[Closed] New XT Brakes inconsistent bite point

Worth a bleed.

Mine have been spot on ages.

Mine are the same (M8000). Recently bled them and got the front up to scratch but the rear was still a bit crap. So I opened the rear brake lever bleed port and dropped a few drops of mineral oil into the reservoir until the oil formed a meniscus, then screwed the cover back on. The bleed procedure guides talk about this bulge of oil after the syringe/funel is removed but suggest it will result from taking the funnel/syringe off, but it doesn’t. Without this ‘bulge’ of oil you will always trap a bit of air in the system which will exacerbate any issues. In my experience it’s virtually impossible to get the oil to match or exceed the level of the bleed port, which it needs to, without a bit of assistance in the form of a few extra drops.

I’ve always wondered if this really is a problem with these brakes or whether they’re just extremely sensitive to bleeding procedure. Personally I suspect the latter. I’ll see how mine go and if they don’t improve I’m going to Hope. Life’s too short. Love Shimano and especially mineral oil systems but can’t put up with not being able to rely on my stoppers.

Hmmm. I've overfilled XTR brakes before, the m985 generation, and they blew the little plastic cap off the end of the reservoir. They didn't like being overfilled!

I'll give them a bleed and see if that helps, my experience with Shimano brakes says it won't though!

On the first pull they come to the bars, then they’re fine if you use them immediately afterwards.

Air in the system, they are more fiddly than the old ones to get all the air out the master cylinder, once the brake is "bled" repeatedly pulling and releasing the brake lever with the brake lever at different angles usualy releases some bubbles.

Ok, I'll give them a bleed. Ugh. Shimano.

Just a lever bleed should sort it. 5 Mins at most if you have the cheap plastic funnel thingamajig

As above - they just need a good bleed. I had exactly this problem with one brake, re-bled it and it's been fine for the past 2+ years.

I had that with my rear brake on my Rallon. Bleeding does nothing - the seals in the lever were shot. The front also shat itself and stuck on. I've been told there are some bad batches that cause things like this - maybe Orbea have a bad batch they're fitting.

Either way I got rid and got a set of TRP Quadiems as something different - early indications are good but time will tell.

Not a bad guide from EPIC Bleed...

http://www.epicbleedsolutions.com/blog/5-minute-shimano-mini-bleed/

I've found I have to take off caliper and rotate / move around to release every last corner hiding air, or low part hiding gunk, or something....But it has worked.

That and a swap from XT levers to simpler Deore...

Try bleeding the old fashioned (automotive) way. Not with a syringe from caliper to lever. See this weeks topic on upgrade from Deore brakes.

Cheers guys - I always do the top-down method for Shimanos. A lever bleed feels more consistent now, left them at full reach/free stroke pulled back to the bars for a good few hours, then bled the lever.

We shall see how it goes.....!

Page 18 onwards.

Shimano recommend a bottom-up and then a top-down bleed.

You definitely want to do at least a bottom up bleed.  If there's air in the lever or hose, trying to get it out through the caliper is going to be a battle against gravity.

I always just do a bottom up bleed.  The only secret is rather than just pushing fluid through gently, give it some short, sharp shoves.  I find this quite often dislodges bubbles that weren't coming out otherwise.  Also, once the lower syringe is nearly empty, I disconnect it, and use it to suck out fluid from the one at the top and push it through again rather than wasting fluid.  When reconnecting the lower syringe, give it a pull first to make sure you don't put new air in.

The other thing is to check for high points in the hose.  If you've got a bubble at a high point in the hose, it's quite possible to push fluid past it without dislodging it.

What pdw said. I re-bled my rear today with the wheels off the bike and the bike hung over my work stand, the crook of the down tube and fork resting over the arm on the stand. Secured it with a strap 😉 Did it this way as I couldn’t be arsed to take the caliper and hose off the frame. I also used the Shimano funnel, with a Jagwire bleed kit. The shimano funnel enables better control of the level of oil in the lever when you remove it. Much more solid feel at the lever; we’ll see how it lasts.