Disc vs. Drum

-
SpeedThrills

SpeedThrills

FABO Gold Member
FABO Gold Member
Joined
Jun 3, 2008
Messages
2,582
Reaction score
1,447
Location
Very South Jersey
I know disc brakes are supposed to stop better after repeated stops. I've never understood why drums aren't good enough for most applications. OEM must use them for some good reason. With them, it's usually about $, but it doesn't have to be. If a car already have discs, fine. It seems like a lot of time and $ to swap to them.

I had a Challenger R/T that of course, had 11" brakes. It stopped very well. When I put on metallic shoes, it would pop your eyes out. (Even cold, cuz they were 11's, I guess.) It should've stopped well, it had big brakes.

Our 4000# (w/ drvr.) Stock Eliminator Road Runner had 10" drums w/ standard linings. (10"er's were lighter.) It ran 116 mph and we never had a problem stopping. (Even at Numidia, a short shut down track.)

Here's where I'm going: My project 74 Dart Sport street/strip car will weigh approx. 3000# and will probably trap at 120-125. Why not use 10" drums w/ metallic shoes? Firm Feel sells them. It has 9" now. Drums offer the advantage of no drag, maybe lower weight? If this is feasible, would a 10" set-up bolt up to the spindle I have? It'll probably get a Dana or 8 3/4 rear.

This all depends on the application, of course. If you need stopping power, that's another matter.
 
Drum brakes have more shoe to surface area.
The advantage to discs is not stopping power, it is straight line stop , especially in panic braking. Thats the reason behind the OEM change in automotive applications

Point to ponder, cable operated evelaters have drum brakes. Difference there is shoes are wrapped around outside of only one drum. But then those can only stop in a straight line. LOL
 
Drums also need to adust themselves as they wear. If they aren't adjusting well, you can always "pump them up", but if someone stops quickly in front of you on the street, you can pump yourself right into the back of their car.

I swap every car I drive to discs. The drums don't work as well in real-world traffic.
 
The surface area note is a worthy note and should be noted that a brake drum has the abilty to stop very well. Now here is the major advantage of disc, heat displacement or getting rid of heat.

Drum do not get rid of heat so fast vs. discs. Or at least should be the case. Well vented discs are better and in repeated applications, do well over drums.

Cooling the brake system with any set up will provide a great advantage in brakeing. If you can route a hose to cool your drums, they will retain better braking just like a disc.

Though I have not seen vented drum brakes yet. (Hummmmmmmmmmmmm)

I'm still running all drums on my Duster with the V8 swap done. I increased the rear drums to 11 inchs from the stock 9 inch at the rear. 9's are still up front.
 
All braking really is, is turning energy into heat. Disk brakes are way better at that, they also give better constant pedal feel and are easier to "balance" side to side. Additionally, they last longer and work much better when wet.

I like disks on the front of a car, and they are usually lighter than drums, but not by as much as you'd think. For the rear, I actually prefer drums, especially if its going to go down the track. The stopping power for one big stop is nearly identical to disk and the maintenance is sooooo much easier with drums.

Some late fifties/early sixties corvettes actually had vented drum brakes

Here's an article that talks about upping the performance of drum brakes. Its got some pretty neat ideas.

http://www.automedia.com/How_to_keep_Drum_Brakes_cool/res20051101db/1

Steve
 
Im a big fan of drum brakes myself. If I didnt have to go to the 4.5 bolt pattern, I would be keeping all 4 corners on drums....
 
For a drag only car drums have 2 slight advantages:

1. The shoes can be adjusted back for zero contact and therefore no friction.

2. A 9" drum has less rotational mass and will accelerate faster.

If you only have to slow the car down once an hour or so, in annice flat dry shutdown lane drums are OK. In traffic they are inferior.

I've never figured out why somebody will spend $5000 on a paint job, $10,000 on an engine and cheap out by refusing to spend $200 on decent brakes.
 
for drag racing,some of the hemi darts and barracudas came with 9" drums....for real world driving go with the discs
 
SpeedThrills said:
Here's where I'm going: My project 74 Dart Sport street/strip car will weigh approx. 3000# and will probably trap at 120-125. Why not use 10" drums w/ metallic shoes? Firm Feel sells them. It has 9" now. Drums offer the advantage of no drag, maybe lower weight? If this is feasible, would a 10" set-up bolt up to the spindle I have? It'll probably get a Dana or 8 3/4 rear.

This all depends on the application, of course. If you need stopping power, that's another matter.
Click to expand...

10" drums use a different spindle than the 9 inchers. Since you have to change spindles for this upgrade, you may as well use discs. Or you could keep what you have if most of your driving is on the strip. Just converted my Valiant from 9" drums to discs. No way would I go back to drums, but then I like having brakes when I get to the bottom of the hill.
 
The big advantage for disk brakes is increased fade resistance. No question about it.

Surprised no one has said how much better disk brakes handle water. If you live where in never rains in southern California, it may not be an issue. Here at the Edge of the World with its crummy streets and easily overloaded drainage, driving through deep water happens. Even dragging the brakes while going through the water produces a much more exciting first stop on drums than disks.
 
My dad's 68 Coronet cop car came with 12 inch manually adjusted manual brakes--no power. He did not order power brakes as they did not feel right.
What a nightmare they were having no self-adjusters. And the drums had hard spots in them-warped and ate shoes. CRAP CRAP CRAP.

When he bought a Mercedes in 72 that had 4 wheel discs, he was amazed what 4 little pads 1/2 the size of a pack of smokes would do when you nailed them from 120 mph.
 
Good mention!!!

Drums in water = bad!!!!!

Discs in water = not so bad.

I experianced this just a few days ago and forgot about what hapens. EEEEEK!
 
9 inch drums + hard rain = wheeeeeeee!!!!! You stab the brakes at highway speed and you never know what direction you're going to swerve.
 
i prefer disk over drum myself. i have disk on my 72 scamp and drums on my 68 dart. stopping the dart in traffic is scary at best when they work right. as soon as i can afford to i am upgrading them to 73+ disk and rear axles. BOTH cars. fnding 5x4 bolt pattern stuff is not easy or cheap.
 
You could try this. I don't know if it will help with heat or water. This was just done to lighten them up a bit.

100_0915.jpg


100_0916.jpg


100_0917.jpg
 
MAN! That's some Chit I tell ya. Never thought about doin that!
 
Any of you guys ever remember seeing Buddy Baker in a Superbird at Daytona set the tires on fire because the drum brakes locked at speed? When the primary shoe pulls away from the anchor pin to "wedge" the pair of shoes against the drum a certain amount of momentum is created from the mass of the shoes. At high speed this can be a real problem....
 
I appreciate all the reponses to this. I'll probably use 10" drums all around w/ metallic shoes (it won't be out in the rain), or '73 up style front discs w/ 10" rear drums. It'll depend on what's available when the time comes.
 
I did a brake test 10" drums vs 4 wheel disc brakes from Master power.

I am at work now and dont have the numbers, but we did braking tests from 20, 30, 40 , &60 mph to zero - the drums fade, the discs dont. The 4 wheel disc brakes were about half the stopping distance of the drums.

When someone pulls out in front of you, you sure could use that extra space, couldn't you?
 
You must log in or register to reply here.
-

Back
Top