H: Hubs, Wheels and Tyres New Rear Brake Drum: To Drill or Not To Drill?

[Gary Gittleson]

Just bought a new H1/6R rear drum for my D Rapide. It has 10 holes for mounting to the hub as well as the sprocket holes, but unlike the old one, it has no drain holes. Should they be drilled or left as is? Or should I just avoid rain (no chance of that)?

 

[timetraveller]

My advice is drill the holes. I understood they were for getting rid of dust as well as rain.

 

[Gary Gittleson]

I'll take the advice and get the drill out. Thanks.

 

[Alyson]

Hmmmm not so quick. Ever gone to the car wash ? Brakes get wet. Most of my old bikes, still ride them, are brake lever/rod set up. Mechanical brakes. If they get wet, I ride the pedal for a spell to keep them dry. No problem. Adding a hole, you might think that lets water out, but it can let oil in. Hmmmmm Just my 2cents.

 

[Vincent Brake]

Thats a heavy breather!!!

 

[timetraveller]

Well I hate to argue with a lady, particularly with one with such a magnificent bustier, but where is the oil coming from? Did you mean water or are you used to very oily bikes? I just checked two brake drums, one a Comet or Rapide, the other a Shadow. The first one has no holes, The second one has ten equally spaced holes, each about 0.125" diameter and inclined at about 45 degrees to the braking surface. So if this is a ribbed drum then I would still advise drilling the holes. That is what Vincents did.

 

[Gary Gittleson]

Well, far be it for me to argue with such a lady but I'm siding with Norman. There's no sign of oil on the old brake, but the centrifugal force of the spinning drum should expel most of the water that gets in. And besides, I don't rely on the rear brake so much. The old drum is badly out of round. That's the reason for replacing it. I had measured it some time ago. I don't remember the measurements, but I do remember that in order to fix it, too much metal would have to be removed. Better a non-functioning or even a pulsating brake than a lock-up due to a broken one.

So why didn't the new one have the drain holes?

 

[Alyson]

Thank You Gentlemen. It was my hope that a discussion would ensue. As God didn't give us three heads, a discussion group will have to do.
I was also thinking centrifugal force would expel any moisture. In my youth, I rode old Harleys, so yes, very oily. The rear end always got the
brunt of it. Much harder for anything to enter a tiny hole when the forces are going in the opposite direction so I lament drilling holes for
water egress should not be a problem. Thank You for setting me straight !

 

[vibrac]

I have yet to use more than 5 holes of a ten hole drum and I would ignore the small drain hole. A Vincent brake is hardly a hermetically sealed volume