M785 rear calliper - where is the leak?

[stirk]

The fuck? No bleed needed for a pad change! I always carry spare pads these days, and have changed them a couple of times mid ride. I had to ride 2 hours of a 3 hour race once, with metal on metal due to abrasive mud. You could learn from me.

Wow, I'm not a fair weather rider and have a 1000km on resin pads, they need replacing now but to wear pads so quickly is nuts. Seriously I'd never had thought it possible.

 

[moorey]

Wow, I'm not a fair weather rider and have a 1000km on resin pads, they need replacing now but to wear pads so quickly is nuts. Seriously I'd never had thought it possible.

Read a bit from here...
http://www.rotorburn.com/forums/sho...6-July-14-Aug-11th/page35&highlight=Redesdale

 

[Flow-Rider]

Wow, I'm not a fair weather rider and have a 1000km on resin pads, they need replacing now but to wear pads so quickly is nuts. Seriously I'd never had thought it possible.

I haven't been game to run resin pads in years, one hill top ride in the wet of about 50k worn them out pretty low but not down to metal.

 

[pink poodle]

This is the brake before I reverse bled it.

This is after.

You have done a very tidy job. Let's see the slow motion footage!

Doesn't everyone carry pliers anyway?
Under what circumstances would someone decide to do some brake pad replacement track side? :noidea:

You must carry a bleed kit in your backpack also I assume.

Who has ever changed pads mid ride? Show of hands.

Yep. Got a "butterfly knife" style that flips between flat and needle. Trackside pad replacements aren't uncommon on a big shuttle day. And yes, when avid were on everyone's bike it wasn't unusually to drop the needles in the shuttle pig. Nobody wants to go on a 5 hour road trip and have their brakes fail the weekend.

When x-tools were doing a comprehensive tool kit on CRC for under $50 it made sense to have one under the seat on shuttle days. Fuck I take a large tub full of stuff - tubes, tyres, tools, gummi bears, track pump, chain, first aid, clown suit, seat, and on and on. What's in your trail pack?

I don't know about Deore. As for "most other calipers", only XT & XTR in the Shimano family have the bolt as standard. SLX have the thread for it, because they're the same calipers as XT, but are fitted with the pin.

Avid...Hayes...hope...I was thinking outside the shimano family. Ive only been using shimano brakes for a short time compared to my time with other brands.

 

[teK--]

Doesn't everyone carry pliers anyway?
Under what circumstances would someone decide to do some brake pad replacement track side? :noidea:

In winter u could burn a set of pads in one ride.

 

[teK--]

You must carry a bleed kit in your backpack also I assume.

Who has ever changed pads mid ride? Show of hands.

Me. Even had to replace missing pads once halfway down mt Buller after they fell out. I forgot to bend the split pin lol. A zip tie worked fine as a temporary.

 

[stirk]

Nah you fella's just brake too much I think, or moorey cooking his pads all the time on the BBQ weakens the pad material :heh:

Just because it doesn't happen to me doesn't mean it doesn't happen right so I thought I'd look into it. There is not a great on the webs but I found a couple of pages talking about super rapid pad wear in mud.

http://velonews.competitor.com/2013...deas-for-disc-brakes-in-wet-conditions_272308
https://www.bikeman.com/CARV-MUDROTOR.html


I found the points about the rotor design interesting in that lot's of cut outs can contribute to the wear, so if you have lot's of little holes and cut outs you might have higher wear in mud than a round rotor with just holes and a solid rotor seems to be the best but is not recommended for downhill style riding due to heat build up.


Are you guys ripping through sintered or resin or something else?


This conversation could rightly be a thread of it's own, there are so many variables, although I'm sure there are many threads in the archives.

 

[moorey]

I've given pads to numerous other people stuck on the trail. Ill prepared people are Ill prepared :rant:

 

[moorey]

Nah you fella's just brake too much I think, or moorey cooking his pads all the time on the BBQ weakens the pad material :heh:

Just because it doesn't happen to me doesn't mean it doesn't happen right so I thought I'd look into it. There is not a great on the webs but I found a couple of pages talking about super rapid pad wear in mud.

http://velonews.competitor.com/2013...deas-for-disc-brakes-in-wet-conditions_272308
https://www.bikeman.com/CARV-MUDROTOR.html


I found the points about the rotor design interesting in that lot's of cut outs can contribute to the wear, so if you have lot's of little holes and cut outs you might have higher wear in mud than a round rotor with just holes and a solid rotor seems to be the best but is not recommended for downhill style riding due to heat build up.


