brake pedal if paired with M-Perf Brake Kit. All North American 3 series have the same Master Cylinder. North American 330i Base Brakes (Floating Calipers) Brake Booster P/N: 34336889801 North American 330i M-Sport or M340i Brake Booster P/N: 34336889796 Europe/Asia g20 3 series European or Asia market 320i/330i with the base floating caliper brakes are equipped with both a smaller Master Cylinder AND the weaker brake booster. This is why these markets sell a version of the M-Perf Brake Kit that comes with an additional Master Cylinder+Brake Booster part. If you choose to install M-Perf Brakes on a EU/Asia base brake car without the upgraded Master Cylinder+Brake Booster, you will have an arguably dangerously soft brake pedal. Additional Notes or Reading These conclusions were made by analyzing part diagrams and part numbers on REALOEM and confirmed with the Shop Foreman at a BMW dealer. For more information on the different g20 brake types, refer to below. Hopefully, they update their thread based on this post https://www.bimmerworld.com/About-Us...rakes-G20-G22/ |
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09-05-2023, 09:21 PM | #2 |
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TorBimmer I can't thank you enough for this info. Going from base brakes all the way to M-Perf. I see you recommend the brake booster. How many are needed? 1 total, or 4 (1 per wheel)?
Stupid question... you listed the part numbers for the base model brake booster and the M-Sport/Perf booster. I assume I need the latter for the upgrade...? Man, you start thinking of an upgrade and someone comes along with the EXACT situation |
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09-05-2023, 10:49 PM | #3 | |
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While you don't technically need need it, it will noticeably improve your brake feel. If you want even more improvement, switch to stainless steel brake lines. Additional FYI, the M-Performance brake discs are loud. They're slotted AND dimpled, so that creates turbulance which results in a shhshhshh sound when you're cruising around. You can only hear it with the windows down. But yeah, it would definitely be nice if there were mods who could sticky or sort these threads into a "Knowledge Base" section or a centralized how-to. It's difficult to find things...I'm still trying to figure out how to code ASD off and add the exhaust valve control menu... |
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09-06-2023, 12:33 AM | #4 |
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WHEW! Because 4 of those priced out to about $1800. Wifes ok with that small additional cost for 1.
The brake sound you describe... must be common to all M-Perf brakes then? That's what I'm drawing from your description. I wonder if that ends up being just slightly annoying or louder than one may like. |
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09-06-2023, 07:27 AM | #5 | |
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09-06-2023, 01:22 PM | #6 | |
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The dimples on the M-Perf are particularly noisy with the shhshhshh sound. I find it annoying, but I never cruise with the windows down so I don't care. The cross-drilled rotors on the G80 M3 are noisy too, but it's a lower frequency helicopter kind of noise lol. But my hearing is sensitive, so, YMMV |
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09-08-2023, 11:58 PM | #7 |
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TorBimmer Sorry... had a last follow up.
1 M-Performance Brake Kit 34-10-8-854-026 1 Brake Booster 34-33-6-889-796... Any additional pieces required? The guys on the site say the Kit has everything I need, but with adding the Booster, I'd hate to not have the one or two things (a gasket, a bracket, a magic screw?) I need when I have my shop install. Thanks! |
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09-23-2023, 12:59 PM | #8 |
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I pulled the trigger on the Brake Kit and the Brake Booster. Next up is finding a good install price from a dealer on local shop. Leaning dealer for quality and piece of mind.
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09-27-2023, 02:30 PM | #10 | |
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I just went out to check on these parts, they indicate they are no longer available. Any ideas? |
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09-27-2023, 05:07 PM | #11 |
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They are very much available. I ordered the both from a BMW Parts Center out of NH. Both are also on Get BMW Parts. The booster has to be ordered from Germany but available. Who did you use?
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09-27-2023, 05:08 PM | #12 |
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09-28-2023, 03:26 PM | #13 | |
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Thanks again, Kevin |
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10-16-2023, 01:43 PM | #14 | |
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I wasn't quoted for any additional parts. Just the brake booster itself, so I'm hoping that means nothing extra is needed for the installation. I hope it goes well for you. |
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10-16-2023, 03:53 PM | #15 |
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All good brother. Friday is the big day. I have the kit and booster.
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10-19-2023, 05:50 AM | #16 | |
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M Performance Brake Kit in Red 34-11-2-450-161/34-10-8-854-026 - i think this has no brake booster. Two3Series858 shared this too. 34-11-2-458-884/34-10-8-857-048 - looks like this has brake booster. the parts break down lists a booster though i cant find this p/n i found a few places that can retrofit the bmw m performance brake kit but i think their kits come without the booster. im told it's extra charge for the booster (34-33-6-889-796 i hope) but what about master cylinder, i see there are 2 parts? do i get both? is this master cylinder the bigger one i should be getting? Brake Master Cylinder Reservoir - BMW (34-33-6-889-802) Master Cylinder - BMW (34-33-6-892-205) |
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10-19-2023, 06:28 PM | #17 |
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The two kits are for the two different sets of markets. Theres a North American market kit and there's a Euro/Asia/everybody else kit. The latter includes a Master Cylinder and Booster because those markets vehicles don't have the same MC and don't even have a BB installed.
The NA market vehicles ALL have the same MC and A booster, but the booster model is different depending on what model vehicle you have. I was not directed to purchase a different reservoir so I only got the kit and upgraded booster. As you discovered, the kit model numbers have changed like all BMW parts tend to do. So info for the most recent NA kit still references the old NA kits info. I'm in that same boat right now with the dealership looking for the most updated install info. |
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10-20-2023, 08:11 PM | #18 |
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Install completed! The dealership techs had to bleed the system multiple times just as others had experienced. Not sure the reasoning why, but eventually they felt right enough to release the car. Maybe someone can unpack that. Bummer that my stock brake pads were damn near brand new.
The techs said they were aware of the brake booster issue and hoped I had one. |
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10-22-2023, 11:59 AM | #19 | |
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10-22-2023, 07:51 PM | #20 | |
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10-23-2023, 02:31 PM | #21 |
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eagerbimmer
You cannot find the 29689220301 part number because it is unique to the M-Performance Brake Kit and not offered standalone. This part is a unique pre-assembled kit of the Master Cylinder + Reservoir + Brake Booster together. It is only offered in non-NA markets in the M-Perf Brake Kit+Master Cylinder kit. You will need this kit if you have a EU 318i (or diesel equivalent). If you have an EU 330i or 330e with the base floating calipers, I'm not sure which kit you need, you'll need to confirm which master cylinder and which brake booster its equipped with. Two3Series858 Congrats on the upgrade! Glad the brakes are feeling good. It's a night and day difference with the right brake booster. |
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11-14-2023, 02:41 PM | #22 |
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Successful brake booster and master cylinder upgrade
Hi Folks
I upgraded my 318i brakes to the M Sport brakes and it had spongy brakes even after proper bleeding by dealership. Purchased and installed the M Performance brake booster and master cylinder. I only bled the FL caliper inner fluid pipe and RL caliper as the car had a brake fluid flush at dealership 2 weeks back. Pumped the brake pedal until I got fluid release without bubbles on both calipers (2 man job without bleeding kit). Brake pedal distance and responsiveness is akin to a stock 330i with M Sport brakes (Tested). The brakes are very responsive now. Huge difference with the proper brake booster & master cylinder. |
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brake booster, g20, m perf brakes, m performance brakes, m-perf brakes, m-performance brakes, master cylinder |
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