[Closed] Brakes that don't. Or are.

BB7s are good value and you don't need anything other than your multitool to keep them in good order.

If BB7s don't work well then your cable is crap or your disk is warped.

Edit: as TJ says XTs are good brakes, if yours are borked, then replacing with the same is an option.

if your XTs are that bad then something is wrong - My guess would be that there is still air in them. Spares are hard / impossible to come by so no point in stripping them. Calliper seals defective means leaks, master cylinder seals defective means air can get into the system

Myself - I'd get hope minis second-hand and rebuild as needed - thats what I have done with my bikes. Hope will rebuild them for much cheapness

I have some Elixir 5s on one bike (£135 for both ends from Merlin) which are okay, but they seem quite keen to rub, regardless of how much time I spend tweaking them.

I have XTs on my other bike, and thus far they seem fine (although admittedly only ridden 10 times so far). I had to move the caliper slightly the other day, but after about 20 seconds of tweaking, there was no rubbing at all.

The XTs are pretty old now, must be three years or so of my erm, not too stringent maintennance. Pretty sure you're right about there being air in there TJ, I just can't quite figure out where it's coming from - I may give them one last drain and refill and see what happens, but I suspect that this summer's Alpine abuse may have done for the seals.

Epic - I never thought of cable discs, I only ever used some briefly and hated them, but they were cheapy ones. And probably badly set up.

I actually have some (very) old Minis that're currently on the housemate's bike, which again are definitely in need of a rebuild, but at 8 years old I'm wondering whether it's time to put those out to pasture too...

Have you considered contaminated pads/discs? Could be an option?

As mentioned above with Elixirs......I find it very difficult to get them completely rub-free.

Yup, I've used a variety of different discs and pads, and it's the same with all of them. Tried cleaning discs, brand new pads and it makes no difference. I'm pretty sure there's air getting in, a couple of pumps of the lever makes a big difference and they're very spongy.

I've heard Elixirs run very close to the disc and can be a sod to set up... Hmm.

Does bleeding them improve it then they deteriorate? If so it could be master cylinder seals but if they are like it all the time it could just be that you didn't get all air out

is it the same both ends?
Edit - hope minis can be rebuilt indefinitely - hope will do it for you if you want but its simple to do.

Similar both ends, but the rear is much worse. It *could* well just be that I'm being useless and not getting all the air out... I may try one last full drain and bleed, and see how they fare after that.

Bleed them top to bottom, it's lot easier to do; just attach a bit of hose to the nipple, shuv the end of that into a sandwitch bag, secure with a cable tie (stops it getting messy), get the leavers level, remove cover and seal, then loosen the nipple and keep pressing the leaver gently and topping the reservoir up until you are sure it's the fresh fluid coming out the other end, close nipple, job done.

(if the seals were gone you would not be able to 'fix' it by pumping the leavers).

Sounds like I might just be bleeding wrong then 😳

I'll try doing it top to bottom and see what happens...

Bleeding bottom up in a brake designed t be bled top down wont work, it will leave an air bubble under the nipple in the caliper in some cases.

Either:

Bleed them the old fassioned way - fill resevoir, pressure on lever, open nipple, close nipple before lever reaches the bar, release lever, repeat.

or:

Use a vacum pump/syringe to bleed them top down, just don't forget to pump the lever a few times to dispell any air as your doing this.

If you do end up going for new brakes you should be looking at Hope Tech X2's not the M4's as a replacement for XT's. Alternatively I have some Mono Mini's I am just about to put up for sale as they've been replaced by the X2's.

Whatever you do, on no account go for Hayes Stroker Trails. The worst grabbiest, on/off, no modulation brake I have ever used

Do you remove the air from the new fluid before bleeding?

Er, how would one go about removing air from new fluid?

The M4s are more of an upgrade to be honest, they're half planned for a more gravity oriented bike, the XTs are on my MmmBop.

Are they M765s or M775s?

Either way, they seem to respond better by bleeding from the caliper up to the lever, as the fluid travels with any air bubbles. Give the caliper a tap when you're doing this to dislodge any bubbles.

Oh and if they're M765s, I had to bin a caliper recently as it was sucking in air through the piston seal, so binned it. You could hear a very slight sucking noise when working the pistons in and out.Felt reasonably firm when bled, but lacked any sort of power.
Typically i replaced the lever and the hose before finding out it was the caliper that was duff. Typical! Replaced with an M595 and jobs a good un.

epicyclo - Member

Do you remove the air from the new fluid before bleeding?

765s.

Caliper up is how I've been doing it, syringe on the nipple and force fluid through. It seems to force lots of bubbles out then not actually make any difference to how they work. I'll have a listen to the caliper...

**edit** I'll try sticking fluid in the freezer. I take it this is with the top off?

Shimano advise that you can bleed either way, but caliper up to the lever is perfectly ok (why else would they manufacture a kit for this very purpose?)

I found that in my case repeated pumping of the lever eventually meant the piston on one side started to get moist with fluid.

Yes top off in the freezer, something to do with all the dissolved gases coming out of solution. However it shouldn't make that much difference. I only tried it out of desparation and couldnt notice any difference really.

flyingmonkeycorps - Member
Er, how would one go about removing air from new fluid?

Draw the fluid into the syringe until half full.
Lock the syringe so no more fluid can enter.
Holding it upright, pull the plunger further up (slowly) so you create a vacuum above the fluid. The air in the fluid gets drawn out. (Give it a few seconds to happen)
Invert syringe, release the lock, and squeeze the plunger so the air is driven out.
Repeat.

Then the fluid is ready to be put into the brake.

I'm not keen on the freezer idea - invites condensate IMO.

(But I still prefer BB7s 🙂 )

Did they ever have that great a performance?
When you say you've changed disc's have you tried going up a size (assuming you have the smallest 160mm rotors). I had a m8's bike that would not stop with a 160mm disc, with 3 different disc brakes (LX/Magura then brand new Juicy 3's), was driving me crazy until I used the next rotor size up and all of a sudden it would stop properly..

Rotate the levers so you can leave the reservoir caps off.
Tape the levers up to the bars, so brakes are on.
Leave overnight.
Not sure how this works but it made me Deores a bit better.
Might be worth a go.

Definitely not too small rotors - I have a 203 and 185 from when I went to the Alps! I did wonder if they were contaminated, but the way it works better when pumps suggests not, plus I've cleaned them with disc cleaner, on two different sets of discs AND put brand new pads on, all to no avail.

I shall try some of the bleeding suggestions and see what happens, many thanks for the advice!

putting your brake fluid in the freezer will cause any dissolved gas (air / whatever) to condense on the side of the bottle.

you can see this working if you put a glass of water in the fridge.

i do it because i'm a geek, but i can't honestly say i've noticed any difference.

don't drain your brakes before you bleed them - just chase the old fluid out with new fluid going in.

you may have suffered from 'shimano brakes going a bit odd and leaky in the cold' disease.

there's a thread on here about it...

Fluid level a bit low? My deores did this a little while ago, needed pumping to get the power and even then it wasnt a great deal. Turned out to be the fluid level had dropped, topped them up and all hunky dory.

Well, since my rear reservoir is now held together with Araldite and a cable tie I think new brakes may be in order. Anyone want some spares or repair XTs?