I have noticed that on the Cobalt SS and SS SC there are disk brakes on both front and back wheels. While on the base Cobalt, LS and LT, they have drums in the back and disks in the front. I have also noticed that other high performance and high end cars such as Lexus, BMW and Mercedes also have disk brakes on both front and back wheels. So I am assuming that disks are better than drums. My question is, what is the difference between the two?

 

http://www.edmunds.com/ownership/tec...7/article.html

 

One is not better then the other. A drum brake actually has better stopping power the a disk. However, the disk can dissipate heat faster and, don't forget; Looks Cool! %90 of the reason a disk brake is on the rears of most high end cars is the looks.

 

Discs can dispel water faster too if you've just splashed through a big puddle.

Personally, if I'm working on my own car, I'll want to have discs every time. 100% easier in my opinion. I hate wrenching on drum brakes.

 

+1 billion. i wont touch drums
i have the patience to strip down an LT1 in a camaro with the motor still in the car, but not for drum brakes

 

I hear ya there. My beater has drums and damn I hate changing the pads on those. I can do disc brakes in about 5 minutes a wheel tops. Drums are a good half hour a wheel job.

 

half hour? thats it? takes me 30 minutes just to decide grab my glock to shoot them off

 

Very interesting article. Thanks!

 

rear wheel discs suck up here in the great frozen north... the sliders freeze up and the rears will lock... my winter beater Lumina is going through that right now... i have a sneaky suspicion that the rears aren't working.

Scott

 

drums have better stopping power than disc brakes? who ever told you that is smoking crack. disc brakes stop much better than drum brakes. thats why EVERY car has discs on the front, 60 percent of the braking is down with the front brakes. it has nothing to do with looks, even though disc brakes do look 100 times better than a big goofy drum. highend cars like mercedes and lexus have 4 wheel discs because they stop the car faster without damaging the braking components.

 

yeah discs are easier to change. I refuse to change the rear brakes on my old cavalier, even when they have the factory (140k+) miles on them....
I'm glad chevy had decided to go with discs all around on the ss models...

 

Semis and trailers use drum brakes because they offer more friction surface area over a conventional disk brake setup. They also run pneumatic systems, so pedal effort is kept to a minimum.

In performance applications, fade resistance and pedal effort are the focus. ANY brake setup can provide enough power to lock up the wheels. The key is having enough fade resistance - determining how long/often that force can be used.

Really, stopping power is mostly dependent on the tire-road friction.

 

discs are used in the front for several reasons, mostly because they're a lot less likely to lock up, so the car stops straighter, safer and with better pedal feel.

drums hold a lot harder.

also, disc parking brakes have a tendency to warp rotors if you park while the brakes are very hot.

bear in mind, this is all speaking generally, obviously the front discs on an enzo stop harder than the drum rears on my old geo prizm.

 

Drums are also heavier

 

drums are not that bad to work on. i can have the whole front of my bronco ripped down in 15 min. and i have to deal with lock out hubs.

 

i could do one drum in my Cavaliers in about 20 minutes... when i started working on cars, i used to take polaroids of how it looked before i started, just in case i got distracted, called away, or whatever... my coworkers thought it was funny as hell.
Discs are much nicer... :P

Scott

 

well keep in mind this is 1966 technology

if you got the right tools and a sound mechanical mind you can do it its easy.

 

Because they dissipate heat faster, they also have a higher stopping power. Which is why discs are on the rears of high end cars.

Drums are cheaper. That is why they are on the rears of most cars.

 

IMO, i would think disc brakes are better, they dissipate heat faster, better stoping power, etc..... i know semis use drums, but if you seen one before, the shoes are about 10 or 12" wide, thats just a guess, i never measured one before, but also remember that, the brakes are not used that often in semis because they use jake brakes. i remember when i was with my boss, loaded, going down a big hill and the jakes quit working.... it was kinda scary, he was able to keep the speed down but all you smelled was brakes the whole day and once we got to the bottom and stoped, their was lots of smoke coming from the wheels.....i think in a semi, drums are better because you can fit a very wide drum, and will have a bigger surface area than a disc brake set up, but in a car, there isnt enough room for wide drums, and it would be alot heavier, which is why the disc are way better.....
disc brakes FTW!!

 

Yes, that is exactly why drums are used on semis.

 

Not totally true, the jake brake is not always used as a brake replacement. Engine braking is the way unless there are noise restrictions in the area. I should know, I drove some big rigs in the military.

Back on topic though..If Drums were so much better then discs in stopping power then why are there so many upgrades for disk brakes? Why are there so many conversion kits? I would take disc over drum anyday, and not just for ease of working on them, disc brakes do look HOT especially when drilled and/or slotted has been added, and they do stop much much better for many reasons. To include heat dissipation, brake fade, ect...

 

I was meerely agreeing that drims on semis are larger than on a car, so they use drums for surface area.

Anyway, drums are definitely not as good as disc. For all the reasons you and I have both listed in our posts

 

lol..I wasn't bashin ya. Thanks for the backing though.

 

Drums on a semi work completely different than a passenger car or light truck, though. The air pressure keeps the two shoes away from the drum service ntil you step on the brake pedal and slowly, through what's more or less a proportioning valve, you remove pressure and cause the pads to hit the drums. Ever see skid marks on a highway from a semi? Many times, it's because the air supply system had failed causing the wheels to lock up.

Scott

 

The method of applying the shoes is different, but the fact that they use drums still resides.