BMW 1 Series Coupe Forum / 1 Series Convertible Forum (1M / tii / 135i / 128i / Coupe / Cabrio / Hatchback) (BMW E82 E88 128i 130i 135i)
 





 

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      10-05-2017, 11:17 AM   #1
turbosl2
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E88 Pad replacement - soft pedal

So the brake pedal was getting soft on my E88, pads were all pretty worn so i decided to change them all.
I went with Akebono for front and rear, and reused my rotors because they were nice and smooth (52k miles) but they do have a small lip on the edge (thickness slightly reduced). The brake pedal doesn't feel as good as i wished it did, its kinda spongy.
Has anyone else experienced this with Akebono, or is it because my rotors are a tad thinner. I would think the hydraulic system would compensate for that.

Also,
I used BMW INPA to bleed all four corners and went throug ha whole Liter of Dot 4 LV
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      10-12-2017, 04:06 AM   #2
titium
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Did you fully rinse the system with a pressure bleeder before running the inpa routine?

Did you have a pressure bleeder on while doing the inpa procedure?
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      10-12-2017, 07:09 AM   #3
juld0zer
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So many people changing to Akebono pads and then complaining about issues such as:
- Pads clunking or rattling in the carrier
- Poor brake response compared to genuine pads
- Soft pedal/requires a lot of leg strength to stop the car

I'm not a hater but you really have to understand the compromise in your choice - you chose to have cleaner wheels instead of responsive and strong brakes!

INPA and any sort of scanner bleed is not a substitute for an assistant pressing the pedal. Ie, it is not designed to operate the ABS pump to pump fluid thru the system. Its main purpose is to 'tickle' the valves to dislodge air bubbles whilst pressurised fluid from a pressure bleeder is passing through, carrying the bubbles away.
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      10-12-2017, 07:36 AM   #4
02Pilot
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I haven't used Akebono pads on my 128i, so I can't speak to what the compound is like in this application, but there are a few things to note.

First, bedding matters. You need to get the pads bedded to the rotors correctly, especially if you reused rotors. Hopefully you at least cleaned up the rotors with Scotchbrite pads and brake cleaner. You'll never get decent performance out of improperly bedded pads.

Second, compound matters. Once you've got them bedded, go out and do several hard stops from speed in rapid succession (find a nice quiet back road to do this, please). If the brakes start feeling better after the first stop, the compound likely needs some heat in it to work optimally (ambient temps matter here as well).

It's important to understand how your chosen braking components work together to stop the car. Everything's a trade-off.
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      10-12-2017, 09:19 AM   #5
turbosl2
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Yes i did clear the system. I have installed many brakes in my life, this is not a compound issue because i am not complaining about the stopping. Its almost like the system has air in it. The pedel can get rock hard when car is off but with the vacuum assist it feels spongy, i am talking about idling in park. I can push on the pedel and almost get it to bleed down to the floor if i press and hold.
The pads do stop the car ok, not like OEM, i get that. This is more of a pedal/hydraulic issue...like air. I did the procedure twice using INPA. I even went back last night with my wife to do it manually(press/hold and crack the bleeder) to see if any air came out, Nothing. Seems like the INPA bleeding worked as it should. Bizzare that i cant get a real firm pedal
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      10-12-2017, 10:02 AM   #6
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So the pedal continues to sink with consistent pressure? That points to an internal sealing problem, most likely in the master cylinder. Did you pressure bleed or use the two-person pedal method? If the latter, it is possible to depress the m/c beyond its normal range of travel and dislodge debris and/or rust that can cut seals.
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      10-12-2017, 11:27 AM   #7
turbosl2
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Correct,
No pressure bleeder, just pump and hold, but mostly using the ABS pump system and INPA. I felt the pedal get like this and figured it was due to the brakes being all worn. It feels like when your brakes are all worn down and u have a low pedal. But yes, i can get the pedal to sink down if i hold it long enough. Its not that bad just not firm and solid i i remember.
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      10-12-2017, 12:17 PM   #8
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Think about how a hydraulic brake system works: pressure is applied to a piston (or two, depending on the design of the master), which transfers that force via fluid to pistons at the wheels. It's a closed system - even if the pedal goes lower than it did before due to air in the system, once any air is compressed, the pedal cannot move any further (fluid being incompressible) unless fluid is leaking, either internally or externally, or the volume of the system is changing (via a soft and now-bulging rubber line). If your pedal is continuing to drop, there is an internal problem (assuming nothing's leaking), probably in the master cylinder.
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      10-12-2017, 01:21 PM   #9
turbosl2
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it is possible
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      10-13-2017, 06:05 AM   #10
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Bleeding with INPA to actuate the valves and pump must be done with a pressure bleeder. If you did it without, that may have caused problems.

Before you start chucking parts at it, i encourage you to take it to a dealer or competent Euro indy with a compatible scanner to do a full pressure bleed and bleed of the DSC module.

It is strange for a car, especially a late model BMW to get a soft pedal suddenly. Usually when BMW pads are almost finished, they get extremely dusty and very bitey.
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