[Closed] Shinano Brakes wandering bite point

Isn’t mineral oil the general term for all oils that are derived directly from crude oil, as opposed to synthetic oils?

If you use the wrong stuff in shimano brakes you run the risk of rotting the seals and killing your brakes.

Think I'd rather have a wandering bite point...

If you use the wrong stuff in shimano brakes you run the risk of rotting the seals and killing your brakes.

If it fixes them it's worth the risk. If it kills them, good riddance.

I'd try it if I was still messing around with my haunted Saints. Thankfully they're long gone.

Scotroutes will be along shortly to tell everyone that they're wrong and the brakes just need bled. That'll fix them for you.

They found that the solution was to use Putoline hpx 2.5 as brake fluid.

I really hope it doesn't work.  The last thing we need is another flavour of Putoline for folk to bang on about.

Scotroutes will be along shortly to tell everyone that they’re wrong and the brakes just need bled. That’ll fix them for you.

My job here is done. 👍

You'll need to get yourself over to Pinkbike, they need your help:

Shimano SLX brakes: Marin put its money into smart choices such as the four-pot disc brakes with a 203mm rotor up front for extra stopping power when that geometry gets you in too deep. Unfortunately, the wandering bite point that afflicted mostly the rear brake took the shine off the otherwise impressive performance, with an unpredictable lever feel when you need it to be consistent. The tool-free lever reach is a nice feature though.

Rear brake points towards poor bleed. I’m with Scotroutes.

IMO, all the doere and above brakes do it and it's due to the viscous mineral fluid which means pads return slower, and the servo-wave thing, which exagerates any slight discrepancy in the bite-point due to the higher leverage ratio at the pad contact point.

'Advancing the pads' appears to help because the pads contact the disc before the servo-wave takes effect. They will eventually settle into their natural bite point and problem will return though.

I plan to change my levers over to the non servo-wave ones like this https://www.bike-components.de/en/Shimano/BL-MT400-Brake-Lever-p67458/ but the brake fluid swap seems like a reasonable (if more risky) idea.

I'm with @scotroutes. Just bleed them properly. You have to be a bit patient and do lots of lever tilting and brake flicking to get the last wee bubbles of air out but ... works for me.

I've been running the same set of XT M8000s for 3 years and no issues with wandering bite point. I guess I'm in the minority?

.....but sometimes you get a set where you can bleed them however many times you like, spending a long time chasing every last air bubble out through every convoluted measure - and they still do it...(and yes, I know how to bleed brakes properly)

I read once on Pinkbike years back that there was a general consensus that the common issue may be down to dodgy anodising on the internal surface of the master cylinder, which as is wears causes the inconsistency - if that's true then there's not much that's going to fix them - anyone else heard of that one?

Mine are defo the worst brakes I've put up with...Hope's next time.

It’s nothing to do with servowave. The most likely cause is the master cylinder issue described above.

Never heard of any issues with the Deore 4 pots.

JP

If it fixes them it’s worth the risk. If it kills them, good riddance.

Unless it kills you as well !

I guess I’m in the minority?

No, you are in the silent majority.

I also agree with  @scotroutes  in my experience with my XT M8000 brakes , bleeding them exactly as Shimano say in their bleed instructions in my experience has kept them running sweetly. Other bleed methods may not solve the problem or may make the problem I dont know....

Yep, done that exactly as per instructions a handful of times, tried other methods too: on or off bike, multi lever positioning, bleeding up, bleeding down, sucking, blowing, wiggling, tapping - makes no difference, they appear well bled in stand then a few rides later it's back...

I have learnt to pre-brake before I brake, if that makes sense...

I have learnt to pre-brake before I brake, if that makes sense…

You need to learn to buy another brand of brakes 😝

I got one of the dud sets that no quantity or quality (bled by....LBS, BPW, mech local race mech, EWS mech, WC BH mech) of bleeds would fix. One of those times was in 35 degree heat in Spain so im dubious of the cold weather connection.

I also have a set on another bike that has only ever been bled twice in 4 years and works perfectly every time.

Mtb brakes, they're all temperamental aren't they? Market's crying out for someone to do them properly.

Mtb brakes, they’re all temperamental aren’t they? Market’s crying out for someone to do them properly.

Sums it up really.

My theory is we are asking a lot from the tiny lightweight parts they are made of. I think a reliable brake would need to use larger more robust components. Motorbike and cars don't suffer the problems we put up with but I think it would need a very very good marketing department to convince us to stick a set of brembos on or bikes!

one of the issues is the thin bendy discs. On a car if you have a sluggish piston the good one hits the disc and as pressure builds the sluggish one moves as the disc does not bend or flex. On a mountainbike the disc will flex before the sluggish piston moves so the sluggish one just gets stickier and stickier

Is it just me that used to get it all the time but rarely does any more?

I think if you get good ones, and bleed them right, they are fine. But some are indeed resistant to bleeding (and Shimano will replace under warranty IME).

