SRAM Brake Scream !

[Zimmerframe]

The pipe is not the problem. SRAM uses glycol DOT fluid and has DOT fluid compatible seals. Shimano uses mineral oil and has mineral oil compatible seals. Mismatch of fluid and seal will cause swelling, disintegration and brake failure.

My theory was that if I went that way, I'd repeatedly flush the sram levers/pipe with mineral oil first and hope dot5 contamination would be minimal. In reality, it's probably not worth the hassle/risks of mix and match (or not match) and easier to just swap the whole lot out if you were changing and accept that you'll have more clamps or buy the adapters :

Onto posts mounts .. just saw these (which also come in pretty colours)

Ultralight Disco Freno Adattatore Posteriore 203mm Seatpost Pm Telaio a Post | eBay

"It fits all brands like SHIMANO, TEKTRO, Hope, MAGURA, PROMAX, HAYES, FORMULA, QUAD, etc. AVID may require Post Avid Spacer Sets. Note: The 203 mm PM / PM adapter is for the default 160 mm PM update on the frame or fork."

 

[Mikerb]

It's been a couple of weeks since I tried the cleaning and sanding .. so as we're starting from "simplest" again .. I thought I'd give it another go and be a bit more thorough ..

Started with @GrandPaBrogan's minimum contamination system, stripped naked and used White Vinegar to clean the disks .. Quite impressive what came off when you consider I cleaned the bike yesterday.

View attachment 21127

Right cloth, both sides like that, first clean. Left cloth, both sides, second clean ..

Vinegar is your friend ..

View attachment 21128

@outerlimits & @Rusty probably uses it as a nice after dinner digestive as they chat on Skype about the good old days of cast iron frames..

Stripped and cleaned the pads and calipers. Sanded the disks and calipers with 150 this time instead of 800 last time.

So will go for another drowning session later, try to bed them in again and see how we get on.

Vinegar is acetic acid so will dissolve salts but not oil based deposits. You need to use isopropyl alchohol.

 

[Mikerb]

Vinegar is acetic acid so will dissolve salts but not oil based deposits. You need to use isopropyl alchohol.

.....and it might be your cleaning routine that is contaminating the discs and/or pads. The calipers and discs need to be covered if you use any lube or protective spray and any cleaning agent you use needs to be free of any oils or wax.....so washing up liquid, car shampoo (most) etc are no good.

 

[Zimmerframe]

Vinegar is acetic acid so will dissolve salts but not oil based deposits. You need to use isopropyl alchohol.

That was chosen on purpose as I didn't want to risk causing any other bike issues from using isopropyl alcohol .. Maybe I'm being overly precautionary, but I figured it made more sense to keep any solvents away from what I was doing and as everything was getting sanded, re-wiped and blown afterwards, this should in theory get everything back to scratch.

Has anyone tried the "Dishwasher Technique" ?

The farrier was here yesterday, I should have just taken the disks off and stuck them in the forge for a few minutes..

.....and it might be your cleaning routine that is contaminating the discs and/or pads. The calipers and discs need to be covered if you use any lube or protective spray and any cleaning agent you use needs to be free of any oils or wax.....so washing up liquid, car shampoo (most) etc are no good.

And yes, always a possibility. But on this bike I've not used any cleaning agents of any form on the bike, not even muc off - though if it's oil deposits, maybe not using muc off is causing the problem . Just used water, leaf blower and microfibre cloth.

 

[khorn]

I would say that the only reason why I very quickly ditched my SRAM brakes on my Levo was because of the crazy loud screaming when breaking in the wet. I tried everything as mentioned in this thread but to no effect what so ever. What solved it was a set of Hayes Dominion brakes that are dead silent in all conditions, no matter if I use organic- or sintered brake pads. The Hayes brakes are btw rated as some of the most powerful 4 pot brakes out there, more powerful than Saints but with much better modulation. The first I can prove, as I did record my first ever OTB on the first ride after I installed them................ Zimmer could not have done it a more spectacular way

Karsten

 

[Zimmerframe]

Donned my frogman gear and headed out to bed in the brakes.

A Quick 20km squirt round the forest with a couple of K on the road to start for bedding in consistently ...

First press .. SCREEEEAAMMMM .. with virtually no pressure .. and dry ..

