Hydraulic brakes help please

T

Tritzzy

New Member
Region
USA
So I recently got zero pressure zero brakes on my logan brakes. Did what every forum and youtube video said. Got a brake bleed kit, topped it off, got out every single air bubble known to man.
STILL zero pressure. So I made sure the pistons were working properly. They are.
So my question is, could it be the brake pads? That might sound silly but when talking about brake lever pressure everyone always says air bubbles and fluid. But that is all good. So could it just be that my brake pads have had it and I finally need new ones?
 
rich c said:
How many miles the pads? Do you ride a lot of hills? Any leaks?
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Not many at all, maybe like 150 max. I do ride hills 24/7 pretty steep ones. And no leaks found.
I will note it went from "some braking" to "zero" after I added the fluid and bled it. So I'm not sure what happened. I will note it still might be the pistons, they move but not much, maybe a broken caliper?
 
Tritzzy said:
Not many at all, maybe like 150 max. I do ride hills 24/7 pretty steep ones. And no leaks found.
I will note it went from "some braking" to "zero" after I added the fluid and bled it. So I'm not sure what happened. I will note it still might be the pistons, they move but not much, maybe a broken caliper?
Click to expand...
so the levers are bottoming out or they stop but you dont have much braking power? if they are stopping before bottoming out then it cold be really dirty pads and or rotors. if they are that bad you would have to try sanding them and cleaning with alcohol. When you bled it did you remove the pads and use a bleed block between the pistons?
 
fooferdoggie said:
so the levers are bottoming out or they stop but you dont have much braking power? if they are stopping before bottoming out then it cold be really dirty pads and or rotors. if they are that bad you would have to try sanding them and cleaning with alcohol. When you bled it did you remove the pads and use a bleed block between the pistons?
Click to expand...
Well now they just bottom out without any braking power at all after the bleed. I did use the bleed block. I currently have the top reservoir open and brake handle tied down fully to see if maybe its a huge air bubble in the line that hopefully comes out overnight. I did clean everything. Pads were about the same thickness as the tiny metal holder. But when testing the pistons they didn't seem to come out much with a brake lever pull. As far as I know I did everything correct. So I'm not sure how they went from barley working, to not working period after the fulid change.
 
ok now we are getting somewhere. you still have air in the lines. you want to bleed them then close the valve on the caliper and squeeze the lever it should stop and be solid. I was having issues and I found my syringe was letting air in. you pushed the pistons in before bleeding too right?
 
fooferdoggie said:
ok now we are getting somewhere. you still have air in the lines. you want to bleed them then close the valve on the caliper and squeeze the lever it should stop and be solid. I was having issues and I found my syringe was letting air in. you pushed the pistons in before bleeding too right?
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Oh yeah. I made sure they were pushed in before and after. Caliper is closed now. Just have the ones up top open with the lever pulled in all the way. Hoping that gets the air out by the morning.
 
Tritzzy said:
Oh yeah. I made sure they were pushed in before and after. Caliper is closed now. Just have the ones up top open with the lever pulled in all the way. Hoping that gets the air out by the morning.
Click to expand...
no the lever should never pull in all the way. after you run the fluid through it you just need to flick the lever a few times to get the air out. then ever should never close all the way. if they do there is something wrong. with the bottom valve closed you should be able to use the lever and it should stop and be firm before bottoming out. Now are the screws that adjust the levers position wrong? I mean f the lever is too close to the bar when its in the normal position that could be it.
 
Sadly everything is in the proper position, full of fluid, flicked and pulled hundreds of times, caliper properly alligned, cleaned, everything you can think of. Still bottoming out.
 
something is messed up. what brand are they? did you happen to squeeze the lever without the pads and rotor in place? because if you pushed the pistons out too far they could have messed up the seals. it sounds like your getting air into the system. myself I would take it to a decent shop and have them check it out. save your hair your pulling out right now.
last time I was checking my pads for wear I took them out on the back saw they needed replaced for some reason I spun the back wheel and make it stop I squeezed the lever with no pads. oops. lucky it jsut took a bleed to fix it. but it could have messed up the pistons.
 
Hmm I could have at some point and not realized it. Because pistons are the only thing that makes sense right now. And they are Logan branded brakes. Thinking it would be cheaper to just get a new caliper and brake than to pay to have it looked at
 
Firstly, are you sure you used the correct fluid ? Ie DOT or mineral ? Because the wrong fluid could have killed seals. One of the advantages of buying a big brand is it's easier to find this information.

