Transmission frequently locks up when writing to Samba share at more than 3MB/s
Download latest version of Transmission
Still having trouble, then limit the DL speed to 2.8MB/sec


I find that when I use Transmission at speeds less than 3.0MB/sec, I tend to not have the problems with a SAMBA share that you are having.

It writes to the disk in a different manner than what a direct connection does. Torrents create an empty file(s) that represent the downloadable content. Then they write to this file. Direct connection sends a request for the allocated space to the share/server and sees if it is available. If yes, it proceeds to start filling in the gap with the data until the transmission is complete and the end of file is written to the file system.

If you want an alternative option, create the download, add it to Transmission, but pause the download for a few minutes - THEN start the download as per normal. That way it should have enough time to write the inflated empty file first, and then start writing the data into it.