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05-26-2016, 11:12 AM | #1 |
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Installing a 135 BBK on a 128
So I have this situation where I got a used stoptech BBK for the 135 and plan to install it on my 128. I know fitment wise, it should be spot on but other than this can anybody advise NOT to do so and if yes, why? I've read about piston sizes being different and all that but that's all I know. Plan on tracking soon and this will be a good upgrade but I wanna make sure I'm not hurting the car doing so. Help?
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05-26-2016, 04:23 PM | #2 | |
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You would probably notice brake bias issues when running the car hard on a track, and likely not in daily driving. You should also look at upgrading your rear pads at least to a brand that will match with whatever you're putting on the front.... |
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05-26-2016, 09:00 PM | #3 |
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I did call them earlier and he said that it will bolt on (this is also what the seller told me; and the rotor specs are the same as a 128's-if that will help at all) but he said that piston sizes are different and it "might" interfere w ABS and something like that. Clearly i am a novice when it comes to specifics like this.
If it helps, i do have a front and rear BBK setup but thats the thing, it's for a 135. i just don't know what step to take at this point. I want to upgrade it but then again if it will not function as it should in high perf situations, then it's not worth it. |
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05-27-2016, 12:00 PM | #4 |
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Go to RealOEM and see if the master cylinder part numbers are different between the models. If they are, research the piston diameter differences. If they are close, you should be OK.
http://www.realoem.com/bmw/ |
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05-27-2016, 01:05 PM | #6 |
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Well, the master cylinder is likely bigger on a 135i, by how much, no idea. One other idea is to sell the stoptech kit (lots of 135 owners would jump at the chance) and use the funds to get a 128i specific kit
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05-27-2016, 01:09 PM | #7 |
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Thanks asbrr yeah thats what I did it's already posted in the FS thread. I did email stoptech to see if they have any specific info re piston sizes. Will it really affect performance though even if the difference is not by much?
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05-27-2016, 02:22 PM | #8 |
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Found the diameters online and it looks like the master cylinders have two diameters. Here's the comparison.
135 D1 - 25.4mm D2 - 22.2mm 128 D1 - 23.81mm D2 - 22.2mm For diameter 1, which probably controls the front brakes, the area difference is on the order of 12-13%%, which would be felt as the pedal being 12-13% softer (more stroke for a given pedal load) than on a 135. The difference in pedal stiffness is greater between new and worn brake pads... Would you notice 12-13%? Maybe, you'd get used to it quickly. Rich |
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05-27-2016, 02:42 PM | #9 | |
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Let me give you an example - I have the 135i calipers on my car, which are identical to the BMW Performance Brake kit sold for the 128. However that kit also comes with upgraded rear calipers, I haven't gotten around to adding those yet. There is also some coding the dealer does to account for the different brakes when the BMW Performance kit is installed. This means I am running a non-factory brake bias, with an incomplete kit. Practically speaking, the car drives great, and there is huge improvement in brake feel as well as braking power. I haven't been to a track with this setup yet....but I know that I may experience non-optimal performance if I did...the brakes would work fine most likely, but over extended use at heavy loads I may find the rears aren't working as much as they should so I'm not getting max braking force...but does that mean the brakes aren't working? no, they are just not optimized. Most importantly, please take all this with a grain of salt...these are all just opinions from forum members, I don't want to be the one to say one thing and be held responsible for a problem with a *slightly* important part of your car! So if you want absolute peace of mind, you should get a kit designed for your car specifically. |
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05-27-2016, 07:59 PM | #10 |
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Appreciate all the help and info. I did have a chance to communicate with David Zeckhausen through email and basically told me that IT WILL WORK provided the rear rotor hats be modified to allow for e-brake functionality. Bias difference between having the "wrong" kit and the "proper" BBK is negligible (2%) and will not necessarily hurt performance, based on the differences in piston diameters between the two BBKs. Pedal feel might be different as well due to more-than-normal (about 8% more than it should) brake fluid that needs to be displaced when the 135 BBK is used on the 128, resulting to a more softer feel compared to having the 128 BBK, but most likely firmer compared to stock/OEM brakes.
