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Hydraulic brake failures

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Hydraulic brake failures

Old 11-23-23, 12:35 AM
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Hydraulic brake failures

I've had a lot of trouble with brakes right out of the box lately. Zoom brakes on Aventons were a total pain when I still carried them. I got some Vaast bikes with Shimano brakes that were mushy and I was told to bleed them. Nutt brakes seem to be almost as bad as zoom.

But the latest was really weird. Customer bought two off brand bikes. He wanted larger chain rings so he wouldnt be "hamstering." I found new chain rings and went to work on the brakes. Both rear brakes did not work. Their appearance is like the Nutts but they are not marked with a brand. Bleeding them spit out a lot of air and the lever was firm again. Same with the second bike. Crazy part was when the customer came for pickup. When I went to load the bikes, bike #1 lost its bleed. I backed up and checked #2. It was also no good too. Heres the quandry- What brakes CAN I bleed, and be certain they will stay that way? Or should I be doing some disassembly of the levers to clean them? I put the customer to work on the company. They admitted that some bikes were assembled without the hose nuts being torqued properly. I had found no leaks at any time, but I checked anyway. Only one nut could be turned a little. The company is sending new brakes, but I dont want to have the same problems. I dont want to be the guy responsible for MFG defects, or find out there was some little known piece of info I had not encountered.

Anyone else having trouble too?

-SP
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Old 11-23-23, 05:10 AM
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Hydrolic brakes are weird. Had recently a bike where I "bled" the air by opening the reservoir screw and pumping the handle. It worked fine for days, but as soon as I turned the bike upside down, it lost pressure completely. On another ebike my handle was replaced by warranty, I simply plugged it in without bleeding and it still firm two years later.
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Old 11-23-23, 07:30 AM
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Depends on the quality of the parts that comprise the caliper. Sounds like cheap, poorly manufactured parts that are failing.
Warranty replace as able and when unable replace with better quality calipers.
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Old 11-23-23, 07:52 AM
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Shimano or really any actual name brand brakes are a start. I vastly prefer mineral oil systems over DOT (i.e. SRAM). Itís normal to sometimes have to bleed when assembling a new bike.
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Old 11-23-23, 09:20 AM
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I mean Zoom I recognize as the cheapest crappiest brakes and Nutt sounds just as bad or maybe worse. Cheap brakes are going to be pretty terrible across the board and cheap hydraulics from Alibaba and his 40 thieves are not going to make things much better. Shimano makes some low cost hydraulic brakes that are decent enough and would be a massive upgrade from Nutt, Zoom, Pubuck, Giblon or whatever names they are coming up with for these hunks of plastic with bits of metal and crap. The e-bike names are equally as ridiculous.

Junk components will always be junky and will never work as well as good known quantity and quality parts so all those savings these people are thinking they are getting from buying whatever junk they find on an internet ad or through some discount site or whatever is all gone down the terlit. Unfortunately I wouldn't say those brakes are a manufacturer defect realistically because they are made to be that way from the factory intentionally. They chose to make that product and sell it. I would still let the customer try and get a credit towards new brakes but I wouldn't do any warranty work on behalf of the customer for a bike not purchased through you unless you are charging them a good fee for it, it is a lot of work and a lot of the companies that use Nutt, Zoom and other unlabeled junk are hard to get in touch with and hard to get warranty out of and it will eat your time and you will be unlikely to get a dime out of the company for your time and they will waste it for sure.

We had a cheap-o bike come through the shop and the company kept insisting the problem wasn't what it was and kept sending the wrong parts to fix the problem they couldn't understand and we probably spent 20 hours working on this and at the end they finally listened to us and sent us the part needed and it fixed the problem and could have saved us at least 18 hours of labor we never got back. Luckily this was a company that had an American office but some of these companies don't really have any support in the U.S.

Just save yourself and save the customer and just say hey you need new brakes and tell them why and be honest and you don't need to be harsh but you do need to be honest and get some Shimano or even Tektro brakes if you have to and tell the customer reach out to the people you bought it from and get a credit and send them an invoice for all the work being done on their new bike and have them pay for it and hopefully if the customer is lucky the company they bought it from or maybe the manufacturer will give them a check for that amount or somewhere close. Don't get emotionally invested in their poor purchase which I have seen people do.
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Old 11-23-23, 11:13 AM
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Editorial aside, if a brake is getting air into it or squeezing fluid out - it is probably from one of the hydraulic connections or the pistons or the reservoir. At a minimum, check the connection tightness and seating, and look for fluid.
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Old 11-30-23, 12:40 AM
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Originally Posted by Kontact
Editorial aside, if a brake is getting air into it or squeezing fluid out - it is probably from one of the hydraulic connections or the pistons or the reservoir. At a minimum, check the connection tightness and seating, and look for fluid.
I had the customer contact the company. Even they admitted to having nuts loose on the hoses, but there were no leaks and only one nut turned a slight amount.

Company sent new brakes. I received them today. We'll see if that is the proper answer or a better brand replacement.
Thanks for the responses.

-SP
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Old 11-30-23, 03:52 AM
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Originally Posted by XxHaimBondxX
Hydrolic brakes are weird. Had recently a bike where I "bled" the air by opening the reservoir screw and pumping the handle. It worked fine for days, but as soon as I turned the bike upside down, it lost pressure completely. On another ebike my handle was replaced by warranty, I simply plugged it in without bleeding and it still firm two years later.
I guess you know you shouldn't really do either of those things? I imagine if you've ensured that there's absolutely no air in the line then turning the bike upside down is ok. Often there is some air up by the reservoir, in which case it's going to migrate when you turn the bike over.

My first bike with hydraulic brakes was a recumbent with Magura Louise brakes. The dealer had fitted the brakes Euro style with the front on the left. When I took it in and asked for them to be swapped he just unscrewed them and switched them, without bleeding, and they were fine. He did check they were ok, though.
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Old 11-30-23, 05:10 AM
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Originally Posted by jgwilliams
Often there is some air up by the reservoir, in which case it's going to migrate when you turn the bike over.
Guess that makes sense, but I replaced them with mechanical. Last thing I need is for my wife's brakes to go dead when she decides to take her bike out once a year. I'll never hear the end of it.
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Old 11-30-23, 05:24 AM
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Originally Posted by XxHaimBondxX
Guess that makes sense, but I replaced them with mechanical. Last thing I need is for my wife's brakes to go dead when she decides to take her bike out once a year. I'll never hear the end of it.
Fair enough. My wife relies on me for all maintenance so it's not an issue.
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Old 11-30-23, 08:02 AM
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Originally Posted by jgwilliams
Fair enough. My wife relies on me for all maintenance so it's not an issue.
Must be a British thing, here in the States we never wrench on our wife's bikes. Not recommended by lawyers. Something do to with "you're tried to kill me to collect life insurance".
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Old 11-30-23, 08:17 AM
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Originally Posted by Kontact
Editorial aside, if a brake is getting air into it or squeezing fluid out - it is probably from one of the hydraulic connections or the pistons or the reservoir. At a minimum, check the connection tightness and seating, and look for fluid.
I agree with this, it's most likely leaking past the seals.

are the pads wet or is there evidence of leakage on the back of the pads

/markp
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Old 11-30-23, 09:38 AM
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Sometimes I wonder if people that are new to hydraulic brakes are too fiddly with them and create their own problems by messing with them soon after they first get them thinking that the brakes aren't working correctly but really are just going through their break-in period and need to be left alone.
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