I am remodeling an early seventies ranch built on slab. One bathroom has an offset flange of cast iron. There is only one t-bolt slot, located on the offset side. There is no place for a t-bolt on the 'close' side.

The flange does not appear to be damaged, although there was a lot of rust that I have mostly removed.

There is evidence of long term seepage from under the toilet, likely due to improper sealing. I would like to install the toilet securely.

I have a steel repair flange that I can install with Tapcon screws, but it does not really allow for use of a t-bolt on the 'close' side, due to interference with the original flange, leaving me with the same problem.

The original flange is a composite of cast iron (or very heavy steel) mated to PVC, which is then solvent welded to PVC drain pipe buried in the slab. Difficult and expensive to replace.

Any suggestions?

"The original flange is a composite of cast iron (or very heavy steel) mated to PVC, which is then solvent welded to PVC drain pipe buried in the slab. Difficult and expensive to replace. Any suggestions?"

Yes, if a flange repair kit doesn't work why not remove the cast iron flange and replace it with a PVC one? How is the cast iron flange attached to the PVC raiser? Regards, Tom

The cast iron ring is (somehow) mated to a PVC offset adapter that is solvent welded (glued) to the riser. Only the cast iron ring is above grade. All PVC components are set within the slab. The iron ring does not seem to be an "add-on", but an integral part of the adapter. There are no bolts, screws, or clamps that can be removed. I am very leery of disturbing the existing iron ring, as I do not want to be forced to dig into the slab.
With all tile (asphalt) removed (bare slab), the bowl rocks slightly when set on the ring. There is no clearance for any sort of adapter, so I am going to glue down new linoleum, set the bowl with a lot of caulk, and depend upon the one flange bolt to locate the bowl. There seems nothing else to do unless I invest considerable expense and effort. I could drill and tap the flange, I'll have to think more about that.

OK! So the flange's a tad high. Get some plastic shims from the hardware store and shim the bowl. Good luck, Tom