Fortunately they improved in sound (or lack of) and grip - became very nice !

It's VERY WET .. most trails are just flowing rivers at the moment. Didn't do any black runs as one of the ones Friday had half eroded at the bottom and was just huge pointy rocks and bike (or rider) swallowing crevices. The guy I met last weekend said it was closed, I though he was just being a bit of a softy..

Here's one on the edge of the forest .. it's just yukky ...

On the whole .. they were much better .. after a few hundred meters of no brakes and gallons of water they would squeal .. but not SCREAAAMMM like a 40 tonne tractor trailer locking up.

Generally then : Much better after de-contamination .. Think I'll try some new Ceramics next.

 

[Mikerb]

In very wet conditions I think you can also make a difference by how you brake. I find SRAM brakes quite progressive and there is more opportunity to have partial contact between pad and disk. If however rather than brake progressively you do the reverse of that...ie brake hard initially and very briefly then ease the pressure I find it clears the brakes of water/mud and ensures the pistons are equalised.

 

[Zimmerframe]

In very wet conditions I think you can also make a difference by how you brake. I find SRAM brakes quite progressive and there is more opportunity to have partial contact between pad and disk. If however rather than brake progressively you do the reverse of that...ie brake hard initially and very briefly then ease the pressure I find it clears the brakes of water/mud and ensures the pistons are equalised.

Nope, I certainly don't do that and I can't imagine I'd ever be able to convince myself to do that. I'd like to think (but I admit I think a lot of strange things) that I brake progressively and feel what the brakes and the bike are doing and adjust as needed based on what I'm getting back from "feel" in relation to the circumstances that are required for the braking situation.

 

[Gary]

View attachment 21134

Why would you even be braking there at all?

Soft wet conditions like this slows a bike down naturally without having to touch a brake lever at all.

 

[Gary]

Oh... and contrary to popular belief 203mm (or larger) rotors is not always the best solution. Especially for a skinny guy riding in Brittany in winter where you'd pretty much never actually get the things hot.

 

[Zimmerframe]

Why would you even be braking there at all?

I just like the sound of my screaming brakes ! I was going up there, so no, not braking (it was just an example of the moisture) and also, finally ..... you were correct - with the conditions it was actually a little difficult to "test" as there was so much natural resistance everywhere.

Oh... and contrary to popular belief 203mm (or larger) rotors is not always the best solution. Especially for a skinny guy riding in Brittany in winter where you'd pretty much never actually get the things hot.

And also interesting that you say that .. because,whilst in summer I found the brakes to be more powerful than the previous 180mm shimano's .. I now find them a bit hit and miss and did wonder about dropping down (obviously I want 220's cos they look cool) but I did wonder if dropping down would give me better winter heat retention, better drying and the disk will be 10mm further away from the wet ground ... or 20mm if I go for 160's ..

Or would it not actually make much of a difference .. anyways .. other than @Rusty .. no ones commented on my putting ceramics on or high carbon organics (which are probably just made from left over bbq waste).

 

[Zimmerframe]

Especially for a skinny guy riding in Brittany

You forgot to add "With a big nose" ..

 

[Gary]

160mm will probably suit you just fine where you are despite all the extra speed gained from your aerodynamic fuselage.

 

[KennyB]

Vinegar is acetic acid so will dissolve salts but not oil based deposits. You need to use isopropyl alchohol.

I think I've been using the wrong IPA.

 

[Mikerb]

I think I've been using the wrong IPA. View attachment 21144

Probably but do you know why it is called that?

 

[Rusty]

"Custom adapter" Why??? I just put regular 6mm washers under the caliper they are exactly 1,5mm thick which is exactly the difference between the radiuses of 200 and 203...

The shape of the caliper - not the spacing. Both sets were 203mm.

 

[JohnJohn]

I'm thinking the reason some bikes squeal and some don't, irrespective of brake brand, is down to the harmonics of the rear triangle...........

Ding....?

 

[outerlimits]

Interesting cleaning method @Zimmerframe.
I find it best to use isopropyl alcohol to clean everything first. I sand the rotors and clean again with isopropyl alcohol. Then sand the pads and wet rinse with isopropyl alcohol.

