Drilling a brake drum

Gun · Post by **Gun** » Wed Jun 30, 2010 6:50 pm

I noticed some fellers drilling out the drum brakes....
perhaps for cooling, or to allow brake dust to exit... both? not sure.
just wondering if anyone had any knowledge regarding this.

my cb77 rebuild isn't going to be a restoration, so i'm okay making changes like these if they improve aspects of the bike (the engine is the only thing I'd like to keep as stock as possible)

davomoto · Post by **davomoto** » Wed Jun 30, 2010 6:54 pm

For cooling and lightness. It was often done back in the day. It works much better if the brake plate has an air scoop on it. Fast Fred taught me another old trick, to drill from the center of the hub, through the metal lining, to reduce weight as well. Everything on the wheels is unsprung, rotational weight, and reducing it helps handling .

Gun · Post by **Gun** » Wed Jun 30, 2010 7:07 pm

Dave, when that time gets closer, would you mind if I contacted you about how to do this properly if i decide to do it? First, I'll have to see if loud mouse scolds me for considering it or if he decides that i'm beyond hope and doesn't bother.

davomoto · Post by **davomoto** » Wed Jun 30, 2010 9:12 pm

No problem Gun, give me a shout, and I can e-mail you some pics.

LOUD MOUSE · Post by **LOUD MOUSE** » Wed Jun 30, 2010 10:36 pm

Bang! Bang!.. :-). .......lm

Gun wrote:Dave, when that time gets closer, would you mind if I contacted you about how to do this properly if i decide to do it? First, I'll have to see if loud mouse scolds me for considering it or if he decides that i'm beyond hope and doesn't bother.

teazer · Post by **teazer** » Thu Jul 01, 2010 2:33 pm

Gun,

It's really simple. Use a hole saw in your electric drill for the brake drum and regular drill bits for teh backing plate.

try to make sure the holes are evenly spaced and are not cutting through webs. Try where possible to break all sharp corners - sharp edges act as crack propagation points, so smooth/round off edges.

LOUD MOUSE · Post by **LOUD MOUSE** » Thu Jul 01, 2010 4:50 pm

Lots of folks aren't aware of that. .......lm

<<<Try where possible to break all sharp corners - sharp edges act as crack propagation points, so smooth/round off edges.>>>

teazer wrote:Gun,

It's really simple. Use a hole saw in your electric drill for the brake drum and regular drill bits for teh backing plate.

try to make sure the holes are evenly spaced and are not cutting through webs. Try where possible to break all sharp corners - sharp edges act as crack propagation points, so smooth/round off edges.