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08-15-2021, 06:30 AM | #1 |
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Brake pedal feel. Soft?
How is your brake pedal?
No matter how I bleed and what I do I can't get the pedal getting as stiff as I want, it's a bit soft and has way to long travel. I bleed it with INPA. My 135I is more or less a track car, current setup is: Stainless pistons both front and rear. Braided lines. RBF660 Fluid. Pagid RSL29 pads both front and rear. All brake / saftey nonsens programmed off. The pedal feel got way better after I programmed it, but still crap. Way to bad to trust it fully on track. Do you feel the same? |
08-15-2021, 09:12 AM | #2 |
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I'm quite sure you know the obvious things - a chance you didn't get the air out, or an actual master cylinder issue of some sort. After that... Do you have an opportunity to drive other 135i's for comparison? There's a chance your pedal is as good as it can get with the car and it just doesn't meet your expectations?
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08-15-2021, 10:04 AM | #3 | |
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Quote:
I've been thinking of the master cylinder, maby swap it for a m3 one. When the car is turned off, the pedal is as stiff as I want it. But asap I start it, it gets softer and when I press is really hard it sinks slowly slowly... Yes, that's a fact. I don't know if this actually is a "good" pedal feel in this platform. |
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08-15-2021, 12:47 PM | #4 |
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If it's a track car, are there not many others at the track who could offer advice too? I use a pressure bleeder and have never had a problem. About 250-300 ml out of each rear, 150 out of right front and 100ml out of left front.
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12-22-2021, 09:43 PM | #7 | |
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Quote:
Good luck solving this.
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E9x M3 front & rear suspension arms; BMW Performance brakes upgraded to drilled rotors in rear; BMW performance shifter; BMW Performance Exhaust; Wave Trac LSD with modified 'nannies'; BMW Euro Intake box; BMW Aluminum Strut Tower bar; ECS front and rear sway bars; 3 stage intake with BPC software; BMW style 78, 17 x 8" wheels with Bridgestone RE 980AS 225/45-17 tires; Koni Special Active struts/shocks, E9x M3 RTABs.
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01-20-2022, 09:29 PM | #9 |
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How did you bleed the brakes? The best way is the traditional 2 person method. This method more aggressively forces fluid through the system and helps drive out air bubbles.
I bled my wifes car ( Volso S70) my 3 times via the vacuum method and the pressure method and still had a soft pedal. Then I grabbed the wife and did it the normal way and sure enough a bunch of air came out and the pedal was firm again. |
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03-05-2022, 11:24 AM | #10 | |
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Quote:
I had my brakes bled recently, and the pedal is mushy again, not like it was immediately after the installation of new rotors and EBC red stuff pads a couple years ago. The explanation I received had to do with losing vacuum (there is a vacuum pump instead of running vacuum off the intake?). Whatever the explanation is, why do the brakes feel different after a bleed? The tech said he'd rebleed the brakes if I wanted (I went through this many times prior to the new brakes a couple years ago) but that, in his opinion, they were quite fine and no air in system.
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E9x M3 front & rear suspension arms; BMW Performance brakes upgraded to drilled rotors in rear; BMW performance shifter; BMW Performance Exhaust; Wave Trac LSD with modified 'nannies'; BMW Euro Intake box; BMW Aluminum Strut Tower bar; ECS front and rear sway bars; 3 stage intake with BPC software; BMW style 78, 17 x 8" wheels with Bridgestone RE 980AS 225/45-17 tires; Koni Special Active struts/shocks, E9x M3 RTABs.
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03-22-2022, 10:32 AM | #11 |
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I have a 128i that I track often and I've struggled with a consistent firm pedal.
Here's my setup -stock calipers w/ blank rotors -Stainless Steel brake lines (I noticed zero difference after installing these, not even placebo) -DTC70 pads front and rear -high temp RBF fluid At a 3 day event Watkins Glen, I was struggling with a soft pedal a few laps in. On the second day I finally decided to have the shop at the track put new fluid in my car midday and it definitely helped, but not enough. The pedal would be pretty soft going into turn 1 and also the brake zone before the bus stop, but after that there's a long sweeping turn where my brakes had a chance to cool. In the next brake zone I had a significantly firmer pedal. My thoughts are the brakes are just getting too hot. I'm upgrading to 335i fronts and 328i rears to see how this helps out. The stock 128i brakes don't have a lot of thermal capacity. Is there any instance on track where the brakes actually feel good? Are they firm for at least a lap or two? |
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03-22-2022, 10:40 AM | #12 | |
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Quote:
https://www.essexparts.com/news-blog...n-my-track-car |
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05-13-2022, 03:53 PM | #13 |
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Location: Santa Barbara, AP, Brembo, GIAC, Koni, Ohlins, Performance Friction, www.hpautosport.com
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At a shop environment the Steirius has been the greatest electric bleeder with 10 liters of capacity. No issues for 17+ years. With so many requests for different brake fluids the Mityvac MV6840 has yield years of trouble free service and very affordable. You will not run out of fluid with this one, even when trying to flush the ABS/DSC system. If used daily, the hose will need to be replaced every 6 months.
https://www.amazon.com/Mityvac-MV684...&creative=9325 |
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