Why did the shia stop making salaam to the right and left at the end of the salaat and what is the true and correct way
That’s a good question!
Sayed Ahmed has clarified that it is obligatory to do the salam facing forwards towards the Qibla. When you are in group prayer, and there is someone to your right.
It is recommended to slightly tilt your head to the right and look right while saying the Tasleem. And it is also recommended, if someone is to your left in group prayer, to do a second Tasleem while tilting your head slightly to the left and looking left.
This is based on Sayed Ahmed’s book شرائع الإسلام, page 52-53. For illustrated examples of these and other scenarios of Tasleem in prayer, please download this guide: http://www.mediafire.com/view/63yg73at34cg329/Tasleem-only_1_is_obligatory_v1.2.pdf and also ppt version click here.
The exact same ruling is in the Shia books of the righteous scholars (here is a link to one such book). I know the 12er Shia’s don’t turn right or left for the Tasleem in prayer. And sometimes they don’t even do the obligatory Tasleem. Inshallah we can inform them of it.