Quote:
Originally Posted by BigTopGT
My question here is:
My drums immediately lock up the tires in my 67, so how is going to discs up front going to do anything other than continue locking them up?
I'm not sure I'm understanding the value of more brake in a non ABS vehicle, I guess.
|
Quote:
Originally Posted by BigTopGT
I'm not asking how brakes work, I'm just trying to continue the brake conversation.
If you're not here to talk about things on the forums, why be here at all??
To tell people to "use the search feature"?
Anyway, in a discussion about going with brakes that should provide greater stopping power, I'm simply curious as to whether anyone is seeing an actual stopping distance benefit to non-abs brakes, when smashing the pedal results in the brakes immediately locking up either way.
Not trying to fight here, man.
|
Keep in mind that disc brakes actually use less force than drum brakes. Disc brakes are "modulated or proportioned" compared to drum brakes. Proof in point is that Front disc/rear drum vehicles have a proportioning valve to limit the disc brakes in proportion to the rear drums.
Drum brakes are exactly that, brakes inside of a drum. This causes several issues:
1- They heat up quickly, and don't extract heat well. This is why they "lock up the wheels" as you say. Heat, caused by friction, is what makes brakes work. The quicker they heat up, the faster they work and harder they bite. This is fine for short, minimal use, but extended use causes brake fade. Brake fade is when the friction material has reached or exceeded maximum operating temperature and no longer holds. This is multiplied in a drum since it can't cool down quick enough
2- Too many moving parts. If you've ever taken the drums off to change shoes, you've noticed there's a lot of parts to make drum brakes operate. Disc brakes have pistons, whether it be a single or multiple. Those extra parts have too many failure points. And guess what the number one cause for these failures....heat....as mentioned in the first point.
3- Inconsistent pressure control. Due to the first two points, this causes the hydraulic pressures to be unevenly divided. You may ask, "What does this mean?" Try to panic stop in an all wheel drum vehicle and you'll find out. You'll get the thrill of finding out which particular wheel all that pressure wants to go first causing the vehicle to dart in one direction before the pressure equalize causing all wheels to finally garb and slow you down. That's if you're not in the ditch or into the back of the car that suddenly stopped in front of you because the brakes "locked up" causing you to slide.
Basically the safety in disc brakes is the ability to dissipate heat quickly, maintain a steady clamping force, and less failure points with minimal moving parts.
Now the reason a disc front/rear drum setup is still acceptable is because over 70% of a vehicles braking is done with the front wheels, causing less dependability of the rear drums to stop the vehicle.