Not sure why you think anything will be going out of alignment. All you are doing is rocking the shoes back and forth as an assembly to determine how far until the lining contacts the drum.

 

Because your drums are warped all drum are warped.

New machined drums are round at first
Then the first time you use the they are out of round.

They get hot they expand they cool down they contract. The shoe area contracts less than the non shoe area. Giving them a oval shape.

 

So what you gathered up is 1'' or 1 1/8'' bore and 12'' 2 1/2'' shoes is stock on these trucks?

Im looking for this hydroboost

 

I've found this to be my experience as well. Even when I put my brand new drums on my truck last week, the drum made uneven contact with the new shoes as you're describing..... oval pattern of scraping the shoe, not scraping, scraping the shoe. This is why I backed off the star adjuster to where they don't touch at all, will drive the truck around for a few weeks, then re-adjust. Otherwise, they feel fine braking wise.

Tonight my buddy with his 97 E250 work van asked me to look at his rear brakes. His van began growling at the rear diff, and he said he didn't want to be without a vehicle tomorrow, as the job he's doing (he's a sparky) he needed his van to work there, as it has all of his tools inside. WHen I removed the brake drums the shoe holddown had fallen off and was tumbling around in the drum. His rear E-brake cables were frozen and his brake linings were cracked and missing for the most part. We went to autozone, picked up a new 12x3 set of shoes, hardware kit, adjuster kit for the passenger side (which was disintegrated) and replaced all of the parts in a couple of hours. His drums were grooved and rusted to heck, yet they weren't out of round at all, as when I adjusted them, they made perfect "full" contact the first time around.

Made me mad as heck that my brand new drums didn't seat like his worn out junk did..

 

I agree completely that all drums have some degree of out-of-roundness, and that there is thermal expansion and contraction involved, which is why the method I described uses setting an amount of free play, rather than adjusting until the free play is gone.

 

Trucks with 2 1/2" wide shoes had 1" wheel cylinders and trucks with 3" wide shoes had 1 1/8

 

Thank you