Bleed Magura MT7’s

[p3eps]

I’ve recently changed from SRAM G2 RSC’s to Magura MT7’s, and after 2 rides I thought they were the best thing ever!!

I’ve just swapped my dropper for an AXS and changed my fork / stem position, so I thought I’d tidy up my brake hoses by chopping about 15cm off each.

I wish I hadn’t bothered!!

The front brake bled fine, and has a nice solid feeling lever.
The rear however is a different story.

I’ve now bled it 4 times, and it still feels really spongy. I can pull the lever, and have it hit the grip. None of the attempts I’ve made have really made it any better. Before I chopped the hose it was pretty solid - and would never been near touching the grip.

I’ve watched several videos on YouTube about how to bleed... from official Magura ones, to random bike mechanics. They all essentially say the same thing.
Empty syringe placed at top with lever horizontal. Full syringe at the bottom screwed in. Push and pull the liquid until it’s bubble free... with an occasional flick of the lever. Seal top, then bottom.

I don’t seem to be losing liquid when I remove the syringe and re-fit the bleed screw at the bottom, so I must still have ‘hidden’ bubbles in the system somewhere. The question is, how can I get them out?!

Any hints or tips that can help? I’m going to have a search for more videos and see if there are any that offer extra info.

 

[Zimmerframe]

Have you tried it with the front of the bike lifted up a reasonable height to "encourage" any bubbles to move up from where they might be trapped on the horizontal sections ?

And then the back of an electric toothbrush against the hose at the bottom for more assistance ..

 

[ebikerider]

Important to move the lever down 45 degrees once you have completed the bleed with the lever level as there is a pocket of air that will stay trapped in the master if you don't. Also I find it advantageous to have the rear caliper hanging loosely so I can tap and maneuver it to get the last of the trapped air out.

Hope this helps. It'll all be worth it when you get it, they are one of the best brakes out there.

 

[118]

as Zim has said, the bleed screw has to be at the highest point possible..If you aren't losing any fluid when you remove the lever syringe, you still have air in that master cylinder. When I bled mine, I made sure the the lever syringe had some royal blood in it, so that I knew all the air was out...

 

[118]

And then the back of an electric toothbrush against the hose at the bottom for more assistance ..

Or any other battery powered vibrating implements, you may have to hand..

 

[Gary]

Oddly I fitted and bled 4 sets of MT7s this afternoon.
Instead of the order you stated in the OP, Once the system is filled/flushed through,
Remove the caliper syringe and replace the caliper bleed port screw while the (filled) lever syringe is still in the lever port. Then depress the lever syringe and flick the lever (much like a Shimano lever bleed) before removing and putting the lever bleed screw back. You should find this method gives a firmer lever feel.
Also.. Is the lever genuinely spongy or just long throw? If the latter and If you're using old/worn pads. Either Advance the pistons before replacing the wheel/disc (by eye, if you're not familiar with this it'll take a little trial and error) or bleed with the pistons still advanced. (the second methed will overfill the system so you'll have issues resetting the pistons fully when you need to fit new pads)

 

[p3eps]

Have you tried it with the front of the bike lifted up a reasonable height to "encourage" any bubbles to move up from where they might be trapped on the horizontal sections ?

And then the back of an electric toothbrush against the hose at the bottom for more assistance ..

No - I just had it in my work stand as normal...
The lever is higher than the rear calliper - but I'll try exaggerating this to make the front higher if it'll help. The hose is routed through the frame - do you just do this at the hose at the calliper end?

Important to move the lever down 45 degrees once you have completed the bleed with the lever level as there is a pocket of air that will stay trapped in the master if you don't. Also I find it advantageous to have the rear caliper hanging loosely so I can tap and maneuver it to get the last of the trapped air out.

Hope this helps. It'll all be worth it when you get it, they are one of the best brakes out there.

I have been tilting the lever back to its normal position before re-fitting the calliper bleed screw.
I have been detaching the calliper from the frame so that the bleed screw is the highest point - and I can re-attach it without it all flowing out. I haven't been tapping or manoeuvring - but will give that a try along with the vibration suggestion above.

as Zim has said, the bleed screw has to be at the highest point possible..If you aren't losing any fluid when you remove the lever syringe, you still have air in that master cylinder. When I bled mine, I made sure the the lever syringe had some royal blood in it, so that I knew all the air was out...

There's fluid coming out of the lever screw when I screw it in. It's fluid dripping out of the calliper when I attach the bleed screw to that I was referring to. Some videos suggest I squeeze a bit extra from the bottom out the top just before I tighten to ensure this is full.
What a mess!

