I am unable to remove bolts holding rear brake calipers on to suspension arms without shearing them off. Have a set of replacement bolts from Citroen,and have drilled out and retapped the threaded ends of the original bolts that sheared.However,the thread on the replacement bolt is microscopically different,and will not screw in. Did Citroen change the spec? What size tap should I use? The thread seems the same,but isn't! Help
with thanks, Andrew

Andrew G Purches, June 2008

lets assume dealer supplied right parts.buy a tin of valve grinding paste from halfords or similar.liberaly coat the new bolt threads with the coarse paste and screw in till resistance is felt then a little farther in ,back out then back in,each time u should be able to progress more.the general theory is the internal threads are corroded and grinding paste is abrasive enough to clean the threads u cant reach or see.before u do place a new bolt onto an old bolt,threads interlocking and hold up to the light.very little light should be visible where they touch.if they dont mesh almost perfictly then as stated u have the wrong pitch.

caine, June 2008

Just a thought here.....perhaps Citroen used a metric fine thread instead of the more usual metric coarse.....there is a difference in the thread pitch, obviously.

John, June 2008