I am not a expert, I am not pretending to be one. I am a simple man with access to the internet, a full bong and hate wasting money because someone said it can't be done. So I am giving this my best shot.
With growing up around equipment such as old tractors, jig bores, drill presses, punch presses of all kinds, mills, lathes, band saws, all machines previously mentioned weighing anywhere from 400 pounds to 13 tons, you start to figure out what will work and what will work better. These machines are all old and require work often when we purchased them. Over the years I have learned to repair these machines, often having to redesign entire aspects of them including clutch driven auto feeds and tool holders such as Morris Taper adapters that they don't even make anymore.
Hallo! I posted on here a while ago asking for a seal kit or rebuild kit for my Magura Marta SL caliper. I was annoyingly told that one does not exist and that I HAVE to send it in to get repaired. So I laughed and started rebuilding it.
So here is a vague tutorial (too strong of a word really), on how to rebuild ANY hydraulic brake system in basically any and all applications but I will just focus on mountain bike brakes.
Here is some insight:
The o-rings in the Magura Marta SL caliper are called "square cut o-rings". People at a hardware store will probably correct you (as they did me a ton of times) saying "no, it's a seal". In reality, they are all seals. But you have a few different types of o-rings.
Square Cut O-ring
O-ring
Double Seal O-ring
Quad O-ring
Backup Rings
Probably more types, but these are the most common types.
Now you have different TYPES of O-rings. Different compounds and materials. Different materials are good for different things. Read about them here: O-ring - Wikipedia, the free encyclopedia
What o-ring do you need for your brakes? Well, what type of fluid do you use? And what type do you want to use? Hell, we can setup your brakes to work perfectly fine using jet fuel as brake fluid (Don't do that).
Reading the wiki, you can tell what works best for your application
1. Fluoroelastomer (FKM)- excellent resistance to mineral oils and greases (AKA, shimano and magura mineral oil)
2.Ethylene propylene diene monomer (EPDM)- excellent for use with glycol-based brake fluids.
Glycol-based brake fluids being DOT 3, DOT 4, DOT 5.1.
But what about DOT 5? DOT 5 is silicone based. DOT 5 keeps a more stable viscosity index over a wider temperature range. But how hot does your brake fluid really get in a bike? On my race car, it gets hot as hell, so hot it burns. I've done a downhill track on my Cannondale, brake line blew and my hydraulic fluid was warm, not scalding hot. DOT 5 brake fluid absorbs a small amount of air requiring care when bleeding the system of air. DOT 5 also prevents all moisture from entering the system, but will not get rid of what is already there. So anyone living in western Washington, good luck. I also read somewhere that DOT 5 can start to feel spongy after a while. I also cannot find anything saying what type of o-ring material is good against DOT 5, but if you are going to use silicone based, just do the next step and use Mineral Oil. Personally, I have swapped my Magura seals to use DOT 3 because a quart of DOT 3 cost the same as 4oz of Magura Mineral Oil. That and you can buy DOT 3 anywhere, ANYWHERE. Gas stations, convenient stores, that shady guy in the back alley, the guy in the rusty 1974 Ford that just pulled up to the gas station, guy probably has a screw driver for his carburetor that would remove your reservoir lid as well.
Brake fluids with different DOT ratings can not always be mixed. It must be of the same type, and at least the same rating. DOT 5.1 can replace DOT 4 and 3, DOT 4 can replace DOT 3. DOT 5 should not be mixed with any of these as mixing of glycol with silicone fluid may cause corrosion because of trapped moisture. (copy/pasta from wiki)
Now we went over the material types for your o-rings and your fluid to match them up. Now, as I learned the hard way on my *****in' Camaro and my dads Ford Danger, NEVER replace a slave cylinder without replacing the master cylinder. In our case, you just used your knowledge of o-ring types and materials to rebuild your caliper, now you will need to replace the seal in your brake lever. Pushing old parts up against new parts makes the old parts generally break.
Doing some research (mostly on the McMaster Carr website McMaster-Carr ). you will see a ton of different types of seals. (Here, was tricky to find so I will help you out, McMaster-Carr ) Personally, I can tell from the picture and what is in front of me, my Magura Marta brake lever uses the U-Cup seals. But, a Stretch-Fit Rotary-Shaft Ring Seal will also work in it's place most likely. (I ordered both). Keep in mind, if you change the type of seal, don't slap it together and go 35mph down some 2 foot wide dirt path hauling ass down a hill, you don't know if the seal will hold. Use common sense here people. Get going quick with the pedals, hammer on the back brake, skid it a few times, hold constant pressure for a while, see if anything bad happens. You could order the right seal but not do a good install job, I am not here to tell you how to take a seal out and put a new one on. I am here to help the mechanically inclined or already instructed people how to pick the right seal the first time.
As my closer for anyone who doubts me. Magura and Shimano aren't Apple, they don't waste the money on proprietary parts to make their already expensive brakes even more overpriced. All these seals and rings existed before hydraulic brakes on a bicycle was even a concept. The EPDM material for DOT fluid has been used on cars since basically forever.
Also, anyone who has any corrections to make, let me know in the comments and I will make the corrections. And anything regarding "just send it to the manufacturer" should just not be posted in the first place. I do not know the ring size of the parts you need. I also forget the ring size that I ordered. I measured with a digital caliper the ID and the OD and matched them up with sizes on the McMaster Carr site and also ordered similar sizes. Wasting 30 bucks on rings to rebuild yourself is a lot cheaper than 100-350 on a new brake setup.
