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Offline dev

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My brakes are very soft
« on: March 15, 2018, 02:57:03 PM »
Hi all!
My 2011 z1000sx has been stored for the winter in the garage for the last 4 months.
Before storing it, I had just bought it and had done the usual maintenance, changed the oil and brake fluids (the mechanic did it, not me).

I have just been to the garage this morning since the weather is starting to get nice to check on the bike.
It starts up fine, and everything seems to be ok - except the front brake.

I've instantly noticed that it's much, MUCH softer than before. It's so soft that I can pull it so much it touches the throttle.
I didn't try to ride it like this to check if it achives max braking like this, but this doesn't seem right.
What could have caused this? I can't imagine that air somehow got in, I didn't ride the bike?
The garage is under ground and the temperatures are colder, but quite even throughout the winter.
Also, when I put in the new oil it was already cold outside, so the temp difference should be the reason (not even sure theoretically it would make difference since the oil system is "open" on the top where the canisters are, right?)

Sorry for my non-technical terms, but what is going on here?

Thanks!

Offline MrPlod

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Re: My brakes are very soft
« Reply #1 on: March 15, 2018, 03:11:22 PM »
If there are no signs of leaks, then it sounds like there is water in the system. When you put the new fluid in, was it from a new, sealed bottle? It's not good practice to use aged fluid from a used bottle as it sucks moisture from the air over time. Replace with new fluid and check again.

Offline dev

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Re: My brakes are very soft
« Reply #2 on: March 15, 2018, 03:26:34 PM »
Thanks for the answer. I don't know, as I've payed a moto service mechanic to do this for me.... Hope this is not the case, because I would be considering that a fraud... Any possible other reasons how moisture got in?

Also, if I understand the reasoning behind moisture, is that if the moisture gets in the system, it will evaporate as the breaks heat, since water has lower boiling temperature than the break fluid, so the evaporation fills the system with gasses, which make the brakes soft after long periods of hard breaking?
Also, if this is the case, leaving the bike to cool of completely will cause the vapors/gases to melt back in the fluid, so the breaks will work normally again until heated.
Am I getting this right?
And if I am, this doesn't really reflect on my case, as I didn't ride my bike for a few months and I have soft brakes.

Thanks again!

Offline MrPlod

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Re: My brakes are very soft
« Reply #3 on: March 15, 2018, 03:45:26 PM »
Yes you are correct. If you didn't ride it after the service, then I think you might need new seals in the system. It has to be one of two things...seals or fluid. You've just bought it, so the easiest way is to tell the seller it has a fault. Maybe it's not best if you try to fix it yourself. Brakes are comparatively easy to fix, but deadly if you get it wrong. Ring him and post the results back to the forum.

Good luck Dev

Offline dev

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Re: My brakes are very soft
« Reply #4 on: March 15, 2018, 03:47:27 PM »
Thanks for the answer, just wanted to say that I obviously didn't buy it new, it's a used bike with 19k KM and from 2011.
I don't think there's much point in contacting the dealer at this point? At least maybe before I get it inspected first?

Offline maccmike

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Re: My brakes are very soft
« Reply #5 on: March 15, 2018, 04:40:53 PM »
I think perhaps you are reading too much into this and simply bleeding will probably cure it. A tip is to pull your brake lever back as tight as possible and fasten with a bungy or similar, this has worked many times for me.

Offline dev

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Re: My brakes are very soft
« Reply #6 on: March 15, 2018, 05:01:42 PM »
Thanks for the answer! Can you tell me more about bleeding? I always presumed it was about removing the fluid completely in order to achieve zero air?
In any case, would this get the air completely out, or do I have to worry about boiling at hard braking?

The question still remains, why did this happen in the first place, the fluids were changed and it was hardly ridden afterwards.

Offline burty

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Re: My brakes are very soft
« Reply #7 on: March 15, 2018, 06:55:25 PM »
It's probably not something to over analyse and it's possible that simply bleeding the brakes will solve the problem. 

That said, if your bike is 2011 then it probably needs new brake seals anyway, if they have not been replaced at some point in the last 7 years.  Also new brake lines.  Technically both should be replaced after 4 years (from memory-may be 5 years) but few owners do it,
2011 Z1000SX, in GREEN, owned since September 2011.  50,000 miles, MCT tweaked front suspension, Maxton Rear shock, heated grips, MRA dark sport screen, PDoiler, Scorpion Serket Exhausts.

Offline dev

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Re: My brakes are very soft
« Reply #8 on: March 16, 2018, 11:58:02 AM »
Thanks for the answer!

I'm not trying to over-analyze, just trying to understand the reason behind it.
And not for pure curiosity, but in fear there's a possible underlying safety issue.
Actually, the information about brake seals is new to me, I didn't know they need to be replaced so early.
So this is a valuable information, and if it's the cause behind the air getting in (at least in theory), that's a serious security risk.
I don't want to play around with my brakes and risk losing them when I most need them.

With the same reasoning, any other inputs are highly welcome! Thanks!

Online mdr1970

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Re: My brakes are very soft
« Reply #9 on: March 16, 2018, 12:46:50 PM »
You mention replacing early, don't forget, as already mentioned regardless of actual mileage your bike is one of the original 2011 machines!
2014 Z1000sx Blacknificent Made in JAPAN, Perfected in the UK   :038:   :008: