Triumphrat

Bonnevivant

Engine seized on my newly purchased 69 Bonne with a 71 engine which has a Routt drop in big bore kit. So I am using that as the kickoff for a rebuild.

Got the rocker box off, got the cylinder head off, got the cylinders off (thanks to the Forum for a nifty trick on how to do that when they don't just lift off). Pistons now exposed but still not rotating on the crank, so the seizure has to be in the lower end. Next big step is to split the crank case and take a look. Triumph manual says to remove pistons before splitting the case, so that is what I am trying to do.

Got the circlips off right piston and am now trying to remove the gudgeon. That is the pin that holds the piston to the connecting rod. Also called a wrist pin or a piston pin by other manufacturers. Triumph manual says to use the proprietary tool to do this. It's a nifty device that fits around the piston and allows you to apply a threaded shaft to the gudgeon, thereby evenly pusing the gudgeon out. Of course I do not have this tool. Manual also says you can remove the gudgeon by hammering it out with a drift, which I gather is piece of wood, maybe like a dowel. Manual really cautions against this method, as it is likely to damage the piston, the gudgeon, the piston, or the rod. Anyone have any thoughts on how to remove the gudgeon?

I suppose I could proceed with the instructions on splitting the case, but it looks like the cases will not full come apart with the pistons still attached. Anyone have any thoughts?

waynemags

you can use a deep socket w/extension on it. carefully use that as a drift. deep socket same diameter as the pin. use a small ball peen hammer to tap it through holding the piston and rod steady with your free hand. ive done it a million times with my harleys and all my dirtbikes and snowmobiles. good luck.

epynt1050

Gudgeon pin removal tool not specific to Triumph. Got mine from a Enfield dealer in UK. Expect most car parts places would have them especially if they cater for older cars.

You can split the cases without removing piston. Just be careful not to damage them. Try rapping in bubble rap.

Try heating piston. Then they should push out. Gentle blow torch or heat gun will do. Try to heat piston evenly and get it quite hot but not too hot. Remember aluminium melts.

thirdbike

If what you want to do is remove the wrist pin but fear damaging something by using blows to move the pin which to my my mind is a real no-no (and don't have the removal tool), its time to ne a little creative. I've used a socket or similar bushing to clear the piston and a C-clamp or F-clamp with a larger socket or similar shaft to fit over the pin on the extraction side of the piston. The clamp's acme thread is designed for force. If the pin is not seized, it will move. You don't need anything at the extraction end till the pin clears the piston wall.
Good luck!