Overall, I am still debating. The set is in the FS thread for now. If I get offers, then yeah I'd probably just sell the whole set to get a new kit. If not, then I will most likely just install them. We shall see. Last edited by $iriu$black; 05-27-2016 at 08:14 PM.. |
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05-28-2016, 02:09 PM | #11 | |
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05-18-2018, 09:30 PM | #12 |
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Hey all,
Recently I ran across this post while re-researching the 335i front brakes I swapped on my 128i. I know its an older thread, but wanted to chime in and get some information out. My retrofit Front 335i Rotors Front 335i Calipers Front 335i Caliper Brackets Front & Rear-Outer Stainless Lines Ate 200 fluid - 1.5 Liters + INPA - ABS Bleed x3 Result: The amount of stopping force increase from the mod was substantial. They look better, perform better in an absolute sense, and only weight a couple pounds or like 1kg more per corner because you are going to an aluminum caliper vs the OE steel one. The caliper alone is significantly lighter than the stock steel caliper which helps offset the increased mass of the front rotor (but not entirely). -------------------------------------------------------------------------------------- But - I do have annoying side effect after the swap. Take this for what it's worth, I like certain cars for their balance. BMWs often get everything right, the steering feedback and the way the effort builds, the brake effort and feedback, the weight and throw of the shifter, the seating position and ergonomics and the way the car rotates and handles dynamically. I like that balance which is why I chose this car over many other options. You don't always get that balance even in a sports car, least of all a coupe or sedan. So, my issue is as follows. As mentioned before me there are two different master cylinders with the larger piston being for the 335i/135i setup, (34336785664) which displaces more fluid to compensate for the larger caliper piston and keeps everything balanced. I'm running the stock 128i part 34336785662 and the issue is reduced pedal feedback and more challenging brake modulation. There was easily a 12% reduction in overall pedal effort and 12% or greater increase in the pedal travel, which coincides with the math. What you also get from the larger diameter rotors is leverage, and significantly larger pad area translates into 25% MORE stopping power per brake effort applied. - Explained another way; your foot travels noticeably farther, requires less pressure, and locks the front tires at a lighter pedal pressure. That's all good things, no? Not always; You also lose about 25% of the pedals feedback "resolution" so instead of braking on a scale of 0-40lbs effort applied, you are working on a scale of 0-30 resolution. And you cant really feel the first and lightest bit of pedal movement, so there is sort of more dead travel before initial bite. (But man they are strong!). - You just have less information translated to your foot, and you have to rely more on g-forces in the seat and harness and tire noise than pedal finesse, its just not as good from a car-control standpoint. This is all well and fine for driving in traffic for most people, as many cars have very light but strong brakes and it works great - until you are trying to heel-toe downshift. Heel-toe shifts became much harder to modulate brake force because you lost feedback in the brake pedal, any little variation in pressure from blipping the throttle dramatically changes the brake force, also the pedal travel is longer which means your foot is not always placed optimally for the throttle since the brake pedal travels longer over its range - not like they need bled, but more like a pickup truck pedal is long and soft, over-boosted and hard to modulate. Frustrating. And one other issue, BMW seems to have some sort of emergency panic braking assist built into the software. I'm not sure exactly, but the brakes are not always consistent. They can be very easy to lock up after traveling for some distance, they will erratically lock a corner up from driving a little quick into a long sweeper and trail braking lightly, like the car thinks you are evading an accident and goes full panic-stop with only a couple pounds of pressure applied. This is true even on stock brakes, I mention this only because it's magnified with my modifications. Once you start pushing the car and brakes, it's almost a non-issue. Some information is available for coding in the ABS module for BBK. I definitely want to try this sometime soon. In short, It's now more difficult to modulate threshold braking, and harder to brake smooth when match-rev downshifting, which makes balancing the car in corners more work and less precise. But the car hauls speed down much easier, over-brakes all-season tires, and there is significantly reduced chance of