Drilled Brake Drums???

[4woody]

Any of ya'll ever tried this or know anything about it? I've got 4 wheel power drums on my 50 Plymouth. They start powerful but fade noticibly, so I'm wondering if this might solve the problem without the expense and hassle of switching to discs... Drum Drilling (http://www.chtopping.com/CustomRod4/)

[Fraz]

Do a search and you'll find we've discussed this about 3 times before.

[4woody]

Yep, found it. Shoulda searched first, I guess. Sounds like it would be what I'm looking for. Thanks.

[Unkl Ian]

Looks like an article from Custom Rodder...
" But the main benefit is the fact that when drums are vented properly, so as to eliminate balance and material integrity problems, they virtually eliminate fade, which is.the primary reason discs replaced brakes while racing at the dry lakes. He figured drums in the first place. Gasses are vented as well, as the holes create what amounts to a venturi effect, venting gases created by compression of air between the shoes and drum that would otherwise be trapped in a stock, unvented drum, hindering braking efficiency. This also holds true with disc brakes (believe it or not), so venting is beneficial here, too.
Another benefit is reduced unsprung weight, which improves ride quality." http://www.jalopyjournal.com/ubbthreads/images/graemlins/confused.gif http://www.jalopyjournal.com/ubbthreads/images/graemlins/confused.gif

"Text by Dave Hill"
That would explain it.

I drilled the drums on an 800 lb racecar.
They eventually cracked.
So on a car weighing 4 times as much,going half as fast would probably meet with the same result.

[4woody]

Who is Dave Hill?

[Machinos]

I see no reason why drums that were in good condition would crack if drilled properly. Also, the "unsprung weight" thing means that drums aren't nearly as heavy as discs. Drilling the drums doesn't improve the handling/ride quality, but adding discs makes it worse.

[Morrisman]

Sounds dangerous to me, drilling drums. All your strength is in the integrity of that outer cast rim, so pop it full of holes and it gets measurably weaker. You can do it happily on discs, as the disc is being squished back into itself when you slam the brakes on, but a drum has hellish forces pushing it outwards. Drill holes and you've intoduced stress risers and possible cracking points.

If you want ventilation open up the inner cover, run little scoops, like plenty of guys do. That'll get air blowing through. Fit bigger drums, fit better material, fit a brake servo, fit a longer brake lever, but don't fill the drum with holes.

Just my home brewed, somewhat bias opinion http://www.jalopyjournal.com/ubbthreads/images/graemlins/tongue.gif

[Unkl Ian]

[ QUOTE ]
I see no reason why drums that were in good condition would crack if drilled properly.

[/ QUOTE ]
Drilling holes in anything creates stress risers.
The stresses around the hole are 3x greater than without the holes.

If you look at the real serious race brakes now,they are not drilled for this reason.