Oddly I fitted and bled 4 sets of MT7s this afternoon.
Instead of the order you stated in the OP, Once the system is filled/flushed through,
Remove the caliper syringe and replace the caliper bleed port screw while the (filled) lever syringe is still in the lever port. Then depress the lever syringe and flick the lever (much like a Shimano lever bleed) before removing and putting the lever bleed screw back. You should find this method gives a firmer lever feel.
Also.. Is the lever genuinely spongy or just long throw? If the latter and If you're using old/worn pads. Either Advance the pistons before replacing the wheel/disc (by eye, if you're not familiar with this it'll take a little trial and error) or bleed with the pistons still advanced. (the second methed will overfill the system so you'll have issues resetting the pistons fully when you need to fit new pads)

I'll give this a try too
The brakes are brand new, and have done approx 30 miles in my 2 rides so far - so the pads shouldn't be worn. They just feel like they have nothing behind them - like a lack of oil!
I was tempted to try letting the piston out a bit to let more oil in... but was unsure of the consequences. This is my first brake bleeding experience!

 

[Gary]

Kinda obvious question but after 30miles are your pads even bedded in? What riding was the 30 miles? Is there any possibility the pads are glazed?
IME
Maguras have quite a light lever feel. A little too much throw (freestroke) and pretty horrible lever ergonomics and not the best lever pivot location.
I'm obviously not a fan. But brakes are personal pref more than ANYTHING. But TBF All brakes are decent these days.

 

[p3eps]

Kinda obvious question but after 30miles are your pads even bedded in? What riding was the 30 miles? Is there any possibility the pads are glazed?
IME
Maguras have quite a light lever feel. A little too much throw (freestroke) and pretty horrible lever ergonomics and not the best lever pivot location.
I'm obviously not a fan. But brakes are personal pref more than ANYTHING. But TBF All brakes are decent these days.

First 30 miles was probably about 22 of fire roads and technical climbs, and 6 miles of flowing fast downhill (gentle braking) and 2 miles of rocky steep descents (with heavier braking).
Not much hard braking at all.

The front lever feels quite firm within a few mm's of it's travel, and no matter how hard I pull it, I can't get it near the grip. The rear lever is over half way through it's travel before the pads even move, and hits the grip without the brake ever being fully engaged.
Before I cut / trimmed the hose, the lever felt much better - and quite firm.

 

[118]

Did you push the pistons back within the rear caliper before you attempted to rebleed?
Have you somehow changed the bite adjustment on the lever?

I'm guessing the front has been set by the factory, as you'd have no reason to rebleed these, as they are a 'direct' fit, unlike the issues, that you had with this rear installation..

 

[p3eps]

Did you push the pistons back within the rear caliper before you attempted to rebleed?
Have you somehow changed the bite adjustment on the lever?

I'm guessing the front has been set by the factory, as you'd have no reason to rebleed these, as they are a 'direct' fit, unlike the issues, that you had with this rear installation..

The bite adjustment on the lever makes no difference to my rear lever.

The front had to be bled after chopping the hose, but seemed to be fairly straightforward.

I pushed the pistons back in before starting the bleeding as per Magura’s instructions. I also put their transport blocks in when bleeding. I wondered if I popped the pistons out, I’d get more oil in - and not have the same issue?

 

[118]

Bite adjuster or the reach adjuster?

Surely, if you over fill the brake line, that would only create rotor binding/brake rub, as the pistons can't retract far enough to give you the required clearance?

When I changed over my pads, I rotated the lever up, and took out the bleed screw. I then pushed the pistons back within the caliper. This forced out a tad of oil. Popped in the new pads and put back the bleed screw. First couple of lever pulls were spongy, as the system settled, then I got a lever that I liked. Whilst I appreciate this don't help your situation, perhaps a fresh days attempted on a full bleed, will succeed. You can't be far away, as you've an acceptable front brake...

I've heard horror stories from others, however I can't say the same, as I've had no such issues, front or rear.. maybe I'm just lucky chap..

 

[Gary]

Take it to a bike shop

 

[p3eps]

2 attempts tonight, and I’ve got it pretty good.
It’s not quite as firm as the front, but not far from it.

I must’ve pushed and pulled the fluid back and forth from the bottom about 30 times. Kept seeing tiny bubbles, so I would leave it a minute between each shot to let the bubbles rise to the top.
A lot of tapping on the calliper / hose, and I had the bike at a very peculiar angle in the work stand.

I’ll try them over the weekend and see how they are. If I’m not happy, I guess it’ll be another couple of attempts at home before taking it to the shop.

 

[Gary]

The bite adjustment on the lever makes no difference to my rear lever.

That's because, like so many brakes with bite point adjustment. the adjusters do very little.
mountainbikers seem to like knobs though.

Surely, if you over fill the brake line, that would only create rotor binding/brake rub, as the pistons can't retract far enough to give you the required clearance?

not if you understand what you're doing, why you're doing it, and how to do it.
Q: What do you think a bite point adjuster actually does?
A: it very slighly allows fine tuning of the amount of fluid in the system

I must’ve pushed and pulled the fluid back and forth from the bottom about 30 times.

