His idea of drilling hole in stud is a good one , go even bigger on that hole .
Unlike later drums / axles there is no large 2”+ centering pilot machined on our hub , you depend on wheel bolt pattern to center brake drum doing it like this . Not enough beef in flange to make a pilot either. Mine ,assembled , ran out like .010 . So pedal will pulsate. We tried to center on lathe then pin with 3/8” roll pins . Failure first time still runout . Trued and tried again , issue is it is extremely difficult to find true lathe centers on the far apart longitudinally tapered hub ends you access . Regular brake drum conical wedges for turning do not do well sitting only on thin edge of taper 8” apart rather than in a big 2” flat pilot on new design later drums —and brake lathe cones do not even fit into narrow taper end . Becomes a party and a half . Drum can then tilt over that 8” two supports distance unless perfect on cones.
We realized mopar might have turned drum to final ID and center the brake machining after swaging drum to hub ( which would , maybe , put the 11 or 12” brake “ hole” off center in a rough cast drum ) . That idea is supported somewhat —as every factory one I have ever seen has a lot of balance weights all around it . But seems a really cumbersome way to do it. I do not know how they made them , but there is no centering pilot on the hub . Assembled in a jig? 5 holes drilled in a jig through flange and drum at same time ?
I think -if you are lucky - this info and part numbers really help , as the new ( assume) 11” drums he mentions may be more precisely machined with respect to centering the bolt patterns to drum shoe “hole” . Have to be , to interchange . Or they are today left loose on bolts (?why they drop right off now) but now using a pilot to center it notvstuds Can’t be loose enough on studs to drop off , yet center brake surface perfectly ? Clamp of nuts does prevent motion once tight . I am not sure this guy gets all this . Or maybe he had no problem . I hope the latter .
11 “ tapered drums are a big supply problem today . 12” drums for F are only available loose I have them from Kantor they are loose on the 300 bolts (!) If you throw on it will probably be off center ..Thought about going oversize press in studs … but will it be in the center ? Why the pinning . Did any cars use 12” drums with 4.5 bolts after 62 300? Buick drums are terrific , like that race B , but not easy , better on front . 5” pattern
If you can center drum and pin on a correctly centered hub that HAS to work .
What we finally did was pin as best we could then turned them larger inside . 010 to the center of the lath spin . As best we could center on taper . Very hard to separate tilt of drum from true runout . Need an axles end to hold it true .
I was looking for old axle to make a really good tool to hold them , in a machinist lathe , I still sort of am ( I never got one). Donations welcome .
My 11” issues ( D500) transfer directly to 300 12” . Never throw out old brake drums and shoes too if only half worn . One day you may love them both dearly . Or leave them in car .
As far as discs , they have lots of their own problems ,been there , lots of pedal travel results —- and stock 12” brakes won nascar ? unboosted . Discs need power boost lots of cc . Brings up balance to rears . Those valves are not so good.
The problem with our stock brakes is present brake mechanics can’t get them right mostly because all new parts don’t fit right unless shoes are arc ground . So long story starts , lots of mouth motion . So : Stick to , “ They won over and over at Nascar”= problem is mechanic skill, not brake design .
Don’t replace pre 62 12 “ unless really really needed .
Thank you so much for this , lots of good info . It helps .
Jg
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On Oct 24, 2022, at 12:19 AM, William Huff <whuff@xxxxxxxxxx> wrote:
