Kawasaki Z1000SX Forum

Z1000SX Chat => Maintenance, Servicing, and Mechanical => Topic started by: dev on March 15, 2018, 02:57:03 PM

Title: My brakes are very soft
Post by: dev 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!
Title: Re: My brakes are very soft
Post by: MrPlod 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.
Title: Re: My brakes are very soft
Post by: dev 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!
Title: Re: My brakes are very soft
Post by: MrPlod 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
Title: Re: My brakes are very soft
Post by: dev 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?
Title: Re: My brakes are very soft
Post by: maccmike 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.
Title: Re: My brakes are very soft
Post by: dev 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.
Title: Re: My brakes are very soft
Post by: burty 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,
Title: Re: My brakes are very soft
Post by: dev 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!
Title: Re: My brakes are very soft
Post by: mdr1970 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!
Title: Re: My brakes are very soft
Post by: dev on March 16, 2018, 12:59:14 PM
mdr1970, I don't understand what you mean by that, sorry! :)
I can interpret that in multiple ways:
- original 2011 model was the best so yay!
- 2011 model is old enough in 2018 that break seals should have been replaced already (it's not early at all)
- 2011 model is so good that it doesn't need anything replaced for 100 years :D

Can you clear that up for me? Thanks :D
Title: Re: My brakes are very soft
Post by: maccmike on March 16, 2018, 01:46:13 PM
I have been in the motor trade for over 40 years and have never heard of changing caliper seals routinely at regular servicing periods, only if leaking. I have looked in the owners manual and there is no mention of changing the seals, only flexible pipes and fluid. I changed the pipes on my track bike a couple of years ago, bled them and thought job done. Next day tried them and lever hit the handlebar. Bled them again and same happened again, not quite so bad but they were still not satisfactory.  Bled them again and pulled lever back as hard as I could and fastened with a bungee. Next day brakes were perfect.
I am 99% sure all you need to do is bleed them, but I would try the bungee trick overnight as well, and I think you would have no problem.
Title: Re: My brakes are very soft
Post by: mdr1970 on March 16, 2018, 02:03:12 PM
 :461: with Mike's posting, but what I meant was that at 7-8 years old, your seals are getting on, so could be considered as a possible fix.

 :431: for the confusion!
Title: Re: My brakes are very soft
Post by: dev on March 16, 2018, 02:05:40 PM
thanks both, that makes sense.

just to make it clear, to bleed my brakes, I need to open the oil canister and press the handle until there are no more bubbles coming up, is that correct?

@mike: after you did this, did it happen again in some time, or was the fix "permanent"?
Title: Re: My brakes are very soft
Post by: mdr1970 on March 16, 2018, 02:35:07 PM
Bleed the brakes as per the service manual. if you have, or check out Youtube:

After, or try this first overnight, don't leave the lid off, just tie back the lever...

Title: Re: My brakes are very soft
Post by: maccmike on March 16, 2018, 06:32:25 PM
*Originally Posted by dev [+]

@mike: after you did this, did it happen again in some time, or was the fix "permanent"?

Brakes stayed perfect so fix was permanent.
Title: Re: My brakes are very soft
Post by: burty on March 17, 2018, 06:56:54 PM
*Originally Posted by maccmike [+]
I have been in the motor trade for over 40 years and have never heard of changing caliper seals routinely at regular servicing periods, only if leaking. I have looked in the owners manual and there is no mention of changing the seals, only flexible pipes and fluid.

Here you go Mike, under periodic maintenance:



Title: Re: My brakes are very soft
Post by: maccmike on March 17, 2018, 08:44:20 PM
Quite right Andy, I stand corrected.

 Mine are overdue but there is no way they will be disturbed and neither will the radiator hoses or fuel hoses. Also let's not forget Kawasaki recommend changing plugs at 7500 when they are quite capable of doing well over twice that mileage. In my opinion a lot of the servicing requirements are unnecessary money makers.
Title: Re: My brakes are very soft
Post by: burty on March 17, 2018, 09:52:32 PM
I agree, i think many of the recommended service intervals are premature.  I believe that Kawasaki probably specify much of this based on a worst case.  I replaced the seals in my calipers around two years ago because the brakes were dragging.  So based on that they lasted 5 years, about 50000 miles, and around 4 sets of pads before needing replacement.    I am pretty sure that with other bikes I have had, the manufacturers have recommended seal replacement with the second brake pad replacement. 

