Cardboard brakes on a 00 pointy

[MavUK]

The brakes on my 00 pointy have turned to cardbaord recently - when you squexe it's like crushing corrigated cardboard - it gives a little, then a little more, then a little more etc etc.

I'm going to replace the fluid today, but would appriciate any pointers for the job (Tried looking in the FAQ but couldn't find anything).

First time I've done brakes so I want to make sure I'm doing it it right...

Thanks in advance,
Stu

[shifter]

Strange one that. I think I'd start with a good visual inspection of the discs and pads, Then as you say I'd give them a good bleed, You could be compressing a load of air in the system.
I've had to bleed them at the union on the brake lever in the past. Put a load of rag under the lever to catch the fluid, apply a some presure to the the lever, crack the union for a brief second, and tighten it up. Then bleed from the calipers as normal.
I've also found that replacing the fluid completly makes a lot of differance.

[MavUK]

I'm going to replace the fluid as it's a couple of years old, I know the pads and discs are good as they only have a few thousand K's on them (but will do a visual inspection when doing the fluid change)

One thing that bothers me is how does air get into a system in the first place (fluid hasn't been played with but air still managed to get in possibly). Could my brake pipes be knacked as well?

[MavUK]

Oh one other thing that may be important... After a few squezes the brakes feel good again. But after a few mins they go back to cardboard... Don't know how significant this is...

[Red Herring]

Do they go back to "cardboard" even if you haven't moved the bike? Sometimes the sliding pins on the calipers get worn allowing the caliper to rock and go off square with the disc. When you apply the brakes the caliper needs to re-align itself before working and this can take a squeeze or two. Easiest way to check is to ride the bike slowly up the road, come to a halt without using the front brake then see if you can rock the caliper by hand.

If you are refilling the brake system from dry, ie:you've drained it, then it can be a right bitch sometimes to get the fluid to start running down through the master cylinder, the air in the pipes keeps going up (it would, air rises). Either take the calipers off and hold them above the master cylinder until you get some fluid through it, or (I joke not) blow up a condom and put it over the top of the fluid reservoir, open the bleed nipples on the calipers and the pressure should push the fluid through for you. Also helps explain to the wife why you keep a three pack in your toolbox!

[MavUK]

Hmm, not sure. I'll go and check once I've finished watching race 2 from last night :)

[Tiger 55]

I did my brakes a couple of weeks back and made every mistake you can make and invented a couple of new ones.

If only I'd read this thread (http://forums.sv650.org/showthread.php?t=90500) before I started...

[John 675]

air can get into the brakes because you have maluable lines get some goodridge to reduce the problem, but as for the calipers, strip / clean / and renew fluid you will see a MASSIVE differance

[Blue_SV650S]

Assuming you have meat left on the pads. This is almost certainly either sticking caliper pistons and/or sticking caliper pins!! ;)

Oh and being pedantic, a 00 is a curvy ... curvy=99-02 pointy=03-08

[MavUK]

Assuming you have meat left on the pads. This is almost certainly either sticking caliper pistons and/or sticking caliper pins!! ;)

Oh and being pedantic, a 00 is a curvy ... curvy=99-02 pointy=03-08
Just checked and if the bike doesn't move the cardboard stays away, I'm going to take a test ride after lunch to see if they come back.

As for the pointy... :oops: What can I say, it was early morning and I hadn't a coffee inside me when I wrote this...](*,)

[jambo]

First off take the brake lever off and clean it up. There is often dirt and crud on the master cylinder or lever and this gives a nasty feel. Cleaning this up with a rag and some WD40, and then lubing with some engine oil can work wonders.

Air will not get into a system through rubber lines unless there is a fault with the brake system. Water is slowly absorbed by the brake fluid over time though, and this makes it visually darker. It also leads to brake fade under hard braking. Braided lines will have very little impact on this.

My next thoughts if the brake lever doesn't help would be the caliper sliding pins. Having pistons on one side only, when you use the brakes the whole caliper moves on two large pins to centre it. These should be cleaned and greased using red rubber grease to protect the rubber boots protecting these pins.

Jambo.

[MavUK]

First off take the brake lever off and clean it up. There is often dirt and crud on the master cylinder or lever and this gives a nasty feel. Cleaning this up with a rag and some WD40, and then lubing with some engine oil can work wonders.


This makes sense. When trying it in the garden (with the engine off) you could hear a noise coming from the lever when feeling the problem. A few big squezes and the noise was gone, and the brake lever was smoth. I'll try cleaning it before going to the test ride.

Air will not get into a system through rubber lines unless there is a fault with the brake system. Water is slowly absorbed by the brake fluid over time though, and this makes it visually darker. It also leads to brake fade under hard braking. Braided lines will have very little impact on this.

Also makes sense, the fluid looks quite dark through the resevoir. Oneof the reasons I was thinking it could be the fluid

My next thoughts if the brake lever doesn't help would be the caliper sliding pins. Having pistons on one side only, when you use the brakes the whole caliper moves on two large pins to centre it. These should be cleaned and greased using red rubber grease to protect the rubber boots protecting these pins.

Guess I'll have to buy some grease for this and give this a try sometime over the coming weeks. Just hope I don't have to pay to have them dismatled...

Thanks,
Stu