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Just took my brakes off to do the forks. They need pads, but they seem to have been leaking a bit. Maybe slightly oily on the back of the pads, and the brake dust looks oily and is caked on around the caliper.
However they were fine in use, when I squeeze them hard (much harder than I would in use) clamped onto an allen key there's no visible leakage.
Is weeping a sign of imminent failure or can it be lived with?
They're BR-M785
I have a few bikes this has happened on (all shimano) at one point the oil will make it onto the pads.
Just had a thought. This is an old caliper thats attached to what I think are 975 levers from 2007. They work, but the chances of a new caliper not having the correct leverage ratio are somewhat higher.
Money is tight, I might keep using it as a stop gap, a full new set is probably best.
They work, but the chances of a new caliper not having the correct leverage ratio are somewhat higher.
As far as I know, all Shimano MTB calipers and levers are compatible, as long as you have the correct hose fittings at each end.
No way.
It will cost you more in the long run, needing to prematurely replace pads.
Would you drive your car if you knew the calipers were leaking oil? I wouldn't.
I would either buy a new caliper, shimano calipers should all fit and work or buy an after market service kit or even a spares and repairs caliper.
You can live with it for a bit - I have a front brake with a microleak that I did plenty on in the Alps recently. Obv I sorted it as a priority when I got back.
The O-ring fix is much discussed and is pennies - if that is the actual problem. If it's the pistons then an aftermarket kit is available but not worth it for such an old brake.
Would you drive your car if you knew the calipers were leaking oil?
You probably have driven a car with the calipers leaking as much as these are. You would never know.
Pads were very worn so it's possible they only leaked a bit on max extension.
I haven't checked out seal kits, could be a good idea.
One day I pulled the front brake just to slow down a bit in a group ride and took a trip over the bars. On inspection I found the caliper (Hayes Nine so DOT fluid) had a slight leak that had just slightly contaminated the pads making the brake grab. No idea what Shimano mineral does to braking characteristics.
Noooo.
they seem to have been leaking a bit
This is the crucial bit. I'd clean them up and go for a ride. I'd certainly not just bin them without checking.
You need a new bike
One day I pulled the front brake just to slow down a bit in a group ride and took a trip over the bars.
That was pretty normal for Hayes HFX's though, they were like a light switch. I always imagined I had the last functioning set left on earth, amazed anyone still uses them.
You need a new bike
I know!
This is the crucial bit. I’d clean them up and go for a ride. I’d certainly not just bin them without checking.
My thinking also. It may not come back, it may have been fork leakage or something. Like I say, no issues whilst riding.
Isopropyl the callipers and discs, sand the pads. Try again and see how long til braking performance diminishes.
Pads were shot, I only noticed the oil when I came to change them.
I have the same calipers BR-M785 and mine started leaking but the bike has done almost 20k miles so I think I got my monies worth. Before changing the calliper, my bike would stop but it was far worse than normal and the squealing was horrendous and it was the squealing that I couldn't live with. Changing a caliper was far easier than I anticipated and I found the same caliper at a good price. I took the caliper apart in an attempt to replace the orings but my lbs didn't stock them and considered Shimano / sram calipers as consumables. Good luck
I have had the exact same problem with brm 785 calipers. I found the slight leak was causing screeching when wet and less power in the brakes. I swapped out the calipers for some xt calipers I found which were post mount and not flat mount as most new ones seem to be. I had to get 2 banjo fittings as the originals had a straight compression fitting. They have been great, silent and just work as they should with the original leavers. My advice is you need brakes you can rely on - get them sorted
Years ago a marshal on an enduro event was concerned about the front of my bike. I had to explain that I'd bled the brakes and then, after cleaning, put talc on the calipers to check for leaks.
It's a quick show if there's an issue.
Oh aye, did ye now?
The question mark and phrasing says you don't believe me and are calling me a liar. You continue chasing me around the forum being as unpleasant as possible whenever possible, Squirrelking.
However unlikely it sounds it happened, and is worth informing others of if it prevents them doing the same. In your case though I recommended you try it just to see. 😉
The question mark and phrasing says you don’t believe me and are calling me a liar.
TBF, I think you’re talking nonsense too. Brake fluid contamination will not make the brake more powerful/grabby, be it DOT, mineral or Johnson’s Baby Oil
Try it, Mashr. Hayes Nine with a leak from a damaged hose connection. The leak had dribbled down onto the pads. I replaced the hose connection and pads and the brake is still in use, currently in a dark shed:
I gave up posting on this forum because of similar stupid arguments about things as unimortant as bikes. Some things aren't worth arguing about. There is a set of circumastances in which a small amount of fluid on hayes Nines will make the bike grab enough to send I rider over the bars. Been there, done it.
