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03-18-2017, 10:37 AM | #1 |
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135i brakes on 128i; softer pedal feel issue?
hey guys,
i just installed bmw performance brakes on my 128i (135i brake setup). the pedal feels slightly softer... its blead properly with no air in bud the pedal feels somewhat a little softer... mind you, bedding isn't finished; freshly installed. anyone felt the same feeling? |
03-19-2017, 12:39 AM | #2 |
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With the engine on, foot firmly on brake pedal does it sink or stay firm at the same height? Is there any mush or springyness if you try to press further?
They can be a pain to bleed those calipers especially the fronts with only one bleeder for both banks. Try thump the caliper with a mallet as you pressure bleed them. Did you wedge the brake pedal down before disconnecting calipers or let the master drain completely? |
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03-19-2017, 08:07 AM | #3 | |
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03-19-2017, 08:44 AM | #4 | ||
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03-19-2017, 08:47 AM | #5 | |
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it just feels so much different when i brake. has ifi didn't have enough braking power. but no air bubble since i still have brakes... mind you, it may be the pads bedding time... |
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03-20-2017, 08:45 AM | #7 | |
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for budget purpose i went with zimmermann discs and trw pads. i believe the pads are just missing initial bite. also, the pedding time is now also complete since i hadquite a drive to do yesterday. they feel much better now. |
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03-20-2017, 08:49 AM | #8 |
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03-20-2017, 04:03 PM | #9 |
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To OP:
I put on 135i brakes on my 128i about 18months ago, with Stoptech street performance pads. They were very lightly used so bedding had already occurred. Compared to stock brakes....there was no comparison. Great bite, and it scared the crap out of me the first time I had to really hammer on them. So - yea likely just bedding time, but after they are bedded go to an empty stretch of road and stomp on the pedal, it should be quite noticeable |
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03-20-2017, 06:12 PM | #11 |
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TRW pads have heaps of bite for a cheap aftermarket pad, not as much as genuine BMW pads but close. Zimmermann paints their rotors, which fouls the pads and extends the 'bedding' (ie until normal performance is achieved) time.
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03-20-2017, 06:42 PM | #12 | |
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03-23-2017, 03:52 PM | #13 |
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^^^ This. Your master cylinder needs to move a lot more fluid to give the same pedal feel and response from the brakes. I know in the case of my F15, when I put the MPBK on, I had to code it for the Sports brakes kit (there's a vacuum accumulator which helps pedal feel). Before and after coding, it was night and day. Not sure if that's the case here or not?
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03-24-2017, 02:23 AM | #14 |
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Master cylinder is same across all non-M E8x models. Yes, for all models except 135i you will need to code the car for Sport Brake. I actually find stock 125i/128i brakes to be far sharper than stock 135i brakes.
First i've heard of a vacuum accumulator for F15 models, not even the M models have one. The software changes are mainly to adjust the DSC threshoulds to update the vehicle order. FWIW i have coded my 135i to have sport brakes even though they come with them from the factory. There was a slight change in pedal feel but you quickly get used to it and forget it has evem changed. You cannot reverse this once it has been done unless you alter it using software other than ISTA/P. Maybe BMW technical might be able to reverse it on request also. Even coding a new DSC control unit did not delete the sport brake |
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03-24-2017, 07:23 AM | #15 | |
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03-24-2017, 07:40 AM | #16 | |
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On the 1ers, this started in 2011. Last edited by MightyMouseTech; 03-24-2017 at 07:46 AM.. |
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03-25-2017, 07:32 PM | #17 |
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Correct, but it's not an accumulator. The only vac accumulator on an N55 is in the rocker cover on early engines with pneumatic wastegates.
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03-27-2017, 09:25 AM | #18 | |
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03-27-2017, 10:45 AM | #19 | |
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Lastly - I have also not done the "coding" for the BMWP brakes...I've had the car on the track a couple of times with no complaints so far so not sure if I will get to that... |
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03-27-2017, 11:07 AM | #20 | |
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The 135i rear calipers are 2 piston? I guess that could over tax the m/cylinder. |
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03-27-2017, 11:45 AM | #21 | |
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Yes the 135i rears are 2 piston and would probably have a larger combined volume than the stock 40mm rear single piston (can't seem to find the rear piston sizes for a 135i caliper easily). So I guess they would be worse for feel and would require a larger master cylinder, not sure how to really quantify the worse feel as there are a few people that have run them on their 128i. You do lose the e-brake if you just swap them onto your 128i rear, keeping the e-brake involves changing out the wheel carrier IIRC. |
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03-27-2017, 12:35 PM | #22 | |
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