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#21
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"jim beam" <spamvortex (AT) bad (DOT) example.net> wrote in message news:27ydneh3Kqnl_s3bnZ2dnUVZ_jWdnZ2d (AT) speakeasy (DOT) net... Michael Pardee wrote: I'm convinced front drums are what gave drum brakes their reputation as second rate. i'd say it differently - it's front drums that /prove/ they're second rate! their action is non-linear and they can only dump heat /through/ the drum metal by conduction, not direct to atmosphere like a disk. They are definitely second rate for the front, where they have lots of heat to dump. Drum brakes fade like crazy in that application. That isn't an issue in the rear. From Edmunds techcenter @ http://tinyurl.com/6r6kh : ".. the truth is that today's disc/drum setups are completely adequate for the majority of new cars. Remember that both disc and drum brake design has been vastly improved in the last 20 years. In fact, the current rear drum brake systems on today's cars would provide better stopping performance then [sic] the front disc setups of the '70s. And today's front disc brakes are truly exceptional in terms of stopping power. Combined with the fact that between 60 and 90 percent of a vehicle's stopping power comes from the front wheels, it's clear that a well-designed, modern drum brake is all that's required for most rear wheel brake duty." |
#22
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Michael Pardee wrote: "jim beam" <spamvortex (AT) bad (DOT) example.net> wrote in message news:27ydneh3Kqnl_s3bnZ2dnUVZ_jWdnZ2d (AT) speakeasy (DOT) net... Michael Pardee wrote: I'm convinced front drums are what gave drum brakes their reputation as second rate. i'd say it differently - it's front drums that /prove/ they're second rate! their action is non-linear and they can only dump heat /through/ the drum metal by conduction, not direct to atmosphere like a disk. They are definitely second rate for the front, where they have lots of heat to dump. Drum brakes fade like crazy in that application. That isn't an issue in the rear. From Edmunds techcenter @ http://tinyurl.com/6r6kh : ".. the truth is that today's disc/drum setups are completely adequate for the majority of new cars. Remember that both disc and drum brake design has been vastly improved in the last 20 years. In fact, the current rear drum brake systems on today's cars would provide better stopping performance then [sic] the front disc setups of the '70s. eh? that's bullshit. whoever wrote that is basing it on the erroneous supposition that because drum brakes are still used, there must be a reason, and is just guessing that it's about performance. but it's just a guess and has no basis in fact if they'd bothered to look up performance figures. the reason drum brakes are used is cost and hand brake implementation. and market segmentation creeps in there too to some extent. |
#23
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Michael Pardee wrote: "jim beam" <spamvortex (AT) bad (DOT) example.net> wrote in message news:27ydneh3Kqnl_s3bnZ2dnUVZ_jWdnZ2d (AT) speakeasy (DOT) net... Michael Pardee wrote: I'm convinced front drums are what gave drum brakes their reputation as second rate. i'd say it differently - it's front drums that /prove/ they're second rate! their action is non-linear and they can only dump heat /through/ the drum metal by conduction, not direct to atmosphere like a disk. They are definitely second rate for the front, where they have lots of heat to dump. Drum brakes fade like crazy in that application. That isn't an issue in the rear. From Edmunds techcenter @ http://tinyurl.com/6r6kh : ".. the truth is that today's disc/drum setups are completely adequate for the majority of new cars. Remember that both disc and drum brake design has been vastly improved in the last 20 years. In fact, the current rear drum brake systems on today's cars would provide better stopping performance then [sic] the front disc setups of the '70s. eh? that's bullshit. whoever wrote that is basing it on the erroneous supposition that because drum brakes are still used, there must be a reason, and is just guessing that it's about performance. but it's just a guess and has no basis in fact if they'd bothered to look up performance figures. the reason drum brakes are used is cost and hand brake implementation. and market segmentation creeps in there too to some extent. And today's front disc brakes are truly exceptional in terms of stopping power. Combined with the fact that between 60 and 90 percent of a vehicle's stopping power comes from the front wheels, it's clear that a well-designed, modern drum brake is all that's required for most rear wheel brake duty." what's required and what's best are not the same thing. |
#24
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You'll note that drums are still used almost universally in semi-trailer rigs, where massive stopping power is of utmost importance. Of course, if you really want to confuse the issue, you can always look at the "hub brakes" used on train cars.... |
#25
