How to use the 'freestroke' adjuster on XT M8000 brakes?

[Nautonier]

I've always maintained that the freestroke adjustment screw on Shimano brakes does absolutely nothing, but now that I've recently purchased a set of M8000s I'd like to be proved wrong. After installing and getting the hose lengths right, I had to bleed both front and rear brakes, which went well. After a few rides, the rear lever is engaging a bit further in towards the bars than the front. I'm a bit OCD with lever position/engagement, so tried the freestroke adjustment screw to try and correct this atrocity.

The screw (on both brakes) is wound all the way in by default. Is this equivalent to maximum lever throw or minimum? If I wind the screw out, should this give me more or less throw? When I tried it, there seems to be no noticeable difference whatsoever - what am I missing?

Surely Shimano haven't included a totally dud feature on their latest brakes? The reason I paid more for these brakes over the Deores was specifically for this feature.

 

[JTmofo]

I've always maintained that the freestroke adjustment screw on Shimano brakes does absolutely nothing, but now that I've recently purchased a set of M8000s I'd like to be proved wrong. After installing and getting the hose lengths right, I had to bleed both front and rear brakes, which went well. After a few rides, the rear lever is engaging a bit further in towards the bars than the front. I'm a bit OCD with lever position/engagement, so tried the freestroke adjustment screw to try and correct this atrocity.

The screw (on both brakes) is wound all the way in by default. Is this equivalent to maximum lever throw or minimum? If I wind the screw out, should this give me more or less throw? When I tried it, there seems to be no noticeable difference whatsoever - what am I missing?

Surely Shimano haven't included a totally dud feature on their latest brakes? The reason I paid more for these brakes over the Deores was specifically for this feature.

Tits on a bull..... that's how useful free stroke adjust is on Shimano brakes. Should have bought some Hopes.

 

[Knuckles]

I thought a missing screw was the reason my 675s were going to the bar, so I sourced one. All the way in, or gone all together, makes no difference. The issue was a leaking master cylinder seal. The freestroke screw is window dressing.

#knuckleswasadrunkenchunt

 

[Nautonier]

Tits on a bull..... that's how useful free stroke adjust is on Shimano brakes. Should have bought some Hopes.

Yup, that's what I thought... I'm perfectly happy with the RSCs on my other bike (especially now I'm getting the levers replaced under warranty), but I'm regretting my foray back into Shimano already.

Seriously, how can a reputable big brand like Shimano include a feature (that you pay extra for) that actually doesn't work?? What if some riders don't want to have one lever sticking out 1" more than the other just to have them grabbing in the same place? Watch this space, you'll probably see some Shimano brakes going real cheap soon...

Worst purchases of 2016/17:

- Giant Connect dropper post
- Shimano M8000 brakes

You really do get what you pay for.

 

[JTmofo]

You really do get what you pay for.

This is the quote of the year.

 

[Mr Crudley]

Although you couldn't call XT brakes down in the bargain bin of Shimano's foodchain.

Can only try to avoid V1.0. If deemed good by the masses then give it go.

 

[The Duckmeister]

The screw doesn't do a lot, but it does do a bit. It preloads the master piston when wound in, shortening the contact stroke.

Try this: wind the screw out for full stroke, pump the brake to set the pad clearance governed by the spring effect of the piston seals, then wind the contact screw in to get the esired stroke. Then use the reach adjust knob to set the lever position.

 

[Nautonier]

The screw doesn't do a lot, but it does do a bit. It preloads the master piston when wound in, shortening the contact stroke.

Try this: wind the screw out for full stroke, pump the brake to set the pad clearance governed by the spring effect of the piston seals, then wind the contact screw in to get the esired stroke. Then use the reach adjust knob to set the lever position.

I can't see how it preloads the piston as there's nothing behind the screw. Looks like just a threaded hole. I tried what you suggested and it made no difference to the bite point/stroke. When the screw was wound all the way out, the throw was exactly the same as all the way in. Pumping didn't change this.

Jeez I wish they'd used an allen screw or torx instead of phillips head! Can see how it would be so easy to ruin it. Probably not an issue as everyone (except me apparently) knows that it doesn't do anything and leaves it alone.

