hey r3v looking for some guidance on on some steering play i am having. i have about 3/4 inch of play side to side on my 1991 318ic and have new CA's CAB's tie rods steering coupler and I'm wanting to know what the nut on the bottom of the steering column in this photo does exactly i believe if i tighten it i will have some success with my problem but i don't want to go at it without knowing what it does exactly. i have searched and found people saying this might be the problem but no one explaining ing what it does any help would be great before i go and swap a steering rack in for no reason.

thanks in advance

heres the photo its the nut that is on the bottom of the steering column/shaft