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Discussion Starter · #1 ·
Recently did a full bleed on my rear Shimano SLX M7000s using the Shimano funnel.

Ended up with a nice firm lever but not much power. Felt fine when you just spin the rear tire but when riding there is no power. Can't even lock up the rear wheel.

So was getting ready to do another bleed and noticed the little o-ring on the bottom of the funnel was missing. UH OH!

Looked everywhere for it and can't find it. I always store the funnel on its little stand and its no where to be found.

I am now fearing when I last removed the funnel from the brake lever the o-ring stuck to the inside of the bleed port.

Then I put the bleeder cap back in and possibly forced the funnel o-ring inside the master cylinder. Although I didn't notice the bleed cap screw going in wonky or needing extra force to seat.

Do you guys think this is even possible? Seeing how I am missing the funnel o-ring and my brakes are way down on power now I just assumed this is what happened. That o-ring is quite tiny.

Is it possible to open up the master cylinder somehow, to see if its inside?

There is that round looking end cap that looks like you could unscrew it with needle nose plier tips.

Couldn't find any vids on master cylinder disassembly.

Appreciate any thoughts.
 

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It seems unlikely that you could force that O-ring into the MC using the plastic cup threads. When you bled the brakes, did you do anything down by the calipers that could be causing the problems? Did you use the bleed blocks?
 

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What you see when you open the plug is actually a reservoir; the MC is further inside. You can open the whole cap and take off the o-ring. Just be careful torquing the screws back, as they are small and require little torque.
 

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You should have two o-rings, one on the bleed port screw and one on the funnel. They usually stay with the screw and funnel but sometimes one might stay in the o-ring groove in the lever.

Agree that it's very unlikely one got forced into the reservoir and if it did wouldn't cause any problems. And, you can remove the reservoir cap and get the o-ring out if you want to.
 

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Agree. Highly doubt you could accidentally force that o-ring down into the brake.

If the existing o-ring is still in the proper place and not mangled, not sure it would be possible to force another o-ring past it.

Bet your o-ring just fell off the funnel and is now held captive by and ornery dust bunny.
 

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Magically Delicious
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Ended up with a nice firm lever but not much power. Felt fine when you just spin the rear tire but when riding there is no power. Can't even lock up the rear wheel.

So was getting ready to do another bleed and...
If your brake lever is firm, you don't need a bleed. You problem is your pads. Did you get any brake fluid on them? Did you remove your pads from the caliper before bleeding?
 

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Discussion Starter · #8 ·
What you see when you open the plug is actually a reservoir; the MC is further inside. You can open the whole cap and take off the o-ring. Just be careful torquing the screws back, as they are small and require little torque.
Do you mean the circular end cap?

Mine SLX 7000s appear to be one single piece. There is no seam where the reservoir cap can be taken off.
 

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Discussion Starter · #9 ·
You should have two o-rings, one on the bleed port screw and one on the funnel. They usually stay with the screw and funnel but sometimes one might stay in the o-ring groove in the lever.

Agree that it's very unlikely one got forced into the reservoir and if it did wouldn't cause any problems. And, you can remove the reservoir cap and get the o-ring out if you want to.
My bleed port screw o-ring always gets stuck in the groove on the lever when I remove it. Gotta slide it out with a small pick. I do still have that one.

The Funnel one is missing, and it seems to be of smaller outer diameter and tinier (than the bleed port screw o-ring) so it crossed my mind that it may have been forced in.

I am positive it was there when I screwed the funnel in. But later noticed it was missing and my work bench is right next to my stand, so within about 3 feet distance it went missing. Which IS very possible.

My lever body and reservoir seem to be all one piece. There is no cap that can be removed. Only a circular type end cap that is about 3/8" diameter.
 

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Discussion Starter · #10 ·
If your brake lever is firm, you don't need a bleed. You problem is your pads. Did you get any brake fluid on them? Did you remove your pads from the caliper before bleeding?
I installed new pads after the bleed.

I left the old pads in during the bleed, and did actually get some oil on the pads and rotor (didn't remove the pads since I was changing them). I did spin the wheel a few times after the bleed with the old pads in to see how the lever felt.

Then I cleaned the rotor thoroughly and installed new pads.

Went for a ride and had a nice firm lever but hardly any power. Even after an hour of riding, so I assume the pads are bedded in now.
 

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Magically Delicious
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I'm betting the new pads were contaminated by brake fluid that was remaining on rotors, perhaps in the rotor cooling holes. I would cook the new pads.

I always remove wheels and pads before any bleeds. Standard practice.
 

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Discussion Starter · #12 ·
I'm betting the new pads were contaminated by brake fluid that was remaining on rotors, perhaps in the rotor cooling holes. I would cook the new pads.

I always remove wheels and pads before any bleeds. Standard practice.
I usually take the caliper off and let it hang down to get a more vertical brake line when doing the rear, so it isn't near the rotor. And take the pads out.

But this time I didn't do it since I was going to do put new pads on. So I probably screwed myself.

Then I assumed the missing funnel o-ring was the culprit ans inside my reservoir. Brain was working over time.

I will clean my rotor again and try another set of new pads.
 

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Discussion Starter · #13 ·
So do we all agree that IF my funnel o-ring is in fact inside the reservoir it probably won't hurt anything?

I envisioned it blocking a master cylinder port and impeeding oil flow and causing issues. Like lack of flow will cause lack of power.
 

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Magically Delicious
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My bet is that the "O" ring is not in the reservoir. I think that you wouldn't be able to easily get that "O" ring in the hole. Fortunately, these are the same "O" rings as the reservoir cap "O" ring and might be available.

Circle Steel
Circle Steel Skateboarding Equipment Nickel Tin
 
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