I recently saw a pic of an old set of brake drums that has been drilled. Is that the same principle behind drilled rotors? Does it actually improve brakeing or create problems of its own?
Outlawed by most sanctioning bodies in most cl***es of drag raceing. Roadracers I guess are still doing it. it allows your breaks to out gas and so it reduces fade considerably, Lots of other things to do to the brakes before drilling 'em. But it doesn't seem like a bad idea, it will weaken the drums a little, but i don't think enough to outweigh the benefits if you don't get carried away. BTW I forgot to call you yesturday, call me this evening, I m not going anywhere, if I do call my cell.
I recall reading a tech article about this in Street Rodder some years ago. the article echoed what porkn****** said. Within reason it can have benefits without compromising the drum. The holes will also help keep brake dust build-up down, keep the shoes cooler and let the drum shed water in wet situations. Hope somebody out there knows what issue that was in 'cuz I sure as hell can't remember but I know I have it somewhere...
Pretty much same principle as with rotors. They help the linings bite better, allow the drums to dissipate heat better, and allow the dust another exit. I have the rears on my 12-bolt cross-drilled (Performance Online offers them for GM apps).
I have drilled drums on vintage motorcycles, both for the road and the track. I can't say it made much difference, other than looking cool, on the road bikes. There was a big difference on the track, however. Under those conditions, with heavy handed braking, the front drums would fade much less/later. I have never witnessed any of the issues with debris or water that people bring up. It is very common with folks road racing vintage bikes. You only get one front drum, in that application, and it had better work. Just use your head, don't do too many holes and cover any 3" holes with some screen/mesh. And don't holes all over the place mean things go faster?
Not for sure if the drilled drums are for me. I was contemplating the idea as an interm while I save up for a real brake comversion (dual master disc/drum). Anymore you just might need a touch of stopping power with the crazy traffic these days. There was a post a couple of weeks back where someone took a hacksaw to the brakepads to slot it and help with water displacement. Kinda made me a bit uneasy but the idea stuck. I found a backyard webpage that a guy drilled the drums and it seemed a bit safer but kinda backyard scary at the same time.
The term "safer" can mean a lot of things to different people under different cir***stances. Look back a few years ago when people first started to drill brake rotors and compare that with what we see today. What you'll notice (I think) is that you'll see alot more modified rotors that are slotted instead of drilled or at least slotted to reduce the number of drilled holes. After contemplating why here's what I rememeber: Your brake rotor/drum is a heat storage device. At each application it absorbs heat - the frequency of application (heat induced) has to be allowed to dissipate or you will eventually heat soak your system. A rotor/drum with MORE m*** will momentarily absorb more heat energy. So there's the dilema - if you reduce the m*** you reduce the ability to hold AS MUCH heat. Consider the dragster - these have thin rotors with a zillion drilled holes - it works because they only apply the brakes once and then have ample time to allow them to cool off. Compare this with a road racer - they often run heavy rotors that have a LARGE capacity to store heat - storing more heat allows you more time to dissipate that heat between uses. I believe this is the reason why you now see the modified factory style rotors with small slots rather than big holes. The slots allow the outgas but keep as much m*** as practical. Ever watch those "when **** happens" programs on TV??? Ever see the one where they drive down those super steep hills??? Every so often you see one where on the 2nd or 3rd attmept all hell breaks loose and they FLY down the hill because the brakes failed. They basically apply the brakes the entire time - the rotor being a good design allows alot of heat to be absorbed, but on the repeated attempts they don't allow enough time to fully cool the brakes. Ooops!!! watch out for that tree!!!!! So applying the same logic to your drum brakes the "trick" is to remove only enough material to provide a benefit. If it were me - and I'm only thinking out loud I would first get brake shoes with a better "bite" then I'd consider slotting the shoes to allow outg***ing - I'd consider venting the backing plates before the drums. The drums are already being squeezed apart - adding holes could lead to cracking or ?? Any serious brake mod like this should be carefully considered IMHO - the consulting with a true Brake Expert might be the only safe way to fly or better stated NOT FLY!! I'm just thinking out loud - take it with a grain of salt.
If heats a concern you scoop the brakes. The deal is not to over do it. If one is good 2 is better very seldom applies in real life. On rotors I was talking with a tech guy from Bendix a few years back and he said that on cast rotors you shouldn't drill them at all. he said the very best thing the average joe could do with a cast rotor is to take a ball mill and dimple them all over. Probably what I'll do with the rotors on my project car.
Thanks for the article! Just what I needed to read. I emailed the company for more info on the cost of the cross drill. I also appreciate everyones feedback.
I thought about slotting the brake shoe - like the newer design pads have the slots in them - slotting the shoe at an angle every 2" or so about 1/2 way through the friction material should provide some of the same benefit of allowing outg***ing of the pads under heavy breaking and not introduce any weak points in to the drum. Also pads are cheap. Just make sure that the pad is bonded completely and not just rivited on the ends or it might be a wild ride
Performance Online also did mine. They worked great and I know Performance Online offers this service to just about any drum. I'm a fan of it... ~Scotch~
I was planning on doing this, but then opted to upgrade to disc. Maybe one of these days, I'lll still do my rear drums. I was planning on doing it myslef though. I made a similar pattern on the computer to the one CHTopping uses. A drill press and a some oil along with a sharp bit is all it would take.
For all interested CHTopping said that its about $45 per drum. They recomended doing the back set for sure but all drums would be the best solution of you want your drums drilled
My bad. I got real busy at work in the middle of that thought. They said "If you only do two at a time do the rears first. It will improve brake considerably." Not to imply just doing the backs but a suggestion when doing the whole car. If I go this route I will do all drums. The price seems reasonable to me for a quick brake improvement.
a thread I found thi s morning, http://www.tffn.net/drilldrum.html As soon as I get access to a drill press, I think I'll drill my rear drums. If it improves my braking, then awesome. If not, it's another cool factor. Never underestimate the cool factor.
Herb adams used to drill (Hole saw) the face of the drum between the studs so the air brought in by the scoops had a place to go. His Firebirds were some pretty awesome machines. On the old road course bikes they used to slot the shoes like you mentioned. I tried it on a Suzuki GT 500 with good results. The hacksaw blade to the shoes is something you can do at home.
That would look trick, except on my ride, no one could see it. A hole saw, huh? That must be some soft drum material.
Old drums aren't as hard as you would think. The drums on my '59 Ford rear were rusted on, I played with 'em for awhile and than said hell with it and took the sawzall to 'em. Made pretty short work of the drums. I don't know that I would be willing to pay someone 45 bucks for something I could do in the garage. its not like you need a CNC machine to do it, a tape measure and a drill press and you're in there like swimwear.
I had CH Topping do the front (they told me to do fronts first) drums on my 50 Plymouth. Noticable reduction of fade, and worth it IMO. But if you are doing a full-on brake rehab with new cylinders, shoes, lines, etc. I'd just skip it and go to discs. By the time you do everything the costs are pretty comparable.
Unless you drill them yourself. For $200 plus shipping, buy a drill press and have at it. I've got $500 into my front Granada disc swap, not including the booster.
CH Topping is real specific about the pattern and spacing of the holes they drill- here's a pic of how they do it. As to cost, If you have to buy all the other brake parts, turn your drums, etc. at least on my car that was several hundred bucks right there.
Is the drum standing up a right side drum?from what it looks like in the pic ,they may have made them"location specific" in the way they drilled them.Of course I could be thinking WAY too deeply.
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