I like Shimano brakes but

[Staunch]

Lightly contaminated pads and can burnt and sanded to remove a small amount of oil/contaminant. It works very well if there is minimal contamination.

If the squeak remains, and you don't see oil on the back of the pads when you remove them from the caliper, you have one (or more) of 3 problems remaining
- Pads are too badly contaminated
- Rotor is still contaminated (ever the tiny amounts of oil that remain in the slots in the rotor can be a problem as soon as you get some heat back into it)
- Rotor is too old/cooked (if it's discoloured from excessive heat cycles)

 

[Cardy George]

In regards to the bedding in process. About half a 24hr race worked wonders for my new pads to match the lightly scuffed rotors.

 

[Dales Cannon]

In regards to the bedding in process. About half a 24hr race worked wonders for my new pads to match the lightly scuffed rotors.

I reckon you should drive a nice new and a bit expensive GT2RS with carbon ceramic brakes. Tap the brake, shit it's not stopping. Push harder, still nothing, push harder fuck I have stopped 50m before the corner and my eyeballs are on the inside of the windscreen.

 

[Calvin27]

In my experience causes of squealing in shimano brakes (in order of how common it is for me):
1. Wrong brakes, they are actually srams
2. Contaminated pads - clean the rotor and caliper assembly, bin the pads
3. Rotors simply suck. Generally it's crappy cheap rotors, but having said that I'd had issues with some earlier RT800 rotors, HS1s never worked without noise and some trp brands don't work too well. Surprisingly the RT66 bottom of the barrel rotors have never been an issue.
4. End of pad life. I swear the compounds change near the last third of the pad, just generally starts making a lot of noise even though there is some life left.

 

[pink poodle]

More fool you sucker! They are good as new thanks to my technique and a dash of @ozzysanding.

- drop of morning fresh + water on braking surface.

- rub braking surface vigorously against each other and watch the dirty suds build up.

- rinse and repeat until the suds are nice and clean.

- same again but with brake cleaner (I hadn't done this before and fuck me it was a gold inclusion).

- light sand with wet/dry ultra fine sandpaper (maybe this wasn't necessary, but ozzy told me to!)

- brake cleaner and clean rag on rotors until clean

- a few bursts of brake on a long steep hill (I took the bike for some jumps and ticked this off on the ride home).



Problem solved. I do also like the dishwasher, especially on the rotors. Shit comes out looking real fresh and works as good as new.

The dishwasher is the true hero - minimal effort for maximum return.

 

[Mr Crudley]

The dishwasher is the true hero - minimal effort for maximum return.

The thought of microscopic brake dust on my dishes outweighs need for turkey gobble free pads.

I have just sprayed them with isopropyl alcohol and then done a few maximum braking runs which has fixed them up most of the time.
Sticky paspalum at rotor height is one of the culprits IMHO.

 

[pink poodle]

The thought of microscopic brake dust on my dishes outweighs need for turkey gobble free pads.

I have just sprayed them with isopropyl alcohol and then done a few maximum braking runs which has fixed them up most of the time.
Sticky paspalum at rotor height is one of the culprits IMHO.

Just run a cycle after you finish the clean and you'll be fine. Or you'll become Akira.

 

[Mr Crudley]

Just run a cycle after you finish the clean and you'll be fine. Or you'll become Akira.

If my future lunches ever tasted a bit ceramic or metal sintered then I would be scrubbing the dishwasher for years with teary eyes.
The dishwasher is one of my favourite appliances that I just can't show disrespect

 

[PJO]

Surprisingly the RT66 bottom of the barrel rotors have never been an issue

Solid agreement from me on that one.
They aren't technically the bottom of the barrel though, Shimano make lower level rotors but they are usually resin only.

 

[Calvin27]

They aren't technically the bottom of the barrel though, Shimano make lower level rotors but they are usually resin only.

Yeah good point, make sure the rotors are metallic pad comaptible. Shimano tells you if they are but a lot of aftermarket ones don't. *looks at trp.

 

[The Duckmeister]

I had a bike through work that had M785 XTs. The stock resin pads would glaze & squeal like a pig every ride. Chucked 'em and went metal compound. Not a peep after that. Resin pads mostly suck (coming from the type of rider they're supposedly better suited to....)

 

[pink poodle]

I had a bike through work that had M785 XTs. The stock resin pads would glaze & squeal like a pig every ride. Chucked 'em and went metal compound. Not a peep after that. Resin pads mostly suck (coming from the type of rider they're supposedly better suited to....)

Slight side tracking but...I ran resin pads in a lot of brakes for years. I think I still do in some. I've nothing to complain about.

 

[rowdyflat]

I did some more research.
'The current theory is that many Shimano brakes are leaking from the oil transfer port which has a 3 mm ID 1.5 mm thickness o ring between the 2 halves of the caliper allowing oil to move to both pistons.
The durometer of the nitrile /Buna O ring should be harder 90 not 70 ?

 

[rowdyflat]

The leaking is very slow so the pads may not be wet but get contaminated .
The oil can be burnt off by a heat gun or heavy braking but will come back.
In the name of science I will try pulling a caliper apart.

 

[rowdyflat]

I pulled a SLX caliper apart ,it would appear that there are several different sized O rings sealing or not sealing the oil transfer port.
It was about 6mm ID x 1.5 mm thickness. Apparently 4 pot brakes have a bigger one.

Shimano transfer port o ring size?

August 14, 2022 - Many discussions about it leaking but no one has said what size we need.

singletrackworld.com

 

[oldcorollas]

like this from a while ago?

Solving That Brake Squeal | Blue Liquid Labs

blueliquidlabs.com

You could just over pressurise the caliper and see what leaks first

 

[rowdyflat]

Renovated a Deore caliper cleaned it thoroughly , burnt the pads cleaned the rotors with alcohol, it squeaked.
Put new pads in the caliper, it squeaked immediately, does this mean the rotors likely still have oil on them ?

 

[Oddjob]

Renovated a Deore caliper cleaned it thoroughly , burnt the pads cleaned the rotors with alcohol, it squeaked.
Put new pads in the caliper, it squeaked immediately, does this mean the rotors likely still have oil on them ?

Yes

Sent from my motorola edge 30 pro using Tapatalk

 

[Stredda]

Renovated a Deore caliper cleaned it thoroughly , burnt the pads cleaned the rotors with alcohol, it squeaked.
Put new pads in the caliper, it squeaked immediately, does this mean the rotors likely still have oil on them ?

Definitely new bike time. Nothing more can be done.

 

[Stredda]

Renovated a Deore caliper cleaned it thoroughly , burnt the pads cleaned the rotors with alcohol, it squeaked.
Put new pads in the caliper, it squeaked immediately, does this mean the rotors likely still have oil on them ?

Have you done anything to clean the rotors? There were quite a few suggestions.
Usually if you have any contamination from a suspected leaking calliper a scorched earth policy is best.
Calliper overhauled, checked for leaks and thoroughly cleaned, pads replaced, and rotors really well cleaned with isopropyl alcohol.