You are describing air stuck in the system - ie no lever pressure so something ( usually air) is compressing. Take a good, long look at the lines - how are you going to help the air travel up from the top of an arc to the lever or calliper? Sometimes, you need to work both directions - drawing air in / out at both ends ( watch the sram video final stages as an example ) . Sometimes, you just need to hang the bike / parts up in a way that allows air to wander out. Sometimes, you can do the same thing 20/30 times and then everything is magically fixed and you can't work out why....
 
PDoz said:
Firstly, are you sure you used the correct fluid ? Ie DOT or mineral ? Because the wrong fluid could have killed seals. One of the advantages of buying a big brand is it's easier to find this information.

You are describing air stuck in the system - ie no lever pressure so something ( usually air) is compressing. Take a good, long look at the lines - how are you going to help the air travel up from the top of an arc to the lever or calliper? Sometimes, you need to work both directions - drawing air in / out at both ends ( watch the sram video final stages as an example ) . Sometimes, you just need to hang the bike / parts up in a way that allows air to wander out. Sometimes, you can do the same thing 20/30 times and then everything is magically fixed and you can't work out why....
Click to expand...
I mean I think I used the correct fluid. I used Shimano mineral oil and the bike manufacturer recommended it. And I guess I will continue to try and get air out. Not sure many other ways of achieving that though.
 

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So at least not the same as the ones I linked.

I guess you need to decide what your time is worth - you can invest hours trying different bleeding techniques and hopefully resolve this, but it might be worth considering what the chances are of getting replacement pads etc in the future and then considering what a big brand set of brakes are worth.

If you want to work through this , try flushing from the calliper upwards using a syringe and ideally the bike oriented so the brake lines go straight up. Then close the caliper end, connect the bleeding kit to the master cylinder and with the lever against bars syringe in / withdraw repeatedly until no bubbles come back. Then leave that syringe vertical but go back to the caliper, syringe fluid in under pressure whilst gently allowing the lever to work it's way out. Tongue poking out of your left side in the southern hemisphere whilst chanting " one last chance you mongrel" .
 
This may be confusing. If you know your calipers as far as piston stroke before the piston passes the seal, you can do this to remove the air:
Take the caliper loose from the frame and off of the disk.
Pump the brake lever, (master cylinder), until the piston extends just shy of going passed the seal.
With the brake line pointing up, manually press the piston in forcing the air up to the reservoir at the lever.
May have to repeat.

One other thought that enters my mind is: For regular bleeding
your bleed valve has to be at the highest point of your caliper, otherwise you will never get the air out, as it will be trapped.


HTH
 
Last edited:
fooferdoggie said:
I squeezed the lever with no pads. oops. lucky it jsut took a bleed to fix it. but it could have messed up the pistons.
Click to expand...

you don't need to bleed to push them back in, park tool (and others ) make a specific tool (brake pad spreader) to force them back in, but you could use anything hard and rigid to push them back, just take care not to scratch anything

looks like this

www.parktool.com

PS-1 Disc Brake Pad Spreader

A dummy disc rotor on a handle, with a tapered edge to safely and easily drive apart and reset hydraulic disc brake pads.
www.parktool.com www.parktool.com
 
It's been a couple seasons since I did my Magura MT-5's, but hydraulics is hydraulics regardless of name brand.......I found what worked for me was to use the Magura brake bleed kit syringe, attach it at the caliper bleed point (filled with brake fluid) AND a similar syringe (filled with brake fluid) attached at the brake lever/"master cylinder" reservoir.

Then, from at the caliper, I reverse flushed the fluid at the caliper syringe until I got free flowing fluid at the top, brake lever syringe.

Having the 2 syringes in the system, with fluid inside them, but with room for the injector to accept fluid from the other syringe.......allowed me to work out any pesky air bubbles. The trick is to inject the fluid slowly and watch for air bubbles to disappear.

Then, I closed off the caliper port; removed the brake lever syringe and manually topped off the reservoir.

Logan brakes......I've heard of Magura, Shimano, Sram, Hayes. Never heard of Logan. At 49 dollars for a complete brake assembly, I suspect you have an unidentified source of air entering your system. You also need to ensure the caliper is correctly aligned and torqued down on it's mounts so the pads have a chance to bottom out on the rotor.

But before you discount the cheap brakes theory, try reverse flushing back up into the reservoir, with that top syringe tightly mounted into the reservoir, to see what happens.
 
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