Disc Brake Issues: no power.

mtb1611

Seymour
Greetings. Having issues with braking power on the rear for both of my son's bikes. One is low level Shmano hydraulic, the other mechanical, but the issues are identical on both; virtually NO bite. I've tried everything I can think of (plenty of net searches) to remedy the scenario but to no avail. Cleaned rotors multiple times, cleaned pads multiple times (sandpaper), ensured brakes are bled properly and cables in place and moving freely, wheels centred....it's doing my head in!

Any suggestions? NB: about the brakes, not the head....
 

Lucaw

Capital punisher
Greetings. Having issues with braking power on the rear for both of my son's bikes. One is low level Shmano hydraulic, the other mechanical, but the issues are identical on both; virtually NO bite. I've tried everything I can think of (plenty of net searches) to remedy the scenario but to no avail. Cleaned rotors multiple times, cleaned pads multiple times (sandpaper), ensured brakes are bled properly and cables in place and moving freely, wheels centred....it's doing my head in!

Any suggestions? NB: about the brakes, not the head....
Cook the brake pad as there might still be oil in them, then sand
 

moorey

Rap god
After you've done this ^^^^, remember to clean your discs again, as they would have picked up residue from the previous effort.

Then bed the brakes in well, and you should be good to go.

Sent from my SM-G780F using Tapatalk
Yes. This.
 

Plankosaurus

Spongeplank Dalepants
As above, cook them. It doesn't work 100% of the time, sometimes pads are just done, but it's worth 5min to try and bring them back.

Remove pads, scuff on concrete/sandpaper, spray with iso or brake cleaner

Cook the fark out of them, either hold them over a flame or hit them with a butane torch. Backing will change colour and pads will smoke or catch on fire if there's enough contaminant in them.

While you let them cool down, clean the rotors and calipers with iso or brake cleaner.

While they're still too hot to touch, pick them up and make swear words because you were too impatient. Now wait properly and install pads without burning yourself.

Bed them in by hitting a decent speed and braking hard. After a few runs you should start getting bite.

Most of my genuine pads have come good with this treatment, I've had some alligator branded ones that just won't come back. But I also won't throw them out so I'll periodically pick them out of the tub wondering why they're not in use and find out all over again.

Sent from my H8324 using Tapatalk
 

ozzybmx

Níl aon tóin tinn mar do thóin tinn féin
so I'll periodically pick them out of the tub wondering why they're not in use and find out all over again.
I've started marking stuff with the fault, can't rely on my old brain remembering what was wrong with the component or part these days.
 

cammas

Seamstress
For rotor cleaning I have had good luck cleaning the rotors with brake cleaner and drill attachment from super cheap that is like a scouring pad, it’s not too aggressive but enough to get the crap off.
Had a rotor that may have had shimano fluid spilt on it and would squeal whilst not working at all, now works fine after a little work with this attachment
 

Flow-Rider

Wheel size expert
Greetings. Having issues with braking power on the rear for both of my son's bikes. One is low level Shmano hydraulic, the other mechanical, but the issues are identical on both; virtually NO bite. I've tried everything I can think of (plenty of net searches) to remedy the scenario but to no avail. Cleaned rotors multiple times, cleaned pads multiple times (sandpaper), ensured brakes are bled properly and cables in place and moving freely, wheels centred....it's doing my head in!

Any suggestions? NB: about the brakes, not the head....
What grade sand paper are you using and have the rotors gone dark in colour ?
 

Flow-Rider

Wheel size expert
Using 80 grit first, then 600. Rotors haven't changed in colour.

Thanks for the advice all, much appreciated.
Most likely bad pads, try it with 80 grit only, avoid using wet and dry paper as it contains silicone in it. I've found with the lower end solid shimano rotors that once they turn dark it's very hard to get them working properly again. Spend a lot of time bedding them in without getting them too hot.
 

mtb1611

Seymour
Tried the cooking method, to no avail. Very slight improvement on one bike, no difference whatsoever on the other!
 

Alexxx

Likes Bikes
My go to method is to ride the bike on the flat and put the brakes on until I can only get to about 5km/h while pedalling as hard as I can out of the saddle (at the start just pull as hard as you can on the levers until the bike starts to slow). As the brakes start getting better I slowly release the pressure but keep my legs burning and speed the same. When the pads are close to done they start to squeal and I only have another minute or 2 of pedalling to go. Depending on how contaminated the pads are you might do this every weekend before riding.
After a month or so when this gets too tiring or your neighbours have had enough. Put the pads in a shallow fireproof container (old tuna can) add shellite until the pads are slightly submerged. Let them soak for 30 mins then set the whole thing on fire and the pads should be good to go.
I would recommend trying step one first, this has fixed most of my pads up and a few mates as well, only needed step 2 after my fork seals went and the pads were well and truly soaked.
 
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