4 years may be premature, but I would suggest that replacement after 7 years is probably not, and almost certain to improve brake operation.
Title: Re: My brakes are very soft
Post by: Scotty001 on March 18, 2018, 06:02:23 PM
*Originally Posted by mdr1970 [+]
You mention replacing early, don't forget, as already mentioned regardless of actual mileage your bike is one of the original 2011 machines!
Tis true, when it comes to rubber components, it isnt just how many miles use they have had but how old they are. With age rubber perishes,  becomes brittle and fails. you could take a bike built in 2000, take it the very second its built on the factory floor, put it in a crate and never ever touch the bike for 15 years. It will look in as pristine condition as the second it came out the factory. BUT almost everything rubber will need to be replaced as due to age they will be dry brittle and perishing, they will fail. Tyre manufacturers will only guarantee a tyre for x number of years against failure, cracking / de lamination for this very reason. 
personally if there is no evidence the brake seals have ever been replaced id be replacing them to be on the safe side, do a fluid change at the same time.
The tip of using a bungee or cable tie to pull the brake lever as far back as it will go and leaving it there is to force any air bubbles in the fluid back up into the reservoir, when ive done this in the past i've also loosened off the master cylinder cap (leaving the rubber bung in place) 

Brake hoses are also supposed to be replaced every 4 / 5 years according to the manufacturers, (part of this is ass covering on their behalf) there are many brake hoses working fin out there that are older than 4 / 5 years old. Rubber brake hoses can with age get weak spots due to the rubber perishing and as you apply pressure a section can give way and either burst or balloon out (either way the result is braking pressure fails).

People often put braided hoses on as the braiding encases the rubber hose, keeps a better pressure and doesnt allow the hose to "flex" as much due to pressures put upon them when braking  and less likely to easily rupture.

Its unlikely your boiling the brake fluid, you would need to be doing some pretty heavy braking to do that (track days with lots of constant heavy braking) for this you could look at maybe dot 5.1 instead of dot 4 brake fluid but please read up on the fluid, the pros the cons and NEVER MIXING THE 2.
Title: Re: My brakes are very soft
Post by: dev on March 22, 2018, 04:12:45 PM
Thanks everyone for contributing, great reads!

I've just talked to my mechanic, he says it's pretty weird that this would happen if there are no leaks or obvious failures.
I've pumped the brakes and tied them, they seem good now.

I'm paying close attention to them and if this happens again it's time for a serious service of everything - I don't like playing with my life :/
Title: Re: My brakes are very soft
Post by: dev on June 05, 2018, 09:13:34 PM
Just to provide a quick follow up on this for anyone with similar problems in the future.
After I've tied down the brake and left if over night, tomorrow it was firm as ever.
But once I left the bike sit for a few days, it went back to being soft.

So, I decided to bleed the brakes (with a help of a friend who knows what he's doing), and we found there was air in the main caliper (obviously).
What was weird is that we found even more air in the (I'm not sure what it's called exactly) upper "chamber" - the one right next to the lever (?).
We bled that as well, although we didn't actually do 100% bleeding, we just circled the same fluid back in (it's new anyway).
Then after 2 weeks of not riding, the breaks were soft again, but this time a bit better. We repeated the same procedure again,
and they seem quite fine now. They are somewhat softer again after not riding, but almost not noticeable - I believe we removed all air now, maybe we'll do another run just to make sure. I hope it won't happen again because I couldn't explain what was causing it.
Will update if there's any new development.

Thanks everyone for the advice!
Title: Re: My brakes are very soft
Post by: whyhaveone on June 06, 2018, 12:55:55 AM
Thanks for letting us know.  :028:
Title: Re: My brakes are very soft
Post by: dev on November 21, 2018, 03:46:36 PM
Ok, I just now got around to posting an update here, as I'm not riding much this season :(

The problem is back. We changed the brake oil, and the brakes were great, very firm.
After I left my bike in the garage for a few weeks, I returned to find the brakes again fully soft, I could easily touch the handle with them :(

So it seems I haven't resolved the problem - what could it possibly be?? There are no faulty brake lines, and there is no oil leaking anywhere.

