ONE thing to consider is that the linings are still GREEN and un-cured. Back when the cars were simply used cars, the owners were usually cautioned to not make any hard stop for several days of use. Although the drums were machined and such, the linings still need some heat cycles to let the various resins and binders cook-out of the linings. NO lining, when out of the box, is ready for any kind of heavy usage, period. Even disc brakes, which is why some brands now claim their pads are flamed before they box them, I suspect.
One set of new brake rotors I bought for one of my cars, I went for the low-cost option, before "Chinesium" was a word. The friction surface was satiny, not machined with the non-directional swirl on it as OEM and some other aftermarket brands come with, but not unlike what some auto supplies had turned rotors to look like, by observation. On the first gentle brake application, things felt normal, but the brakes were fading badly by the third gentle application. No problem, just getting the surface and pads adjusted to each other. So I continued to my shadetree shop for a few hours. When I drove home, I still used gentle applications. A bit less heat and fade. After about the fourth hot/cold cycle, things got to feeling better with a better/firmer pedal. Things got better and more normal past that, until I put new rotors on it about 200K later. Those replacement rotors were not OEM, but had the factory-style machining with the non-directional swirl on them.
We had a quality control tech who was notorious for ruining brake jobs. He would take a fresh brake job out "to test" by nailing the brakes several times. Each time, he came back with "pulls to the left, then pulls to the right" complaints. Our brake guys went crazy, trying all sorts of magic milk/soaks/coatings to prevent that. In reality, all it would have taken is an accepted procedure to cure the frictions with successive stops from various speeds, in sequence AND putting the final non-directional swirl on the rotors to start with. This was in the mid-1980s. Several service shop magazines had done articles on how to best cure brake frictions over the years at that time.
IF a lathe is used to cut the drums, no real issue if the brake shoes are mostly asbestos, but for the newer semi-metallic frictions, it might become an issue. Why? The metallic particles in the frictions will seek to follow the machine marks just like a phonograph needle follows the grooves in a record. Which can cause noises from the brake shoes getting to the "end of the record" (my front end/brake operative's explanation). SAME thing happens with disc brake pads, too, which is why the factory went to the expense to get the non-directional swirl on their rotors! Once the break-in period is done, the rotors are smooth, no problems. But as that happens, until the rotors are smooth, "playing well" with the pads, noises/chatters and such can happen.
Some of the older brake drum machines, I believe, used a rotating drum rock for their abrasive. Still, it had to end up with a smoooth finish for best results, just like putting new pads on a used rotor.
I know many recommend "arcing" the shoes to match the drums, which is good, but similar will happen after a thousand miles or so of actual use, I suspect. Especially as most aftermarket replacement brake shoes are claimed to be "oversize" to allow for drum wear.
When I had Randy put the 11" rear brakes (factory part numbers) in place of the 9.5" rear brakes on my '77 Type LT Camaro (10 bolt rear axle), the new drums had a pulsation in them when stopping. New name brand drums. Obviously stored standing up in the warehouses. Rather than cut them immediately, I told Randy I wanted the drums cured before they were cut. He agreed. So after a few weeks of mild pulsations, I got time to get the car back to him. He trued the drums and that was the last pulsation, period, after gentle stops for the parts to get used to each other. When I might smell the rear linings, I did not apply the parking brake!
My rule on brakes, which can support my frugal approach to some things, is that UNLESS there is brake pulsation, DO NOT CUT anything, just replace the frictions and continue on down the road. Then stop gently for a week or so to gently heat the linings as they get used to doing their job. Works very well, at least for me, over at least 40 years of such.
I fully understand the "everything new" orientation. Nothing wrong with that. Sometimes it's necessary. Just do NOT expect everything to be optimum until after some break-in time happens, especially in anything past a gentle stop, with the stopping intensity increasing after the brake pedal feel gets firmer. Use that firmness as a measure of when the break-in period if over.
Sorry for the length,
CBODY67