brake fade from extended lapping. My theory moving forward: Swap the master cylinder to the larger-piston variant #34336785664 to bring the brakes back to an OE baseline identical in characteristics to the 335i setup. OR I may put some sort of vacuum restriction inline to the brake booster. But that may make the brake erratic instead of heavier in a linear manner which could be worse, initially getting full over-boosted brake assist, and tapering to almost no assist at 10/10 when you need it with a restricted vac line. So I may just disconnect and plug the vacuum line all-together and take it for a trial run with manual brakes. Yes, they will be significantly heavier than stock. But probably Less so than a 335i with it's vacuum booster disconnected, because the 128i Brake Master I have has a smaller diameter piston, and the car is much lighter and smaller which helps in a manual application. - Worst case it goes back together as is. Which is usable and safe, if only more frustrating for me to drive near the limit. --------------------------------------------------------------------------- [I like the 335i swapped fronts. I recommend them in place of big brake kits, they are that good that unless you just have money to spare you don't need anything else, I just personally need to dial them in with the correct master, or some reduction in brake boost, for half or more people out there that extra effort is totally unnecessary as you may actually enjoy the lighter pedal effort and significant gain in stopping power for your daily commute]. Alternatively: Possibly the best budget option for an OE-like balanced and affordable kit is probably to keep the stock steel calipers. Now you dont have to open up the brake system it's now just a routine pad swap. Upgrade the rotor to the 330mm found on the '06 range 330i. (up from 300mm on the 128i) Then only upgrade the caliper mounting bracket to offset the caliper to fit the rotor. It's a mod that has been done before. Increases brake torque by 10% simply by the leverage of the rotor and increases the mass of the rotor over 10% which will go a long way towards brake fade resistance. Presumably your brakes need replaced anyway, so your added cost is really only the brackets since you are buying pads and rotors anyway. There are also two-piece 330mm rotors available with aluminum hats, possibly from a mid-2000s Z4 model making for a bigger-brake kit that's also overall lighter than stock. And the best part; stock caliper uses the stock brake master and remains a balanced system. Note: Certain very quick 1-series race cars use this setup with great results, albeit having a lighter chassis. Food for thought. |
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05-19-2018, 02:02 PM | #13 |
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Excellent post with a well worded explanation. The word "feel" doesn't really explain much in the context of braking, and it is a very good observation to state how the usable range of brake pedal travel has now reduced and you have less "resolution" along with the side effects of difficulty modulating brakes when doing a heel-toe downshift.
As a similar example, one pet peeve I have is how the clutch feels on this car, I've done all the popular mods (CDV upgrade, BMS clutch stop, brass clutch pedal bushings) and I hate the way the clutch lacks progressiveness and "feel". Yes I can change the engagement point (clutch stop), have the engagement be more linear and stronger (CDV upgrade), but I can't make the clutch feel progressive over a usable pedal travel distance. This makes for annoying 1-2 shifts unless I really really concentrate.....but I digress.. This is something many people miss when it comes to modifying their cars...these are subtleties that BMW engineers spend a lot of time working on and the average driver cannot really put a finger on but qualitatively makes a difference in driving enjoyment. We are in most cases poorly coordinated animals, and having the ability to "meter out" braking force, acceleration, clutch action, steering with our less than precise limbs is a huge part in driver engagement, feedback, and ultimately enjoyment. |
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05-20-2018, 03:37 PM | #14 | |
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05-21-2018, 01:08 PM | #15 |
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@Zombie_Head I think the best option would be to get the larger master cylinder, or a machine shop could possibly bore your existing one...
Restricting the assist will simply make the pedal firmer, but you'll still have to move the pedal the same distance for the same working force from the brakes as with full assist. The larger master cylinder will shorten pedal travel, but (IIRC...) will make the pedal light. I'm having this debate right now. My pedal is strong when the brakes bite, but the pedal is long, and makes it impossible to heel-toe into corners.