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Dave Kelsen wrote: On 5/20/2007 4:59 PM jim beam spake these words of knowledge: Michael Pardee wrote: "jim beam" <spamvortex (AT) bad (DOT) example.net> wrote in message news:27ydneh3Kqnl_s3bnZ2dnUVZ_jWdnZ2d (AT) speakeasy (DOT) net... Michael Pardee wrote: I'm convinced front drums are what gave drum brakes their reputation as second rate. i'd say it differently - it's front drums that /prove/ they're second rate! their action is non-linear and they can only dump heat /through/ the drum metal by conduction, not direct to atmosphere like a disk. They are definitely second rate for the front, where they have lots of heat to dump. Drum brakes fade like crazy in that application. That isn't an issue in the rear. From Edmunds techcenter @ http://tinyurl.com/6r6kh : ".. the truth is that today's disc/drum setups are completely adequate for the majority of new cars. Remember that both disc and drum brake design has been vastly improved in the last 20 years. In fact, the current rear drum brake systems on today's cars would provide better stopping performance then [sic] the front disc setups of the '70s. eh? that's bullshit. whoever wrote that is basing it on the erroneous supposition that because drum brakes are still used, there must be a reason, and is just guessing that it's about performance. but it's just a guess and has no basis in fact if they'd bothered to look up performance figures. the reason drum brakes are used is cost and hand brake implementation. and market segmentation creeps in there too to some extent. Christ, Jim; is there any fucking way you could be more pompous? Man! For what it's worth, you might try actually reading the paragraph above yours. Nothing is said about the reason drum brakes are used. Only that they are better than they used to be, and in the following paragraph, that they are adequate to the job requirements. Through the years you've shown yourself to be very knowledgeable, as well as high-handed, overbearing, impatient and rude. Or maybe it's just me. Ah, well, it's usenet. "the current rear drum brake systems on today's cars would provide better stopping performance then [sic] the front disc setups of the '70s." is bullshit. it has no basis in fact - it's simply supposition for the reasons i outlined before. |
#26
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Dave Kelsen wrote: On 5/20/2007 8:54 PM jim beam spake these words of knowledge: Dave Kelsen wrote: On 5/20/2007 4:59 PM jim beam spake these words of knowledge: Michael Pardee wrote: "jim beam" <spamvortex (AT) bad (DOT) example.net> wrote in message news:27ydneh3Kqnl_s3bnZ2dnUVZ_jWdnZ2d (AT) speakeasy (DOT) net... Michael Pardee wrote: I'm convinced front drums are what gave drum brakes their reputation as second rate. i'd say it differently - it's front drums that /prove/ they're second rate! their action is non-linear and they can only dump heat /through/ the drum metal by conduction, not direct to atmosphere like a disk. They are definitely second rate for the front, where they have lots of heat to dump. Drum brakes fade like crazy in that application. That isn't an issue in the rear. From Edmunds techcenter @ http://tinyurl.com/6r6kh : ".. the truth is that today's disc/drum setups are completely adequate for the majority of new cars. Remember that both disc and drum brake design has been vastly improved in the last 20 years. In fact, the current rear drum brake systems on today's cars would provide better stopping performance then [sic] the front disc setups of the '70s. eh? that's bullshit. whoever wrote that is basing it on the erroneous supposition that because drum brakes are still used, there must be a reason, and is just guessing that it's about performance. but it's just a guess and has no basis in fact if they'd bothered to look up performance figures. the reason drum brakes are used is cost and hand brake implementation. and market segmentation creeps in there too to some extent. Christ, Jim; is there any fucking way you could be more pompous? Man! For what it's worth, you might try actually reading the paragraph above yours. Nothing is said about the reason drum brakes are used. Only that they are better than they used to be, and in the following paragraph, that they are adequate to the job requirements. Through the years you've shown yourself to be very knowledgeable, as well as high-handed, overbearing, impatient and rude. Or maybe it's just me. Ah, well, it's usenet. "the current rear drum brake systems on today's cars would provide better stopping performance then [sic] the front disc setups of the '70s." is bullshit. it has no basis in fact - it's simply supposition for the reasons i outlined before. Thank you for your reasonable response to my outburst. I would think that to test that claim, you'd have to find figures on vehicles from the 70's which had disc front brakes - not difficult - and current vehicles which have drum front brakes, as well as similar weight and tire characteristics to those 70's cars, which I imagine would be awfully difficult. Maybe tractor-trailer rigs? no, the baseless bull is that current /rear/ brakes are more effective than disks of the 70's. and for testing, you want to eliminate variables, especially tires. |
#27
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a number of manufacturers don't have slide pins on rear disks - they use old fashioned twin-piston calipers because there are no steering geometry constraints. [single piston front calipers were originally born of the desire to create negative steering scrub radius.] |
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