Shimano brakes

[fatbikephil]

I'm at my wits end with these (to be fair that's not very far,) both the SLX ones on the Jones and the deore ones on the ICT regularly lose lever pressure. Holding the lever closed for a bit and much pumping gets it back but its a PIA. I've bled them repeatedly, made absolutely sure there is no air in and I've used both shimano oil and cheapo stuff meant for a Citroen ZX's hydraulics which also makes BA difference. I'm seriously thinking of going back to hopes and Dot 5 but can anyone offer any wisdom as to whether there is a cure for this before they go over the back fence.

[Bearbonesnorm]

Do they squeal when working?

[fatbikephil]

Nope. In fact when they are working they are bang on. As far as I can tell they aren't leaking through the piston seals

[Bearbonesnorm]

It's really got to be either something at the master cylinder or a damaged hose ... I once had a hose that had started to come apart inside and was acting as a one way flap valve but what are the chances of two having the same problem unless it's a common(ish) fault that isn't a micro-leak?

[fatbikephil]

Nowt obvious as far as the hoses are concerned. As usual due to laziness I CBA fanny arsing around fitting new hoses unless they were obviously knackered. I'll leave this as a last resort if nowt else works (i.e yet another brake bleed).

[boxelder]

Do you hang them by a wheel to store them? A quickish answer may be to use an elastic band to hold the levers 'on' when not in use. A section of roadie tube works well. Pain, I know.
Also worth trying, is once you remove the bands, see if you can top up the fluid at the lever/master cylinder (just once, not every time......hopefully).

[Bearbonesnorm]

Have you tried bleeding them backwards through the bleed nipple Phil?

[AlexGold]

Have you tried bleeding them backwards through the bleed nipple Phil?

Good shout, I've got two syringes that I attach top and bottom for tough bleeds - squeeze most of the fluid through from the top (using the squeeze/unlock/lock/release method) then push it back up. The brake fluid equivalent of flossing! Also it might need the bike/bars/hoses rotating/banging to get rid of any particularly stubborn air.

Another motorbike trick is to leave the syringe/funnel attached on the lever, zip tie the lever to the bar and come back tomorrow. Worked on my motorbike when nothing else would....

[Charliecres]

I have this exact same issue. I’ve tried everything. New brake time, I think

[fatbikephil]

Have you tried bleeding them backwards through the bleed nipple Phil?

Aye but not recently. Currently using epic bleed solutions method which is faff tastic but evicted a lot of air when I first tried it..... I think another bleed is on the cards before I take the axe to them.

Another motorbike trick is to leave the syringe/funnel attached on the lever, zip tie the lever to the bar and come back tomorrow. Worked on my motorbike when nothing else would....

Funnily enough, the first time it happened (on the Highland trail in 2015 no less, due to pumping the lever with the bike lying on its side) a variation of this was how I got the brake back - I strapped the brake lever back and left it for 10 mins. There are now two bits of inner tube permanently round both grips on both bikes. I think that part of the problem is that shimano systems do need to be entirely air free rather than a trad M/C which will have a bit of an air gap in it.

Do you hang them by a wheel to store them? A quickish answer may be to use an elastic band to hold the levers 'on' when not in use. A section of roadie tube works well. Pain, I know.
Also worth trying, is once you remove the bands, see if you can top up the fluid at the lever/master cylinder (just once, not every time......hopefully).

And again nope, both bikes stored right way up. For a while I wondered if part of the problem was bleeding the bikes in the warm house and then taking them out on a cold day which resulted in the fluid vol shrinking. It wasn't....

I have this exact same issue. I’ve tried everything. New brake time, I think

Aye actually nearly bought a pair of the new hopes the other day (LBS is cheapest on the net) but I'm reluctant to go back to horrible dot 5 fluid as it always ends up everywhere, including in my mouth! Complete rebuildability is a big appeal though

[u02sgb]

There's meant to be a method one of the Santa Cruz mechanics uses that helps. Think this is the video https://youtu.be/piWBVDh1pTE

[ScotRoutes]

I’ve only once had this issue with my own brakes. I bled them thoroughly and it has never recurred. I'm still using the same brakes 5 years later.

FWIW I use the method outlined by Shimano. I think that rotating and tapping the levers at the end of the process is the essential bit for getting some trapped air out.

[fatbikephil]

There's meant to be a method one of the Santa Cruz mechanics uses that helps. Think this is the video https://youtu.be/piWBVDh1pTE

Interesting, particularly winding out the wee 'free stroke' screw, which I've never found to do anything. The bleed method is more like a trad bleed undoing the bleed nipple a 1/4 turn, pumping lever, closing repeat (or using a non-return valve) but more messy, something you can get away with oil instead of brake fluid. The easy bleed method just does this but with a syringe but I take his point about vacuums. It also 'cycles' the fluid to help get air out. The shimano method is similar but doesn't do the cycling, its just one process. I guess thats the benefit of Hopes, you just use the bog standard method used on motorbikes and cars....

[u02sgb]

I also thought the comment about dirt in the bleed valve on the caliper perhaps getting pushed in was interesting.

[ledburner]

for what it worth magura MTx's use mineral fluid as well, not dot fluid.
mt4vs and above are reasonable. I found it fit and forget, t years later just a pad change....

[Linkpin]

If it's happening on both sets it sounds like it's worth having a go at changing your bleed process. I've had some success with changing to purely lever bleeds on Shimano brakes, including, as someone mentioned above, leaving the bleed screw out of the lever with an elastic band on overnight.

With the full bleed, making sure you have the whole system running low to high (including all cable bends, with nothing dipping below horizontal) and tapping with something firm all the way up it beginning at the caliper might help too.