I shal return to the chat forum and leave people to find things out the hard way.
It will cost you more in the long run, needing to replace manky contaminated disks.
There is a set of circumastances in which a small amount of fluid on hayes Nines will make the bike grab enough to send I rider over the bars.
No there's not.
Ever.
A picture of a 15+ year old brake doesn't add plausibility to am otherwise implausible story. Those brakes are not special, nor are the pads. When pads get contaminated with any sort of hydraulic fluid their efficiency deteriorates (as well as their structure if left long enough) . As an ex-rally driver you know fine and well this is true so why are you insisting otherwise?
I gave up posting on this forum because of similar stupid arguments about things as unimortant as bikes.
Sorry have I accidentally logged on to gaslightingworld or something.
Back on topic.
I've noticed a correlation between folks that seem to not actually ride their bikes very much and folks that complain about their brakes not working very well.
Makes you think doesn't it.😉
People for years people believed the sun, planets and stars moved around the earth and those that said otherwise were heretics. Sometimes telling the truth just isn't worth the trouble.
Yep planitary rotation will defo make your brakes work better when they have a coating of oil on the pads...
As it was Squirrelking who first called me a liar I put it down to him continuing his vendetta, now two others have joined in this is turning into an interesting psychological exercise. At least three people find it easier to call me a liar than to accept that a small amount of brake fluid on pads will make them sticky enough to grab. When I picked myself up, happily uninjured (but with a scuffed jersey that I could also post a pic of too) it didn't take long to find the reason for my flight. The leak made the brake grab, reapeatedly, verifiably.
So what you’re saying is, if I find my brakes to be lacking power, I should rub brake fluid on to the pads or rotor?
I’ll pass, thanks.
I shal return to the chat forum and leave people to find things out the hard way.
Posted 48 minutes ago
People for years people believed the sun, planets and stars moved around the earth and those that said otherwise were heretics. Sometimes telling the truth just isn’t worth the trouble.
Posted 18 minutes ago
Shortest flounce ever
I blame the planitary rotation myself.
For what it's worth I think you're more confused by simple stuff than a liar.
I shal return to the chat forum
Don't let me hold you back.
No I'm not saying that tomhoward. Read my posts if you wish to know what I'm saying.
To help you all I'll give you some more exact circumstances. We'd ridden some kms along a dusty slightly uphill trail then pulled out onto a road, the brake hadn't been used for a few minutes, 5 or 10. I braked to adjust speed in the group, so not hard, and was instantaly ejected. The leak was slight, the caliper was oily to the touch and dust had stuck to oil on the caliper making it visible, same for the pads, the disc was not wet with fluid either visibly or to the touch.
🤣
Edit, my laughing face was in response to a few posts above, not to you falling off. Busy forum caught me out!
Oh, now you’ve explained further…
…I’ll still pass.
You get yourself back to the important stuff, that really matters, on the chat forum.
This is like reminding people on UK forums of Armstrong's 99 positive test for Cortizone in the early 2000s. Don't worry, Scotcroutes I'll soon be back in the chat forum.
It's TJ's fault I'm here in Bike, I rarely look through the bike forum but as he's posted the French leg of his journey in Bike I have to click on Bike to get to his thread. Have a look at my contributions to that that thread - being helpful or lies?
It’s TJ’s fault I’m here in Bike
He forced you to click on this thread, did he?
This is what drives people away from STW.
Some things aren’t worth arguing about.
I disagree.
I could believe that there's a very specific set of circumstances where a weeping caliper degrades the braking efficiency of a pad enough so that a rider brakes harder and harder in order to achieve the same effect. Then the pad gets a dusty coating and is therefore dry. Rider grabs the brakes but now is putting a lot of force through a pad with suddenly increased efficiency and over they go.
But I'd say it's not a likely or common occurrence. Someone would need to experiment a bit.
could believe that there’s a very specific set of circumstances where a weeping caliper degrades the braking efficiency of a pad enough so that a rider brakes harder and harder in order to achieve the same effect. Then the pad gets a dusty coating and is therefore dry. Rider grabs the brakes but now is putting a lot of force through a pad with suddenly increased efficiency and over they go
Poor maintainance combined with rider error.
I could believe that.
I had shimano brakes on my computer bike.
They frequently had leaky calipers, this normally resulted in lack of braking power and a howling noise.
I used to just ride the bike until I felt motivated to do something about it.
Sometimes a month or two.
I never had any sort of grabing from the brake, just howling and lack of performance.
This was Manchester which is flat and might be very different off road.