Can I upgrade to disc brakes front and rear? '05 Accord

i really, really enjoyed all of your posts until this one. you are an idiot. go away.

bob z.

bob zee wrote in news:1179619151.088326.69490 @p47g2000hsd.googlegroups.com:

Except that I happen to be right.

I see so many people go on and on about the friction area of drums vs that of discs, and cite the better heat-shedding capabilites of discs. The problem is...all that is IRRELEVANT.

Rear brakes of either type generate so little heat that fade is NOT even close to being any kind of a concern. Heat-fade is a concern with the FRONTS (which handle 80% of braking effort), which is why all road cars use discs at the front these days.

Rear discs heat up so little in use they cannot even reliably burn off the moisture they collect, which is why they rust up so badly. Rear drums don't heat up much at all either, but they are basically sealed from the weather.

A test if you want to try it. Procure the use of a rear disc-braked car and a rear drum-braked one. Drive both vehicles up to 30 mph or so on a deserted road. Now apply the parking brake hard, just short of lockup, as though you were going to stop the car using just that brake. You will find both systems feel exactly the same, and any "fade" will be identical on both. Of course, I assume both cars have rear brakes in good repair...

That's my experience, too. Here in Arizona rust isn't a problem, but discs still have more noise problems than drums do and the slide pins are still troublesome. The only problem I've ever had with rear drums is worn-out self-adjusters. Replace the self-adjuster assembly (usually when the linings are worn out) and they are good for the rest of the life of the car.

I'm convinced front drums are what gave drum brakes their reputation as second rate. I learned to drive on cars that had drums all around, and they were completely unacceptable for highway use.

Mike

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.] bmw, volvo and subaru use twin-piston iirc.

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 @

: ".. 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." Mike

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....

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.

what's required and what's best are not the same thing.

it's true that most trailers use them, but it's not because of superior performance.

the way of the future. and hopefully, rigs having to use runaway ramps will be a thing of the past.

The part before the excerpt notes that drums are used because they are less expensive. Their point is that drums are adequate for the application. Maybe not "best" but "good enough."

Mike

In trucks and trains the brakes are pre-engaged; air pressure is required to release them. It is easier to do that with drums than disks.

Mike

true!

jim beam wrote in news:27ydneh3Kqnl_s3bnZ2dnUVZ snipped-for-privacy@speakeasy.net:

No. Single-piston brakes are CHEAPER. Way, WAY cheaper. Single piston brakes were adopted for economy reasons and for no other.

not that simple.

regarding the single/double thing, there's a few factors at play, one being that the caliper casting for single piston needs better q.c. to take the fatigue load of spanning the disk in a single piece and the more complex shape. with twin piston, there are two halves that bolt together and q.c. on a single more compact part is easier to cast. the extra piston is more expensive, but the housing can be cheaper and machining access is easier.

but the biggest factor is steering geometry. by far. that's why you have "double piston" calipers like this:

get negative scrub radius, you have to get the hub face as close to the bottom swivel as possible. you can do that easily with single piston [single sided] caliper, but not easily with double [sided] unless you have shallow pistons and thin pads. that's not acceptable for production cars.