With growing up around equipment such as old tractors, jig bores, drill presses, punch presses of all kinds, mills, lathes, band saws, all machines previously mentioned weighing anywhere from 400 pounds to 13 tons, you start to figure out what will work and what will work better. These machines are all old and require work often when we purchased them. Over the years I have learned to repair these machines, often having to redesign entire aspects of them including clutch driven auto feeds and tool holders such as Morris Taper adapters that they don't even make anymore.
Hallo! I posted on here a while ago asking for a seal kit or rebuild kit for my Magura Marta SL caliper. I was annoyingly told that one does not exist and that I HAVE to send it in to get repaired. So I laughed and started rebuilding it.
So here is a vague tutorial (too strong of a word really), on how to rebuild ANY hydraulic brake system in basically any and all applications but I will just focus on mountain bike brakes.
Here is some insight:
The o-rings in the Magura Marta SL caliper are called "square cut o-rings". People at a hardware store will probably correct you (as they did me a ton of times) saying "no, it's a seal". In reality, they are all seals. But you have a few different types of o-rings.
Square Cut O-ring
O-ring
Double Seal O-ring
Quad O-ring
Backup Rings
Probably more types, but these are the most common types.
Now you have different TYPES of O-rings. Different compounds and materials. Different materials are good for different things. Read about them here: O-ring - Wikipedia, the free encyclopedia
What o-ring do you need for your brakes? Well, what type of fluid do you use? And what type do you want to use? Hell, we can setup your brakes to work perfectly fine using jet fuel as brake fluid (Don't do that).
Reading the wiki, you can tell what works best for your application
1. Fluoroelastomer (FKM)- excellent resistance to mineral oils and greases (AKA, shimano and magura mineral oil)
2.Ethylene propylene diene monomer (EPDM)- excellent for use with glycol-based brake fluids.
Glycol-based brake fluids being DOT 3, DOT 4, DOT 5.1.
But what about DOT 5? DOT 5 is silicone based. DOT 5 keeps a more stable viscosity index over a wider temperature range. But how hot does your brake fluid really get in a bike? On my race car, it gets hot as hell, so hot it burns. I've done a downhill track on my Cannondale, brake line blew and my hydraulic fluid was warm, not scalding hot. DOT 5 brake fluid absorbs a small amount of air requiring care when bleeding the system of air. DOT 5 also prevents all moisture from entering the system, but will not get rid of what is already there. So anyone living in western Washington, good luck. I also read somewhere that DOT 5 can start to feel spongy after a while. I also cannot find anything saying what type of o-ring material is good against DOT 5, but if you are going to use silicone based, just do the next step and use Mineral Oil. Personally, I have swapped my Magura seals to use DOT 3 because a quart of DOT 3 cost the same as 4oz of Magura Mineral Oil. That and you can buy DOT 3 anywhere, ANYWHERE. Gas stations, convenient stores, that shady guy in the back alley, the guy in the rusty 1974 Ford that just pulled up to the gas station, guy probably has a screw driver for his carburetor that would remove your reservoir lid as well.
Brake fluids with different DOT ratings can not always be mixed. It must be of the same type, and at least the same rating. DOT 5.1 can replace DOT 4 and 3, DOT 4 can replace DOT 3. DOT 5 should not be mixed with any of these as mixing of glycol with silicone fluid may cause corrosion because of trapped moisture. (copy/pasta from wiki)
Now we went over the material types for your o-rings and your fluid to match them up. Now, as I learned the hard way on my *****in' Camaro and my dads Ford Danger, NEVER replace a slave cylinder without replacing the master cylinder. In our case, you just used your knowledge of o-ring types and materials to rebuild your caliper, now you will need to replace the seal in your brake lever. Pushing old parts up against new parts makes the old parts generally break.
Doing some research (mostly on the McMaster Carr website McMaster-Carr ). you will see a ton of different types of seals. (Here, was tricky to find so I will help you out, McMaster-Carr ) Personally, I can tell from the picture and what is in front of me, my Magura Marta brake lever uses the U-Cup seals. But, a Stretch-Fit Rotary-Shaft Ring Seal will also work in it's place most likely. (I ordered both). Keep in mind, if you change the type of seal, don't slap it together and go 35mph down some 2 foot wide dirt path hauling ass down a hill, you don't know if the seal will hold. Use common sense here people. Get going quick with the pedals, hammer on the back brake, skid it a few times, hold constant pressure for a while, see if anything bad happens. You could order the right seal but not do a good install job, I am not here to tell you how to take a seal out and put a new one on. I am here to help the mechanically inclined or already instructed people how to pick the right seal the first time.
As my closer for anyone who doubts me. Magura and Shimano aren't Apple, they don't waste the money on proprietary parts to make their already expensive brakes even more overpriced. All these seals and rings existed before hydraulic brakes on a bicycle was even a concept. The EPDM material for DOT fluid has been used on cars since basically forever.
Also, anyone who has any corrections to make, let me know in the comments and I will make the corrections. And anything regarding "just send it to the manufacturer" should just not be posted in the first place. I do not know the ring size of the parts you need. I also forget the ring size that I ordered. I measured with a digital caliper the ID and the OD and matched them up with sizes on the McMaster Carr site and also ordered similar sizes. Wasting 30 bucks on rings to rebuild yourself is a lot cheaper than 100-350 on a new brake setup.