Fitting a new set of Zees this week, wish me luck with them!

If people fit dodgy Taiwanese copy brakes called Shinano, what do they expect 🤣🤣🤣

In other new my M8000 lasted rather well being bled as per the instructions. In fact they're still going strong to this day.

XT front/SLX rear, the last two years - no problems.

BB7s, the 11 years before that - no problems.

Hope C2s, six years before that - no problems.

Maybe I'm just lucky...

Lack of oil in the master cylinder due to pad wear is usually the cause. The reservoirs are small. keep em topped up and you'll be ok.....

Was a lot of talk about it being the calipers but the backs of the pads and pistons on mine are always bone dry and never contaminated.

The newer SLX M7000 with the smaller reservoir (same as XT etc) are the worst and need bleeding after nearly every ride, been like that from new! There's always an air space at the lever. The old square reservoir Deore 615 I have are not as bad, have a consistent bite point but still end up with air at the lever after a few rides. I've had the dreaded Avid Elixirs, which got bled once maybe twice a year and worked problem free for about 5 years!

It's the lever that seems to be the problem, they suck air in, sometimes you can hear a squelch on the back stroke LOL. I've spent hours bleeding a single lever for it to continually produce tiny air bubbles when the lever is operated!

What @scotroutes said on another brake thread. Give em  good bleed first.

Although. Seth bike hacks ran baby oil for a while with no issues.

I found pumping more fluid in through the piston nipple and crimping it off worked. However, i have always noticed that the fluid goes murky quite quickly which does suggest it's getting contaminated, either from the hose lines and/or ingress from pistons..

on the old saints it was def the lever end that was ballsed. I've kept the pistons and put an M8000 lever on and they work nicely now (with the exception that somehting is now sticking)..

I’ve spent hours bleeding a single lever for it to continually produce tiny air bubbles when the lever is operated!

Yep, this is what I've noticed with mine-  chase all air out with a good bleed, go for few rides then check again and there will be air in the system. It's getting in somewhere...

I know of people that have discovered this problem after shouldering a bike up a hill, only to find that having the bike flat is enough to move the air into the system to the place where it gives you zero brakes, nothing like walking a bike up a hill on your back only to walk it back down again....have had a similar thing happen to me after having the bike laid flat in car, got to ride destination and zero brakes - now you'd expect this is down to just a bad bleed but in practice you'd need to be bleeding every ten rides or so to avoid this...

anyone know of the solution then please let on, other than consigning said offenders to the bin.

having the bike flat is enough to move the air into the system to the place where it gives you zero brakes, nothing like walking a bike up a hill on your back only to walk it back down again….have had a similar thing happen to me after having the bike laid flat in car, got to ride destination and zero brakes –

So, air was still in the system and moved to a different place?

i have always noticed that the fluid goes murky quite quickly which does suggest it’s getting contaminated, either from the hose lines and/or ingress from pistons..

I've read a suggestion that the discolouration is from some sort of "dye" in the seals. I've no opinion on this myself as I tend to set the brakes up and leave them be. I don't hold with the idea of re-bleeding them as some sort of maintenance schedule so I still have some older XTs that are 10 years old and XT8000s that are from the first release (is that 4 years ago?) running on the original fluid and bleed.

I have had the wandering bite point on one of my own bikes. I changed the hoses for aesthetic reasons and obviously hadn't been thorough enough. A proper bleed fixed it.

So, air was still in the system and moved to a different place?

No, no chance....professionally bled multiple times by a number of different highly competent mechanics following shimano guidelines to the letter, bled myself (Im fairly competent) using variety of alternative methods deduced from T'Internet...spending far too long on it assuring every last minisucle bubble chased out - few rides later there's air in the system-  but yeah, the air in the system then causes the problems and if enough gets to the wrong place you're goosed.

This is XT M8000 by the way. I've always suspected a tiny amount of air gets in through piston seals or as above suggests is pumped into the system through lever...and due to the small reservoir and also the exaggerated effect of servo wave (not a fan) it leads to the problem.

Mine were fine for few years while still in warranty but are now garbage.

What's the brake du Jour...won't touch Sram/avid again....  are Hope Tech X2 still good, had a early version years ago that were faultless if a bit underpowered. If money were no object which it isn't then Trickstuff look amazing.

Its a difficult one this, there obviously seems to be problems with some Shimano brake units but most I suspect are fine (when you consider the numbers of units Shimano shift this has to be the case) and its unfortunate if it happens after warranty has expired. What I do find a little odd is whenever certain magazines review bikes with Shimano brakes (especially XT and XTR) or brake units themselves they seem to almost 100% have this issue, or they say they do, which I find a bit strange as this would indicate that they are either very unlucky or all XT and XTR brakes have this problem which clearly isn't the case, its all a bit of a mystery.

