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Posted

Should they move or not? not sure, didn't look at that. Here is the breakdown. Bike was fine, everything set. took the front wheel off to transport in the car - put it back on, was not right, aligned it, was better, but not good enough still rubbing.

 

The outside pad is fine with enough clearance, but the inside is tight onto the rotor. if i spin the wheel and look at the gap on the outside pad, the rotor runs smoothly in its line - so its not bend or damaged. Just need to know if I should maby take apart the pads and reinstall them, or what else can I check.

 

A business card don't fit in the inside - its that tight- even if I loosten the bolts.

 

Come to think of if - the outside pad moves if I push it with my finger but the inside one not.

 

 

 

Posted

OK first you need to tell me.

 

Which model brake it is. M575 is non series so does not carry SLX or Deore branding.

 

You say SLX but SLX is M665.

 

 

Ok lets assume it is M575. This is a post mount caliper which means there is an adaptor which mounts to the frame and then the caliper mounts to the adaptor.

 

Now the easiest way to centre these is too undo the bolts securing the caliper to the mounting bracket, pull the brake lever and tighten the bolts. then let go. The Caliper should now be centred.

 

If stil not centred then you have a lazy piston which is going to require a bit of work.

 

Remove the disc brake pads.

now squeeze the brake lever to see if both pitons move the same distance. Yes, then the problem is probablywith the spring.

No, then you have have a lazy piston.

 

Squeeze the brake lever some more till the pistons are about 5mm out of the caliper body. trake some mineral oil brake fluid, the red Shimano stuff an lube the piston. Now push both pistons back into the caliper.

Repeat the exercise.

 

still have a lazy piston, then take ike back to LBS and submit a warranty claim. The caliper will need to be replaced.

 
Posted

 

OK first you need to tell me.

 

Which model brake it is. M575 is non series so does not carry SLX or Deore branding.

 

You say SLX but SLX is M665.

 

 

Ok lets assume it is M575. This is a post mount caliper which means there is an adaptor which mounts to the frame and then the caliper mounts to the adaptor.

 

Now the easiest way to centre these is too undo the bolts securing the caliper to the mounting bracket' date=' pull the brake lever and tighten the bolts. then let go. The Caliper should now be centred.

 

If stil not centred then you have a lazy piston which is going to require a bit of work.

 

Remove the disc brake pads.

now squeeze the brake lever to see if both pitons move the same distance. Yes, then the problem is probablywith the spring.

No, then you have have a lazy piston.

 

Squeeze the brake lever some more till the pistons are about 5mm out of the caliper body. trake some mineral oil brake fluid, the red Shimano stuff an lube the piston. Now push both pistons back into the caliper.

Repeat the exercise.

 

still have a lazy piston, then take ike back to LBS and submit a warranty claim. The caliper will need to be replaced.

 
[/quote']

 

Cool man, will try this. Not sure what brakes they are.

Sounds very problematic, if I can't figure it out i will take it back to the LBS

 

Posted

You're welcome,

 

it can be a phaff if the lazy piston syndrome does not disappear because it's quite frustrating to continually adjust the caliper on it's mount as the seals bed in.

 

Good  luck
Posted

It is the M575 - it has a adapter frame thing and then the caliper. Can I move the adapter a bit of is this fixed/ round boltholes?

 

I'm at work, so just trying to figure out what to do when I get back, to still be able to do a night ride tonight.

 

Is it quite easy to remove the pads and stuff - to oil the piston? Break fluid - as in the blue can of stuff ? Can I use WD40 ?

 

Posted

no not WD40 not at all.

 

The bolts holding the bracket to thefram should be left alone.

Losen only the bolts holding the caliper to the bracket. these are facing along hte length of the bike.

 

Just losen so that the caliper is loose, not falling off.

 

Then squeeze the brake lever. If the pistons are moving evenly then the pistons will centre the pads and hence the caliper in relation to the disc rotor.

 

Tighten up the bolts an then release the brake lever.YOU must continue to pul the brake lever while tightening the bolts. If you release then the torque of the bolt tightening will drift the caliper slightlyover to one side and you will have the same problem. this normally results in some spanner throwing in most homes.
Posted

It is the M575 - it has a adapter frame thing and then the caliper. Can I move the adapter a bit of is this fixed/ round boltholes?I'm at work' date=' so just trying to figure out what to do when I get back, to still be able to do a night ride tonight.Is it quite easy to remove the pads and stuff - to oil the piston? Break fluid - as in the blue can of stuff ? Can I use WD40 ?

 

[/quote']

 

 

 

never take oil/lube anywhere near a brake pad. Don't touch the brackets, they can not be moved. Just try and move the calipers as suggested in the 10 previous suggestions.

 

 

 

.

Posted

Yep - all the post lead to the same idea. Thanx, will keep the oil away from the pads and will try and sort it out.

 

Thanx again

 

Posted

SO this is what happened. Tok everything appart - pushed bach the pistons - looks like the one was a bit "lazy" - worked fine when I pulled the lever like this - pushed it back etc: then replaced the wheel.

 

end of story - No brakes - no presure in the tube/lever. What now ? Think that the hidroulic fluit just need to be topped up or something to restore the presure, and other thing thin the pad still rubs. WTF ?

 

Will let my LBS check it out-have no idea what went wrong and how to fix

 

Posted

argh, it seems you have air in the system.

 

This is a possible cause for the lazy piston.

 

Which LBS do you use? I would recommend either Shane at Bowman in Cape Town or Lance at Epic in Plumstead. Either can sort this out cos they're both very technically minded problem solving people.

 

William Keith of Williams Bike shop in Somerset west is another I trust with this sort of thing.

 

However what is required here is for the piston to be removed, the seals either cleaned or replaced, lubed with a dab of silicone grease (dow Corning MS40) and the piston refitted. The system will need to be bled and then it should be fine.

 

Often if the caliper is not running true with the rotor and the pads are very worn the piston is forced into an angle with the body and it does retract properly allowing dirt between it and the seal. eventually you replace the pads but the seals are not cleaned out and the dirt leads to problems such as this.

 

It't an hours worth of work. Go ahead make that call

 

Posted

Cool man - wil either use Flandria or Masons in Stellenbosch - because my brother is taking my bike in, I'm at work.

 

Sounds hectic for a new bike. Will let the shop I bought from know and figure out what to do.

 

Just crazy that where I'm form, where I live and where i work is all different towns

 

Posted

ok if new bike then its probably just a seal with a bit of a burr so it needs to bed in but the lever going all the way to the bars tells me air is in the system.

Often they are not well bled at the factory and need to be sorted before they leave the shop.

Not many LBS take the time to bleed brakes on new bikes and rely on the customerto identify the problem and mention it at fiorst service time.

 

nothing to be concerned about. It's an easy fix.

 

Posted

cool man, thanx for the time. Guess it will all be ok again and i can go back to Training. Had to sit on the rollers with my road bike last night after I couldn't fix it myself.

 

Hopefully back out tonight after work

 

Cheers man

 

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