monkeyseemonkeydo Posted May 12, 2008 Report Share Posted May 12, 2008 What spray do you mean?The spray, Luke, the spray! Gosh... Quote Link to comment Share on other sites More sharing options...
Luke Rainbird Posted May 12, 2008 Report Share Posted May 12, 2008 I actually have no idea what you mean by "the spray"Do you mean where the pod was painted? Quote Link to comment Share on other sites More sharing options...
spaceman Posted May 13, 2008 Report Share Posted May 13, 2008 That piston had a wee crack in it before the pads killed it you know that yeah?I can tell by the dark metal by the snap.I second that. If it had snapped clean off in one blow, it would be a brittle fracture, which means the fracture area would be shiny.Most probably due to creep stress, it bent, then fatigue sets in, and it finally breaks.What a shame though. My friends at my side have warned me about it cos I guess I'm the only one using cnc backing, but so far so good on the cousts. *Phew, wipes forehead* Quote Link to comment Share on other sites More sharing options...
OD404 Posted May 13, 2008 Report Share Posted May 13, 2008 I second that. If it had snapped clean off in one blow, it would be a brittle fracture, which means the fracture area would be shiny.Most probably due to creep stress, it bent, then fatigue sets in, and it finally breaks.What a shame though. My friends at my side have warned me about it cos I guess I'm the only one using cnc backing, but so far so good on the cousts. *Phew, wipes forehead*I don't think creep has anything to do with it as creep is a temperature based failure mode where a part is under high static loads for long periods of time. The dark patches are synonymous with fatigue failures, another confirmation is a beaching effect on the fracture face where you can see rings relating to the way the crack propagated though the metal.I've seen these failures on brakes running standard Magura backings so I wouldn't be confident saying that cnc backings caused this. Infact given how bad the casting detail of these parts is and the number of potential stress risers in the failure region, I'm more tempted to say that it would have broken no matter what pads you had. Quote Link to comment Share on other sites More sharing options...
GyTrials Posted May 13, 2008 Report Share Posted May 13, 2008 i have snapped 4 sets of Rear pistons exactly the same way as this using normal pads backings. One set broke using standard black maggy pads on my other bike,Doesnt really help i know but....Steve Quote Link to comment Share on other sites More sharing options...
Josh Greenan!!!!!!!!!! Posted May 13, 2008 Report Share Posted May 13, 2008 Never seen that happen. Thats unlucky. Quote Link to comment Share on other sites More sharing options...
Andrew Smith Posted May 13, 2008 Report Share Posted May 13, 2008 it has happend to me many times before with cnc backings but that is down to the fact that my brake had soo much bite and i used to do a lot of manuals and drag my brake a lot (i liked the sound so much ) but i wouldnt use a maggie with out them but maguras are crap quality any way so i got a vee soo much better Quote Link to comment Share on other sites More sharing options...
Bionic Balls Posted May 13, 2008 Report Share Posted May 13, 2008 it has happend to me many times before with cnc backings but that is down to the fact that my brake had soo much bite and i used to do a lot of manuals and drag my brake a lot (i liked the sound so much )you may laugh...but that reminds me of a jet engine failure I read about where the pilots heard one engine making a nice whiney noise as they flew along... They decided to try and make all of the engines make the same noise by angling themselves into the wind slightly...suddenly all the engines failed due to the vibration (very fast fatigue cycling) and they were f**ked.so...next time you're on a plane... Quote Link to comment Share on other sites More sharing options...
Ash-Kennard Posted May 13, 2008 Report Share Posted May 13, 2008 happened to me too ages ago at a demo at beaulea Quote Link to comment Share on other sites More sharing options...
Nick Manning Posted May 13, 2008 Report Share Posted May 13, 2008 i've been using my Heatsionk red cnc's since christmas and have not had any problems. As for people trying to get heatsink pads, try Dan @ trials-uk he seems to have stock of them, as I ordered a pair of red replacement pads recently. Quote Link to comment Share on other sites More sharing options...
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