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05-21-2018, 02:26 PM | #16 | |
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Just incase at some point in the future, if i ever wish to sell the car (hopefully not) i want to be able to sell it with ease. Meaning at little mods as possible or as many OE BMW genuine parts as possible. As of now, my experience, my main concern with the brakes on track is the running hot/overheating of the factory front brakes. I am looking at several options from Zimmermann cross drilled, to Nitrac slotted to Mtec grooved and so on coupled with something like EBC Red Stuff pads. I already have the F20 style back plate with a scoop to aid cooling, but when you are at the Nürburgring or the Gp track and constantly braking as hard as possible, as late as possible for as little time as possible from speeds between 160 kph-200kph down to 80-120 kp constantly, the brakes are always going to be running really hot. I have seen several 130i E87s with stock front discs glow red right before Ex-Muhe corner (miss-hit miss at 130-140, you reach 160-170 and brake hard to drop down to 120-130 then hard again to reach 70-80 and so on). In my head, no matter how big the solid discs are in the front, cooling is the key (from what i see), so that is why as of now, i am looking into disc options without any changes to the brake system (calipers and hydraulic system). Still a lot of disc options in my head (stock size) and maybe upgrade to Yellows instead due to higher temps, but still undecided. I forgot to mention, despite being undecided, i really think using the E9x caliper brackets combined with the Z4 2 piece rotors are what i am leaning towards. Last edited by Zombie_Head; 05-21-2018 at 02:40 PM.. |
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05-21-2018, 03:53 PM | #17 | |
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I totally get you on not doing anything crazy. One thing you can do is run some ducts from the bumper into the wheel well, or have high-temp tubing dumping air into the hubs. I deleted my fog lights and used their housings to catch air, and then used a piece of PVC pipe to attach hose to, and then routed the tubing into the fender. I have yet to get it to the hub, but that's my next project. Anyways, it was noticeable how much better the brakes felt after a long straightaway... Two-piece rotors would be a great way to go. A little freer expansion for the friction ring (IDK if that's a good thing) and less rotational weight (better handling and ride).
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05-21-2018, 04:11 PM | #18 | |
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08-24-2018, 10:12 PM | #19 |
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The BMW performance brake kit is still the best option for the 128. They're basically 135 brakes. I've had fronts on mine for 4 years now...the slight increase in pedal travel can be mostly offset with braided lines. I've recently acquired rear performance calipers, in the same metallic yellow color as my fronts. But the big problem is with the rotors; the parking brake circle is about 1" (25mm) larger. I bought the larger 135 shoes, adjusters and backing plate, but they simply don't work, even with modifications. The cast tab on the hub is too high for the 135 shoes, they sit too high. I believe the 135 uses 3-series hubs, which are different, even though the calipers & rotors sit perfectly. I'm looking at 2 options: modifying the 135 shoes to sit lower, about 3/16". Or modifying the 128 shoes to bring them out 1/2"...tricky. Stay tuned...Meanwhile, I have no e-brake, which is not a big deal, you just put it in 1st or 2nd when you park...BTW, the big rears have added a noticeable improvement...the braking is superb now...
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08-25-2018, 08:35 AM | #21 |
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Hey, call them whatever you want...the 135 hubs are 105mm where the parking brake mounting plate sits, the 128 hubs are 90mm. Since the BMW Performance brake kit, part # ending in 769, fits E90 cars with no parking brake modification, those cars must have the same rear hub as the 135...
NOTE: I have "solved" the parking brake problem...you will be able to use the 128 parking brake setup with the larger 135 rotors, which have a 1" larger drum diameter for the parking brake...I'll post pix & description shortly...
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08-25-2018, 11:52 AM | #22 | |
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Nice waiting for result, I am fitting BMW Performance brakes to my 125I Msport Coupe when I get home in about week & have been looking for a solution, See my post I was talking with andrey_gta https://www.1addicts.com/forums/show...=975919&page=6 |
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