Brake woes

[Forcefield]

Following this... i too have had my pads off recently. Only to clean/service things so not fitted new ones, not moved the pistons much other than to get the calipers off. But Ive notice this week that my front brakes are very spongy. theres too much travel of the lever before any braking happens, and when it does its very soft.

Im new to K's, so I dont know how sharp they are ment to be, but Im guessing it could throw me off like a bucking horse if i squeezed too hard?

[nealchaykin]

How are your rear brakes? Mine have always been on the ‘spongy’ side but I think I read somewhere that that is usual for a K. I’ve never locked my rear brakes no matter how much the brake pedal is pressed.

[Phmode]

Following this... i too have had my pads off recently. Only to clean/service things so not fitted new ones, not moved the pistons much other than to get the calipers off. But Ive notice this week that my front brakes are very spongy. theres too much travel of the lever before any braking happens, and when it does its very soft.

Im new to K's, so I dont know how sharp they are ment to be, but Im guessing it could throw me off like a bucking horse if i squeezed too hard?

The ABS won't let it toss you off unless you are holding on with only a couple of fingers. The rider manual advises to grab the brake lever hard and let the tech do the work.

I have only ever triggered the ABS a couple of times, once in panic and once in desperation. It's a big bike and it has the brakes to match so if they are spongy or lacking feel then something is not quite right.

[Forcefield]

My rear seems ok. I have had a weird knocking through the pedal a few times when approaching a junction to stop. I believe this is the abs kicking in...

The front just feels too weak and soft. I did open the reservoir cap the other week, as I didn't know there was a sponge in there and was wondering what it was. Maybe I introduced some air into the system somehow? I'm pretty sure when I bought the bike, when I qst tested the brakes I was impressed with the sharpness.
Next dry day I get in gonna go try a few emergency stops and see how they feel perform

[Phmode]

The only way to get air in to the system is by letting the fluid level drop out of sight, dismantling a hydraulic fitting, pushing a piston out past the seal or incorrect bleeding. Other than that, a hydraulic leak would show you had a line integrity problem.

Hydraulic fluid is hygroscopic, (it absorbs moisture from the air) so old fluid may well be contaminated and therefore compressible as the water turns to steam next to the pistons and the water gets in to the fluid in the first place because the cap on the reservoir is ventilated.

Those of us who don't pay the man to do the annual service always run the risk of contaminated fluid.

[TomL]

A tip to improve the front brake is to park the bike on the side stand with the steering fully to the left. Pump the brake lever and tie it back to the handlebar. Leave overnight. I use a cycling toe strap to pull the brake lever back to the bar.

Supposedly air in the system migrates upwards to exhaust out through the fluid reservoir which is the highest point.

Works on mountain bike hydraulic front brakes as well.

[Phmode]

Nice tip Tom. I've heard it before and forgotten it 

[andym2]

I put a Rekluse left hand rear brake kit on my CRF and that was the only way I could get the air out of the line from the lever down to the rear master cylinder.

[Grumpy jase]

If your stuck I'm not too far away in Plymoth with a GS911, just need a sunny day to ride up :-)

Thank you so much for the offer.  Did a good ride out yesterday, positively spring like in Mid Devon, and brakes felt great.  It felt like the small amount of air in the front had been there for a while as they felt sharper than I'm used to.  Rear is still a bit soft, but I'm putting that down to heavily worn pads, and will re-assess once the new pads are fitted.

[Forcefield]

If your stuck I'm not too far away in Plymoth with a GS911, just need a sunny day to ride up :-)

Thank you so much for the offer.  Did a good ride out yesterday, positively spring like in Mid Devon, and brakes felt great.  It felt like the small amount of air in the front had been there for a while as they felt sharper than I'm used to.  Rear is still a bit soft, but I'm putting that down to heavily worn pads, and will re-assess once the new pads are fitted.

Great to hear! what did you do to fix?

[chriscanning]

Did the rear brake bleed last night,cap back on the res,tighten it and all is good,go out for a test run this morning doesn’t feel right and then brake warning light comes on  and I’m thinking Jeeze….just about to phone my other half to bring the van!!! Have a look at rear res see I’d tightened the top too much and it had twisted in the metal clip twisted the rubber brake pipe  ,twisted res the other way and all’s good….phew

[Forcefield]

Did the rear brake bleed last night,cap back on the res,tighten it and all is good,go out for a test run this morning doesn’t feel right and then brake warning light comes on  and I’m thinking Jeeze….just about to phone my other half to bring the van!!! Have a look at rear res see I’d tightened the top too much and it had twisted in the metal clip twisted the rubber brake pipe  ,twisted res the other way and all’s good….phew

Phew... Close one, and pretty scary

[Phmode]

Of all the weird stuff. Nice spot though.

[alaskier]

Just a thought but how long has the brake fluid been in the system? It should be changed every two years or so. If left in too long the brake gets all spongy so that may be your problem

[Phmode]

I put a Rekluse left hand rear brake kit on my CRF and that was the only way I could get the air out of the line from the lever down to the rear master cylinder.

Flash git 

I couldn't justify the expense on my Rally so tried, in vain, to fabricate my own out of bits of bicycle levers and cables but gave up because there was insufficient room on the bars to have a second lever. I have reduced sensitivity in my right foot so really liked the idea of the Rekluse kit.