Help me with brakes please!

[Swedie]

Hiya! I gave my girlfriend a ZXR 400 to race with and we've now after a year encountered a brake issue. There is no pressure in the system anymore. And the brake lever is extremely soft and touched the handlebar.

What I've done:
I've changed ALL seals in both the calipers and also the pump have had everything inside changed, but there was zero difference and it actually sort of got worse. So I bought new brake pads, even though the current pads wasn't even half used. It didn't help either. I tried bleeding more (hours), and it's a little bit better. I've tried to follow the lines and find the airbubbles and squeeze them out. I've successfully removed a lot of air. I also use a vaccum based pump to suck fluid through the system, and gone through about 0.5 liters of brake fluid (Motul RBF600). There just cannot be anymore air in there.

What I've not done:
The only thing I have not changed, are the pistons in the calipers. But I figure, since they don't leek, they do their job. Am I correct? They are also way too expensive. They are 1/10th of the bike's value at a sale.

In action:
The brakes fade the warmer they get, and eventually... while riding the bike, the brake lever is touching the handlebar on hard braking.

Note 1:
Watching the pistons move as I press the brake lever, they travel very far, maybe 1(maybe more) mm before touching the brake discs. Upon releasing the brake lever, they travel back the same 1-2 mm distance. I am thinking, shouldn't the pads be much closer and almost touching the discs when the brake lever is not used? This is the way on my race bike (riding an aprilia rsv1000r factory bike). The front wheel on the ZXR can spin without stopping for atleast 10 cycles. On my race bike, I can hardly get 1 cycle when spinning the front wheel.

Note 2:
Something I've noticed is that if I squeeze in a wrench between the brake pads on both sides, where the wrench is almost 1 cm thick, the brake system get FULL and VERY good feel in the brake lever. The lever about stops in just 1-2 cm.

[masterofinsanity]

have you changed the master cylinder? if you have bled the brakes as much as you can then usually the master cylinder is at fault and very often overlooked.

[deviant]

and also the pump have had everything inside changed,

i'm guessing he has done the master cylinder.

[Caz]

I'm assuming that you have already done this, but just incase.... Have you changed the brake lines? standard rubber lines degrade over time

[Northern ANdy]

sounds,like,warped,discs,constantly,knocking,the,pads,into,the,calipers,meaning,you,have,to,pump,them,back,up,again,before,they,can,apply,any,friction.

seriosly,need,to,sort,this,spacebar,issue

[Swedie]

andy, f*** you

thanks to the rest.

erase the thread... stupid ass folks here rather bitch and moan about my use of commas than reading and trying to be helpful instead.

[Caz]

Swedie - he's not having a go at you - he seems ot have a problem, if you look at the swingarm bolt thread on free for all it will explain more

are you a Swede btw?

[Northern ANdy]

http://zxrworld.co.uk/zxr400oc/viewtopic.php?f=1&t=4253

linkage,for,the,nice,gentleman.

[masterofinsanity]

andy, f*** you

thanks to the rest.

erase the thread... stupid ass folks here rather bitch and moan about my use of commas than reading and trying to be helpful instead.

well thats fine coming from someone thats only made 2 posts here, if you stick around you'll realise that the regulars post a lot and are the utmost helpful, we are an amazingly friendly bunch here so an apology wouldn't go amiss to Andy methinks.

[Northern ANdy]

andy, f*** you

thanks to the rest.

erase the thread... stupid ass folks here rather bitch and moan about my use of commas than reading and trying to be helpful instead.

well thats fine coming from someone thats only made 2 posts here, if you stick around you'll realise that the regulars post a lot and are the utmost helpful, we are an amazingly friendly bunch here so an apology wouldn't go amiss to Andy methinks.

ahh,give,him,a,chance,Baz,he's,only,just,got,here,besides,I,can,see,the,funny,side,of,the,situation.

(until,habbit,makes,me,use,the,space,bar,and,I,loose,a,lengthy,post.Drat.)

[Caz]

well thats fine coming from someone thats only made 2 posts here, if you stick around you'll realise that the regulars post a lot and are the utmost helpful, we are an amazingly friendly bunch here so an apology wouldn't go amiss to Andy methinks.

come on mate, that's a bit harsh dont you think? It was a bit of a misunderstanding. Andy can see the funny side of it. Life is too short for arguments!

Swedie - dont give up on this place yet! the folks round here are friendly and helpful!


SO to try and sum up what was said before we got side tracked with Andys spacebar/comma issue

- if you are running standard lines, try changing those. Rubber lines deteriorate over time.
- possibly warped discs - does the lever pulse when braking? If the discs are warped, you should be able to feel this under braking.
- another one to throw into the equation - are your discs worn excessively? check the thickness of them

/Caz

[masterofinsanity]

bollox!

[Caz]

/Caz

PS im sure i can make a more pointless post if I really try

[rene]

LOL at this thread!

Swedie i think you lost somthing on your way to the computer..

[Swedie]

I do have a sence of humor... really! it's just that he sort of hit a nerve I guess. I didn't register here to receive a bunch of jokes on my behalf. I wanted help with my brake issue!

anyhow, I solved the problem. If someone wants to know, I simply took the calipers apart and lubed pistons and seals with brake fluid. I apparently forgot to do that... now the brakes works a lot better!