brake drum fins

[Ron]

Hi all, does any one know the function(s) of the fins on the 113's rear brake drums.  Is it cooling or balance or both?  The reason I'm asking is there are two types of fins on each drum, thin, and 4 that are fatter, at 90 degrees.  That is on one of my drums I see 4.  On the right drum, two of the fat "fins" are missing, but the surface where they should be seems smooth, like they were never there.  So were they removed at the factory for balance?  Or should I be looking for a new drum?  Thanks, Ron

[mdsalemi]

Ron,

You got it right--brake cooling.

A popular after-market upgrade for many sports cars and rods of years past was, and remains "Alfin" (or, "aluminum fin") brake drums, which are cast and or machined aluminum with steel linings.  The aluminum of course, dissapates heat quite a bit better and faster than cast iron.

[Ron]

Thanks Michael, but is my right drum missing the two big chunkier fins by accident?  Will it be unbalanced without them?  Or did M-B balance the drum by leaving them off?  Thanks, Ron

[ja17]

Hello Ron,

It should not cause you any problems. If you plan to go racing with it next week you may want to change it, otherwise you will be fine.