Overhauling Squeaky Hydraulics

Det87

Hello guys, I'm wondering if you could help me.

I am in the process of overhauling my permanently squealing hydraulic brakes, apart from the levers (RS505). That includes the rotors, pads, the calipers and even the hose.

Old setup:
- Caliper: RS785
- Hose: BH59

New system:
- Caliper: R8070
- Hose: BH90

I have internal cables, so am probably going to use something like: https://www.youtube.com/watch?v=QZaGL83RMFI (with e.g.: https://www.parktool.com/product/intern ... kit-ir-1-2)

According to the Shimano Compatibility Chart: http://productinfo.shimano.com/#/com/2.4?acid=C-499 and this thread: http://weightweenies.starbike.com/forum ... p?t=147493, ST-RS505/R8070 should work just fine using a BH90 straight-straight kit.

My questions:
1) Does a BH90-SB/-SBS kit imply BH90-SS (+extra parts)?
2) Is there anything else I should be aware of?

Det87

Forgot to mention, I've replaced both the pads and rotors before, rebled the system a couple of times, and the squeak keeps coming back again and again (dirt layer on top of pads), so I can only assume it's the calipers.

The hose change (BH59 -> BH90) is only because the new calipers (R8070) depend on it.

veronese68

Your second post answers my original question. The only thing I can think of is that is it possible just to change the fitting on the caliper end of the hose? That would save messing about with the hose through the frame.

w00dster

Not sure if its relevant, but would it be worth buying a can of disc brake cleaner before you spend any significant money?
I use it on my bikes and have found it really stops the squealing brakes even in the wet.
I spray the disk rotors and the callipers, then wipe excess off. Leave them overnight and all is quiet. I'm sure folks may say its a waste, but I ride MTB (about 3 times a week) and use it on my brakes with no ill effects.

Det87

@Veronese68, Well, the BH59 is 2.3mm, while the new BH90 is 2.1mm, and it's not recommended by Shimano to use BH59 on a newer system. BH90 on older will work better.

@w00dster, I've used regular Fairy Liquid, normal bike cleaning solutions and even the automotive CRC Brakleen, which people say have worked fine for their bike brakes.

It's all good until a few brakes, and the squealing & dirt layer comes back. With new pads and with new rotors. Now I just wanna overhaul everything.

Det87

This thread doesn't seem to agree with that?: https://singletrackworld.com/forum/topi ... -confused/

If you wash it away even, how could it leave a residue? Shouldn't all dinner plates have oily (toxic) residues in them as well then?

sloppyschleckonds

Seems a lot of faff, have you considered a rim brake bike?

perfectmark

Det87 wrote:

This thread doesn't seem to agree with that?: https://singletrackworld.com/forum/topi ... -confused/

If you wash it away even, how could it leave a residue? Shouldn't all dinner plates have oily (toxic) residues in them as well then?

The surface of a dinner plate is very different to the surface of a brake pad though. I tried washing up liquid once to clean some squeaky pads, can't say it worked for me ether.

kajjal

One thing to be careful of is make sure you thoroughly clean the caliper inside and out with disc brake cleaner, as well as rotor and pads. Sometimes oily sludge gets inside the gaps inside the caliper and rapidly recontaminates the rotor and pad again.

Also clean the top as well as the sides of rotors and pads.

Make sure you use proper disc brake cleaner as soapy water will not work.

pilot_pete

Never done any of the above, just wash my bikes as normal. Never had squealy disk brakes...

PP

super_davo

Once pads get contaminants soaked in, which can easily happen when cleaning the bike, they are a nightmare to stop squeaking. I don't think you need to change the calipers mind.
The only thing that works for me is to take the pads out, sand them, clean rotors with disc brake spray. And when doing a drastic clean of your bike where you fully wash it, ping the pads out.

First.Aspect

Likely down to how you are bedding them in. Discs can squeak for the same reasons as rim brakes - i.e. if they judder. If you induce this the first time you use a set of pads and discs then the odds are that it will keep happening.

I've ridden with dirt on the discs and while that can massively effect braking power, it tends not to be related to how much noise they make. Whereas, when they get wet, they can be deafening. Same thing.

cooldad

Totally overthinking things. Disc brakes need minimum maintenance, flush with water when gritty and avoid spraying anything near them.

Brake cleaners (for cars) contain additives that burn off on car brakes, but bike brakes are more delicate and don't reach the same temperatures.

If they do get contaminated clean rotors with IPA and replace the pads.

Most brake issues are caused by unnecessary faffing.

And they squeal at times, often when using hard (sintered) pads. As does dragging the brakes, which can glaze the pads and make them squeal.

Det87

perfectmark wrote:

The surface of a dinner plate is very different to the surface of a brake pad though. I tried washing up liquid once to clean some squeaky pads, can't say it worked for me ether.

Can't imagine that'd be down to the fairy liquid then? If they squealed before?

In addition to that thread, this guy's also recommending washing liquid: https://www.youtube.com/watch?v=08ePb4_C0JA

super_davo wrote:

Once pads get contaminants soaked in, which can easily happen when cleaning the bike, they are a nightmare to stop squeaking.

Never heard of that. Long as you don't use a degreaser why would bike cleaners contaminate pads?

Answering my original questions:

Det87 wrote:

1) Does a BH90-SB/-SBS kit imply BH90-SS (+extra parts)?

No. A specific BH90-SS kit is needed.

Det87 wrote:

2) Is there anything else I should be aware of?

Det87 wrote:

Old setup:
- Caliper: RS785

New system:
- Caliper: R8070

This won't be possible (flat-mount calipers on a post-mount frame/fork).

Anyways, unimaginably, a quick test of 1/5th the price resin pads instead of finned sintered ones completely muted the brakes (exact same method of bedding in - brake firmly from good speed without locking wheels about 10-15 times).

However, one of the pistons in the other caliper doesn't move at even speeds even after cleaning and numerous bleeds, which keeps bending the rotor. They don't sell those separately, so gonna have to replace the whole caliper.

Otherwise, everything's nice apart from few things nothing to do with brakes. Completely fixable as well tho.

-b