Originally Posted by
Jeff Wills
Nope- not going to help. Once the splines develop some play in them no amount of force will re-form the crank into the correct shape. Besides, hammering on a crankarm will destroy the bottom bracket bearings in short order unless the other side is supported.
IMO: replace the left arm at very least. Tighten it correctly, with a socket and a torque wrench. There's no way to get it tight enough with a little 6 or 8-inch long Allen wrench.
i didn't say it would re-form the crank. i just know from experience that a few small taps can sometimes push the crank arm on a bit farther and allow the bolt to be put in farther which can stop the crank arm from working its way loose.