Dumb question - are there wear and tear parts on Drum breaks?

[vi edit]

I am break maintanence impaired. One of my cars has drum breaks. Are there parts in there that regularly need to be replaced? I'm only used to owning cars with disk breaks and having to replace pads and rotors.

 

[Zenmervolt]

The return springs, and the slave cylinders come to mind. The shoes and drums themselves too I suppose, though it's common practice to replace the shoes when new pads are needed IIRC.

ZV

 

[notfred]

yes. They work the same way as disc brakes, only the pad rubs on the outside edge of the disc rather than the side (basically). And it's brakes, not breaks.

 

[woodie1]

For sure the shoes and wheel cylinders wear. Possible other parts on some cars.

 

yes. They work the same way as disc brakes, only the pad rubs on the outside edge of the disc rather than the side (basically). And it's brakes, not breaks.

What ?

Generally there are several parts besides brake shoes and wheel cylinders that will wear out over time.

(1)Brake hardware (Springs, retainers and self adjusters).
(2)The brake shoes will wear grooves into the backing plate where they make contact.
(3)E-brake cables/crosslink bars


All drum brakes except very early designs (1950 and earlier) are self energizing, meaning that when the shoes come into contact with the drum, they pivot and cam themselves against the friction surface.


How drum brakes work

 

[desertdweller]

Originally posted by: vi_edit
I am break maintanence impaired. One of my cars has drum breaks. Are there parts in there that regularly need to be replaced? I'm only used to owning cars with disk breaks and having to replace pads and rotors.

Are you having a specific problem?


DD

 

[vi edit]

Are you having a specific problem?

No, not really. Just really had no idea what was involved with the upkeep of drum brakes. Under similar driving conditions, do drum brakes tend to have more less maintanence than disk brakes?

 

That is too broad of a question to answer

Usually drum brakes are only found on the rear of vehicles, this is because as the vehicles brakes the weight shifts to the front, the front brakes on most vehicles do 75% of the work.

Drum brakes have more moving parts than disc brakes do, also because drum brakes are not vented to the atmosphere, they tend to collect brake dust.

Generally when doing your front brakes it is wise to pull the drums off on the rear and check for wear and clean and adjust the shoes.

 

[notfred]

Originally posted by: Roger

yes. They work the same way as disc brakes, only the pad rubs on the outside edge of the disc rather than the side (basically). And it's brakes, not breaks.

What ?

Generally there are several parts besides brake shoes and wheel cylinders that will wear out over time.

(1)Brake hardware (Springs, retainers and self adjusters).
(2)The brake shoes will wear grooves into the backing plate where they make contact.
(3)E-brake cables/crosslink bars


All drum brakes except very early designs (1950 and earlier) are self energizing, meaning that when the shoes come into contact with the drum, they pivot and cam themselves against the friction surface.


How drum brakes work

I just meant that there are two friction surfaces that rub against each other, and hence will eventually wear down. I also said they're in a different orientation than in disc brakes.

 

[vi edit]

Thanks for the replies guys

And yes, the car has disks up front, and drums in the rear. I was going to take the car in and the pads replaced on the front and wanted to be a little more familiar with the terminology of the drum breaks before asking them to look at the rear.

 

[Zenmervolt]

Originally posted by: Roger
That is too broad of a question to answer

Usually drum brakes are only found on the rear of vehicles, this is because as the vehicles brakes the weight shifts to the front, the front brakes on most vehicles do 75% of the work.

Drum brakes have more moving parts than disc brakes do, also because drum brakes are not vented to the atmosphere, they tend to collect brake dust.

Generally when doing your front brakes it is wise to pull the drums off on the rear and check for wear and clean and adjust the shoes.

More parts yes, but I'd understood that drums were simpler overall so the extra parts weren't problematic. Have I got the wrong impression? I can't believe I forgot about the self-adjusters. Oh well, both my cars are 4 wheel disc now.

ZV

 

More parts yes, but I'd understood that drums were simpler overall so the extra parts weren't problematic. Have I got the wrong impression? I can't believe I forgot about the self-adjusters. Oh well, both my cars are 4 wheel disc now

Disc brakes are much more simple than drum brakes, in a disc setup, you have a rotor, a caliper and brake pads, when energized the caliper squeeze the pads, the pads contact the rotors and you have braking action.

Drum brakes on the other require the following steps to operate properly;

When energized the piston(s) in the wheel cylinder(s) come out of there bore and push against either the upper or lower section of the brake shoe, this causes the shoe to move outward and come into contact with the drum.
As the shoes touch they start to rotate in the direction of drum travel, this causes the drum to expand harder into the friction surface. (this is caused by the location of the pivot point of the shoe).

When the brakes are released, the springs pull the shoes back into place causing the pistons to also retract into the wheel cylinder bores.
Also, drum brakes usually have small valves (Residual pressure valve) installed after the master cylinder but before the wheel cylinders.

