[Closed] Whats up with my XT brakes?

hhmmm - interesting. My M9020 XTRs did this from new. Got one bleed at the bike shop to no avail. I just kinda got used to it.

What I was wondering at the time was whether it was a mechanical issue as opposed to hydraulic, my reasoning being...

I think these brakes have a Servowave feature? Although no Googling ever gave me any good answers. To my thoughts Servowave means the initial lever pull gives low mechanical advantage and quick pad travel to quickly get to the bite point and then on contact changes to high mechanical advantage for strong braking. The change is due I think to a pin or pivot point shuttling across when the load comes on. So I wondered if the 'switch' between modes got stuck sometimes??? My brakes always needed the initial pull which gave long lever travel, then quick release and then on reapplication gave good braking with the lever a bit further from the bar.

Don't know if there's anything in that or not. Maybe I'm just getting confused with ancient Shimano cable pull brakes which definitely did this and the mechanism was clear to see:

[url= http://faqload.com/faqs/bicycle-components/brakes/xtr-servo-wave-brake-adjustment ]http://faqload.com/faqs/bicycle-components/brakes/xtr-servo-wave-brake-adjustment[/url]

My brakes have never felt like they actually needed a bleed - they are not spongy as if there's air in the system...

Mine do this too!

I've bled them multiple times, same issue.

Also bled some road hydraulics in the same way and they are fine.

I think both SLX and XT have Servowave too.

On the XT rear I tend to have to run the rear leaver further away from the bar than I'd like as that's the only way it can't possibly end up pulling to the bar and usually that's enough leaver throw to have bite where I expect it to be which suggests servo wave is in action. On the SLX I can position the leaver where I want and it'll always work ok.

I may ask at my LBS when I next go in.

If you're having a problem I suggest you email Madison to inform them of it. I got a reply and apparently they're not aware of any issues. Which is odd because if you Google it you can find dozens of discussions just like this one.

I'm really getting the arsehole with this now - mine aren't the M8000 but they're brand new, multiple bleeds and they're woefully inconsistent - first pull almost now power, second a bit better, third rock hard - pretty much where you want them - was riding a horribly slippery Caffel at the weekend, had to take evasive action on one section and ride out of a turn and into the trees because I was never going to make it at the speed I was going at, later on I'm fighting a high side when the front locked without warning. I took to pumping them up and then riding with the lightest of brake drag on to hold pressure.

To me it feels like the pads aren't self-adjusting and want to go back to fully open even when the pads are part-worn, there's certainly a lot of light between them compared to my Deores which are perfect.

I am sending this thread to Madison on Facebook and see what they have to say.... I almost had a horrendous crash today as pulled the brakes to stop rapidly and nothing happened... to have to pump the brakes in advance of when I need them is not right!

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OP here, i cant believe how common this problem is! I thougt it would be a simple fix! Has anybody actually had this problem and solved it (without buying new Brakes)?

Has anybody actually had this problem and solved it (without buying new Brakes)?

From Madisons reply to me;

There is no re-build kit available, so it would be a case of purchasing new parts to try and resolve the issue.

In other words, you pays yer money you takes yer chance.

No more Shimano brakes for me.

I brought them 10 months ago from CRC and this Problem has been from new. Warranty job?

Yeah go for it. I left mine too long because I rarely use the DH bike and thought I'd be able to fix them. Bit gutted now as they're in near mint condition but technically a write off.

I love how polarised this thread is to all the Hope vs Shimano, or SRAM Guide vs Shimano.

I've had all my sets of Shimanos do this, and lots gone back under warranty. Nothing would make me use them again, total pain to own and disposable.

My Hope e4s never did anything that would possibly injure or kill me, and neither have my Guides.

I'd argue a failure mode that has a good amount of anecdotal evidence, and that is serious enough to injure needs investigation by Shimano.

I'd urge those with the same issue to file a complaint, to ensure its recorded and dealt with.

This is odd I thought the latest shimano xts 'just work' and were the best thing since sliced bread?

2 year warranty btw. Get them returned whilst the weather's shite.

I've got 2 pairs of SLX (latest model) and one set was doing this.

Bled them with the Epic Bleed Solutions kit. (as part of the process, when I removed the pads I realised they were all right down)
Post-bleed, they're rock solid.

EBS FTW.

I don't get the random level pull issue but i do get the upside down issue.

If the bike is upside down for a period then the levers will pull to the bar a couple of times.

I need to bleed them properly.

Bled them with the Epic Bleed Solutions kit. (as part of the process, when I removed the pads I realised they were all right down)
Post-bleed, they're rock solid.

