Can't get SLX brakes to work - help please...

nickfrog

Front brake is perfect, I hardly need to touch the lever. OE pads.

Rear brake works at 20%, however hard I pull the lever.

Took it to shop last week and they bled it. I stupidly didn't check it as I could feel that the lever travel was much shorter so I assumed all fixed. Just tested the bike and zero improvement apart from a shorter travel lever. I still can't lock the wheel, let's put it this way.

I then took the pads out and sanded them down as well as the discs. Very very slight improvement maybe, not even sure. Still not working as it should though obviously. It's like if there was oil on the disc, permanently.

Photo of the pads before sanding :


They are Superstar Sintered I think (bronze colour backing plate). I had changed them because of the exact same symptoms on the OE pads and to start with the new pads got the braking back to normal (ie instant lock up).

Any help gratefully received.

PS : shouldn't the shop have checked brake efficiency ?

nicklouse

Depends on what you asked them to do.

Did you clean everything before you fitted new pads?

What did you use to clean them?

nickfrog

Cheers Nick. I hadn't cleaned anything prior to fitting the new pads. I just took the old ones out and put the new ones in, sorry. What was I meant to clean and what am I supposed to use to do that ? Do I need new pads now anyway ?

Thanks btw!!!

Not Mechanically Gifted of Sussex

coulddobetter

If the discs are contaminated then any new pads would get contaminated.

nickfrog

Thanks. Would sanding the disc decontaminate it ? Or clean with brake cleaner ?

coulddobetter

Brake cleaner or isopropyl alcohol

cooldad

Use isopropyl alcohol.
But how do you get 20%. Can you lock the back wheel?

coulddobetter

Have a look here re cleaning rotors viewtopic.php?f=40073&t=12666026

FishFish

Also check that the disk is in the middle of the caliper nd that the bolts are tight and try pulling the brake 20 or so times and look for fluid leaks. Sanding the disk is not advised - it would work but if it ever became contaminated you would not be able to clean it so you would b=need a new one.

nickfrog

Thanks for the advice.

No luck despite trying everything. Basically I can't lock the rear wheel. I can actually pedal while pulling the lever as far it will go. There seems to be oil coming out of the lever too in small quantity.

I do miss my XTR V-brakes badly.

The Rookie

Where on the lever do you think it's leaking.....

Your LBS appear to have done what you asked and bled the brakes, dont blame them for the contamination.

No one thing is difficult to sort, just work through the issues.

nickfrog

I hadn't asked them to bleed the brake. I had asked them to fix the brake.

Anyway. I popped in just now and they were quite apologetic and sold me a pair of Aztec pads for £15. They insisted on fitting them and cleaning everything there and then so full marks to them.

The leak comes through the adjuster (which is totally mechanical) which is bizarre. They agreed it leaks a bit but they can't say where it's from as they checked the reservoir and no apparent leak. They asked me to keep on eye on it and they explained that Shimano levers were disposable if they leak. Not sure I can buy levers separately ?

Previous post moaning about the shop now edited as they were quite helpful.

They suggested to put a plastic bag around the brakes when cleaning/lubing the bike, which I will do.

The Rookie

You can get rebuild parts for the levers, see the Shimano techdocs.

You can get levers separately

Which adjuster, none go through to fluid to the best of my knowledge.

nickfrog

The Rookie wrote:

Which adjuster, none go through to fluid to the best of my knowledge.

Agreed, very bizarre. I can only guess it ends up there but comes from somewhere else, the reservoir being the obvious source. Will have a little look later. Thanks for your help either way

nickfrog

Other problem being to find a large hill in Sussex ;-)