# Why are disc brakes more expensive than drum brakes?

**URL:** <https://boards.straightdope.com/t/why-are-disc-brakes-more-expensive-than-drum-brakes/74581>\
**Category:** Factual Questions\
**Created:** [August 2, 2001, 2:22am UTC](https://boards.straightdope.com/t/why-are-disc-brakes-more-expensive-than-drum-brakes/74581 "2001-08-02T02:22:29Z")\
**Posts on this page:** 4\
**Page:** 1

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**Author:** ![Sultan\_Kinkari](https://avatars.discourse-cdn.com/v4/letter/s/7bcc69/32.png) [@Sultan\_Kinkari](https://boards.straightdope.com/u/Sultan_Kinkari)\
**Post date:** [August 2, 2001, 2:22am UTC](https://boards.straightdope.com/t/why-are-disc-brakes-more-expensive-than-drum-brakes/74581/1 "2001-08-02T02:22:29Z")

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IANAM, but after studying cutaway drawings of both drum and disc brakes, the latter seems like it would be much less complicated and expensive. One reason might be because disc brakes are usually accompanied by costly hydraulic systems, while drum brakes are unassisted. Is there such thing as an unassisted disc brake? Another reason might be that disc brakes require a greater attention and costly, warp-resistant alloys in production.

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**Author:** ![stuyguy](https://avatars.discourse-cdn.com/v4/letter/s/ec9cab/32.png) [@stuyguy](https://boards.straightdope.com/u/stuyguy)\
**Post date:** [August 2, 2001, 3:08am UTC](https://boards.straightdope.com/t/why-are-disc-brakes-more-expensive-than-drum-brakes/74581/2 "2001-08-02T03:08:03Z")

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Yeah, I think it’s those damned expensive rotors. Not your ordinary melted-down bowling trophies, I wager. They’re designed to withstand crushing rotational pressures – but, I’ve read, are very vulnerable to side impact damage. Try to replace one on a motorcycle and it could set you back hundreds of bucks.

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**Author:** ![Sultan\_Kinkari](https://avatars.discourse-cdn.com/v4/letter/s/7bcc69/32.png) [@Sultan\_Kinkari](https://boards.straightdope.com/u/Sultan_Kinkari)\
**Post date:** [August 2, 2001, 3:20am UTC](https://boards.straightdope.com/t/why-are-disc-brakes-more-expensive-than-drum-brakes/74581/3 "2001-08-02T03:20:47Z")

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Same for [mountain bikes](http://www.mtbr.com/reviews/Brake_System/product_20481.shtml), but well worth it. Nothing can even come close to the stopping power, except for maybe a parked car. :eek:

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**Author:** ![ModernRonin2](https://avatars.discourse-cdn.com/v4/letter/m/c37758/32.png) [@ModernRonin2](https://boards.straightdope.com/u/ModernRonin2)\
**Post date:** [August 2, 2001, 4:41am UTC](https://boards.straightdope.com/t/why-are-disc-brakes-more-expensive-than-drum-brakes/74581/4 "2001-08-02T04:41:54Z")

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Disc brakes probably need to be hydraulic in order  
to work. I can’t think of any other way you could  
generate sufficient clamping force reliably.

A lever system would fatigue and break, if it didn’t  
melt straight down from the intense heat. It would also  
make the pedal travel a lot farther when the pads  
were worn down.

Other than that, cost of materials (because of  
the heat factor) and the necessity of precision  
machining those very tough materials.  
-Ben