[TheBrownDog]

Shimano brakes are great when they're working but I gave up on them a few years back because of this very issue. For no reason, grabbing a handful resulted in the lever coming back to the grip and some poo coming out of the back end.

I'm very glad some people find them reliable but for me there's a ghost in that machine. Frankly, the cheap Clarke brakes which are on my kids' bikes are more reliable.

I've now got Hopes on my downhiller and bikepacky bike and, almost hilariously, on my Fatty are the same Avids that it came with nearly 10 years ago.

[Alpinum]

If you have a wandering bite point, it's likely (since you have bled the system well already) that your brakes' orifice holes are too small.

I've had similar issues (so far with 8 Shimano brake levers) and was able to solve them (unless sub freezing) by using Plutoline HPX 2.5 wt oil. Lever feel is much better, lighter and snappier.

Another way is to disassemble the lever and drill the hole to 0.7 mm. Never done it myself, so can't comment further on it.

I tend to flush the system with about 40 mL of the new oil and do a (nearly) regular bleed afterwards. No need to make the mess Mr. Marsh does imho.
Whilst oil based brakes usually don't require regular bleeding, I try to bleed mine ever year or two. It's quite amazing how much wear comes out with the old oil.
I usually go a bit futher once I start giving the brakes some love:

I'd check the alignment of the pads (to the rotor) and if it's an older caliper, I'd take the wheel out, remove the pads, pump the lever a little for the cylinders of the caliper to move out (inward to where the rotor would be), then clean the (once) white cylinders with a cord wetted with isopropyl alcohol by slinging the cord around the cylinders and pulling on it to remove dirt. Once that's done, a drop of mineral oil (the one you use to bleed the brakes) on the cylinders, push them back in with a tyre lever or so, clean any residue inside the caliper with a cloth and alcohol, reinstall the pads and wheel and see if it's any better. This usually helps to mobilise the cylinders and can make quite a difference. When running through that procedure the only critical parts are to not move the cylinders inward too far or else they pop out which gives a nice mess and requires bleeding and to give it at good clean before re-installing the pads (to not contaminate them and the rotor).

Well worth making sure the brakes are in top condition. Our life depends on them.

[fatbikephil]

Right, some good info here, cheers all. Will try the plutoline 2.5 wt and do some bleeding. Bleedin 'ell....
If I go down the hope route for both bikes that's 700 bar

[Lazarus]

I'm reluctant to go back to horrible dot 5 fluid as it always ends up everywhere, including in my mouth!

Are you bleeding them by sucking on straw?

Personally I find all shimano brakes to be a pain and not really worth bothering with [ great when they work but high maintenance IME]
I have some Hope mono minis [ 15 years ish ??] and whilst not the most powerful they still work every time i pull the lever and I can store the bike anyway i want
When I has shimanos I had to remember to always store the bike with the levers pulled closed
I also have SRm ,Magura and not had issues with either of thsiose but brakes seem to be Shimanos weak point

[Cyclepeasant]

Am with stu on this one re Shimano mineral brakes.
Using a Shimano or aftermarket ie. Clarks bleed kit.
It Usually works best back bleeding via the caliper bleed nipple and exiting fluid via the master cylinder assembly.
Rotate the master cylinder on the bars so the exit/bleed/top up port is uppermost.
Screw in the appropriate adapter and fit the hose and catch bottle to it.
Fit mineral oil filled syringe with air bubbles removed and attach to the bleed nipple. Open valve and gently squeeze fluid through the caliper until fresh colour fluid is visible in hose exiting the master cylinder. Close bleed nipple.
You might have to ping the brake lever like a bell a few times and then rebleed system again a few times.
This works for me.
I recently discovered a hose nut was cross threaded in the master cylinder on my cube front brake causing a micro leak ,it was hidden by the shimano black boot. I suspect it was a factory assembly fault ,either from Shimano or cube. Beware!
I am sure out of all the suggestions other bbers have mentioned,one will work.
Good luck!

[ScotRoutes]

FWIW I will happily take any crap Shimano brakes you are consigning to the bin.

[redefined_cycles]

Do they squeal when working?

I swapped my caliper after the bb200. During the end of the bb200 they'd gone from squealing like a pig, to really squealing like a pig and losing pressure and grip. Stu had suggested (when the original squealing happened year or so ago) about the micro leak thing. Anyway, swapped to a new caliper and everything fixed. Front (or whichever I haven't changed yet) was just bled but still squeals but grips again for the mo. Hopefully that'll be sorted once I swap that out too and rebleed.

Anyway, that's my suggestion, to just swap the calipers Phil. If you want my old ones to experiment and explore then just let me know and I can send em out to you in the name of research and forward growth

[redefined_cycles]

FWIW I will happily take any crap Shimano brakes you are consigning to the bin.

Hi Colin. Shall I send you my old calipers (slx m7000 I think, bout 2 years or 3 old).

[fatbikephil]

Do they squeal when working?

I swapped my caliper after the bb200. During the end of the bb200 they'd gone from squealing like a pig, to really squealing like a pig and losing pressure and grip. Stu had suggested (when the original squealing happened year or so ago) about the micro leak thing. Anyway, swapped to a new caliper and everything fixed. Front (or whichever I haven't changed yet) was just bled but still squeals but grips again for the mo. Hopefully that'll be sorted once I swap that out too and rebleed.

Anyway, that's my suggestion, to just swap the calipers Phil. If you want my old ones to experiment and explore then just let me know and I can send em out to you in the name of research and forward growth

I'm trying to avoid that but funnily enough there is a trace of oil on the Jones front caliper - this brake is working fine!