DIY Hydraulic Brake Service (Push Bike)

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heylinb4nz

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#157150 21-Nov-2014 09:22

Looking for some advice from any road or mountain bikers here.

I have a Merida Crossway 500 with Tektro Auriga Comp Brake System. Bike is not quite 2 years old and i've done about 500 kms of commuting (3km a day). Been experiencing poor braking with front brake so decided it was time to change fluid and save $50 getting someone else to do it.

- Well hours and days later, and numerous bleeds I finnally managed to get all the air out of system by syringing fluid in from bottom via the bleed (air bubbles came out top of resivour).

Still no good braking

- removed pads, sanded them, wiped with iso alcohol, sanded discs with 120 grit and wiped.....still a no go.

Where to from here ? new pads ??, cant believe bike shops can get away charging $40 a pair ($80 to do front and back), car brake pads are way bigger and also cheaper.

ubergeeknz

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#1180579 21-Nov-2014 09:24

What's the symptom? Brakes feel spongy? Or hard with no stopping power? How much meat left on the pads?

1101

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#1183238 26-Nov-2014 12:00

My mtn bikes brakes are a nightmare to bleed. It usually take 3 or 4 attempts to get them to work. Even with the manufactures bleed kit .
It may just be a better idea to take it to a bike shop. Save yourself alot of grief

Are the pads genuine or some generic brand ? Is the disk warped at all ? Did you get any brake fluid on the pads ?
Did you take the brakes off the bike & push the cylinder all the way in first (thats whats recommended for my brakes)
Did you follow the manufacturers instructions EXACTLY, or just wing it :-)

Are the rotors/disks actually a bit small. My 1st bike had poor braking on the fr. Put a bigger disk on & problem instantly solved.

1101

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#1183239 26-Nov-2014 12:05

One other thing to try, take the top/lever end off the handlebars & get the whole cable as vertical as possible . Have had a mates brakes with air trapped
in the hose that wouldnt come out till I tried this.

Looks like a similar brake bleed system to mine. Good luck, you'll need it
http://bicycletutor.com/bleed-tektro-auriga-comp-disc-brakes/

You need
"an outlet valve" , part of the bleed kit. Dont just let it squirt out the top
Mineral Oil, NOT brake Fluid

heylinb4nz

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#1183946 27-Nov-2014 11:35

ubergeeknz: What's the symptom? Brakes feel spongy? Or hard with no stopping power? How much meat left on the pads?

Hard with no stopping power.

Meat on pads should be ok considering ive only had it 1.5-2 years and travelled around 500 km (town commuting) Seems the front pads had oil on them (so throw away job) and ive got the dreaded bubbles\oil around the piston under braking. Pretty crappy to only get 1.5 years out of a set of calipers before needing to replace them $200 a set)

So at this stage ive given up and taking to bike shop, ive got nice new dual compound pads for them to fit and will let them sort out the hydraulics.

So annoyed, should have got good old cable system.

Crappy quality for a $1000 bike.

Jase2985

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#1184041 27-Nov-2014 13:45

generally spongy means fluid related and hard with no stopping power means pad/disc related

heylinb4nz

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#1184162 27-Nov-2014 15:28

Can pumping the caplier with no pads in cause the piston to over travel and seals to leak \ damage ? or worn brake cause over travel ??

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Jase2985

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#1184315 27-Nov-2014 18:01

worn pads shouldnt cause over travel but with out the pads in there might not be good for it. But thats how you generally get the piston our to replace it

04fuxake

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#1187049 2-Dec-2014 12:59

I have Tektro hydros on my bike and the stock pads that came with them were rubbish. No matter what I did, they never stopped well and were loud and raspy. I replaced them with some Alligator semi-metallic pads and they immediately came alive.

Just remember to bed the new pads in with several hard stops to allow the pad surface and disc to get to know each other.

If you over-pump your pistons (with the pads out), you can separate them again with a large flat-blade screwdriver.

heylinb4nz

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#1187256 2-Dec-2014 17:35

All fixed $100 at bike shop

- full bike service $45
- new front and rear pads (dual compound Ashima) $40
- fix leaky piston seal on front caliper $15