Brake Drum Runout

What is excessive runout for new drums?. I bought new drums from a repo place for the '47, I used a brake lathe and dial gauge to check them out before I install them. They range from 15 to 30 thousandths and was wondering if I should return them. Last set I got I didn't check out and they were REALLY bad, put on the car and shook, ended up taking 75 thousandths off and they were still warped. I'm going to call on monday but wanted to find out if there's a norm for runout on new drums.

 

I am sure there is some junk out there, but I would question, what are the drums centering up on. Are they spindle mount, hub, or lug bolt. If they were put on a drum lathe and showed out of round, they are probably bad. You wanta give us a heads up on what brand they are, so we can avoid them too?

 

They're centered on the hub as they're new slide over the stud type for a '40-'48 ford cars. I had the last set for a few years, same maker but I bought them from a repo parts place and they might have stacked them wrong. this time I bought them from the source and was wondering what is the norm for runout. one new cars I sometimes had to turn new drums or rotors straight out of the box to make sure the customer was happy, but I didn't mic them first to see how far they were out.

 

Excessive run out would be where you had to go + .060 over original spec (should be stamped on drum).

If these are off-shore repros, don't expect much. And yes, drums and rotors can be warped during shipping/storage.

Late design rotors (brand name) seem to not warp as easily (in fact, most have a warranty to not be).

I would mic them before install so I could return them if excessively warped.

 

Drum ID (shoe surface) runout should not exceed .005", so either you have real junk parts on your hands, or you are not setting them up and centering them properly. If you took .075" off the ID you just ruined new drums.
"

 

both set of drums (the new ones and the ones I bought 2 or so years ago) are "made in the USA" drums. The first set I painted and modified the rear drums BEFORE I put them on, so when I found out they were warped it was too late, so I turned them close to the max so I could at least used them. The drum Max is stamped on the outside and it's 12.09 and the starting diameter is just under 12.

Main problem being that I have to counter sink the inside of the drums slightly to clear the little bit of shoulder from the studs sticking through the hub....... That makes it not returnable.