Rip Posted March 19, 2022 Report Share Posted March 19, 2022 (edited) Not mine but a mate went over the bars earlier and now his back brake doesn't work at all, lever to bar with zero resistance. No visible damage on the outside, no oil leaking anywhere, everything done up tight etc. Tried a fast bleed then a full bleed but exactly the same. We've decided he probably needs a new lever because the internals are not serviceable but does anyone have any idea what could have happened as I'm curious? He's going to take it apart but hasn't as of yet. I'm wondering how an internal part got damaged so badly without any significant visible damage. Aso I assume nowhere sells the actual master cylinder without the HC3 lever blade? Not having to buy the blade would take a chunk out of the £98. Aso anyone know if an MT5 lever would work with an MT7 caliper? Edited March 19, 2022 by Rip Quote Link to comment Share on other sites More sharing options...
Ali C Posted March 19, 2022 Report Share Posted March 19, 2022 this is one reason why I stopped using their levers, this would happen every 6 months or so and would mean a new lever, fortunately we had plenty of spares but it was a joke how many perfectly good calipers we had in the flat connected to broken levers like yours. The good news is the MT7/5 lever is mostly the same so a straight swap is possible (the MT5/7 uses the same calipers anyway). If you want a stronger lever then get a Shimano on for a Shigura setup...or just get a Hayes 1 1 Quote Link to comment Share on other sites More sharing options...
Rip Posted March 19, 2022 Author Report Share Posted March 19, 2022 6 minutes ago, Ali C said: this is one reason why I stopped using their levers, this would happen every 6 months or so and would mean a new lever, fortunately we had plenty of spares but it was a joke how many perfectly good calipers we had in the flat connected to broken levers like yours. The good news is the MT7/5 lever is mostly the same so a straight swap is possible (the MT5/7 uses the same calipers anyway). If you want a stronger lever then get a Shimano on for a Shigura setup...or just get a Hayes Thanks man, any idea exactly what fails inside when they take a knock? Quote Link to comment Share on other sites More sharing options...
AdamR28 Posted March 19, 2022 Report Share Posted March 19, 2022 https://www.mtbr.com/threads/help-magura-mt7-pro-brake-sudden-loss-of-power.1199171/#post-15539005 Quote Link to comment Share on other sites More sharing options...
Rip Posted March 19, 2022 Author Report Share Posted March 19, 2022 10 minutes ago, AdamR28 said: https://www.mtbr.com/threads/help-magura-mt7-pro-brake-sudden-loss-of-power.1199171/#post-15539005 Thanks, possibly just needs more attention when bleeding then, either that or damaged seal on main piston? Quote Link to comment Share on other sites More sharing options...
Rip Posted March 20, 2022 Author Report Share Posted March 20, 2022 Confirmed blown seal on piston in lever. It wasn't even a hard or fast crash, just a slow over the bars. These plastic MT levers are rubbish. I'm personally switching to Hayes Dominions before this happens to my set. Quote Link to comment Share on other sites More sharing options...
Swoofty Posted March 20, 2022 Report Share Posted March 20, 2022 Did you try contacting Magura about this? They have a 5 year warranty and they've always been easy to deal with for me. Quote Link to comment Share on other sites More sharing options...
Rip Posted March 20, 2022 Author Report Share Posted March 20, 2022 6 minutes ago, Swoofty said: Did you try contacting Magura about this? They have a 5 year warranty and they've always been easy to deal with for me. It's a mates lever that it's happened to, he bought the bike from Tarty last year I believe, I'll pass the message on. Quote Link to comment Share on other sites More sharing options...
Rip Posted March 21, 2022 Author Report Share Posted March 21, 2022 (edited) So what causes a seal to blow like this (and in two places) after a very low speed over the bars crash? The lever being pushed in to quickly? Edited March 21, 2022 by Rip Quote Link to comment Share on other sites More sharing options...
AdamR28 Posted March 21, 2022 Report Share Posted March 21, 2022 What does the inside of the piston bore look like? Quote Link to comment Share on other sites More sharing options...
Rip Posted March 21, 2022 Author Report Share Posted March 21, 2022 2 minutes ago, AdamR28 said: What does the inside of the piston bore look like? Not sure, I'll ask my mate to take a look and get back to you. Quote Link to comment Share on other sites More sharing options...
Rip Posted March 21, 2022 Author Report Share Posted March 21, 2022 (edited) Bore looks ok initially but he's going to get an endoscope down there later. I made a mistake earlier, the bike didn't come from Tarty in the end because it was bought at the time when everyone was having major stock issues. Edited March 21, 2022 by Rip Quote Link to comment Share on other sites More sharing options...