Could it be that the Master Cylinder is letting in air? How would that even be without letting the oil out?
Should I get a Master Cylinder Repair Kit? I'm lost.

Title: Re: My brakes are very soft
Post by: sc00bie on November 21, 2018, 08:44:27 PM
Hi,
Sorry not read through all the post... horrible tracing slow pressure loss!

Its possible for the master cylinder seal to be allowing air in
Its also possible for air to get in at any of the brake line connections.
Have you also checked the flexi hoses for cracking/perishing/damage especially at the working bends and the rubber hose to metal banjo connectors
There is also the piston seals in the caliper's, so I would check there is no sign of any fluid misting there.
Has there been any history of accident damage to the bike?
Checking the banjo bolts for tightness (each fixed bolted connection) or simply replace the copper washers, ensuring the surfaces between each face is clean and no pitting/high spots, torque off the banjo's, re-bleed brakes and test

Process of elimination suggestion

Clamp of one side of the brakes nearest to the splitter for the R/L sides, you must ensure that the clamped side not under testing does not allow fluid movement.
For clamping off the flexi hoses and no proper hose clamp I use a pair of long nose mole grips, putting something between flexi and mole grips and just enough pressure to close of the hose. A bit Heath Robinson but …. Alt buy a brake hose clamp and be safe avoiding any damage to the hose.

DO the pressure test and check for softening of the brake after a reasonable period of time day /2 day's etc

If there is no loss of brake pressure then that side is good.

If there is pressure loss then clamping the flexi nearest to the caliper – test – check -
All Ok move clamp nearer to m/cyl or next brake hose - re-test.

Do this as far as you can go with the one side until you reduce the distance between m/cyl and clamp point.
Determine if it could be banjo bolt connections or m/cyl or if lower down between the clamp point and last non clamped section.
If its e.g happening without anything on the one side clamped, clamping the hose nearest to the caliper will highlight caliper or connections, some calipers are a 2 piece affair and I have seen leaks between the faces of the 2 sides due to corrosion.

If no loss of pressure at all then clamp this side off nearest to the splitter for the R/L sides and repeat on the opposite side
The idea is to rule out where the air is being drawn in or if indeed there is a leak.

I have come across worn brake lever cam, this is the point where it meets the master cylinder and compresses the piston forcing the fluid to move in the hoses, although this was on a bike in the 1980/90's the interaction of the brake levers may have changed since, but thought it would be worth mentioning. Because the lever is under tension the cam wears flat reducing the pressure exerted on the m/cyl and therefore loss of brake pressure.

Also possible for the hoses to expand if they are getting on in years again causing the pressure to drop but may not be showing any signs of leakage.

I hope this might help and you find the problem.
good luck
Title: Re: My brakes are very soft
Post by: dev on November 22, 2018, 09:56:21 AM
*Originally Posted by sc00bie [+]
Hi,
Sorry not read through all the post... horrible tracing slow pressure loss!
...
I hope this might help and you find the problem.
good luck


Hi sc00bie, thank you very much for the long and helpful post! I admit that I'm new to the terminology (and English is not my native language), so I will have to spend some time with Google to understand what all the parts you mention actually are :)

But to be on the safe side, would you say I can account for most of this work by completely replacing the brake lines (they are 7 years old and I might just go for it, even take the braided ones), and rebuilding the master cylinder (the rebuild kit is not that expensive, around 50€). Would that be better than trying to clamp and test as you described?

Thanks again!
Title: Re: My brakes are very soft
Post by: sc00bie on November 22, 2018, 10:50:53 AM
Hi Dev,

if you do the brake lines and master cylinder, the only things you wil not have tested is the brake calipers.

Braided hoses should also improve the brake feel.

What you suggest and if its within your budget will take care of 90% of the brakes on the front.

Try to bleed one side at a time and make sure there is 100% no air in the brake lines. When rebuilding the master cylinder lubricate seals with clean brake fluid.

I would still still fully pressure test when you have replaced all the hoses, copper washers etc and make sure there is no loss.

best wishes
Title: Re: My brakes are very soft
Post by: burty on November 22, 2018, 05:21:26 PM
Don't replace the brake lines before replacing the seals in the calipers first.  My money is on this bring the source of the problem.

