Hydraulic Brake Failure

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gbs

Guru
Location
Fulham
What are the warning signs of a failing hydraulic system? Do these brakes fail catastrophically or gradually over time?
 

Drago

Legendary Member
Both. It depends very much upon the mode of failure.

However, instant and total failure is, thankfully, very rare indeed.

Stack the odds in your favour my keeping pistons clean, regular inspections, and bi annual fluid changes as a minimum.

Unfortunately, hydros are often touted as the fit and forget, minimal if any maintenance option, and that isn't the case. The components are not in the same league for robustness, durability and long service life as cars or motorcycles because of the need to keep the weight of everything to an absolute minimum. To keep them in good fettle requires a similar investment in time and discipline as cable brakes, ie, not a lot, but skip that minimal effort and they can bite. When they do they can often be far from simple or inexpensive to sort.

They're great, but they still put their trousers on one leg at a time, metaphorically speaking.
 
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battered

Guru
Catastrophic failure is very rare. What you usually get is a mushy lever and poor performance, and an attempt to bleed is unsuccessful. Any leaking is very bad news. Usually by the time they get to that stage they are 10+ years old and parts are unobtainium. Hayes 9, take a bow. At this point it's easiest and cheapest to just replace them, which I don't like because they aren't worn out, they just have leaking seals.
 

I like Skol

A Minging Manc...
Usually a gradual degradation in performance but can fail suddenly as I have experienced.

In my case I lost the front brake in just two lever pumps when mountain biking in Wales after the front hose got damaged and braking went from mushy to zero. Still had a perfectly functional rear brake so stopped safely and continued the ride, possibly even quicker than before..... :laugh:

@Hacienda71 @fossyant @dan_bo
 

Ming the Merciless

There is no mercy
Location
Inside my skull
If the lever travel or feel changes at all it’s a sign there wasn’t enough fluid in there to start or there is a leak etc. The reason for two independent brakes, regardless of type, is precisely to protect against complete failure. Even if one fails it’s unlikely the other will at same time. But if the characteristics of one changes do check it rather than leave it to give the other one time to go wrong as well.

A point of note. A wet day riding off road in a gritstone area, with steep or many descents, and you may find the pads are completely worn away in one ride.
 

fossyant

Ride It Like You Stole It!
Location
South Manchester
Usually a gradual degradation in performance but can fail suddenly as I have experienced.

In my case I lost the front brake in just two lever pumps when mountain biking in Wales after the front hose got damaged and braking went from mushy to zero. Still had a perfectly functional rear brake so stopped safely and continued the ride, possibly even quicker than before..... :laugh:

@Hacienda71 @fossyant @dan_bo

I would have pooped myself with a loss of a front brake on that Trail.
 
I've had both types of failure as on my recumbent trike as the brake lever points up.
So depending on what got blown/washed onto the top of the piston seal it either went slowly or fast.
It normally lasted about a year before it got too soft to give useful brakes and refilling it didn't make that much difference.
But I have had it fail on a very wet ride where the lever came back further and further each time I braked.
I now have a cover over the lever/brake body to keep dust/grit off the top of the seal to prevent that failure mode.

Luck ........... ^_^
 

HMS_Dave

Grand Old Lady
Just use the handbrake in the event of brake failure...
 

dan_bo

How much does it cost to Oldham?
Usually a gradual degradation in performance but can fail suddenly as I have experienced.

In my case I lost the front brake in just two lever pumps when mountain biking in Wales after the front hose got damaged and braking went from mushy to zero. Still had a perfectly functional rear brake so stopped safely and continued the ride, possibly even quicker than before..... :laugh:

@Hacienda71 @fossyant @dan_bo
And he's got all his teeth to prove it.
 
OP
OP
gbs

gbs

Guru
Location
Fulham
Thanks everybody, well nearly everybody, for the thoughtful commonsensical comments that have debunked disc bake mystique for me.
 

silva

Über Member
Location
Belgium
I had a sudden failure last year, a Magura lever that broke off due to thin construction and weak alu.
When I posted that, I had ridden 7 months without brakes, instead resisting pedals to slowdown (fixed gear).
3 months ago I let install a new lever by the dealer of the bike. He did it under guarantee, and added oil to the system.
The front brake worked again (no time for the rear).
It didn't last long. Within a month, barely using the brake, screw back to end position and still no braking force.
The new brake pads only lost 1 mm.
Last week went back. An employee of the dealer did it. No oil leaks found, but the new Magura brake lever had alot play.
It was again replaced under warranty. There was air in both front and back oil circuit, causing the no braking force.
Both brakes work now, how long, I'll see.
The guy applied sewing machine oil to the entry of the brake cilinder. And said that dirt etc blows in it due to headed in riding direction. The oil should block it from reaching the seal.
As said the brake lever was warranty replacement, but the price was on the invoice: 50 euro. Hefty price, for such fragile die-cast aluminium thing with design flaws.

The rear brake lever also had some play, but it was declared as acceptable.
What causes the play I don't know. Aluminium that gets worn off during operating?
But the real reason for the loss of braking force is thus air that got in.
The brakes on the bike never worked long, from its purchase in 2017.
Apparently Magura didn't design it well, and/or used seals that fail to do the job.
It could be that the sewing machine oil also serves as a block for air to slip in.

In order to protect the fragile brake levers somewhat, I turnt the levers inside my handle bars. I have to operate them with my thumb tips now, but that's okay since I resist pedals for the big part of the slowdown.
The dealers employee had turnt them up about 45 degrees to the front.
Also, I have a frame + bag above my front wheel, that is covered with a raincoat, I repositioned it so that it now also covers the brake pistons.

Maybe this all together will have solved the brake problems of the bike.
I'll see.
If over a couple months the story repeats (then likely again air in the oil), then I'll draw the line. Aka dump the Magura and go for something better than that crap. I got no other options than hydraulic.
 
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