Shimano Hydro levers

Bonnet

Likes Dirt
Hey all

I have a Deore brm-555 hydraulic caliper, and a deore lever and have had a lot of issues with air in the system. i have bled and re-bled it numerous times to a point where i am certain there is no air in the lines or trapped in the caliper and what not. the lever is nice and firm and braking conditions are normal. however if i pull the lever a little harder it will 'give' and eventually (after pulling the lever hard 6 or so times) i will now be able to touch it on the handle bars. i then go to re-bleed it and there is air again (5 mins after the previous bleed).

what im thinking is that, somehow it is drawing air into the system from somewhere, after a bit of trouble shooting i think i've narrowed is down to the lever. im not sure whether air is coming through from the olive and hose side, or through from when the piston in the lever is actuated. when i squeeze it hard it makes a creaking sound, as well as a squelching sound. almost as if sucking air in BUT when i greased the pivots this sound disappeared too, so im not entirely sure if this was a contributing factor.

what do you guys think? is it time for a new lever? or just reinstall the system, new olive and all. also, do you have to use shimano specific olives, or will any brake kit olive do (ie from super cheap or Repco auto)?

Cheers
ASH

its a bummer because now i cant ride this weekend! :evil:
 

Daver

Kung Fu Panda
Well if you're sure its coming from the levers then get a new pair. If they are the ones where the hose is at 90 degrees to the lever then thats your problem, and a new olive should sort you out.
 

shaun7005

Likes Dirt
Hey,
I've seen this a few times with Hayes, but i think what's happened is that the internals of the lever (that being pistons and o-rings) have been compressed under high speed... Ie, smashing into tree. What this does is scores either the piston or the o-ring, allowing the fluid to rush back past the o-ring inside the piston... The result is a lever which feels firm and works at first, but then fades and loses all the braking power as it squeezes to the lever. the lever can be rebuilt. shouldn't cost too much. hope this helps...
Shaun
 

beno

Cycle Solutions
Another thing to consider is that you have a hole or leak in your hose. As it only seems to happen when you put the system under high pressure, suggesting to me that you are pushing fluid out of your system and that when you release the lever the fluid has to be replaced by something to fill the vacuum you have created (hence the air). When you re-bleed your brakes are you having to add more fluid every time?

What can happen is that after a big stack you crease the hose and rupture the inner lining, causing the fluid to leak into the gap between the inner lining and the outer lining. It can take ages for the fluid to actually start leaking so that you can see it.

Check your brakes over closely, looking for any signs of fluid leak (sorry if I'm stating the obvious!)

I'd start by checking all your fittings to make sure they are tight, then look at the seals and o-rings on your banjo's before resorting to major surgery like rebuilding your caliper , lever or replacing your hose.

Hope this helps.

Beno.
 

Cave Dweller

Eats Squid
Ash,

There are two types of deore levers. Either the hose leaves at 90 degrees, or it goes straight out like hayes.

I assume you have the straight one? If this is the case then there is no seals at the lever end. There is a brass compression olive which expands between the lever body and the hose to form the seal. If the hose was not assembled properly you may need to redo it.

But from the sounds of it you don't have any leaking fluid. I say you have air in the system. It should take around 20-30mins to bleed those brakes properly.

Also, if you are using old fluid it could be contaminated with water. Try using some new mineral oil (and im assuming you are using mineral oil and not DOT fluid)

Another possibility, under the plastic reservoir cap on the lever there should be a rubber seal. If that is missing it won't work properly.

-Matt
 

udi

swiss cheese
I've got a similar problem now, thought i'd not post another thread.

No matter how I bleed or what I try doing, my brake lever (grimeca 4 pots... most of you guys would have seen my other thread) the lever keeps squeezing past the engagement point all the way to the bar.

Now I know that means air in the system, or a leak - and guessing by the times ive tried bleeding, i'm pretty sure it's a leak.

Can someone give some instructions on how to find where leaks are, pleease?

There aren't any obvious problems. Oh yeah, my lbs said if when I squeeze the lever, the hose straightens then it means it is expanding or something, and that would be the cause of my squishy lever issues - is this true, can anyone confirm? because my hose sure does move/straighten when I squeeze it, pretty noticeably.
 

Bonnet

Likes Dirt
thanks guys

ok, what ive done so far...

1- checked all the connections at both ends. re-greased o-rings and so on.

2- the lever is a the straight out style, not the 90* one. i've taken that out and drained the system, the olive and little pin were a little askew, ie not flush against the hose and the olive was twisted. im not sure how much an effect this will have on the the system and the olive SHOULD be pressed hard against the inside of the lever.

3- i noticed when bleeding before that there was a wavy look to some of the mineral oil, indicating that in fact there was water in the system, however my style of riding means that the pads will not heat up sufficiently to boil the water into air/steam. but nonetheless, there was water in there...i think.

4- all the parts are there, so missing bits are out of the question.

5- not too sure about a leak in the hose, i did have to add more fluid when bleeding, but only a tiny little bit. not enough to make any significant difference.