That said, if they are 7 years old, the replacement of the brake lines is well overdue.
Title: Re: My brakes are very soft
Post by: sc00bie on November 22, 2018, 06:37:58 PM
Burly, good to hear if you have experience of the seals leaking.
Hence tbe pressure testing I suggested.

What drives your piston seals replacement advice?

Dev is not local and looks like he needs to translate what we write...
Title: Re: My brakes are very soft
Post by: dev on November 23, 2018, 09:11:04 AM
Wouldn't the caliper seals leaking mean oil getting out? At least that's how I imagine it. But there's no oil leakage AT ALL!

p.s. my English is quite good actually, it's just the new terminology around this topic that I need to catch up on, so feel free to type away as you would normally :)
Title: Re: My brakes are very soft
Post by: NorfolkNinja on November 23, 2018, 09:46:30 AM
This might help.
My mate rides a 2012 Diavel and no matter what a service technician did he couldn't get rid of sponginess (to my mates satisfaction) to the point he could almost get the lever back to the grip when pulled really hard. When riding he would have to pull the lever twice to get rid of the initial sponginess. When investigating on the forums he found 'they all do that' and even checking new ones in a showroom weren't much better. On the point of giving up and selling on the technician suggested a racing Brembo master cylinder, the difference is night and day and a magic fix but cost him £250.
He mentioned this to tech at the bike show yesterday and they are aware of the problem and suggested using Motul brake fluid.
Maybe using a sledgehammer to crack a walnut but my mate is one happy bunny now.
https://www.bikehps.com/acatalog/Brembo_Radial_Front_Brake___Clutch_Master_Cylinder.html?gclid=EAIaIQobChMIxcHh55rq3gIVy7_tCh0mrQ6-EAQYASABEgLgTPD_BwE#a51079
Title: Re: My brakes are very soft
Post by: sc00bie on November 23, 2018, 03:41:20 PM
Dev - thanks, yes there would be signs of leakage, dampness.

NorfolkNinja - I'll keep that in mind  :028:

I lnoe moving brake fluid from dot 4 to 5 can also improve feel.
I'm hedging its brake hoses expanding with age or wesr in master cyl...
Title: Re: My brakes are very soft
Post by: burty on November 23, 2018, 08:19:04 PM
*Originally Posted by sc00bie [+]
Burly, good to hear if you have experience of the seals leaking.
Hence tbe pressure testing I suggested.

What drives your piston seals replacement advice?

Dev is not local and looks like he needs to translate what we write...

My rationale is that seals within the brake calipers can cause very similar symptoms.  I've experienced this on the zrx that I had a few years ago.   

Essentially there are three causes of this type of problem:. Air in the system.  Too much give in the system.  Or flex in the rubber components. It's likely that air can get in at either master cylinder or brake caliper without any obvious leaks.  It's possible to have leaks a brake hose joints but this normally comes with an indication of weeping. 
Personally,  I would check how well worn the pads are and change them if they are well worn.  I would change caliper seals, then master cylinder internal rubber components, then brake hoses.  All of these will make a difference as they are 7 years old anyway.
Title: Re: My brakes are very soft
Post by: sc00bie on November 24, 2018, 05:48:23 PM
thanks burty, I'm a mechanic to trade so wondering if there were specific issues on certain manufacturers,

Been mostly brake hoses that have been issue Ive seen in my limited time with bikes, cars .... well different beasties

cheers
Title: Re: My brakes are very soft
Post by: dev on November 26, 2018, 11:38:34 AM
*Originally Posted by NorfolkNinja [+]
This might help.
My mate rides a 2012 Diavel and no matter what a service technician did he couldn't get rid of sponginess (to my mates satisfaction) to the point he could almost get the lever back to the grip when pulled really hard. When riding he would have to pull the lever twice to get rid of the initial sponginess. When investigating on the forums he found 'they all do that' and even checking new ones in a showroom weren't much better. On the point of giving up and selling on the technician suggested a racing Brembo master cylinder, the difference is night and day and a magic fix but cost him £250.
He mentioned this to tech at the bike show yesterday and they are aware of the problem and suggested using Motul brake fluid.
Maybe using a sledgehammer to crack a walnut but my mate is one happy bunny now.
https://www.bikehps.com/acatalog/Brembo_Radial_Front_Brake___Clutch_Master_Cylinder.html?gclid=EAIaIQobChMIxcHh55rq3gIVy7_tCh0mrQ6-EAQYASABEgLgTPD_BwE#a51079

Thanks for the answer! But I don't think my problem is similar, because my breaks are great after I bleed them, and as long as I ride regularly they keep like that for weeks. The problem I notice is when I don't ride for a few weeks, they degrade quickly and become very soft (I can't even break with 100% before hitting the handle, so I have to pump them previously, or tie them overnight to get some air out).

