I found this article in an old Classic Trucks mag. I thought it interesting to learn that Disc brakes are actually 50--60 lbs. heavier than drums!! And that with vented drums they work as good as discs, for much cheaper!! Money talks. Enjoy.

The original brakes on 50s classic trucks leave a lot to be desired by today s standards. Their singlebore master cylinders leave you with no stopping power when a wheel cylinder fails. There is always the emergency brake, of course, but you will probably end Up doing a donut when your back wheels lock—assuming you can apply it in time Then there is the problem of brake fade At today s freeway speeds, and on long downhill runs, your old truck's original drum brakes can heat up, fade and fail.

Luckily, these problems are easily remedied by a little inexpensive updating that still leaves your classic close to original I'm talking about installing a power dual-bore master cylinder and venting your truck s brake drums. Together, these two tricks will make your truck stop like one equipped with front disc brakes, all for about a third the price and a tenth the hassle. And you won't be increasing your truck s unsprung weight either.

Unsprung weight includes all the components on your truck that are not supported by its springs, such as wheels and tires, axles and brake drums (or discs in the case of disc brakes). Why is unsprung weight undesirable? Because unsprung weight is what causes your truck to ride like, well… a truck. The more of it you have, the worse your truck will handle.

Brake drums weigh about a third of what rotors do, and brake cylinders weigh less than a quarter of what calipers do All told, we re talking about 50 or 60 unwanted pounds in the front with disc brake conversions, just where you really don't want added weight on a pickup Also, front disc conversions cost in the neighborhood of $1,200 to $1,500 and require a lot of fiddling, finding parts, and cobbling them together to make them work. So unless you just have to have front disc brakes to impress your friends, why go to the trouble?

I had my drums vented, picked up a dual-bore master cylinder with power booster, and got all the components I needed to do a complete brake job for under $600 from Vince Bunting at C H Topping in California Vince acquired the skills and techniques for venting drum brakes from the inventor of brake ventilation, a fellow named Mel Hamer. Hamer liked to run his hot rod at the dry lakes back in the fifties, but he didn't like the way the brakes faded when he tried to slow down after a flying mile run.

He reasoned that if he drilled a few holes in the drums, the heat would escape and the car would stop better. Hamer experimented and figured out a way to drill the holes so his drums would not be weakened or become unbalanced, then ventilated his car's drums. What he didn't realize at the time was just how well this would work for him.

After a couple of nuns and stops at the lakes, Hamer's friends were so impressed that they urged him to do their drums too. Soon Hamer was venting drums full time and couldn't keep up with demand.

 

Iv actually been wondering about venting the drum brakes for a while now... But been too afraid of weakning them...
Has anybody done or seen this before, any sugestions or better yet pictures???

Would vented drums have the same cracking problem as drilled roters???

 

Look up that article at CH Topping Brakes. I think it was from 98. It looks like he drills them right at the edge where drum is a 90 degrees, just four little holes or so.

 

I would rather have better stopping power than lighter brakes

 

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I guess I forgot to make the point: drums have equal if not better stopping power than discs.

Discs, however, have fewer moving parts, are easier to maintain, and cheaper to make. That is why the car makers go with them.

 

I can't add much except I have had drums on three of the 66-77 Broncos I've owned, and discs on a fourth (factory on the 77). My current 70 Bronco has drums with a Duff Enterprises brake booster and it seems to stop as well or better than the discs I had on that 77. Much better than the drums alone on the two 67s I owned.

No data in terms of stopping distance, etc., just driving observations. Also no saying how F Series trucks perform with one versus the other.

 

I really have to question this, I was a truck driver for many years and that industry would really latch on to something like this if it was really better. In trucking lighter means more weight can be devoted to the load which means more money. Yet many newer trucks are coming out with disk brakes, in the hopes of being able to eliminate the need for engine brakes which drive up maintenance costs, and add weight. Even with venting the drums will still heat up under heavy braking, the drums will expand and the pads will not make as firm a contact with the drums and your brakes will fade. Venting may help minimize this, but will not eliminate it.

 

I agree. It looks to me like the author is trying to convince himself he doesn't need to convert to discs.

 

I find this believable. Drum brakes require several hundred PSI less brake line pressure than disks do, which tells me that for a given size drums have more braking ability than disks do. Disks will always vent their heat faster than drums and so they tend to fade less, but this article suggests that improving the heat sinking ability of drums is a significant improvement. Meaning you don't have to convert to disks to upgrade the brakes. The 4 wheel drums in my 73 work just as good as the front disks in my 91 bronco. And the 73 is heavier.

 

Drums get wet and do not dry very efficiently. The shoes retract and allow contaminates like mud, sand, oil and water to get in between the surfaces, this distance from shoe to drum is why drum brakes feel 'mushy'. If you off road with drum brakes you will soon find this out. Drums do have more swept area and are still used on truck with 80,000lb GVWR. Drums will lock before a disc and are harder to control. The anti-lock brake on a Tractor Trailer will not rapidly pulse like a disc system, it leaves 5 to 15 foot black marks in between pulses.
The wieght difference should be considered mass differences. The more mass then the less heat penetration. The disc rotors with the center fins can dissipate heat much better than an enclosed drum. Ride the brakes on the drum and see how quickly the brakes fade. Again with Tractor Trailers there is instructions on how to use them, ride the drum brakes on a down hill run and you will crystallize the shoes and fuse them to the drums, well when you eventually come to a stop/wreck. F DRUMS!

 

Disc brakes by design don't fade as drum brakes do. Brake fade happens when drum brake heat up and expand thereby causing the brake pad to lose contact with the drum. This is the flaw in drum brake design. Venting no doubt improves this problem, but cannot eliminate it.

I guess it depends on what you are going to ask of your brakes at to whether or not this will be enough of an improvement to stay with drum brakes or convert to disc.

 

When is the last time you saw drum brakes on a NASCAR car?

 

My 2 cents says yes, you can make drums as effective as stock discs, but discs offer far more potential and positives. Not to mention, these days you can do a rear disc swap for not much more than what a full drum rebuild will cost you. I have a couple local shops that sell complete disc kits for a 9" for $350.

 

This guy definitely isn't comparing d60 or corp 14 to disks.

Anyone who has converted one of these rears to disks knows what I am talking about!


As for drums working as well as disks - sure. When they are not wet, muddy, etc. like others have already discussed.

 

I switched my 73 Highboy to a front disc axle after the front axle broke due to a crappy design of NON captive spindle studs...Other than the wet brakes not working..I could get it to stop good...but it was a constant battle...the self adjusters would never work. I was always having to adjust myself...I could care less if the discs and all weigh more...they are much less of a headache than drums by far...and a hell of a lot faster to change brakes on!!