Rip Posted March 21, 2022 Author Report Share Posted March 21, 2022 Bore looks ok, only thing we can think of right now is that the seals are slowly getting damaged every time they pass the bleed port up until a point where they can't take the pressure any more and just fail. Quote Link to comment Share on other sites More sharing options...
AdamR28 Posted March 21, 2022 Report Share Posted March 21, 2022 Hmm. Possible! So those are two different pistons from two different levers pictured above? Quote Link to comment Share on other sites More sharing options...
Rip Posted March 21, 2022 Author Report Share Posted March 21, 2022 4 minutes ago, AdamR28 said: Hmm. Possible! So those are two different pistons from two different levers pictured above? I got the impression both photos are the same piston and seal. I've asked if that's the case so I'll update once I know. Quote Link to comment Share on other sites More sharing options...
Rip Posted March 21, 2022 Author Report Share Posted March 21, 2022 @AdamR28yes confirmed both photos are the same piston so that seal clearly had two potential failure points. Quote Link to comment Share on other sites More sharing options...
Rip Posted March 22, 2022 Author Report Share Posted March 22, 2022 Well, he's fitted a new seal and it seems to be working again. Quote Link to comment Share on other sites More sharing options...
ben_travis Posted March 22, 2022 Report Share Posted March 22, 2022 Where did he get that seal from? Quote Link to comment Share on other sites More sharing options...
Rip Posted March 22, 2022 Author Report Share Posted March 22, 2022 30 minutes ago, ben_travis said: Where did he get that seal from? www.123bearing.co.uk He got these because they were in stock US-6X10X3-PU94 but said that UT-6X10X3-PU92 would possibly have been a better fit but they were out of stock. They are just hydraulic u-cup seals with 6mm internal diameter, 10mm outer diameter and 3mm height. The PU92 is apparently softer than the PU94 and the US vs UT is the length of the lips. I'll update the thread when we know how if they work long term or end up failing short term. So far the brake seems to work fine. Quote Link to comment Share on other sites More sharing options...
LEON Posted March 22, 2022 Report Share Posted March 22, 2022 Standard modern Magura quality. Quote Link to comment Share on other sites More sharing options...
Rip Posted March 22, 2022 Author Report Share Posted March 22, 2022 4 minutes ago, LEON said: Standard modern Magura quality. Seems so, their seal looks very weak compared to the replacement. Quote Link to comment Share on other sites More sharing options...
LEON Posted March 22, 2022 Report Share Posted March 22, 2022 The seals are the least of Magura's issues. Quote Link to comment Share on other sites More sharing options...
Rip Posted March 23, 2022 Author Report Share Posted March 23, 2022 8 hours ago, LEON said: The seals are the least of Magura's issues. Mine have been absolutely fine so far, I've dropped the bike a few times and they still work fine. I'm not a fan of how fragile the master cylinders are but so far they've held up. Quote Link to comment Share on other sites More sharing options...
LEON Posted March 23, 2022 Report Share Posted March 23, 2022 I've watched two MT7s snap from a light drop to grass. I've seen Sam Pilgrim loop out going up to back wheel because the lever blade just flapped out of the lever, he had to smash it back in with a stone. Then they release a special high end lever blade that doesn't snap (comforting) of course for more money. Dozens of others have had the same problems. I had MT5s, the flex in the plastic levers was ridiculous and gave me no confidence. I've heard nothing bad about their calipers. These are common issues on a premium brake at top money. I know they can be powerful in that brief window when they work, but all things considered their levers are just a shit product. Quote Link to comment Share on other sites More sharing options...
La Bourde Posted March 24, 2022 Report Share Posted March 24, 2022 Not a big fan of Magura neither. Recently, mtb-news.de organized a chat with some Magura guys. The members of mtb-news.de could then ask questions. It was insane how many users complain about the brake levers. There is consensus about how they perform when they worked, but also that the Cabotecture levers are just a source of problem - I mean there is a reason why every two Magura owners switches to Shigura. All the answers of the Magura team were bullshit marketing gibberish. I know the brand for more than 25 years and never understood how they manage to still be present on the market with such an attitude. They ignore the customer. I mean, trials riders used HS33 for more than 30 years now but still have to bleed the circuit with a special oil, to change the lever for one that is long and strong enough and get some pads and clamps from other brands. It is so sad because the calipers (HS33 or disc) are excellent (good brake power, reliable, etc.) and the brakes are produced in Germany (maybe 50 km away from where I live currently) 1 1 Quote Link to comment Share on other sites More sharing options...
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