Shimano rear brakes - glazed ?

[ChrisF]

I am having some issues with the Shimano rear brakes on my Merida XT Edition.

 

It WAS good when I got the bike ... I know this as I have locked up the brakes on tar when a car turned in front of me.

 

 

It started screeching .... at first I thought I got something on the pads when I washed the bike.  But I use the same chemicals when I wash my TREK.  Blue Chems for the frame, Pink chems for the chain - normal stuff you buy from a bike shop.

 

 

Then I noticed the rear brakes DONT slow the bike down ... you can PULL on the lever, but the bike just rides on and on .....

 

 

I lightly sanded the surface of the pads.

 

I cleaned everything with alchol

 

No joy ....

 

 

I then took it to my local bike shop, had the breaks bled, and asked them to check out the back brakes as well.

 

 

Got the bike back, and tested in the parking lot ... same ! 

 

Took it back i, they sprayed some break cleaning fluid on, tested again and it was perfect. 

 

Second ride it is doing the same again ....

 

 

 

Do I just replace the pads ? Or is there something else I should check out ?

 

 

 

[JCA12]

Could be oil leaking in Caliper.

 

If it is just the screeching could be bolts not tightened. But with the loss in power, I think the oil leaking is more likely imho.

 

Could try with changing pads and/rotors.

 

Can you swap rotor from the Trek over to check?

[FrikkieMeyer87]

You might be able to save them with some elbow grease (There are some YouTube vids that cover this) but 90% of the time it's not worth it, especially with all of the year end specials currently happening. Rather gooi some new pads on there, bleed your brakes and be amazed at your new stopping power*.

*...which will take effect once the new pads are properly bedded.

[Bateleur1]

Had the same problems on my XT rear brakes.  Mentioned it in other threads here.  After replacing the pads it still made a noise and then went down a looong hill and kept the brake down and warmed it up quite a bit and that seemed to have sorted it.

[ChrisF]

Could be oil leaking in Caliper.

 

If it is just the screeching could be bolts not tightened. But with the loss in power, I think the oil leaking is more likely imho.

 

Could try with changing pads and/rotors.

 

Can you swap rotor from the Trek over to check?

 

I doubt it is oil leakage .... bike is CLEAN  (no dust collecting on any oily residue)

 

doubt it is chain lube .... I drip it onto the chain, and work carefully not to make a mess.  but who knows .....

[CdT85]

if its oil contamination. let them lie in petrol for a while, then take them out and light them on fire (in a safe place). Afterwards, sand them with light sand paper.

 

Worked on my deore brake pads. been 6 months since the "hack". No issues since

[ChrisF]

You might be able to save them with some elbow grease (There are some YouTube vids that cover this) but 90% of the time it's not worth it, especially with all of the year end specials currently happening. Rather gooi some new pads on there, bleed your brakes and be amazed at your new stopping power*.

 

*...which will take effect once the new pads are properly bedded.

 

thanks.

 

 

might just do the Youtube thing - just to experiment a bit ....       Who knows, maybe one of those vids actually works ... 

 

 

I often spend hours watching these Youtube vids ..... 

 

 

Then get a new set of pads ....

[dasilvarsa]

Sometimes Oil or Chain lube gets inside the holes in the rotor and keeps contaminating the pads. Before putting new pads take out the rotor and clean it a few times paying special attention to the holes. If there is a mineral oil leak you should see it on the back of the old pads.

After fitting new pads the caliper needs to be centralized so that the rotor is not rubbing on the pads. The pistons need to be pushed back before replacing pads. If the pads are contaminated with oil it is difficult to clean if it has soaked into the pads. It causes a bluish tinge on the rotors squeaking and a performance problem.

[ChrisF]

if its oil contamination. let them lie in petrol for a while, then take them out and light them on fire (in a safe place). Afterwards, sand them with light sand paper.

 

Worked on my deore brake pads. been 6 months since the "hack". No issues since

 

HEHEhehe .... this sounds like FUN ....       

[CdT85]

HEHEhehe .... this sounds like FUN ....       

 

Even more fun if you pour the left over petrol out over them while burning

 

disclaimer; I do not take any responsibility for injuries attained by lighting flammable liquids

[FrikkieMeyer87]

thanks.

 

 

might just do the Youtube thing - just to experiment a bit ....       Who knows, maybe one of those vids actually works ... 

 

 

I often spend hours watching these Youtube vids ..... 

 

 

Then get a new set of pads ....

 

As a fellow Bellvillian, you can most likely get sorted out in an afternoon by oom Chris for less than 100 randelas it seems: https://www.cwcycles.co.za/parts/brake-pads-mtb

[HowardSteele]

Firstly check if it is the pads switch the rear with the front.if they work on the front and the rear still has a issue it might be the dreaded Xt lever failure..

[ChrisF]

Firstly check if it is the pads switch the rear with the front.if they work on the front and the rear still has a issue it might be the dreaded Xt lever failure..

 

THANKS !!

 

Easy way to KNOW for sure ...

 

WILL do this first.

[ChrisF]

As a fellow Bellvillian, you can most likely get sorted out in an afternoon by oom Chris for less than 100 randelas it seems: https://www.cwcycles.co.za/parts/brake-pads-mtb

 

uhm ja ... nee ..... 

 

let's not go there 

 

 

had enough of buying things on "special" to see it marked down two days later ....

[PhilipV]

get new pads anyway. You always need a set of pads in the toolbox. 

It sounds like oil contamination, so I'll put new pads on, try to clean the old pads by burning them (I've heard that baking it in an oven also works, but I dunno) after which they will still go in a marked bag in the toolbox as second set of spares. 

Pads are relatively cheap for how important they are. See if you can save them, but don;t mess around, you may need to stop quickly in traffic one day. 

[ChrisF]

.....

Pads are relatively cheap for how important they are. See if you can save them, but don;t mess around, you may need to stop quickly in traffic one day. 

 

THIS !!!!

 

 

I am NOT enjoying my commute knowing that my braking is compromised ....

 

Normal cycling is okay ... but in an emergency I wont be able to react as the bike should ....

 

 

I certainly will do the following:

 

- swop front to back to test the glazing theory ....

 

- play with the various youtube options ....

 

- and if I am not 100% satisfied I will be replacing the pads !!

 

 

just wrapping up a small building project (base for another JoJo tank), then I will garage space again, and time for this ....