Hi,
Whilst I was changing my Rear discs and pads, I found that I did have to remove the calipers to allow the disc to be removed from the hub and undo the 2 very tight bolts that hold the calipers to the car (M9 bolts about 6 inchs long made of high tensile steel 10.9 stamped on them), I did manage to do the passenger side ok, the bolts do have lock tight on them and because the caliper is alloy and the swing arm is steel there was a built up of about an 2-3 mm of white corrosion behind the caliper which has been making the pads wear at an angle which had to be cleaned off.
Question is, I have broken off just one of the bolts flush with the swing arm, do i use an easy out or do i drill out the bolt with a colbolt drill to the correct size to tap a new thread into it? does any body know the Tap & drill size i would need? any ideas would be helpfull and has anybody done the same in the past!
Edited by Webmaster on 17/01/2010 at 22:12
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What I do if possible on such occaisions, is to lay a nut over the end of the broken stud and weld it on, this gives you a good grip and the heating and cooling will often loosen it.
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Thanks for your reply and sharing your experience, I really didn?t think you could break a high tensile steel bolt of this size, I will let people know how I get on and I will buy some of the same new bolts, I have thought about just using a longer bolt and drill a hole right through and put a nut on, but I do want to stick with the original bolt if possible.
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I now have new caliper bolts from Citroen, very helpful at stoke! and I have found out the thread size is a M9 x 1.25 pitch, most tap sets you buy don't have this size, they have M8 Then Jump to M10, very strange! I vhave bought a spiral tap on it's own and a 7.8mm drill, I have tryed easy out on it and heat but no joy, hopefully will be able to dril it out, very hard bolt to drill, using colbolt drills which make it easyier, will update if all goes well,
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Drilled And taped the hole out and everything went well considering, thanks for help!
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Clean off the corrosion on both faces and apply something like copper grease (sparingly) to the faces to stop it happening again. There have been cases where the corrosion has caused the bolts to shear. The one which broke on you could well have been already weakened.
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i have Cleaned off all of the corrosion on both faces and applyed grease to the faces to stop it happening again, suggest people do this as the corrosion & lock tight on the bolts would of caused any bolts to shear & weakened. Thanks Brian
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