EBS FTW.

i agree...i use the Epic bleed kit and never had a problem yet. mates brakes did have a problem but a good couple of bleeds using the Epic kit forced some nasty looking brake fluid out which was then replaced by some genuine shimano mineral oil. they work perfectly now.

2 year warranty btw. Get them returned whilst the weather's shite.

again i agree with this....if you have an issue that doesn't seem to sort itself with a bleed, send them back...that's what the warranty is there for
if you have XTR kit then its covered by a 3 year warranty

Mine are fine. Wonder if cold and damp/wet affect them? Dry and warm here. Of course, I've just jinxed myself, no doubt.

How do the people who have issues use the Free Stroke (or screw of pointlessness)? Seems to do bugger all for me.

i agree...i use the Epic bleed kit and never had a problem yet. mates brakes did have a problem but a good couple of bleeds using the Epic kit forced some nasty looking brake fluid out which was then replaced by some genuine shimano mineral oil. they work perfectly now.

I'll be that guy and disagree. EBS kit in action here, definitely better than the Shimano method but still not great. The fact that it needed "a couple of bleeds" tell you a lot too. Older Shimanos took one 5-10min bleed* and they'd go for years.

Also, does anyone else get a worse bleed when using the yellow piston spacer?

*top down only and half the time you just had to open the bleed nipple and leave it for a while

Also, does anyone else get a worse bleed when using the yellow piston spacer?

*top down only and half the time you just had to open the bleed nipple and leave it for a while

On previous generation Shimano brakes (with no method of adjusting lever travel) I use a thinner, hand-made spacer. It allows a certain amount of "over-fill" to move the bite point out.

Edit: that's for my own bikes because I like it that way.

Watching this thread with interest....
I've bled quite a few sets of Shimano brakes for friends and my own, using the Epic kit and whilst all but one set have been fine , one set did keep coming back with "it's gone spongy again" ... Although 3rd time lucky might have got it.
Must admit I don't use Shimano fluid or the yellow spacer I found the Green bottle opener key ring MBR gave away a couple of years ago fits Shimano and Hope callipers perfectly.

Also, does anyone else get a worse bleed when using the yellow piston spacer?

*top down only and half the time you just had to open the bleed nipple and leave it for a while

i use the yellow block for my front zee but i wasnt sent one for my rear slx....so i use about 4 1pence coins wrapped in tape....does the job

i usually bleed form both ends...i first start at the caliper and use the srynge to force the fluid up the brake and out of the lever reservoir and into the big syringe thats screwed into the lever. i tap the caliper, hose and lever to knock out any air bubbles. i then fill the top syringe with fluid and let it drain through the brake from lever to caliper and out though the bleed port valve. again i will tap the lever, hose and caliper to knock out any air. i then repeat this process if needs be until the brake feel and lever movement is right. on my mates i had to do this about 4 times....took about 30 minutes per brake but it was worth it in the end.

dont use the weldtite mineral oil like my mate did....absolutely useless!!

I found this with a set of second hand xts, but have had no problems with deores or slx on mine or the other halfs bikes.

The newer shimano brakes do seem to be a lot more susceptible to pad wear though- my older 775s and 765s could both be into the backing pad and they'd still feel the same (if conditions were bad enough you hadn't noticed by then) but the newer ones seem to need changing at the stated wear point or they feel off, which is shocking!

email Madison to inform them of it. I got a reply and apparently they're not aware of any issues.

That's why on a daily bases they replace faulty shimano brakes without question, because they are not aware of any issues.

I have become a high level expert on the tricks of bleeding shimano brakes and even fitted goodridge hoses and bled them vertically, left them overnight and then did mini bleed on the bike. The result was a superb feeling brake with tonnes of power and a consistent lever feel................for about 2 rides, then back to the same problem.

I think back to Hope for me because failed but cheap is useless in the middle of the mountains. Would much prefer Hope to produce a powerful 2 pot brake as I always find the 4 piston stuff to be fiddely and less reliable.

Hope to produce a powerful 2 pot brake

do you have to run the full-retard vented rotor with the V2?

I really want to run the shimano fluid, royal blood and others through a GC-FID and see how different they are in composition. There's obvious difference in viscosity of the green cyclo stuff and the shimano fluid. Higher viscosity would suggest longer carbon chains and with that a higher boiling point, but Shminano claim that their mineral oil is the highest boiling point, despite it being so fluid.

Read an article once where they had all the boiling points, cant remember where it was though. They had all the brake companies, all talking about mineral oils and dot fluids etc. Why you shouldn't put royal blood in shimanos and vice versa.

do you have to run the full-retard vented rotor with the V2?