Are you guys ripping through sintered or resin or something else?


This conversation could rightly be a thread of it's own, there are so many variables, although I'm sure there are many threads in the archives.

sintered or resin, any rotor, in the right conditions, no ones pads last more than a few hours, like at the race I linked.

 

[stirk]

sintered or resin, any rotor, in the right conditions, no ones pads last more than a few hours, like at the race I linked.

That thread will take a few hours to go through! Relevant post #?

 

[moorey]

That thread will take a few hours to go through! Relevant post #?

only a page or 2 of relevance from where I linked. Essentially, even only about 1/4 of A grade finished the race, as no one had pads left. One guy went through metal backing and had Pistons on rotors. I wasn't far off.

 

[The Duckmeister]

I don't know about Deore. As for "most other calipers", only XT & XTR in the Shimano family have the bolt as standard. SLX have the thread for it, because they're the same calipers as XT, but are fitted with the pin.

Avid...Hayes...hope...I was thinking outside the shimano family. Ive only been using shimano brakes for a short time compared to my time with other brands.

Avid, not sure about Guide/Trails, but aside from them fairly sure only Elixirs are bolted; Juicies, BB7s & I'm pretty sure Codes clip in, BB5s use magnets.
Hayes, mostly clip to piston posts or magnets, some use the split pin.
Some Tektros are bolted, others pinned.

 

[mitchy_]

Avid, not sure about Guide/Trails, but aside from them fairly sure only Elixirs are bolted; Juicies, BB7s & I'm pretty sure Codes clip in, BB5s use magnets.
Hayes, mostly clip to piston posts or magnets, some use the split pin.
Some Tektros are bolted, others pinned.

Guide R, RS and RSC all use the bolt with circlip. i assume trails would as well, as they are the same caliper?

 

[pink poodle]

Avid, not sure about Guide/Trails, but aside from them fairly sure only Elixirs are bolted; Juicies, BB7s & I'm pretty sure Codes clip in, BB5s use magnets.
Hayes, mostly clip to piston posts or magnets, some use the split pin.
Some Tektros are bolted, others pinned.

Of all the times to no longer have any juiceys in the house! I'm sure they were bolted...old style codes were bolted, don't know about the current style. I'm pretty Hayes strokers were bolts as well. Anyhow I say split pins at 10 paces at dawn!

 

[moorey]

Just this morning. I'd just started riding to the meet point. Had used my own spare pair on the trail a few weeks earlier and forgot to replace spares in my bag.

 

[pink poodle]

Avid, not sure about Guide/Trails, but aside from them fairly sure only Elixirs are bolted; Juicies, BB7s & I'm pretty sure Codes clip in, BB5s use magnets.
Hayes, mostly clip to piston posts or magnets, some use the split pin.
Some Tektros are bolted, others pinned.

The lowest level elixir has a split pin...I discovered this today when one of my no maintenance riding buddies asked for help with a strange noise from his brakes. The caliper was pushed up hard on the rotor on one side and the spring had caught. There was a little bit of it dragging on the brakes...looks to have been a long running problem as one pad is almost gone and the other is barely worn. Why don't people look after their shit???

Just this morning. I'd just started riding to the meet point. Had used my own spare pair on the trail a few weeks earlier and forgot to replace spares in my bag.

Did your buddy rock up late as well?

 

[fridgie]

The lowest level elixir has a split pin...I discovered this today when one of my no maintenance riding buddies asked for help with a strange noise from his brakes. The caliper was pushed up hard on the rotor on one side and the spring had caught. There was a little bit of it dragging on the brakes...looks to have been a long running problem as one pad is almost gone and the other is barely worn. Why don't people look after their shit???



Did your buddy rock up late as well?

With no brakes he probably got there early....

 

[c3024446]

Follow up to the thread - the rear brake continued to get squishy quickly and lack power, and the front brake was lacking power too. I bit the bullet and bought new callipers (SLX) for both the front and rear.

Result - power is back! Squishiness is gone! I tried to pull the pistons out of my old xt callipers to check the seals - they were impossible to get out until i drilled a hole in the back and pushed them out with a nail from the back. Couldn't see anything wrong with them :noidea: There has to have a been a microscopic leak in both callipers causing pads contamination - either from the seals leaking, or from the two halves of the calliper body leaking.

Anyway, if this doesn't solve the issue permanently, i'm getting elixirs.

 

[teK--]

maybe the pistons had a very fine crack in them. They've been known to do this with Shimanos.

Or the banjo or banjo gaskets were leaking.