Brake lever coming back to the bar

[Sprocket Dog]

Good morning folks, I'm hoping someone can give me some advice on a little problem that my bike has developed recently - the front brake lever is coming back to the bar and there is little, if any, braking force applied to the disc.The bike is a Giant 4.5 XtC with hydraulic brakes front and rear.The pad thickness is fine as are the condition of the pads.I'm assuming I have air in the system somewhere as if you rapidly pull the brake lever ten or more timers the brakes begin to bite quite well.What I'm concerned about is with the air is getting into the system. I have a slight oily residue where the lever bolts to the master cylinder though I cannot be sure if this is simply road grime or a fluid leak.The bike hasn't been used for a month and has been left outside under a cover in that time. The rear brake is completely fine.Does anyone have any thoughts or suggestions? Do I need a rebuild kit for the master cylinder?Cheers,

 

[Mr Pig]

Is there an adjuster screw under the lever?

 

[Sprocket Dog]

Is there an adjuster screw under the lever?

TBH, I don't know but I don't recall seeing anything as such. I'll have a wee lookie when I venture to the bike store.

 

[Mr Pig]

Might just need bled. Has the bike been stood upside down or put on its side at all? That can get air in the lines.

 

[Sprocket Dog]

Might just need bled. Has the bike been stood upside down or put on its side at all? That can get air in the lines.

Nope, the bike's been sat on its wheels for the month, though it do that jack-knife thing a couple of times and my folks (who were cycle-sitting) didn't notice. I'll take a wander to Evans and get some fluid just in case.

 

[Sprocket Dog]

Just checked the bike, there's no adjustment screw beneath the lever. I've managed to buy a brake bleed kit, though the oil bottle seems to have a tapered nozzle suggesting that it 'plugs' into the brake fluid reservoir/master cylinder - is this correct?I'm familiar with bleeding motorcycle brakes but you have to open the system up thus exposing the brake fluid to the air.Unfortunately the kit doesn't have any instructions.

 

[02GF74]

there are at least 3 type of brakes i have seen.
1. bleed nipple fitted to caliper - e.g. Shimano, you bleed these like motorcycle or car brakes.
2. hex bolt fitted to caliper e.g. magura, you either fit a bleed screw and bleed as in 1 or buy expensive bleed kit
3. no bleed screw on caliper!! e.g. formula, need a kit to bleed these

your best bet is to google as that owuld descbie the process beter than me.

also brakes use DOT 4 (car brake) fluid or minearl oil - shimano red stuff.

the shimano bottles have a nozzle that I guess make is easier to add drops into the reservoir a precise manner.

 

[Sprocket Dog]

there are at least 3 type of brakes i have seen.
1. bleed nipple fitted to caliper - e.g. Shimano, you bleed these like motorcycle or car brakes.
2. hex bolt fitted to caliper e.g. magura, you either fit a bleed screw and bleed as in 1 or buy expensive bleed kit
3. no bleed screw on caliper!! e.g. formula, need a kit to bleed these

your best bet is to google as that owuld descbie the process beter than me.

also brakes use DOT 4 (car brake) fluid or minearl oil - shimano red stuff.

the shimano bottles have a nozzle that I guess make is easier to add drops into the reservoir a precise manner.

Thanks mate. My calipers are the Shimano type (as is the kit that I've just bought) and have a bleed bolt on the caliper. The reservoir has a single screw on the top face of it, hence me wondering about the tapered nozzle (I thought I might be able to stick the nozzle in the hole without fully opening up the reservoir).

 

[Mr Pig]

Pity you've bought the Shimano oil. Giant stuff is just he same and a fraction of the price.

On mine you take the lid off the reservoir, fill it, then bleed the brakes like you would on a car. Very simple.

 

[Sprocket Dog]

Pity you've bought the Shimano oil. Giant stuff is just he same and a fraction of the price.

On mine you take the lid off the reservoir, fill it, then bleed the brakes like you would on a car. Very simple.

Must admit, I was a bit stunned at the £12 price but then I bought the kit (though the only additional item in the kit was a catch bag for the caliper oil). The reservoir was half full when I checked last night. I didn't get a chance to do much else as the light was going. I shall report back my findings when I do get a chance to tinker. B)

 

[racingaway]

It is probably just some air in there and needs to be bled or I find that tying an elastic band around the lever and handlebar so the lever is on overnight gets rid of this problem.

 

[Mr Pig]

If you sit the bike overnight so that the pipe is running up the way with the reservoir at the top the air bubble might well work itself out. Saves bleeding.

 

[Cubist]

I'm a bit concerned about the oily residue. You need to make sure that the reservoir isn't leaking though a perished seal or whatever. If it is, then that's how the air is getting into the system. Whatever else you do, if the reservoir is only half full you need to find out where it's going, or else you'll be pissing in the wind by bleeding them.

 

[Sprocket Dog]

Sorry for the belated update but I only got around to looking at my brakes last night. Seems that all that was required was a quick bleed of them to remove the trapped air.Thanks for all the input folks.