Hi everyone, sorry if this has been covered before, but this is driving me crazy.

My new style rear SLX brake is refusing to play nice (front has bled fine).
I’ve bled it using the Shimano funnel, both up through the caliper & back down through the lever and have no bubbles coming through. This results in a nice firm lever while the bleed block is in place, but once I put my new pads back in the lever pulls back to the bar & refuses to firm up.
I’ve tried overfilling the system with a thinner block to take up the space, but again while the block is in place it’s nice and firm until the pads & wheel go back in. The only way to firm the lever is to set the pads so close to the rotor that it scrapes through.

Any suggestions welcome, other than throw them in the bin 😆

Edit: I have taken the brake off the bike so the hose is straight, bleed ports to top etc.

I have had similar issues with my XT brakes, despite trying all the tricks suggested on previous threads. This week I took them off the bike completely, hung them from the levers for 24hrs, and then deliberately bled them in a very messy manner holding the levers so the bleed port was sideways but uppermost, I.e. The reservoir was vertical not horizontal. You drip fluid everywhere but it was the only other thing I could think off. (If you take the lever apart a bit you can see why I tried it – there is a ‘bulkhead’ in the reservoir between the main space and the end where the bleed port is, with a small hole in the middle of it). I then put the Shimano cup onto the bleed port and did all the usual pumping the lever whilst moving the lever about until no more bubbles. Quite messy, a bit wasteful, evidently unnecessary for most people who manage it fine, but it does seem to have worked, so far.

Have a look here ➡

http://www.pinkbike.com/news/tech-spotlight-5-minute-bubble-bleed-2014.html

How have you got the lever reach set? Try setting it as far out as possible, then repeatedly pulling to the bars. It sounds like you’re not moving enough fluid to get the pistons to slide through the seals so they’re not self-adjusting.

When you say “set the pads close to the disk” how are you doing that? Didn’t think SLX had a clearance adjuster?

I had an instance where the dust cap had long come off the caliper bleed nipple. When I attached a tube and syringe to bleed up, I pushed dirt lodged in the nipple into the caliper, result spongy brakes. Eventually, after much hair pulling out, I stripped the whole brakes down and when I unscrewed the bleed nipple out came the bits dirt.

Thanks for the replies,

thegreatape: I’ve not gone to the extreme of tipping the leaver on its side, but i did take it off my stand and squeezed the leaver while keeping the oil in the funnel.

downhilldave: Tried similar technique from http://www.epicbleedsolutions.com/blog/5-minute-shimano-mini-bleed/. Was supposed to overfill the system, but i think because the pads weren’t able to adjust & set them selfs up correctly it did nothing, i just kept pulling the soft lever & the pads kept moving slightly in & out.

pdw: I have tried with reach adjuster all way out & got a nice firm feel with the block. The farer i wind it back towards the bar the softer it gets. You’re correct, SLX doesn’t have contact adjust so i squeezed a little more oil through caliper.

B.A.Nana: The dust cap has always been on, but i did think about opening it up to have a look. I didnt want to make anything worse though, so left it. Does it go back together easy, without leaks?

What about bleeding with the old pads in, once bled loosen the bleed nipple, place a rag around it to absorb excess fluid and then push the pistons home?

What rotor are you using?
I had a similar problem when I used my old avid rotors, things got much better when I changed to superstar rotors. Comparing the rotors the superstar ones are visibly thicker

I have tried with reach adjuster all way out & got a nice firm feel with the block.

But did you keep it all the way out after swapping in the pads and wheel and then pumping to advance the pads?

If you remove the block and don’t put pads or disc in, does pumping the lever result in the pistons advancing, or just going back and forth?

That pumping trick that pdw suggests did it for me, lovely and firm now!

notsospeedydaz: I had wondered if using my 5 year old formula rotor could cause problems, but just assumed the pistons would take up any room just as they should when pads wear down???

I have had another couple of hours today but still no better. I’ve got a little more air out through the funnel by pumping the pistons out then pushing them back in (similar to dirtydog’s suggestion) but not made any difference.

pdw: Once i remove the bleed block and pump the lever the pistons do advance out of the calliper, it is then that i have spongy feel and no power – unless i advance them far enough that the rotor is court and can no longer spin through, then it feels good again.

