Why do Ford still use Drum brakes?

[geronimo183]

I was in my local (UK) Ford showroom this week having a look at the new Ecosport small SUV and noticed that despite its size it was fitted with brake drums on the rear. I know that the Fiesta still uses drums and the Ecosport is based on the Fiesta, but I would have thought that they would have upgraded them to rear discs due to increased size, however I then noticed that they are still used on the Focus apart from the more powerful units.

 

This is surely old technology so I can only think that it is for reduced cost purposes that Ford carry on using them when most other manufacturers in the UK fit discs all round. Other than cost is there any other benefit to fit drums rather than discs?

[akirby]

Of course it's cost, but there is nothing wrong with drum brakes.

[YT90SC]

Rear brakes just keep the butt behind the front. Plus properly adjusted drums produce ZERO parasitic loss from friction.

[SoonerLS]

At one point, it was simply a cost issue, but I have to wonder if that's still true, as most Ford products have discs on all four corners. It can't make much sense from an assembly line point if view, as they're quite a bit more complicated to assemble than discs, plus they have a unique ABS setup.

Rear brakes just keep the butt behind the front.

A friend of mine used to be a lineman for Southwestern Bell, and he hated it when they first got their then-new Ford trucks with the rear ABS drums back in the early '90s; with the big toolboxes on the back, the rear brakes did most of the braking, and with ABS on the rears, it really caused problems with stopping on the gravel roads where he spent most of his days--the ABS would sense the slip and keep the truck rolling when it needed to dig in to stop.

Plus properly adjusted drums produce ZERO parasitic loss from friction.

Yup. Drums have springs that pull the shoes away from the drums, while discs have to rely on wobbling of the rotor to get the pads out of contact. They're also harder to warp than discs.

[fordtech1]

Yup. Drums have springs that pull the shoes away from the drums, while discs have to rely on wobbling of the rotor to get the pads out of contact. They're also harder to warp than discs.

Actually the square cut seal inside caliper does more for retracting piston. Unless a rotor is warped, it should not be wobbling. We are talking a spec of 3 thousandths or less of lateral runout.

 

I say they are used strictly as a cost saver. Drums don't dissipate heat as well and can fade easier. Plus they aren't as good in wet weather. However, they save money by incorporating parking brakes with in. As disc require additional system to make a parking brake.

For instance cheap focus get drums, higher line models get disc.

Edited September 7, 2014 by fordtech1

[RichardJensen]

I can't fathom how drums are cheaper than discs.

 

Does anyone have an explanation of why this is?

[mustang_sallad]

I can't fathom how drums are cheaper than discs.

 

Does anyone have an explanation of why this is?

 

I've always wondered the same thing. They seem so much more complicated. I've got rear drums on my focus, i'm considering painting them red to make me feel better about them.

[SoonerLS]

I can't fathom how drums are cheaper than discs.

 

Does anyone have an explanation of why this is?

When discs were rare and drums were common, I could see it being cheaper, but not with it being the other way 'round. Do they even use drums on anything other than the Focus?

[RangerM]

Perhaps drums can be made with lower tolerances and less expensive materials--enough to offset the (apparent) cost of complexity?

[sullynd]

It may also allow them to upsell a more expensive model which more than offsets the cost.

[RangerM]

It may also allow them to upsell a more expensive model which more than offsets the cost.

Perhaps, but I'd think such logic would also apply to power locks/windows, and those are largely standard nowadays. Most non-enthusiast car buyers aren't like you and I and would attribute more importance to things like that I'd think.

 

Where I could be wrong is the cost of offering differing door panels/switches--largely true for the lack of manual trannies, anymore.

[sullynd]

Perhaps, but I'd think such logic would also apply to power locks/windows, and those are largely standard nowadays.

Doesn't the base Focus have manual windows in the rear? I wonder if that doesn't cost ford more.

