Servicing Magura MT trail brakes

yuley95

soft-arse Yuley is on the lifts again
So, I seem to have blown up something in the master cylinder of one of my levers on Magura MT trail brakes.

Lever goes straight to the bar. I’ve bled it now about 8 times and am convinced there is not a single air bubble in the system.

Every time I finish the bleed, the lever just goes straight to the bar again. Not squishy or spongy, just straight to the bar.

Anyway, I need to find a mechanic in Melbourne familiar with Magura brakes, OR find a diagram of the internals so I can crack it open and check the seals.

Any recommendations or ideas?

I would probably prefer to use a mechanic as the carbon (sort of carbon) lever body scares me to work on. Seems easy to over torque or crack...
 
Z

Zaf

Guest
So, I seem to have blown up something in the master cylinder of one of my levers on Magura MT trail brakes.

Lever goes straight to the bar. I’ve bled it now about 8 times and am convinced there is not a single air bubble in the system.

Every time I finish the bleed, the lever just goes straight to the bar again. Not squishy or spongy, just straight to the bar.

Anyway, I need to find a mechanic in Melbourne familiar with Magura brakes, OR find a diagram of the internals so I can crack it open and check the seals.

Any recommendations or ideas?

I would probably prefer to use a mechanic as the carbon (sort of carbon) lever body scares me to work on. Seems easy to over torque or crack...
Bleed block still in on lever pull?

Sent from my Agora 4G Pro using Tapatalk
 

Dales Cannon

lightbrain about 4pm
Staff member
There are a few exploded diagrams on the webs and they look pretty simple. Assuming those are the levers, I googled "Magura MT lever exploded".

Is there any resistance at all? Even a split o ring will have some resistance. If there is nothing it is more likely a big air bubble. Anyway they look simple to strip.

Can you source parts?
 

Flow-Rider

Burner
Bleed the master cylinder with the hose off by placing your finger over outlet port, if you get pressure build up it means there was air trapped in there and it's working fine.
 
When did it stop working correctly?

What bleed kit and bleed procedure are you using?

I have heaps of magura brakes and most of them are easy to bleed but there is one lever that seems to always hold air in it somewhere.
It's currently off the bike and I have been meaning to pull it apart and see whats up. When/if I get time I will disassemble and take some pics of the process.
 

yuley95

soft-arse Yuley is on the lifts again
Bleed block still in on lever pull?

Sent from my Agora 4G Pro using Tapatalk
Yep, bleed block still in on lever pull
There are a few exploded diagrams on the webs and they look pretty simple. Assuming those are the levers, I googled "Magura MT lever exploded".

Is there any resistance at all? Even a split o ring will have some resistance. If there is nothing it is more likely a big air bubble. Anyway they look simple to strip.

Can you source parts?
my google-fu must be off. I’ll try again. Magura website was no help though.
Bleed the master cylinder with the hose off by placing your finger over outlet port, if you get pressure build up it means there was air trapped in there and it's working fine.
Magura make it hard to bleed just the master cylinder as they don’t have a sealed fitting for the bleed port. You just push fluid up from the caliper. Unless I am misunderstanding you...
When did it stop working correctly?

What bleed kit and bleed procedure are you using?

I have heaps of magura brakes and most of them are easy to bleed but there is one lever that seems to always hold air in it somewhere.
It's currently off the bike and I have been meaning to pull it apart and see whats up. When/if I get time I will disassemble and take some pics of the process.
it stopped working properly after a minor incident that included a heavy, ham-fisted yank on the brakes and me hitting a tree as slow speed with my shoulder and hip. No apparent damage to the brake though there must be something internal.
I’m using the basic Magura bleed kit. Attaching full syringe at caliper, rotating lever so port is at highest point, removing EBT screw and inserting top syringe (open). Then holding the caliper low but with bleed port at highest point and pushing fluid though until only a few ml left. Removing top cup/syringe and closing EBT screw then raise the caliper above the lever and remove the syringe from the bleed port and replacing the screw.

I’ve done it enough times now that I’m really confident the bleed is good but a seal is failing.

One test of this was to connect the syringe at the caliper (with fluid innit) but leave the EBT screw in the lever body then pull gently on the syringe plunger to create a vacuum. The result was a seemingly endless stream of bubbles coming through.
 

Flow-Rider

Burner
Magura make it hard to bleed just the master cylinder as they don’t have a sealed fitting for the bleed port. You just push fluid up from the caliper. Unless I am misunderstanding you...
Can you use the fitting and syringe from the caliper end or an avid bleed fitting ? A lot of times they will just gravity bleed without the hose on, as long as you can keep the fluid up to it . You need to determine whether the master cylinder is able to push fluid at pressure.
 