This has annoyed me in the past.

There’s a passage in the destructions with the funnel that advises that off they don’t bleed easily, to dump all the fluid and start again from scratch. I found it after I’d sorted my last set, maybe it’s what you need?

Make sure reach adjust is set so the lever is all the way out.. And unscrew the free stroke screw as far as possible…you can take it out with no problem..
I push fluid up from the caliper and fill the funnel.
I then suck it back down which gets air out in the caliper end if there’s any, don’t empty the funnel.
Then do the squeeze lever and open close bleed nipple quickly..
Push fluid back up into funnel.
Tighten bleed nipple.
keep squeezing brake lever until no more bubbles come out the reservoir..change the angle of the brake lever while doing this, tap the lines with something to free and air bubbles that maybe trapped..

A bit late now but why are you having to bleed new Shimano brakes? Used 6 sets SLX,Saint,Deore and 485 and never had to bleed any of them even when I shortened the hoses.Leaving the lever pulled back over night brings any air to the lever,release lever bleed screw , top up with oil,pull on lever and that’s it.When pads are worn and need replacing make sure you undo lever bleed screw to push the calipers back when you put the new pads in.

Reach adjustment will make no difference to your bleed; it’s just the position the lever sits in but it changes nothing inside the lever cylinder. “Free stroke” on the other hand does change the piston position inside the cylinder, only a little but still worth thinking about. Bleed with the free stroke screw all the way out, do the Epic Bleed 5 minute bubble trick, give them a test, tighten the free stroke back up and recheck. For Zees or SLX, get hold of the tiny two-pronged screwdriver for cheap on eBay.

Failing that, pump once with the wheel removed and recheck, but I end up with the pads constantly rubbing on the rotors when I try that.

Just wanted to bring some closure to this post,

I emptied all the oil out of the brake and re-bled, but it was still very soft, so I tried nick1962’s tying the lever back trick which seems to have worked. I did the front too, which also feels much firmer now.

Too soon to know if it’s permanent but if they feel as good over the weekend I’ll be a very happy man.

Thanks everybody 😀

Mine went back to being shite despite my efforts as described at the start of this thread. I got in touch with Bird who told me this:-

“Sorry your having problems, from my experience a spongy lever is caused by air behind the master cylinder, in the lever, but is easily fixed as a rule… maybe you’ve tried this but I would recommend:

1. Don’t use the syringe bleeding method, or at least only one on the caliper end if you like. The brakes bleed better as a gravity bleed in my opinion.

2. Check the master cylinder levels when they go soft. You can do this by levelling the lever to horizontal, and opening the bleed port on top. You will probably find that you cant see the oil level. This is your issue. The oil should be full to the top (or near enough). To fix this, its easier with a shimano funnel, but you can use a syringe to do it to, as a dropper (don’t screw it in). This operation is best done with the bleed block in, but as you’re not touching the caliper it works wheel in too.

a) remove the top bleed cap (which you will have done after setting the levers horizontal).

b) pump the lever

c) add oil to to the port until its full to the brim. If using a shimano funnel then just attach the funnel and add 1cm or so of oil, if you don’t have one, use a syringe as a dropper to drip oil into the port.

d) pump again, the level will likely drop. Pump, flick and pump the lever a good few times. Its likely the oil level will drop again.

e) repeat as needed until the oil stays at the top.

Once done, pop it back together and you should have a firm lever. If it happens again, don’t bleed, just repeat. A couple of goes and you should be set. I think, and don’t quote me, the pressure from the syringe bleed means that you cant get the air out as it causes the seals to work too well. I find that its when you store the bike on its side (in a car) or hanging, or something other than bolt upright that the air moves from behind the master cylinder into the cylinder itself. Once you get it all out I’ve found the performance to be consistent.”

Posted as it may prove useful to someone else too.

Thanks greatape, looks like some good information.

Did that come from Bird, as in birdmtb.com? If so which one you got? What’s it like?