[Anthony]

Believe it or not, REAR drum brakes are actually cheaper to produce (where the parking brake is incorporated). They also weigh less them a comparable disc and caliper setup.

Edited September 8, 2014 by Intrepidatious

[Biker16]

I can't fathom how drums are cheaper than discs.

 

Does anyone have an explanation of why this is?

 

lower tolerances for the internal components.

 

Can be made out of cheaper materials without a loss of performance.

 

They are lighter too.

 

Simpler parts. (My old focus had 3 springs, pair of shoes, adjuster plate, drum with integrated hub assembly, with a simple slave cylinder ) with most part made of simple stamped parts and grey iron.

Edited September 8, 2014 by Biker16

[RangerM]

Doesn't the base Focus have manual windows in the rear? I wonder if that doesn't cost ford more.

If so, I definitely didn't know that. Would seem awfully strange.

[fuzzymoomoo]

Doesn't the base Focus have manual windows in the rear?

Yes it does, and it's hilarious every time I see it on the line.

[lfeg]

On rear drum brakes, Especially in areas where road salt is used in the winter, rear discs seem to have more maintenance issues due to corrosion than rear drums.

[630land]

The Chevy Cruse LS base model has all 4 power windows, why can't the Focus S? Is it really saving money having an extra type of rear door to stock?

 

I kind of agree that there is cost saving with drums on base models though, but glad I got all wheel disks now.

[xr7g428]

Rear disc brakes also incorporate a drum brake that is used as the parking brake. So you are getting a set of drum brakes and a set of disc brakes. A single slightly larger drum brake is not much more cost and serves both purposes. Unless you are towing heavy trailers, rear drums are easily up to the task. As it turns out, about the time they had made the switch to disc brakes, the big issue with drums was resolved by venting the drum radially (drilling holes through the drum). As it turned out most brake fade was being caused by a layer of gas in between the shoe and the drum. The venting solved this. Conventional wisdom had been that this would allow water into the drum, but as it turns out it actually allowed the drum to dry out faster, like a disc brake.

[Biker16]

Rear disc brakes also incorporate a drum brake that is used as the parking brake. So you are getting a set of drum brakes and a set of disc brakes. A single slightly larger drum brake is not much more cost and serves both purposes. Unless you are towing heavy trailers, rear drums are easily up to the task. As it turns out, about the time they had made the switch to disc brakes, the big issue with drums was resolved by venting the drum radially (drilling holes through the drum). As it turned out most brake fade was being caused by a layer of gas in between the shoe and the drum. The venting solved this. Conventional wisdom had been that this would allow water into the drum, but as it turns out it actually allowed the drum to dry out faster, like a disc brake.

the disc/drum hybrid is only used on trucks, and it's required on Cars where loads are much lighter.

[xr7g428]

The parking brake has to hold the weight of a fully loaded vehicle at a 30% grade (for vehicles with manual transmissions, 20% for vehicles with an automatic). There are also limitations on the amount of force that must be applied to make the brake effective. It takes considerably less force to achieve the standard with a drum brake than with a disc, and the mechanism to apply the force can be simplified where less force is required.

 

The point of all of this is that the rear brakes have a dual purpose that makes it incrementally more expensive to use discs than drums. Unless disc brakes are required to meet the engineering goals of the brake system, drums are a money saver. Conversely, ABS systems for discs are more effective as the disc brake responds in a more linear way than a partially self-energizing drum brake design.

[RichardJensen]

The supplemental drum parking brake seems to best explain why you'd have drums standard.

[SoonerLS]

The supplemental drum parking brake seems to best explain why you'd have drums standard.

I've had quite a few Fords and Lincolns with discs on all four corners, and none of them had supplemental drums on the rear. My truck might, I suppose, but I've not had a call to do anything with its rear brakes yet.

[lfeg]

Also, drum brakes can be designed to be self energizing. Very useful for parking brakes. Also reduces application force required for service brakes.

[RangerM]

What do commercial trucks use? Tractor trailers, I mean.