The bleed fitting will thread into the lever port but I have never got it to seal well enough to pull a vacuum.

During your normal bleed procedure, once you have fluid in the lever end syringe, pull the lever a few times which should force fluid into the caliper end syringe if the master cylinder is functioning
 

Flow-Rider

Burner
The bleed fitting will thread into the lever port but I have never got it to seal well enough to pull a vacuum.

During your normal bleed procedure, once you have fluid in the lever end syringe, pull the lever a few times which should force fluid into the caliper end syringe if the master cylinder is functioning
If there's air stuck in the caliper or hose it will end in the master cylinder and or compress the trapped air then give the dead lever feel .

Bleed it in reverse by pushing the fluid down but remove the hose and bleed it with your finger over the outlet port by using your finger as a one valve. If you can't get pressure to build up, the lever is dead.
 

yuley95

soft-arse Yuley is on the lifts again
The bleed fitting will thread into the lever port but I have never got it to seal well enough to pull a vacuum.

During your normal bleed procedure, once you have fluid in the lever end syringe, pull the lever a few times which should force fluid into the caliper end syringe if the master cylinder is functioning
With fluid in the lever end syringe I pull the lever and a small amount of fluid gets displaced up into the lever end syringe. not sure about the caliber end though...

If there's air stuck in the caliper or hose it will end in the master cylinder and or compress the trapped air then give the dead lever feel .

Bleed it in reverse by pushing the fluid down but remove the hose and bleed it with your finger over the outlet port by using your finger as a one valve. If you can't get pressure to build up, the lever is dead.
I'll try threading the sealed syringe into the lever body though I'm pretty sure the instructions say it won't fit.. I'll have a look
 

goobags

Likes Dirt
Sounds to me like something is busted internally, would need to be a fair bit of air to pull the lever the whole way to the bar without much resistance


Sent from my iPhone using Tapatalk
 

shiny

Go-go-gadget-wrist-thingy
I'll try threading the sealed syringe into the lever body though I'm pretty sure the instructions say it won't fit.. I'll have a look
Don’t thread anything but the EBT screw into the port as you can risk stripping it out.

If the bleed looks good I think I read it on a thread on MTBR but the main o-ring seal can go. It doesn’t leak, just causes air to be sucked in and make the lever mush.
 

yuley95

soft-arse Yuley is on the lifts again
Don’t thread anything but the EBT screw into the port as you can risk stripping it out.

If the bleed looks good I think I read it on a thread on MTBR but the main o-ring seal can go. It doesn’t leak, just causes air to be sucked in and make the lever mush.
yeah, I reckon that's it. The fact that I can attach the syringe at the caliber with fluid in it an pull a vacuum only to get a strong stream of air bubbles coming through means air is getting on at the lever pretty easily
 
I just pulled apart an MT5 so hopefully this helps.

You didn't say if you have the trail sports or trail carbons, the first step of the procedure differs slightly for each as they use a different lever

Step 1: remove lever blade
If you have MT trail sports, MT 5,4 or 2 you simply punch out the silver pivot pin taking care not to lose the spring.

For the MT6,7,8 & trail carbon you need to remove the contact adjuster and peel up a sticker before punching out the pivot pin.

The video below is in german but shows the procedure to swap a lever blade for both styles of lever

Step 2: access master cylinder
On all levers once the blade is removed you will be able to access a small torx screw. Undo and the main piston assembly will slide out. It is spring loaded so go slowly if you don't want to lose anything.
 
I found that the piston seal in my MT5 had a small nick in it.
So what I thought was air in the lever was actually the seal intermittently letting fluid past the piston.

Going to contact magura to see if I can get a replacement
 

yuley95

soft-arse Yuley is on the lifts again
I found that the piston seal in my MT5 had a small nick in it.
So what I thought was air in the lever was actually the seal intermittently letting fluid past the piston.

Going to contact magura to see if I can get a replacement
Thanks @lachy177 I have the trail carbons (but with alloy levers... strange combo) so they are based on MT7 & MT8 levers. I can see what you talking about in the vid and can see the Torx screw.

I’ll leave it for now as I have contacted my place of purchase and am seeing if they can help me out but may have to dig into them if no luck there.

Just one question- one the torx is out, does just the plunger/piston come out or does the whole cover come off to give you full access?

Thanks
 
Top