I bought a new pinion for a tilton starter and put the C-clip on the pinion shaft but it's impossible to open the c-clip and clamp it back down to a snug fit.  It works a few times and spits the shaft out.   Can i tach-weld the c clip to the shaft as the c-clip always expands once you release pressure on it.

Two part question. Do you have all the parts shown here?

ok, but the larger ring has two counter bores, one is for the spring side, the other (smaller counter bore) side is for the retainer clip. once you put the clip on you need to somtime force the larger ring around the clip because it is over streched. The clip should not be able to come off. welding it works too.