 

[Zenmervolt]

Originally posted by: Roger

More parts yes, but I'd understood that drums were simpler overall so the extra parts weren't problematic. Have I got the wrong impression? I can't believe I forgot about the self-adjusters. Oh well, both my cars are 4 wheel disc now

Disc brakes are much more simple than drum brakes, in a disc setup, you have a rotor, a caliper and brake pads, when energized the caliper squeeze the pads, the pads contact the rotors and you have braking action.

Drum brakes on the other require the following steps to operate properly;

When energized the piston(s) in the wheel cylinder(s) come out of there bore and push against either the upper or lower section of the brake shoe, this causes the shoe to move outward and come into contact with the drum.
As the shoes touch they start to rotate in the direction of drum travel, this causes the drum to expand harder into the friction surface. (this is caused by the location of the pivot point of the shoe).

When the brakes are released, the springs pull the shoes back into place causing the pistons to also retract into the wheel cylinder bores.
Also, drum brakes usually have small valves (Residual pressure valve) installed after the master cylinder but before the wheel cylinders.

Wow. With all that it's quite surprising that drums have survived so long, seems like it would be cheaper to just put discs all around and be done with it.

ZV

 

[vi edit]

If drums are so much more complicated, how come they are always the standard braking system on economy cars? Is there something about disk breaks that make them inheriently more expensive? Or do manufacturers just jack up the prices because they are considered a "performance" item?

 

The reason why drum brakes are still with us is because they came along well before disc brakes did, they are cheaper to manufacture because of the infrastructure that was built around them before disc brakes came along.
Also you must realize that most of the time disc brakes are not needed for the rear because of the aforementioned 75% front/25% rear braking requirements of most vehicles.You really do not need the type of pressures generated by disc brakes on the rear.

 

[Electric Amish]

Originally posted by: vi_edit
If drums are so much more complicated, how come they are always the standard braking system on economy cars? Is there something about disk breaks that make them inheriently more expensive? Or do manufacturers just jack up the prices because they are considered a "performance" item?

I think you've got it.

The only thing I've ever repaired on drum brakes are the shoes (pads). Never had to do anything else.

I think Roger has you pretty much covered.

amish

 

[Zenmervolt]

Originally posted by: Roger
The reason why drum brakes are still with us is because they came along well before disc brakes did, they are cheaper to manufacture because of the infrastructure that was built around them before disc brakes came along.
Also you must realize that most of the time disc brakes are not needed for the rear because of the aforementioned 75% front/25% rear braking requirements of most vehicles.You really do not need the type of pressures generated by disc brakes on the rear.

Well, disc brakes are more easily modulated I've heard, so rear discs are less likely to lock, if I've heard right.

ZV

 

[Evadman]

I would like to point out something that no one has really mentioned yet. Mostly because the one doing all the talking has been doing this since dinosaurs were chasing his kids and has only done it 200,000 times.

When you do drum brakes, only do one side at a time. This way you can look at the other side to see how they go back together. You will also need a few specialized tools to remove the springs, which pep-boys and some other places will laoan ya for free if you buy the parts there.

I hate drum brakes. (just in case you couldn't tell ) I would rather pay someone else to do it. For me, it is not worth the hassle. *shrugs*

Also, remember you can not have the emergency brake on when you do this. But you would figure that out as soon as you got the wheel off

One of the things Roger forgot to mention about why drums are still on vehicles (since I know he knows it, his brain is just frying from the longer than hell days he has been working ) is that drums are mush easier to add an emergancy brake setup too. Just a quick cable. if it were disk, it is much harder, and more expensive to make an emergancy brake work.

 

[Electric Amish]

Originally posted by: Evadman
I would like to point out something that no one has really mentioned yet. Mostly because the one doing all the talking has been doing this since dinosaurs were chasing his kids and has only done it 200,000 times.

When you do drum brakes, only do one side at a time. This way you can look at the other side to see how they go back together. You will also need a few specialized tools to remove the springs, which pep-boys and some other places will laoan ya for free if you buy the parts there.

I hate drum brakes. (just in case you couldn't tell ) I would rather pay someone else to do it. For me, it is not worth the hassle. *shrugs*

Also, remember you can not have the emergency brake on when you do this. But you would figure that out as soon as you got the wheel off

One of the things Roger forgot to mention about why drums are still on vehicles (since I know he knows it, his brain is just frying from the longer than hell days he has been working ) is that drums are mush easier to add an emergancy brake setup too. Just a quick cable. if it were disk, it is much harder, and more expensive to make an emergancy brake work.

Good advice.....

You don't HAVE to have special tools...it just helps. I've done it without them.

amish

 

[Evadman]

Good advice.....

You don't HAVE to have special tools...it just helps. I've done it without them.

amish

Then you can take a spring in the face . I am just happy that the first time I ever did a set of drum brakes I was wearing safty glasses. I took a spring right off the lens.

Safety glasses = your friend.

 

I would like to point out something that no one has really mentioned yet. Mostly because the one doing all the talking has been doing this since dinosaurs were chasing his kids and has only done it 200,000 times.

If you ever visit the East Coast, don't post it here in OT, I will hunt you down

 

[Evadman]

If you ever visit the East Coast, don't post it here in OT, I will hunt you down