I second everything John says. I also happen to have a brake shoe arc machine and know how to use it with both the fixed anchor and floating anchor grinding heads.
One thing that I see happen. Ammco, when they first made the machines did NOT include the clearance specification into them and the operator had to do the math then set the machine. At some point that changed the machines so that if a drum
was say 10 thousand over you just measured the drum and set the machine to the drum diameter and then ground the shoes.
I have seen people fighting ground shoes that do not fit right and the issues is a miss-match of operator technique with the machine they are using.
be careful ; if you have well worn in shoes etc with more than 30% or so left, leave it alone . scratches and lines are normal and your newly turned shiny smooth drums will look just like that in a few thousand miles anyway .
After fighting with getting total contact brakes to work right ( they are great when calmed down / worn in ) it took a lot of pain and lesson learned the hard way stuff to figure out how critical the match of drum ID to shoe OD is .
See that chrysler factory service publication on these brakes published in this period —- probably on our site thanks to Mr Merritt , They had big problems …. we do too, if you mess it up .
Even all brand new parts will get you pulling sometimes even locking , constantly adjusting etc for several thousand miles . It is critical that new pieces that are put into turned drums have the shoes ground to match that new size .
Drum grinding is not that hard to find , but shoe grinding almost impossible now and finding someone who knows how to do it right is even harder . It was standard stuff in 1960 . It takes real skill and correct machine
Many were scrapped due to “ asbestos dust” that they made . Brutal stiff , no one knew .
This issue happens because of the dual self energizing shoes in front . If a wrong fit in one direction you get almost no braking effort , other way grabbing . Both ways very unhappy for you . It is not “ bad brake design” leading to
wholesale changes , it is incompetent work on them . And not incompetent “ on purpose” , .. It is through not knowing how/ why . .
After , what , 25 cars , lesson here is leave it alone even if shoe half worn or scratched drum . You are ahead of game and not like you are driving the car 100 k more miles ..I do not think even deep circumferential grooves hurt anything
, despite the visual reaction to that . But wet side must be kept AA++
Related , it will often grab after winter storage , this really threw me down a rathole in the early days , leading to needless painful brake jobs . The reason is rust on drum face makes it randomly self energize way way more . = lock
up in your driveway ( typically on one side(!) The cure ?—- apply brakes backing up quickly 4-5 times , fixed .
I think bendix brakes on other cars will self center don’t do this as much . Of course all this applies to 62 back , but still makes sense to me on any old car . I Just rebuilt a 37 small packard ( beautiful brakes , would you believe
same 12” as our cars on a car half the weight — and brake lines twice as large ?) all new on the wet side but used the drums and shoes as is . .
Not telling anyone what to do , just info .
Don’t make it worse . And drums are getting really rare too , and trying to change them on the old hubs ( Kanter drums) has been a disaster for me . It gets eccentric, or tilted to axle axis ( try to measure ID with that going on) even
with competent machinist help ,= you end up turning your new drum slightly afterwards — to fix that eccentricity, impacts balance etc — ? Ever notice all the balance weights welded on some stock ? and trying to get it centered on a modern lathe takes a
really large live center lathe as you need to come from behind to cut it right — and the taper on the rear hubs drives a machinist crazy to get perfect .. you only get a thin line of contact on the mouth of the taper ends .
I spent 3-4 months on and off in early 23 on doing the above ,(yet once again)with engineer hat on — “ Im going to fix this” ,, why this e-mail . The car now has used unturned drums back on it. Working fine . No more pulsation .
Yes, a brake lathe with tooling supposedly fixes all that but they often do not have the cones for holding 60 year old mopar tapered hubs , especially small outer end of taper ( euro VW one fits but a different size smaller main arbor
.. of course!) — So they cobble stuff up , (being an expert) , you end up with drums turned beautifully but off center or tilted in casting . “ Sorry , I tried”
Once you turn them to max they are gone in terms of future . another aspect
Brings up using new shoes hopefully turned to size in used scratched drums . I think ok if shoes are truly gone, No choice ..
And thin drums will warp or get out of round much easier than full thickness .
Say you are lacking all this stuff to do it right—- it will settle down in 2 k miles ,which may take years and adjusting for rapid wear every 300 -500 miles ,,and aggravating pulling , noise , pedal drop and general unhappiness . Why
the shoe adjuster nut is so often stripped ( see site for a cure for that too )
PS if you have a way old brake shop equipped with shoe turning and a way old timer , ? go for it . , But not on rumor of “ I know a great guy” type stuff . Been there . Even then , why ? Someone will say l know shop etc etc ., which
is great info . But was it needed is worth asking .
PPS keep old shoes and their matched drums together … may make your day — one day in future , 4 hours instead of forty .
