What was the purpose of the finned 9 inch front drum on early 70's A-bodies.I have seen two cars with these brakes on them,my ex wifes 71 Demon and the 72 Valiant that I just bought for my daughters first car.
It seems to me that if you wanted a heavier duty front brake that you would opt for 10 inch drums or disks.Can these finned drums be found in the aftermarket?I havent found them in the usual parts sources.Do these brakes use the same shoe as the non finned 9 incher?Do they perform any better?
The drums are in good condition and car stops very well but I was thinking about future maintenance.

Thanks
HyperValiant

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1960 Hyper-Pac Valiant(rolling test-bed)
1963 Valiant V2OO(Son's summer project,- he just turned 15 )
1972 Valiant 4dr(Daughter Kelly's repair in progress)
1974 Valiant (v8) daughter Kelly's work in progress

Same as fins on any other air-cooled hunk of metal (such as the engine on your lawnmower or in a Porsche 911, or the processor heat sink in your computer): To shed heat more quickly! The finned drums were used from '70-'72 on cars with 9" drums.
Correct.
Raybestos 2956 or 2956R.

You can also use the '73+ front wheel cylinders, Raybestos WC 37269 and 37270, to get a little more whoah out of those 9" brakes.

All of these P/Ns can be had at RockAuto or your local stockist.

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一期一会
Too many people who were born on third base actually believe they've hit a triple.

Can the 9" finned drums and the 73+ cylinders be used on earlier non-finned cars?

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Ed
64 Valiant 225 / 904 / 42:1 manual steering / 9" drum brakes

Sorry, meant to mention that. Yes, these parts interchange all the way back to the 1960 Valiant.

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一期一会
Too many people who were born on third base actually believe they've hit a triple.

RockAuto has pictures and I don't think the wheel cylinders are interchangable. (73+ has rectangular mount, 72- circular)

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Ed
64 Valiant 225 / 904 / 42:1 manual steering / 9" drum brakes

Thanks for the info Dan,I knew you would have it.What I meant about upgrading was that I couldnt understand why the factory would offer an upgrade on 9 inchers when they could just pull out 10 inchers and bolt them on.
Thanks again for the info.
HyperValiant

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1960 Hyper-Pac Valiant(rolling test-bed)
1963 Valiant V2OO(Son's summer project,- he just turned 15 )
1972 Valiant 4dr(Daughter Kelly's repair in progress)
1974 Valiant (v8) daughter Kelly's work in progress

I'll confess to not having looked super closely; you may be right. I'd want to hit a parts store and have both pulled and check to see. Worst case scenario, you could swap on the backing plates from a '73+.

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一期一会
Too many people who were born on third base actually believe they've hit a triple.

that is correct-- they have a rectangle style w/cyl & oval style---- I do not know the year cut-off -- the older models have the oval style w/cyl---