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Old 09-22-2011, 09:32 PM
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Aluminum rear drums cross drilled

Do you ever think about Aluminum drums, or cross drilled iron? They advertise superior brake fade and performance from a drum system. After some looking unfortuneatly, the places that used to lathe them out are gone. Where do you get replacement AL drums?

Could machine out your own 6061 alumnum drums out a 12" stock on a lathe? Would it be a cake walk , but my lathe chuck goes up to 4".

Cross drilling the stock drums is a second choice. Try to save some weight and reduce heat. Anybody try this or feel it is not safe / worth it?

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Old 09-23-2011, 12:46 AM
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Al. drums aren't made anymore. They're weaker than Cast Iron to start with, not sure about X-drilling them.
I'd just go with Discs before I went thru all that trouble.

They're getting very hard to find, thanks to "$$ for Clunkers".
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Old 09-23-2011, 08:41 PM
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Rear brake drums

How would one go about "cross drilling" a drum brake?

Solid aluminum drums would be way to prone to distortion IMO. Aluminum drums- like were found on various midsized GM products in the 70's-80's had an iron liner to them. They weren't particularly large/wide, though. But they do save some weight over a similar sized iron drum.

On the domestic front, there are also the old Buick-type finned aluminum drums that can be found repop or rebuilt. There were also Pontiac aluminum drums- but they had a unique 8-lug wheel pattern (both also w/iron liners). Big money for any of these, though

IMHO, for the tiny amount of weight that you could ever save by machining on an OEM iron rear brake drum, I'd say to forget it. You'd be better off (weight- and safety-wise) going to a small disc brake set-up if unsprung weight was such a huge factor. Otherwise, just keep the iron drums in adjustment, use a good shoe compound and they'll do fine in many rear brake applications.

Last edited by cobalt327; 09-23-2011 at 08:52 PM.
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Old 09-24-2011, 06:12 PM
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The aluminum drums had an iron liner like Cobalt said. I have a couple sets.I put one set on my 79 Bu and the other on my 70 Nova. You can find them on 78 and up A/G-bodies. You have to open up the centering hole a little bit to get them to fit the pre-78 stuff though. I got mine from the salvage yard and through a friend that is a scrap metal dealer. You can save approx 5 lbs per drum by using the aluminum drums.
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