Posted by Wayne [162.158.78.151] on Thursday, March 08, 2018 at 19:31:47 :
In Reply to: Brake drum machining on it's hub posted by Keith Hartman [172.69.69.79] on Thursday, March 08, 2018 at 12:38:11 :
Keith: So I'll jump in with my opinion... How perfect do you want them.... I took a short cut the first time and ignored advice and just turned the drums. Slapped them on... and they weren't right.... So next time I brought them to the machine shop I was working at (I use that word lightly...) and before we did anything we took them off the hubs and Wayno spent an hour wire brushing both the hub and the mating surface of the drum. Then we put the bolts in and cranked them down and then I got to turn them. I spent all that time wire brushing them (because I was told to...) because any rust or dirt between the two surfaces will impact your results. A small rust or dirt bump close to the hub gets mulitplied because the drums are so big. Think of a ruler, and when you move it at one end, the other end jumps a lot... So you get the point.
If you take the drums off AND MARK which HUB AND MATCH up to the same holes you will be ok, but you still can't turn the hub alone.
I bought two NOS drums from John B, and they were NOS for sure. I still turned them down ON THE HUB to get them perfect. Now they might have warn in a little bit and been fine, but we don't know how imperfect our hubs are and how many curbs or stumps they hit...
So for anyone wanting a perfect OEM brake system, I'd strongly advise getting drums well within spec, or better yet NOS or the reproduction ones. That will make your brake adjustment a lot easier. If the drums are out of spec, you can crank the adjustments all day long and the shoe will never contact the drum...
So yes, we even turned rotors and drums for people at the shop. And before we ever mounted them Wayno or some other guy got to wire brush them clean so they mated perfectly flat.
So to end my story... Last year coming home at night, my right turn signal was on... But I didn't know it... And when approaching an intersection the guy coming in from the right side pulled in front of me because he thought I was turning right... I jumped on the brakes hard, the truck stopped probably about as good as it ever did, and the Prius driver didn't end up with an MU2 as a hood ornament!
Most any old school shop with a brake lathe can do these drums, they are not that big.
Wayne
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