LEG INJURY
Chris O’callaghan asks if I have any idea why, after fitting new front fork bushes to his 1970 Bonneville, the forks stick. He says that although he can’t see any sign of damage, the bottom sliders have to be physically knocked down off the stanchions to dismantle them.
Assuming Chris hasn’t damaged the bushes fitting them and assuming (not always wise) that the new bushes are made to the correct size and not too tight, the usual cause of this is an internal bruise caused by an over-long mudguard bolt. The sliders are made of thin-walled tube, with bosses for the mudguard brackets welded on outside. On early models these were threaded bosses, on later bikes a steel pressing that held captive a square-headed nut – but in either case, using a longer bolt will dent the bottom of the hole and make a bump that catches the bottom bush.
Fixing this is tricky. By sliding the fork bottom over a steel bar and bopping the outside of the bracket with a flat block, you may be able to get most of the bump out – but it may still need to be buffed down with a small grinding wheel and you’d probably need a flexible drive to reach down the hole.