WinRAR used many naming sequences for split multi-volume archives through its numerous versions. You cannot convert individual pieces, you would need to first merge all the pieces and then repack them. In case of RAR archives, renaming it may also work, provided you rename all the files in the sequence.
Convert Compressed archive file to RAR compressed files from a multi-volume archive.
We have found one software suitable in our database for this conversion.
Microsoft Windows software - convert 098 to r82 on Windows
One of the oldest and most popular shareware file archiver and data compression utility
Convert from 098 file format
The table with program actions contains information about what each program is capable of doing with their files. This may be a good pointer for further searches for certain file conversions and help you find the converter you are looking for if our search result is insufficient for you. However, it is far from perfect and may sometimes show results which are not really usable because of the nature of the software handles the files. So a conversion that appears as possible, just because of matched actions, may in fact not be possible.