It would be interesting to know how many XT / XTR brake units Shimano have sold and how many have this problem. This might indicate whether its within the range of normal expected failures due to some form of production fault or if its in a big enough range to be a inherent design fault. Unfortunately I dont think we will ever know.

The other side of this is how people have really maintained their brakes, have some people done a few things like lubricating the piston seals and if so what with or used non Shimano mineral oil. Shortened the hoses and perhaps not made an air tight connection (or many other possible things) and could these be contributing to some of these issues. One of the problems with bike maintenance is its temptingly easy for people to try stuff they are not competent enough to perform, or try to fudge because they dont want to buy the correct tools. When you see some of the videos on YouTube on maintenance they can be decidedly dodgy....

With the above statement I am not pointing a finger at anyone who has posted on here, just simply making an obvious comment in general.

It's also possible that many sets have the problem but riders don't notice. I'm lucky enough to have a 600m winch and plummet slope out my back door, it's steep and techy enough to have to be on and off the brakes repeatedly and is pushing the limits of over-heating and it's here that you really notice it. It's as if each time you pull the lever the bite point is fractionally different. Mine only does it slightly, possibly were talking less than a few mm's of lever travel, but it's enough to be disconcerting when trying to hit braking points precisely.

Out of interest I did an experiment once and car-park tested the lever feel of other riders brakes, seeing as they're probably the most popular brakes around...so 5 riders all with same brakes, all the levers I tried felt like they had way too much travel...like they had air in the system, the riders didn't seem to mind that feel though.....

The other side of this is how people have really maintained their brakes

Worth remembering that some of these have done it out of the box. My last set (Zees) it was the front that arrived wonky and was never any better (or worse) by the time it was sold on. Previous to that I had SLXs that were terrible for it, warrantied, fitted and tried out before cutting the hoses and were also terrible.

I'd had no issues at all with the older Shimano brakes that i'd had before, so it was a bit dissapointing to find that I could make Avid/SRAMs work far better!

Worth remembering that some of these have done it out of the box.

I am sure they have and for that I refer to the earlier part of my post. I tried to cover all possible points on why this problem might be happening and then someone picks on 'One' point , silly me.....  😉

One thing that didn't occur to me - and what @endoverend said in their post made me think - is maybe this is how they are meant to feel and it just doesn't appeal to some riders. I love my XT M8000 brakes and dont think they have any problem, you might try them and come to the conclusion they suffer from this wandering bite point issue. That would sort of explain things....

....and also, on flatter terrain or flowy trail centre type riding where you're only braking occasionally, the tendency is not going to be so apparent....when you're sessioning a known track and letting it hang out, not looking at the view so to speak, that's when its obvious.

If shouldering the bike caused a differnt bite point / faulty lever throw then it can only be air in the system that was not fully removed by the bleed

If air is getting into the master cylinder and bubbles can be seen then the master cylinder is faulty

endoverend

Subscriber

….and also, on flatter terrain or flowy trail centre type riding where you’re only braking occasionally, the tendency is not going to be so apparent….

That's just nonsense I'm afraid. People how like the bite point close to the bars can find it's hitting the grip on the first pull. It's certainly not a design feature either for the same reason + they wouldn't be happy to warranty the brakes people are sending back. Alternatively the Zee I had that didn't wander was actually the faulty one?

So is the consensus that if you have a set that's doing it then nothing you try will fix them, and I suspect there's a strong correlation between those that have wandering bite point and air getting into master cylinder regardless of the last bleed... this may save me a lot of bother. Has anyone got a warranty replacement when they're out of warranty...as it seems to be a common thing? Or do we just 'No Emotion' them towards the bin...

If it is air in the system then pumping the lever should move the bite point further from the bars then, if you keep presseure on the lever you should feel it slowly sink towards the bars. Dunno if I explained that well, but has anyone tried this? And I don't mean while riding.

IME it’s the bite point that changes, and nothing else

Just to add my experience when this happens: it is not cured by repeated bleeds of any method.

After bleeding they will work fine for a few hours of hard use: then need bleeding again. I've had enough bubbles out of mine to fill any number of Prosecco bottles 🙂

There is no mush in the lever when it happens. Just no braking until the bite point : from there on its perfect. Pre-braking fixes it on the trail.

How "soon" bleeding is required again seems related to pad wear : eg crappy weather / gritty trails = it comes back sooner.

I just send them back under warranty when it happens. So effectively they last 2 years.

Forgot to add: we have 6 Shimano brakes on the go at any one time usually. Only 1 or 2 of them will suffer this issue.

it's all a flaming mystery then... I've also tried to investigate whether it's that tiny little servo wave cam that alters the leverage ratio on the plunger. It's a tiny but essential little part, maybe not so robust design - maybe as it wears and gets a bit notchy in lever feel it's also not moving sometimes then a bit more next time..is that even possible? In the heat of the action it's almost impossible to tell. Shinano - Its sausages and hammer time.