JackHammer
[url= http://www.bikerumor.com/2013/04/11/tech-speak-brake-fluid-break-down-and-implications-for-road-disc-updated/ ]This one?:[/url]

Ecky-Thump - Member

JackHammer
This one?:

Well, I'm a fuggin idiot - I've been letting the free stroke screw out to bring the bite point out. Should have read the destructions.

Total toss bag.

Thats the one Ecky, was just about to post the link.

There's a few 'I know better than Shimano' types who could do with reading it!

I had this on my xt's for ages. Then, as I was trying out 27.5+, I dropped in wheels with some cheap and nasty discs. Low and behold problem gone. Ice tech discs out and some cheap discs that were marginally thicker installed.

The bike that the ice tech went onto (with xt brakes also) now has a slightly iffy initial pull

JackHammer
This one?:

Yeah that's it!

Also there's some stuff on epic bleed solutions website.

JackHammer
This one?:

that was a very interesting and educational...thanks 😀

@alexh

Yeah I'm leaning towards the worn rotor/pads side of things now.

As far as my understanding of the servowave goes, it allows for wider piston spacing, therefore a bigger gap between pads and rotor so less "shhhhinnngg shhinng" from warped rotors (which was something I always used to get with avids).

This bigger gap is then accommodated for by the "servo" pivot or whatever which instigates more movement at the pistons for the initial lever pull travel (top the bite point).
So it would suggest that this "servo" part of the lever travel is tuned into the width of the rotors and pads, only varying a small amount (ie pad wear). When you add on rotor wear, pad wear and maybe misaligned pistons (not-centered) you get the lever having to go beyond this large movement zone to the "modulation" zone of the lever throw, where there's comparably little movement of the pistons and a spongey feel on initial pull.

As with the elixir brakes the reservoir on the shimanos may not hold enough fluid to push the pistons out far enough to self adjust to the wider spacing, so require a second pull to get the pistons and lever throw servo tuned bit to bite at the right time.

I am not an engineer so sorry for the terrible technical language.

Rotor and pad wear should have no effect on an open brake system - the whole point is that the pistons move out to compensate for the wear using fluid from the reservoir.

Well, mine have never worked like that. On both bikes, as the pad gets low, the throw to biting increases (it's slight, but enough to notice when my pads are low).

The only thing I changed on my bike, were the discs. It went from circa 8mm throw (on the lever) to the pads biting, to about 1mm throw.

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Get out!

years of happy Avid use here too.

What frustrates me is that shimano don't seem to be addressing the issue, which is obviously a big one as so many people are suffering the same/similar issues.

I wonder if it really is 'a big one' [problem] given the number of Shimano brakes out there and the fact that at least some of the issues seem to be down to user maintenance error? I'm not saying it's not annoying or unheard of, just that it may statistically be quite a small problem, even if it's a really annoying one if it happens to you.

Fwiw,, we have seven sets of Shimano hydraulic disc brakes on various bikes and they've all been hassle free. Which conversely doesn't mean there's not a problem, just that the internet tends to amplify frustrated voices. Maybe...

Well i've replaced everything but the rotor and caliper on my dodgy one, and there's a definite a lip from the spider arms to the pad contact strip. So i'll swap the rotor and put some fresh pads in it in the near future and see how it goes.

Well, mine have never worked like that. On both bikes, as the pad gets low, the throw to biting increases (it's slight, but enough to notice when my pads are low).

I know - I have a set that do this too - but this isn't a "feature" of the brakes. Its an indicator of a brake not working correctly for whatever reason.

This is my understanding of how an open brake system SHOULD work....

The caliper seal acts as the spring to return the slave piston to its original starting position after you pull the brake lever. But the seal is also designed to allow the the piston to move a little bit past the seal in the event of the piston moving further than a set distance (i.e. if the lever pulls all the way to the bar).

The result of this is... if you push the pistons all the way back into the caliper and then keep pulling the brake lever, the lever will travel all the way to the bars on the first few pulls but gradually the pistons will move outwards bit by bit until the pads contact the disc. At this point the lever should be biting at the correct point in the lever stroke and the pads should remain a set distance from the disc when the brake is not applied. The size of the gap between the pads and the disc is determined by how springy the caliper seal is (i.e. how far the seal can move outwards with the piston before the piston breaks away and slips past it).

This system is designed to cope with pad wear as the pistons will move out over time to compensate for the loss of pad material while always maintaining a set distance from the disc.

As the pistons move out over time, fluid from the reservoir flows out to compensate for the increased volume of the system...but this can only happen when the lever is not being pulled. When you pull the lever past a certain point the port to the reservoir is closed off in order to allow the brake to powerfully bite down on the disc.