Tom Tollis reports that they have a tendency to split along the keyway, so if the rubber part is still OK and you have a timing cover modified for an oil seal, the solution is attached below.
You will need a lathe or access to a machine shop, keyway broach, and a press.
Oh, and a piece of mild steel 100mm diameter and 50 mm long.
With a bit of time it should work out cheaper than sourcing a new one!
Tiger Tom Ehrhart commented:
Slick idea to salvage the old balancer. I have never heard of anyone doing this. After all, it has been cheaper to by a replacement unit for $300 (SS) if still available. However, for the Sunbeam owner with professional skills and access to a machine shop with the proper tooling, it would be a fun project.
It essentially removes the inside area of the original harmonic balancer with a precision made replacement pressed in and keyed to secure and maintain timing mark reference. This is a job for a professional machinist.
Main concern would be engine vibration on integrity of press fit and pining. The big unknown is how tight the press fit should be. It is defined as “light press fit” which most machinist know. Also, the material is not specified. I would like to think most would know to use steel and not Al.
So will this work? I think it can if the press fit and pining are properly done. There is a complex science related to stress analysis of interactions of different materials. It’s the kind of analysis and testing a manufacture would go through before producing this kind of product. In this case, trust common sense.
BTW, all this assumes the rubber on the balancer is still functional and not petrified or turned to jello.