About a year ago I replaced the steering rack in my minivan. That replacement rack blew out during the cold snap in December. The good news was the part was covered by the warranty. The bad news was after I replaced the rack, I needed to do a wheel alignment.
Since I had the alignment done a year ago, I knew the castor and camber were fine, I just needed to adjust the toe in. I was not willing to expend another hundred bucks for an alignment.
I set up four jack stands in the garage at each corner of the van. I strung yellow carpet thread between the two left and the two right jack stands. I used carpet thread as it is strong, and thin. It gave me a very thin and straight reference point to take a measurement from. I was able to extend the jack stand, at exactly the same height as the center line of the axle (through the center of the wheel), giving me a reference line extending through the axle center line, from the front to the back of the vehicle. To ensure the left and right string lines were exactly parallel, I ensured the two front and two rear jack stands were exactly the same distance apart. I used the 3,4,5 rule to ensure the two rear jack stands formed a right triangle with one of the front jack stands. Three feet out on the base line from one rear jack stand to the other jack stand, four feet out from the rear jack stand toward the front jack stand, then the hypotenuse, connecting these two points was five feet.
I used a ratchet strap to hold the steering wheel exactly in the dead straight ahead position. I adjusted the tie rods to achieve a slight 1/16″ toe in on each front wheel, achieving an overall 1/8″ toe in. I checked the measurement between the edge of the rim and the string, with the front measurement being 1/16″ more than the rear.