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aluminum drums


Guest oldtimer

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On the 12-inch drums, the "early" drums have 45 fins. The "later" drums have something like 90 fins. I'm not positive of the count on the later drums, More importantly, I'm not sure of the year spread for either of them.<BR>We've done this topic before in the last few months, but we never settled on the fin count for the "later" drums, and we never settled on the years for each.<BR>(incidently, I just found out that '69 Skylarks came with 9.5-inch finned aluminum drums, with 63 fins on them)

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Guest oldtimer

sorry i must have missed that last topic. my main concern is the 12" front drums, are the hubs different from year to year. just i case if come across some at the swap meet or in the paper. i have some from a '66 rivi and i'm putting them on my '50 jetback along with a 455, 700r4 and 9" (adapting buick 12" rear drums to the 9"). anyway one thing at a time....... just tring to gain some knowledge about the drums also does anybody know if those drums can have a new ring (steel)put in them or are they cast in the drum (and junk when at the max limit).

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I'm putting aluminum drums on the front of my '54 Special, and have started with a set of the wide-spaced fin drums. The stock hub didn't fit (after a lot of bearing cross matching), so what I settle on is to press the stock hub out of the iron drums and put the aluminum drums on the stock hubs.<BR>The problems I ran into: The OD of the hub mating surface where the drum slides over was a touch big, so I had a machine shop turn down that shoulder on the hub (keeping the register on the drums as the universal fit part for future replacement).<BR>Next was that where the drum and backing plate come together at that lip. The backing plate bottomed out in the lip so back to the machine shop to have the "valley" at the back of the drum made a bit deeper so the backing plate doesn't bottom out.<BR>Next problem was the wheel bolts. The stock set up uses wheel bolts to fasten the wheel to the drum/spindle, while the aluminum drums use standard lugs and bolts. The wheel bolt holes in the hub have to have the screw threads reamed out of them to press modern wheel studs pressed in, or the holes in the drum need to be enlarged so the stock wheel bolts to through. When swapping to the aluminum drums, you'll lose the locating pin to line the wheel up with the bolt holes in the hub, so switching to modern lugs and bolts is probably the better way to go (makes putting the wheel on the car a lot easier). <BR>I wanted to get the car back on the road, so instead of sending the stock hubs back to the machine shop again, I put the stock iron drums back on until the next time I have to take the front of the car apart.<BR>Secure the drums to the hub by tapping the three rivet holes in the hub and secure the new drum to the old hub using Grade 8 button head screws and Loctite.<BR>Also, the stock drum face is much thinner than the aluminum drum face, so keep that in mind when ordering new wheel lugs from the parts store. There are a ton of different lugs available, with dimensions that will fit what you need (shoulder, overall length, threaded shaft diameter, etc.) <BR>To do it on the back of the car, it's a lot easier: Adapt the axel flange to the 12-inch backing plate and have the axel register or register hole in the center of the drum machined to fit. Make sure the axel sticks out of the rear end far enough to cover the width of the drum.<BR>Don't know if this is what you were looking for, but it might help.

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Guest oldtimer

Thanks, i haven't started it yet. i was told that they would bolt on with some backing plate (cut lip slightly) and grease seal modification (need to make a spacer for spindle where grease seal sits, because seal from the aluminum drum has a bigger hole on the spindle.) as far as the rear it should be no problem, i helped a friend mate a 9" backing plate to a '40 ford backing plate so he can run '33 spoke wheels on his '30 model a.

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I can add this: The later style definately have 90 fins exactly (just counted my NOS drum twice). I also know that '64s use the 45-fin drums, and my NOS drum is in it's original box which is marked "66-67" on it, so the question is- which do '65s use?<P>From an article in 10/58 Motor Trend on the drums: "The new method of making the drums has a cast iron liner grit-blasted down to pure metal, then immersed in molten aluminum at 1375 degrees. By slow agitation the aluminum combines chemically with the raw iron, forming a surface coating of iron aluminum alloy. The iron liner (maintained at 1375 degrees) is transferred quickly to a permanent mold, where the aluminum drum body is cast around it." <P>Popular Mechanics got a new '60 Invicta 4-dr to average a 60-0 stopping distance of 138'. Imagine what a set of even marginal tires of today could do to shorten that distance! <P>brad54, can you elaborate a bit on the studs story? I want to retain my stock front 12" drums on my '59, yet swap over to studs instead of the bolts. The aftermarket wheels I'm using can't be used with stock lug bolts. Is there a reason a quality grade 8 stud (not a knurled wheel stud) can't merely be threaded into the existing drums threaded holes (from the backside) to project out and be used with lugs nuts/ aftermarket nuts?

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That info on the year change is gold! Do you have the copies of the articles you quoted? I'd gladly pay you for photo copies. <BR>(Got anything concrete on the 9.5x2.5 finned drums from '67-69 Skylarks?)<BR>As for the stud question, I don't know what the bolt diameter is for your wheel bolts. I do know on the drums I have (from a '63), the hole in the drum is a lot smaller than my '54s wheel bolts.<BR>Sometimes manufacturers put left hand threads on one side of the car due to tire rotation/lug nuts loosening, but that theory seems to have gone by the way side. I don't know how that would affect bolts on the back side of the wheel.<BR>You might also have a clearance problem with the bolt heads.<BR>My personal (and I stress that) opinion is that it'd be better to go with a wheel stud. A drill press will clean the threads out (I didn't have one at the time), and a look at the book at NAPA or somewhere will show that there are a ton of differnt combinations for wheel studs, with the dimensions listed including bolt diameter, bolt width, shoulder diameter, shoulder width, etc. Check out the studs before you make a decision.<BR>Thanks again for the info on the years!!!<BR>-Brad

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Guest oldtimer

hmmmmm, i don't think that the drum iron ring is replacable. on the grade 8 stud question, you need to find some way to make the stud lock in place so it won't turn in (and poss. hit something or only have a few treads in the nut). I just though of something, if you have mags (with a deep hole) you can measure the drum and mag (take into consideration the depth of the mag). get a stud and thread it into the nut (and use locktite), make whatever type of nut you need into the same stud/nut you have stock. you also might need to remove the locating pin on the drum (if yours has one).

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brad54- E-mail me [ventiport@earthlink.net] your address & I'll send you some copies of what I have. I don't have much info on the small Buick's brakes. <P>On the 12" drums: Bolt head clearance wouldn't be any problem. I already cut off the locating pins. In fact, I have to use wheel spacer discs to clear the rivets on the stock drums, and I had to enlarge the hole in the (universal) spacer to fit over the hub. Left-hand threads are not used in '59. <P>You're right tho- it's a simple procedure to drill out the threads & use conventional lug studs. I can see how the tightening of the lug nut would want to loosen the lug stud. Thanks for the info, guys. <P>Actually- it may be possible to replace the iron liner. There is one guy who relines Pontiac 8-lug aluminum drums, but they are an interference fit & were not constructed like Buick aluminum drums. Still, I don't see why the liners couldn't be machined out and a new one installed, tho no one would be happy at the price tag that would have to come with the job!

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