dantxtpro Posted April 1, 2014 Report Share Posted April 1, 2014 As you may have read in my other thread my front calliper was dragging causing the system to get so hot it boiled which produced air and thus I lost all brake pressure. I spoke to the chap at splats and I decided to go for a complete seal kit so I have the reassurance the calliper will have fresh pistons and seals, hopefully reducing the chances of binding in future. I removed calliper and obviously the top ( longer ) calliper bolt acts as the calliper joining bolt and to attach to the bike through a mounting hole. The bottom bolt however purely acts as the lower calliper bolt ( holding the 2 halves of the calliper together) this is a 5mm Allen head and the bolt is so tight that eventually my Allen key rounded also rounding the internal faces of the bolt. Being a steel bolt in aluminium threads there is a corrosive reaction that's taken place effectively seizing it solid. Previous to the Allen key rounding I did apply heat to the threaded end of the bolt but to now evail. I'm literally screwed as I can't think how I'm going to undo this bolt without a secure place to apply torsional pressure. Trying to weld a nut to it is going to be hard and potentially damage the aluminium body. I was thinking of drilling the head off then splitting the calliper and using mole grips on the remaining stud or place the stud in a vice a twist calliper. Does anyone know if the bolt head is stepped into the calliper body or if it sits flush on top? I see now they use normal hexagonal bolt heads so a socket can be used!!! Mine is a 2009 please people I need help I can't be the only person to have experienced this!! Quote Link to comment Share on other sites More sharing options...
lineaway Posted April 2, 2014 Report Share Posted April 2, 2014 Drill the head off. Split the halves. First try to double nut the remaining thread. If that fails try a stud remover or at worse vice grips. If that fails weld a nut to the remaining bolt. Should never have used heat on the caliper. Using a torx instead of an allen would have given more grip. Could always start checking for a used caliper. Quote Link to comment Share on other sites More sharing options...
thats_a_five Posted April 2, 2014 Report Share Posted April 2, 2014 (edited) Put away that drill! Take a torx bit and drive it into the socket with a hammer. It may take some repeated hits to drive it to the bottom of the hex socket. Don't be gentle. Then use the torx bit to unscrew the bolt. If it is super tight, you may need to put some heat to the caliper to get it to release. I recently had to do that to one of my front caliper bolts. It worked a treat. New bolts and some anti-seize were used during reassembly. *** When I notice my hex drivers getting loose in the bolt heads, I grind the end off the hex driver to get to a nice, new, full size portion of the driver. This really helps prevent stripping out the heads when using the hex driver. Edited April 2, 2014 by thats_a_five 1 Quote Link to comment Share on other sites More sharing options...
motopelli Posted April 2, 2014 Report Share Posted April 2, 2014 Torx bit seems like your next step but: if that doesn't work and you do need to get the drill out, order up a couple of left twist drills (they drill counter-clockwise). There's a good chance the the drilling will pull out the screw before you get too far Quote Link to comment Share on other sites More sharing options...
clay Posted April 2, 2014 Report Share Posted April 2, 2014 Been there, snapped a bolt half way through the caliper, so could not get any grip of remaining bolt. Tryed to drill out with top notch drill bits, but they just bounced of it, Just about to give in to defeat. And use the caliper as a paper weight. When I found a local engineering firm, they said they would have a crack at drilling it, or spark erode it , Thankful success with a big pillar drill. Hope you get a bit of luck bud Quote Link to comment Share on other sites More sharing options...
dadof2 Posted April 2, 2014 Report Share Posted April 2, 2014 I would be very reluctant to use heat on a cast, precision machined component to the extent needed to release a seized thread, you could distort it. Drilling the head off removes tension from the threads, potentially loosening them. If you cant undo the remains with mole grips, heat the bolt (not calliper) red hot then try to undo it when fully cooled. When trying to undo the bolt make sure you apply torque evenly to both sides at say 3 and 9 oclock. This is very important. Pulling on one side only (as with allen key) pulls the bolt over and greatly increases friction. T handle keys are far better. If all else fails phone Phoeton Aptec, the solution they use to clean barrels dissolves steel and aluminium oxide without harming aluminium. If you were to drill the core of the bolt out they may (I have never asked them to do this) be prepared to dissolve the threads and corrosion out whilst they are treating barrels. If the will, get both half's of the calliper cleaned as the probable cause of you pistons binding was corrosion in the seal grooves. Quote Link to comment Share on other sites More sharing options...
lineaway Posted April 3, 2014 Report Share Posted April 3, 2014 Put away that drill! Take a torx bit and drive it into the socket with a hammer. It may take some repeated hits to drive it to the bottom of the hex socket. Don't be gentle. Then use the torx bit to unscrew the bolt. If it is super tight, you may need to put some heat to the caliper to get it to release. I recently had to do that to one of my front caliper bolts. It worked a treat. New bolts and some anti-seize were used during reassembly. *** When I notice my hex drivers getting loose in the bolt heads, I grind the end off the hex driver to get to a nice, new, full size portion of the driver. This really helps prevent stripping out the heads when using the hex driver. It`s not the mounting bolt. If he striped it round already there is not much left. Quote Link to comment Share on other sites More sharing options...
thats_a_five Posted April 8, 2014 Report Share Posted April 8, 2014 Dad, did you get the bolt out? Quote Link to comment Share on other sites More sharing options...
dadof2 Posted April 9, 2014 Report Share Posted April 9, 2014 thats-a-five - I think you mean Dan Quote Link to comment Share on other sites More sharing options...
thats_a_five Posted April 10, 2014 Report Share Posted April 10, 2014 LOL, you are right Dadof2 Quote Link to comment Share on other sites More sharing options...
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