 

[linkl8r]

Agree that there is not alot of adjustment here, but it definitely helps if you bleed with the free stroke screw set in the middle, not all the way in or out. Also make sure your pad contact is perfectly even, and that the pistons are advancing evenly.

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[moorey]

Does do a bit. Enough to notice.
Haters gunna hate.

 

[The Duckmeister]

I can't see how it preloads the piston as there's nothing behind the screw.

The screw pushes on the piston.

 

[pink poodle]

The screw doesn't do a lot, but it does do a bit. It preloads the master piston when wound in, shortening the contact stroke.

Try this: wind the screw out for full stroke, pump the brake to set the pad clearance governed by the spring effect of the piston seals, then wind the contact screw in to get the esired stroke. Then use the reach adjust knob to set the lever position.

Does the position of this screw during bleeding make much difference to the feel of the lever or actual braking?

Agree that there is not alot of adjustment here, but it definitely helps if you bleed with the free stroke screw set in the middle, not all the way in or out. Also make sure your pad contact is perfectly even, and that the pistons are advancing evenly.

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What if it is all the way out..?

 

[pink poodle]

The screw pushes on the piston.

So it just impedes the piston's movement? Or does this position effect the flow of mineral oil?

 

[The Duckmeister]

It's a bump stopper basically. It limits how far the piston can retract up the cylinder. Winding the screw in pushes the piston down the bore, which of courses shoves the displaced oil down to the caliper.

 

[kemosabe]

I had the EXACT same issue when I did a fresh XT install two weeks ago. I have OCD tendancies too. The screws do work, but the effect is small.

Even with a perfect bleed (which I'm sure you did considering your own admission of OCDness) the rear lever is typically going to bite a little closer to the handlebar due to the longer cable. Without going into the physics of it, the longer cable results in more 'throw', as you put it. This is likely related to volume, compressibility and pressure in the (supposedly) closed system.

My solution to get the bite point in the same position relative to the handlebar was to bleed the rear again, but this time do it with the screw all the way (or close to) out. This effectively increases the volume of the cylinder. Do your perfect bleed again (well, just a top up really to get rid of any bubbles) and close the system. Now when you wind the screw down you will find that the bite point moves away from the bar. Not much, but it's noticeable. I view it as effectively increasing the pressure in the system when you wind the screw down.

If you run out of screw on the rear cylinder, match the bite point on the front lever by screwing out. That should get you somewhere close to being matched, if not perfectly. It worked for me.

 

[pink poodle]

It's a bump stopper basically. It limits how far the piston can retract up the cylinder. Winding the screw in pushes the piston down the bore, which of courses shoves the displaced oil down to the caliper.

Cheers. Would this cause some level of pad creep?

 

[Nautonier]

I had the EXACT same issue when I did a fresh XT install two weeks ago. I have OCD tendancies too. The screws do work, but the effect is small.

Even with a perfect bleed (which I'm sure you did considering your own admission of OCDness) the rear lever is typically going to bite a little closer to the handlebar due to the longer cable. Without going into the physics of it, the longer cable results in more 'throw', as you put it. This is likely related to volume, compressibility and pressure in the (supposedly) closed system.

My solution to get the bite point in the same position relative to the handlebar was to bleed the rear again, but this time do it with the screw all the way (or close to) out. This effectively increases the volume of the cylinder. Do your perfect bleed again (well, just a top up really to get rid of any bubbles) and close the system. Now when you wind the screw down you will find that the bite point moves away from the bar. Not much, but it's noticeable. I view it as effectively increasing the pressure in the system when you wind the screw down.

If you run out of screw on the rear cylinder, match the bite point on the front lever by screwing out. That should get you somewhere close to being matched, if not perfectly. It worked for me.

Thanks, makes perfect sense and definitely something I will try.

 

[Nautonier]

The screw pushes on the piston.

Could I put in a longer screw and push a bit more so that I can actually notice a difference?

 

[The Duckmeister]

It's a bump stopper basically. It limits how far the piston can retract up the cylinder. Winding the screw in pushes the piston down the bore, which of courses shoves the displaced oil down to the caliper.

Cheers. Would this cause some level of pad creep?

Absolutely, that's the bite point adjustment!

 

[Rider_of_Bikes]

Are you gents burping the caliper during your bleed? I have had good results by backing out the bite point screw then burping the caliper during the bleed process.

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