6- i have had a big stack that would have compressed the lever at high speed, so i'll check the seals of the piston if i can.

i'll give shimano a call today, and order a new olive and pin kit and rebuild it from scratch. its just a bugger not knowing where air is getting in or where its from.

cheers
ASH
 

Cave Dweller

Eats Squid
Bonnet said:
thanks guys
2- the lever is a the straight out style, not the 90* one. i've taken that out and drained the system, the olive and little pin were a little askew, ie not flush against the hose and the olive was twisted. im not sure how much an effect this will have on the the system and the olive SHOULD be pressed hard against the inside of the lever.
That pin should be flush with the hose. You need to make sure that the hose is cut at 90deg. Brass olive should be straight. I don't think you can resue it, and you shouldn't reuse the olives.

When puttting back together you need to make sure the pin is pushed hard against the inside of the lever while doing up the black screw to compress the olive

Bonnet said:
thanks guys
3- i noticed when bleeding before that there was a wavy look to some of the mineral oil, indicating that in fact there was water in the system, however my style of riding means that the pads will not heat up sufficiently to boil the water into air/steam. but nonetheless, there was water in there...i think.
Water is not very good but shouldn't be a problem with mineral oil
 

Bonnet

Likes Dirt
ive ordered a new hose kit from shimano, so thats new hose and fittings. olive/pin, and o-rings. i cant re-use the old olive even if i wanted too, it gets compressed to fit when you screw the hose into the lever. i think my problem was that the hose was not cut at precisely 90deg's and hence a poor interface.

we'll soon see if thats the problem...bloody $30 later, and thats shop price, not retail :roll:

ASH
 

arnott

Likes Bikes and Dirt
is there an easy way to cut the line a precisely 90 degree's with a utility knife or something else i could find at home, and also for the reservoir, mine has a rubber triangular insert is that meant to be there when you put the mineral oil in or is it just meant to have a top cap on.

(sorry for the hijack)
 

Bonnet

Likes Dirt
arnott said:
is there an easy way to cut the line a precisely 90 degree's with a utility knife or something else i could find at home, and also for the reservoir, mine has a rubber triangular insert is that meant to be there when you put the mineral oil in or is it just meant to have a top cap on.

(sorry for the hijack)
that rubber thingy is meant to be in there. it acts as a seal and keeps the oil in the lever from spilling/seeping out from under the top cap. i cut it at 90deg using a sharp knife and a custom made device...you know the yellow clamps you get with the brake kit? well i customised one of them with a hack saw, pretty basic i know, but its worked on my 'test' hose. simply cut a channel into it to keep everything squared up.

ASH
 

arnott

Likes Bikes and Dirt
Bonnet said:
arnott said:
is there an easy way to cut the line a precisely 90 degree's with a utility knife or something else i could find at home, and also for the reservoir, mine has a rubber triangular insert is that meant to be there when you put the mineral oil in or is it just meant to have a top cap on.

(sorry for the hijack)
that rubber thingy is meant to be in there. it acts as a seal and keeps the oil in the lever from spilling/seeping out from under the top cap. i cut it at 90deg using a sharp knife and a custom made device...you know the yellow clamps you get with the brake kit? well i customised one of them with a hack saw, pretty basic i know, but its worked on my 'test' hose. simply cut a channel into it to keep everything squared up.

ASH
yeh thanks for that, ill do that tomorrow
 

Bonnet

Likes Dirt
DAMMIT

I bought a new bloody hose kit from shimano, fitted that on, did the best bleed of my life. but alas after riding for not more than 5 minutes the lever is squishy again, albeit not as bad as before, but squishy nonetheless.

i might have to pull the lever and caliper's apart now...i dont look forward to that. can anyone tell me, can the primary piston in the lever be serviced? im looking at the exploded diagram, and by the looks of it it cant be, but i may be missing something somewhere. i think thats where my problem lies...in fact, now im sure of it.

heres a link to the brake system im running -
http://www.shimano.com.au/publish/c...003.File.tmp/EV-BR-M555_BL-M556-2159-2161.pdf

thanks for any help.

ASH
 

udi

swiss cheese
Dude take it to your (best) LBS, and tell them you want them bled so that theres a firm lever feel. Ask for the price before hand, and then leave it to them. Maybe tell them you put a new hose on and they can check it all out, for leaks or whatever. It might save you some frustration and perhaps wasting more money.

Otherwise you'll just get really really frustrated.. I wouldn't go pulling the callipers apart just yet.... FYI my friend has been running the exact same brakes for a year and they work great and he has had zero problems so yeah im guessing theres just a fault in the line mounting or bleeding somewhere.
 

j5ive

Jonny Sprockets Bike Shop
He works at a LBS I believe. How old are the brakes? Why not send them back to shimano for warranty?
 

Bonnet

Likes Dirt
yeh, i work at a bike shop.

I'll admit I'm not the most skilled bike mechanic, but i do know what I'm doing. more-so than the average rider (you'd hope so anyway). we've bled it numerous times to no avail. my mate runs the same brake as well, and he's loving them, no probs at all and great power too.

I'll have a chat to the guys at shimano, it may well be a warranty job, they are only about 4-5 months old, i was trying to fix it without worrying about warranty. oh well, just a good excuse to try out the new LX disc brakes....oohh I'm so excited. haha

ASH

ps- thanks for your help guys. I'll let you know what happens for future reference.
 
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