Magura MT 8's
I recently finished up my Niner R.I.P. 9 build, and I went with Magura MT 8's for the brakes. Pardon my ignorance, but this is my first set of hydraulic brakes. I've always used BB7's in the past...
Question or two......or, well...four...
How long did they take to burn in? I've followed the procedures a few times, and they still don't seem to be grabbing as much as I'd like.
How far are you pulling in the lever before they engage? I can get mine to stop me, but the lever is practically pulled back to the grip.
Should I re-bleed the brakes? Is it possible that there's still air in the lines?
Should I clean them with some brake cleaner? I ask this, because I stopped by the shop right when the mechanic was finishing up bleeding the brakes, and I noticed him cleaning everything up with rubbing alcohol. When I watched Magura's brake bleed video, they said to use warm, soapy water or brake cleaner. Nothing about alcohol...
First off, it sounds like the brakes need a good bleed.
What size rotors are you running? If you have a 160mm up front, you will definitely notice more power with a 180mm.
I've never used brake cleaner on my disc brakes, so I won't comment on that. I do use rubbing alcohol for cleaning the outside of calipers/levers or on brake rotors...or any other oily part. This probably has little to do with your problem.
Hi Chris and thanks for trying Magura.
Rubbing alcohol is great for cleaning brake fluid and will not damage a thing, even yourself.
Make sure the pads and rotor are super clean after your bleed because a messy bleeds fluids can find its way towards that rotor and then onto the pads.
I would also recommend scotch-brite on the rotors and emory paper for the pad's surfaces but lay the pads face down on a flat surface to surface grind the faces clean again.
Look to see if there is a shiny or mirror like appearance on the brake pad's faces. That would be a sure friction issue no matter how well the brakes are bled.
An area for a quick check is to make sure both caliper pistons move freely. One of the two pistons could be stubborn and sticky within its caliper bore and need "unsticking."
Hold the freely moving pad in its bore with a tire tool, then squeeze the lever blade forcing and allowing the previously stuck piston to move outward. Careful not to allow the either piston to push its way completely out of its bore or you will certainly have a mess and the need to re-bleed.
"Exercise" both caliper pistons one at a time to assure a sticky piston is not the issue. Then if the lever feel is still squishy, move on to the bleed.
At this point, I assume you have air in the system possibly from the line shortening routine. You should be able to perform this move without having to bleed but its not guaranteed!
Let me know if you need more assistance and thanks again for riding Magura!
Thanks! I took the bike out again today to work on burning the brakes in. I only messed with the rear system, and it is really starting to feel like it is coming around. The pull on the levers feels a lot stronger, and the braking power has improved substantially. I didn't get a chance to start on the front system. I will work on that in the morning and post an update!
Originally Posted by judemonica
Maybe I just wasn't giving the brakes enough time...
Thanks again for your help!
Also with any brand new set of brakes you have to give extra time for the rotors and the pads to get burned in. Mainly the rotors, the more they get that new shiny finish worn of the better they work.
Magura's use mineral oil as 'brake fluid" like Shimano don't they?
Brake cleaner is better at removing oil. Alcohol is only good at removing "greasy finger marks" IMHO
Or I would use "soapy water" or simple green then wipe with alcohol if I didn't have brake cleaner.
Alcohol is good for DOT brake fluid clean up.
It can take 30 to 40 stops to bed brakes in.
Duct tape iz like teh Force. It has a Lite side and a Dark side and it holdz the Universe together.
Good news! I took the bike out for about 10-15 miles this morning, and the front system failed completely, providing maybe 5% stopping power. Not good news, I know. However...
I brought the bike home, re-bled both systems, and they are working perfect now! I took the bike back out for another 20 miles this afternoon, the brakes worked without fail. Hmmm... The wrench who bled them at my LBS might need to watch this video again:
Filling/bleeding of a MAGURA disc brake (MT8, MT6, MT4, MT2) - YouTube
Thanks everyone, for your replies!
Yeah...kinda got that feeling when you said that you saw him cleaning up the brakes with rubbing alcohol. There shouldn't be much cleaning up needed - atleast in my experience setting up and bleeding my MT8s. My guess is that he didn't remove the caliper and in turn didn't get a good bleed.
Originally Posted by chrisgardner73
Glad you got it figured out.
Originally Posted by ncfisherman
This was my first crack at bleeding hydraulic brakes, so I made a little bit of a mess. Not too much of one though. I ended up with just a little bit of fluid on each of the calipers and about 3-4 tablespoons on the floor. I cleaned the hell out of everything afterwards.
I'm still really impressed with how simple the procedure was. This is one task that I was always kind of nervous about trying on my own. The Magura service kit and YouTube video helped a ton!
Last edited by randalnelson; 04-26-2012 at 08:28 PM.
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