30 times???
Why?
Despite what Magura advise, You don't actually even need to pull the fluid out of the caliper end at all.
Simply pushing enough fluid in through the caliper to the lever will eventually remove all air.
Sounds to me like while you've been pulling fluid out of the caliper you've actually been introducing air to the system

 

[p3eps]

30 times???
Why?
Despite what Magura advise, You don't actually even need to pull the fluid out of the caliper end at all.
Simply pushing enough fluid in through the caliper to the lever will eventually remove all air.

I kept getting bubbles, so I kept pushing / pulling. The videos all say I should keep doing it until I see no bubbles.

So in theory, I could get a massive syringe with say 200ml instead of 25ml, and put a big pot under the lever - and just push the lot through in 1 shot?

 

[Gary]

No

*sigh*

 

[p3eps]

No

*sigh*

Well what does this mean then?

“Simply pushing enough fluid in through the caliper to the lever will eventually remove all air.”

Pushing 200ml from the bottom up to the top in 1 shot - is that not what you’re describing?

 

[Gary]

Well what does this mean then?

It means I CBFA anymore

I obviously meant using the 2x30ml syringes you have

 

[p3eps]

It means I CBFA anymore

I obviously meant using the 2x30ml syringes you have

So what you’re saying is to just push into the calliper rather than the push / pull method?

As I said in the first post... this is my first time bleeding a brake - so sorry if I’m sounding stupid!

I have large syringes at work, and my bleed kit came with a tube to attach to the lever.
Didn’t see why I couldn’t just fill a large syringe and push from the calliper - and put the lever hose into a bottle and catch what comes out. I could probably feed through 150ml in 1 shot.

 

[Gary]

so you don't actually even have a Magura bleed kit?

See post #13

 

[p3eps]

so you don't actually even have a Magura bleed kit?

See post #13

I have an Epic Bleed kit for Magura brakes.
2 x 30ml syringe, fittings, pipes etc, and a bottle of Royal Blood.

As I said in post #14, it’s sorted now. I’d be scared to put my bike into the shop at the moment anyway incase we all get locked down!

I was just wondering if your suggestion of “pushing enough fluid in through the caliper to the lever” would be a better way of doing it in future since you thought I was introducing the bubbles myself with the push / pull method.
I’m only trying to learn so that I can do some things myself without the need to go to a shop all the time.

 

[Gary]

2 x 30ml syringe, fittings, pipes etc, and a bottle of Royal Blood.

STEP1
attach short hose with magura specific caliper bleed port adapter to the first syringe.
fill that syringe and attach to the caliper bleed port (obviously remove the bleed port screw first). keep that syringe upright so no air is introduced to the caliper when you push fluid in.
push one (empty) syringe with no fittings into lever bleed port (obviously removing lever bleed port screw first)
SLOWLY purge fluid from the bottom syringe to the top
Don't pull on the top syringe. let it fill SLOWLY
Tap the caliper/hose if it makes you feel better.
flick the lever if it makes you feel better.
air rises so will come to the top with the fluid.
i've already given you the final steps earlier.

STEP 2
Send me the £15

(STEP1 assumes you have levelled out the lever and wound out its adjusters)

You're basically ignoring MAGURA as they're twats and doing a shimano bleed on your Magura system

 

[deksawyer]

p3eps, for feck sake man. You've spent more time fecking about with this bike than actually fecking pedaling the fecker.

What was wrong with it in the first fecking place? I understand the desire to add some farkles (as we call it in the motorcycling world), but you're not meant to add everyfeckingthing at once.... ?

Best of luck though.

 

[p3eps]

What was wrong with it in the first fecking place? I understand the desire to add some farkles (as we call it in the motorcycling world), but you're not meant to add everyfeckingthing at once.... ?

Best of luck though.

Simple answer to this...
I returned the Trek Rail 9.9 - which was significantly more expensive than the SL Expert.
My wife was happy for me to buy the Rail at this price, so when I got a huge refund, I kept the money for upgrades rather the putting it back ?

TBF - the stock brakes were sh1t, and I really didn’t like the stock fork.
The AXS stuff is something I loved on the Rail and wanted on this.

I’m actually really enjoying learning how to do the upgrades myself. I’d barely ever done anything before, and now I’ve swapped half the bike over.
The forum and YouTube are great resources for a novice bike mechanic!

 

[p3eps]

STEP1
attach short hose with magura specific caliper bleed port adapter to the first syringe.
fill that syringe and attach to the caliper bleed port (obviously remove the bleed port screw first). keep that syringe upright so no air is introduced to the caliper when you push fluid in.
push one (empty) syringe with no fittings into lever bleed port (obviously removing lever bleed port screw first)
SLOWLY purge fluid from the bottom syringe to the top
Don't pull on the top syringe. let it fill SLOWLY
Tap the caliper/hose if it makes you feel better.
flick the lever if it makes you feel better.
air rises so will come to the top with the fluid.
i've already given you the final steps earlier.

STEP 2
Send me the £15

(STEP1 assumes you have levelled out the lever and wound out its adjusters)

You're basically ignoring MAGURA as they're twats and doing a shimano bleed on your Magura system

Thank you! Appreciate the explanation. ??