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Lots of people struggling with the bite point on XT and XTR brakes. Here is what I am doing to fix this.

The problem is air in the caliber. To get this air you need to suck it out. After pushing fresh fluid through the system. I fill the bleed cup at the top 1/2 full and put fill bleed syringe 1/2 way. I then attach and alternate pushing and sucking fluid out. I just about always pull air from the caliber. Be careful to not empty either the cup or the syringe.

I have Shimano brakes on a bunch of bikes and have zero issues with bite point after doing this.

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Elitest thrill junkie
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The bite point problem due to the system pushing the lever engagement further and further out with each subsequent pull, not closer in. This happens on steep terrain with extended braking. If your lever is pulling to the bar or going that way inconsistently, sure, air, but air is not the problem with the inconsistent bite point problem. It's the lever engagement traveling the other way, out. That points to a flow problem due to their port/orifice sizes. I had old formula brakes that worked like this too. It was like a "closed system" until you could let off of the brakes long enough for the fluid to equalize.
 

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I personally stopped pulling fluid from the caliper. You're going to see air in no small part because you're creating vacuum and whatever is going on with the physics there. This is a bad place to be introducing air into your process.

I use a syringe at the caliper, but I only push the fluid up to the funnel. I run the fluid through a few times. My increasing lever throw all but vanished after changing my process to pushing rather than pulling. When it starts coming back I know it's time to bleed again.
 

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Discussion Starter · #6 ·
The bite point problem due to the system pushing the lever engagement further and further out with each subsequent pull, not closer in. This happens on steep terrain with extended braking. If your lever is pulling to the bar or going that way inconsistently, sure, air, but air is not the problem with the inconsistent bite point problem. It's the lever engagement traveling the other way, out. That points to a flow problem due to their port/orifice sizes. I had old formula brakes that worked like this too. It was like a "closed system" until you could let off of the brakes long enough for the fluid to equalize.
That is something that happens but isn't the main problem a lot of people are having with shimano brakes right now. People are struggling with the fact that everytime you squeeze them they engage in a different place. Having worked on a lot of brakes the common issue is air in the caliber.

What you are describing is fluid getting hot and expanding. I am yet to ride a brake from any manufacture that doesn't do this. Even those with Dot fluid struggle with this but to a lesser extent.
 

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Personally I believe it is an air issue.

My theory goes like this...
When the pads get low, it allows infinitesimal amounts of air to sneak past the pistons. The system is gaining air somehow and it's been my observation that it's always when my pads get low. I simply don't let them get as low as I would on another brake system and for the most part you can go a long time between needing a bleed... which does correct the issue... which, again, suggests air.

In any event, the very latest nomenclature of Shimano brakes are not only absolutely fantastic but they don't seem to have this problem.

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Personally I believe it is an air issue.
I agree that it's an air issue. I don't mean to discredit the port/orifice theory, and this may contribute to some degree, but when I changed my process...either pushing up from the caliper, or doing a gravity where I completely remove the bleed nipple and just let it flow through...the wandering bite point pretty much vanished. It's air and it has to be purged.
 

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I've always used Shimano brakes and had great luck with them, but this last set of XTs I've been running for the past year and a half have been nothing but a headache. I've replaced lines, bled them a million times and I still have fading problems like it's got a bubble.

I finally gave in and ordered Magura MT-7 Pros. Tired of fighting it.
 

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Discussion Starter · #16 ·
I agree that it's an air issue. I don't mean to discredit the port/orifice theory, and this may contribute to some degree, but when I changed my process...either pushing up from the caliper, or doing a gravity where I completely remove the bleed nipple and just let it flow through...the wandering bite point pretty much vanished. It's air and it has to be purged.
I haven't had as much success doing a gravity bleed. Some calipers just want to hold to air.
 

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Discussion Starter · #17 ·
Personally I believe it is an air issue.

My theory goes like this...
When the pads get low, it allows infinitesimal amounts of air to sneak past the pistons. The system is gaining air somehow and it's been my observation that it's always when my pads get low. I simply don't let them get as low as I would on another brake system and for the most part you can go a long time between needing a bleed... which does correct the issue... which, again, suggests air.

In any event, the very latest nomenclature of Shimano brakes are not only absolutely fantastic but they don't seem to have this problem.

Sent from my Pixel 4a (5G) using Tapatalk
I have the same theory too. Usually my first hint that my pads are low is the bite point starts to wander.
 

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It also means the seals at the caliper let dirt in. That's usually where the air gets into the system.
☝☝ This exactly. Years on Shimano XT and XTR I always found that when flushing the system ~2x/year the oil came out gritty and gross. If that much dirt is getting though the caliper seals, it seems likely air is too. In contrast I've never found fluid to be anything but pristine even after a full season of use with SRAM or Hayes.
 
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