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      03-22-2010, 06:16 PM   #1
sipman
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Brake pedal sinking

Hi,
I'm having an issue where the brake pedal sinks. If I apply decent pressure on the brake pedal, it stops firmly, then it will continue to drop about an inch or two. In really fast stops, I find the pedal ends too low for me to roll my foot onto the accelerator for heel-toe downshifts.

I bled the brakes twice and used ATE blue fluid, as well as R-4s (pads). So I'm guessing I have eliminated a brake overheating issue and hopefully, a boiled fluid issue too.

Anyone have any ideas why the brake pedal does this? And is there a solution that'll give me back a higher pedal so I can downshift properly?

thanks
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      03-22-2010, 07:14 PM   #2
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Quote:
Originally Posted by sipman View Post
Hi,
I'm having an issue where the brake pedal sinks. If I apply decent pressure on the brake pedal, it stops firmly, then it will continue to drop about an inch or two. In really fast stops, I find the pedal ends too low for me to roll my foot onto the accelerator for heel-toe downshifts.

I bled the brakes twice and used ATE blue fluid, as well as R-4s (pads). So I'm guessing I have eliminated a brake overheating issue and hopefully, a boiled fluid issue too.

Anyone have any ideas why the brake pedal does this? And is there a solution that'll give me back a higher pedal so I can downshift properly?

thanks
Sounds like there may be air in the lines. What method did you use to do the bleed?
I find the Motive Power Bleeder to give me the best results with no chance of introducing air into the system.
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      03-22-2010, 08:18 PM   #3
sipman
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First bleed was by a PCA approved shop to meet tech requirements so I don't know how it was done. But second bleed was with the power bleeder.
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      03-23-2010, 11:20 AM   #4
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I read your post then a few hours later read this other post by another person. It may be of help to you.

http://www.bimmerfest.com/forums/sho...=433232&page=3

Post #68

Might want to contact him and see if he got his resolved.
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      03-23-2010, 12:12 PM   #5
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This may not be an accurate comparison as this was on a Datsun track car years ago. If you hit the pedal hard the result would be the expected pedal firmness and reduction in speed. If you tried to feather or use moderate pressure, the pedal would slowly go to the floor while slowing the car. The problem was found to be a bad seal in the master cylinder unit.
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      03-23-2010, 08:07 PM   #6
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Thanks for the link. I was actually at the same event as F360C, the poster you referred to. He and I couldn't figure it out. We talked about it and his solution was to use his heel for heel-toe. I can't do the same with my heel after my ankle was crushed by a car that t-boned me on my motorcycle.
I had one person PM me that Stop Techs solved his problem. Not sure if a pad can be the issue. They aren't designed to compress much... i think.
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