*Originally Posted by sc00bie [+]
Dev - thanks, yes there would be signs of leakage, dampness.

NorfolkNinja - I'll keep that in mind  :028:

I lnoe moving brake fluid from dot 4 to 5 can also improve feel.
I'm hedging its brake hoses expanding with age or wesr in master cyl...

There is no leakage of oil anywhere, nor is anything damp...
Also, the brake hoses expanding with age or whatever is not consistent, because everything works great after bleeding, and then becomes soft as the bike sits for a few weeks. So it's definitely something happening over time, like air getting in somehow.

*Originally Posted by burty [+]
My rationale is that seals within the brake calipers can cause very similar symptoms.  I've experienced this on the zrx that I had a few years ago.   

Essentially there are three causes of this type of problem:. Air in the system.  Too much give in the system.  Or flex in the rubber components. It's likely that air can get in at either master cylinder or brake caliper without any obvious leaks.  It's possible to have leaks a brake hose joints but this normally comes with an indication of weeping. 
Personally,  I would check how well worn the pads are and change them if they are well worn.  I would change caliper seals, then master cylinder internal rubber components, then brake hoses.  All of these will make a difference as they are 7 years old anyway.

Thanks for the answer, this one seems right on point - since my brakes are doing well after bleeding them,  and degrade after a while, seems to point air coming into the system somehow, not so much that the hoses are stretching due to age, etc.
About brake pads: that would make sense if the softness is permanent, but it's not - if I bleed them, they are good for a while. I will check the pads anyway though.
My concern about the caliper seals is this: how can air get inside a pressurized system, without oil getting out ever?
So it has to be master cylinder? Or does the same apply there? I can't really make sense of it all because I don't have any experience with brake systems :|

By the way, I just checked and OEM Kawasaki hoses are ~420€ JUST FOR THE FRONT END! Oh man, I wasn't expecting it to be that expensive :/ are there good quality solutions from other manufacturers which would be cheaper and widely used perhaps? :D
Title: Re: My brakes are very soft
Post by: maccmike on November 26, 2018, 12:20:38 PM
Definitely don't go for oem hoses. Braided pipes from HEL or Goodrich are much better quality and give far better feel as well as being much cheaper. For instance on link below £95 for full kit for non abs bike.

https://www.helperformance.com/kawasaki-z1000sx-2011-2015
Title: Re: My brakes are very soft
Post by: dev on November 26, 2018, 12:39:22 PM
That's extremely helpful, thank you very much!
And wow, what a price difference. My bike has ABS, so that's £159.99, which is still just 40% of the OEM price :D

So to summarize and get your guys blessing for further actions:
- check for mist around calyper seals
- test hoses as sc00bie suggested, or just replace them entirely with a braided version (thanks maccmike)
- rebuild the master cylinder with one of these kits (https://www.ebay.co.uk/itm/Tourmax-Front-Master-Cylinder-Kit-Kawasaki-Z-1000-SX-ABS-2011/332863431082?epid=647437339&hash=item4d8034e1aa:g:8w8AAOSwJtJb2-~p:rk:1:pf:0) (still have no idea how to do that, but I'll learn as I go)

Does that sound right? I would do each step and evaluate results afterwards. Is this the order you would recommend?
Is there something else I'm missing?

Title: Re: My brakes are very soft
Post by: maccmike on November 26, 2018, 12:52:08 PM
I have these on my SX, really good quality & only £125 for the full ABS set.

https://wezmoto.com/product/kawasaki-z1000-sx-abs-2011-2015-oem-standard-layout/
Title: Re: My brakes are very soft
Post by: dev on November 26, 2018, 02:34:53 PM
*Originally Posted by maccmike [+]
I have these on my SX, really good quality & only £125 for the full ABS set.

https://wezmoto.com/product/kawasaki-z1000-sx-abs-2011-2015-oem-standard-layout/

Excelent! Thank you maccmike! :)