hydraulic disc brake questions

[raleighrider21]

have a few questions about my hydraulic disc brakes as I have no clue how they work or what they should be like etc only ever had v-brakes and cantis :S

1. The rear brake sometimes barely works and just about slows me down but when it really works it judders but still works fine ? does it need bleeding or something?

2. The previous owner told me he had just had the front brake pads changed hence why there is a very loud squeal from them when used which makes a lot of fun scaring the locals Im guessing they haven't been done and they need doing?

3. When the brakes come up for needing doing (fluid, pads etc) do I need to change the pipes too and will I need any specific kit to do it all or am I just better off taking it to the shop rather than risking doing it all myself and messing it up?

seriously im crap with disc brakes in general any help is appreciated !

 

[widowmaker]

What make are the brakes ?

What's the lever travel like, much pressure ?

Have you check the brake pads, its pretty easy to whip them out ?

And I have never heard of changing the pipes, unless they are damaged/corroded :?

If the rear works intermittently it sounds like it has some air in it and needs a bleed, pretty easy to do if you have the kit

 

[raleighrider21]

only name on the brakes are QUO GH4-D ? nothing else on them so im presuming theyre crappy make (will get replaced at some point I suspect)

plenty of pressure on the front brake lever, rear lever not as much but doesn't pull all the way in to work to its full potential when it wants to work that is.

not touched it with any tools etc apart from adjusting the saddle height so haven't whipped them out, afraid to pull them out incase the pistons slide out and I totally f**k them up like I tend to do on cars :S

as ive said ive never really had disc brakes and have never worked on them so don't know what the hell im doing at all, I do them on my motorbikes when I do the brakes there just didn't know if I should on these :facepalm:

got no kit but suppose I should get the kit at some point just got to wait until after the car insurance is paid for :roll:

 

[drystonepaul]

Disc brakes aren't that difficult to sort out and maintain.

Firstly, if the lever feels spongy or they are pulling too close to the bars then they probably need bleeding. The method can vary depending on the type of brake you have. Before bleeding though it's worth checking weather your levels have reach or bite point adjustment.
If you do need to bleed the brakes then you'll need to make sure that you are using the correct type of brake fluid.
Magura and Shimano use mineral oil while most others use DOT 4 or 5.1 oil.
You don't need to replace the brake hoses when bleeding unless they are badly damaged.

It sounds like you may have Quad brakes, which I think use DOT 4 oil. Post up a photo to confirm this.

A major factor in performance will be whether or not the pads and rotors are clean.
Any oil or grease on the rotors will find it's way onto the pads and contaminate them too. This will cause horrible brake squeal and poor performance.

You can clean the rotors will Isopropyl Alcohol or disc brake cleaner (same thing), but contaminated pads are best replaced as they are almost impossible to clean. You can also roughen the surface of rotors with emery paper to improve braking.
For pads I always use gold sintered versions for long life and good all weather performance. Resin pads are good in dry weather and kevlar pads are great but generally expensive.

If you remove the pads, the pistons won't just fall out of the calipers. Be careful not to pull the brake levers though while the pads are out as the pistons can be pushed out this way.

There are loads of useful videos online for bleeding your brakes and I can also highly recommend this website for bleed kits, parts and instructions.
http://www.epicbleedsolutions.com/