You then have to cook the pads over a clean flame like a gas stove top. This burns any contaminates from deep within the pad material and avoids later contamination once the pads get up to working temp. The pads will catch fire over the flame so be careful not to put too much heat into them.
I also find that when the pads catch fire, then making a wish while blowing out the flame works wonders. I usually wish for quiet braking ?

And really, your rotors should be as true as possible.
I use the WTAF GaryOn rotor trueing tool as pictured ? it works so well, it upsets people they did not use it sooner ?

 

[GrandPaBrogan]

Just used water, leaf blower and microfibre cloth.

You sir are a genius!

Why have I not thought about this sooner? I have a nice lightweight cordless leaf blower - that would be perfect to dry off the bike quickly. Or maybe even a chain that has been through a degreaser wash... so that I don't have to wait long to reapply chainlube.

 

[Zimmerframe]

You sir are a genius!

Why have I not thought about this sooner? I have a nice lightweight cordless leaf blower - that would be perfect to dry off the bike quickly. Or maybe even a chain that has been through a degreaser wash... so that I don't have to wait long to reapply chainlube.

Yup, I have a nice small cordless 18v makita one and its perfect for it, also as you say for blowing the moisture from the chain and the cassette !

 

[outerlimits]

Yup, I have a nice small cordless 18v makita one and its perfect for it, also as you say for blowing the moisture from the chain and the cassette !

Except a micro mist of grease and oil from the blower covers the brake rotors ?‍

 

[Zimmerframe]

Except a micro mist of grease and oil from the blower covers the brake rotors ?‍

Ah ha .. that's what does it ! Don't need a bell though if you have SRAM !

 

[outerlimits]

Ah ha .. that's what does it ! Don't need a bell though if you have SRAM !

I have SPAM brakes and they don’t make noise in the wet or dry ?‍ When looked after properly. I have a bell, it is big and loud and shiny. I fn love my big shiny bell ?

 

[GrandPaBrogan]

There he is Master Luke... he's the guy that stole my...

 

[HORSPWR]

Sadly no snow here or due .. just rain .. so they've been re-aligned repeatedly at home and out on rides.

If I use wd40 or gt85 on the disks that solves it

I don't know why brake manufacturers haven't introduced a floating caliper to MTB's like they have on the rear of MX bikes for decades, as soon as you apply the brake it pulls everything into line.

 

[HORSPWR]

Presumably there's some intrinsic design problem if they're resonating/squealing (with loss of effectiveness).

I thought they'd magically fixed themselves yesterday .. 5km's in heavy rain .. not a squeak ! then the squeak began and wouldn't stop, even with riding the brakes for 40k to try and keep them dry.

Was just looking at different disk possibilities.

I thought by now I'd have stumbled across some info on someone cunningly using the sram levers (as they're neat) with shimano calipers (also change the fluid).

Tempted to try the organic pad test first before I start replacing hardware - though I'm still slightly on the fence as if that doesn't work I've gone down the usual route of trying all the cheaper bits before plumping for the more expensive route.

Do you excessively clean your rotors?

Good brakes rely on a build up of brake pad material to deposit itself onto the rotor, clean them too often and you remove this important deposit. I never clean my rotors - EVER, even if I wash my cassette and get the greasy over-spray on the rotor and I never have noisy or ineffective brakes.

I look at it like this, when I drive my Mustang on wet roads and all that oily shit off the road combines with the water and splashes up onto my rotors, my brakes still work awesome, I've never had to clean my Mustang's rotors for them to work so why do it on my MTB.

 

[Rusty]

I don't know why brake manufacturers haven't introduced a floating caliper to MTB's like they have on the rear of MX bikes for decades, as soon as you apply the brake it pulls everything into line.

Have floating rotors now.

 

[HORSPWR]

Vinegar is acetic acid so will dissolve salts but not oil based deposits. You need to use isopropyl alchohol.

Works best on:

 

[HORSPWR]

Have floating rotors now.

Not rotors, calipers. They actually don't bolt down, held in place on a slider but free to move sideways.

I don't know why they market MTB rotors as floating, all the floating ones I've seen are fixed solid without any movement unlike the dirt bike ones which actually do float.

 

[Rusty]

The hope ones I fitted to a friends bike a few months back floated.