problem with soft brake padel that drops half way when pressed

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QUOC2008
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problem with soft brake padel that drops half way when pressed

Post by QUOC2008 »

My brake padel is soft and seems to firm up when i pump it then goes soft again, How do i fix this i have got the master cylinder changed but its the same... im running d2 8pot big brake kit would this cause the issue
Peter Gidden
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Re: problem with soft brake padel that drops half way when pressed

Post by Peter Gidden »

First re-bleed and ensure all air is removed from system.

Did you do all the mathamatical calculations to ensure your calipers are matched to your master cylinder?
QUOC2008
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Joined: Thu Apr 11, 2013 4:33 pm
Location: london

Re: problem with soft brake padel that drops half way when pressed

Post by QUOC2008 »

No i did not... oh is that a problem maybe its the d2 kit
Peter Gidden
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Re: problem with soft brake padel that drops half way when pressed

Post by Peter Gidden »

QUOC2008 wrote:No i did not... oh is that a problem maybe its the d2 kit


It may well be.

All braking systems involve moving fluid around. There are fundamental relationships between the sizes of the m/c, caliper pistons, disc sizes and if they're not right the brakes will not work properly.

Air in the system is a different issue.
Adam86
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Re: problem with soft brake padel that drops half way when pressed

Post by Adam86 »

You can also make an adjustment to the rod that goes from the pedal to the master cylinder.

After changing my front pads my pedal went soft when pumping the right front after the pad change. I could however pump the pedal up on the second push. I had to adjust the rod and they are sharp again now but you have to be careful or you will get permanent brake drag.
Peter Gidden
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Re: problem with soft brake padel that drops half way when pressed

Post by Peter Gidden »

Adam86 wrote:You can also make an adjustment to the rod that goes from the pedal to the master cylinder.

After changing my front pads my pedal went soft when pumping the right front after the pad change. I could however pump the pedal up on the second push. I had to adjust the rod and they are sharp again now but you have to be careful or you will get permanent brake drag.


Weird. Never had to do that on a stock braking system.
Adam86
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Re: problem with soft brake padel that drops half way when pressed

Post by Adam86 »

It's actually happens twice. First was after a fluid change and we made the adjustment after completely ruling our air being the cause. Had no issue on the next fluid & pad change. Next pad change was the issue I spoke of and the most recent fluid change was perfect.

A strange one.
QUOC2008
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Joined: Thu Apr 11, 2013 4:33 pm
Location: london

Re: problem with soft brake padel that drops half way when pressed

Post by QUOC2008 »

Well its not a air issue... bleed the whole system 3x times in the past 2 years. Maybe i will try the adjustment but i think its d2 kit 330mm disc with 8 pot d2 calipers too be honest d2 kit is pretty rubbish with i went with ap kit
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