Most GM engines and transmissions are removed by unbolting the upper strut mounts, then lowering the entire cross member with those parts on it. What you must do is mark the orientation of the four large bolts to the cross member so you can reinstall it exactly the same way. Here's a drawing I posted yesterday for a fellow with this problem on a Cadillac. When the cross member is reinstalled off to one side as little as 1/8", that moves the lower control arms and ball joints to the side and tips the tires. An alignment will straighten them up, like they're shown here, but steering axis inclination will be unequal resulting in miserable handling. All alignment computers measure SAI automatically but we rarely look at it unless we're looking for the cause of an elusive problem. The mechanic uses a pry bar to slide the cross member until SAI is equal on both sides, then he can begin the normal alignment.
This is only an issue on GM front-wheel-drive cars. Cross members on Chrysler products are centered by the use of special bolts. Fords' are welded on and not removable.
Wednesday, February 20th, 2013 AT 4:20 PM