Re: IML: Why did drums hang around so long?

["Klebert L. Hall" <crocuta@xxxxxxxxxxx>]

> From: Kenyon Wills <imperialist1960@xxxxxxxxx>
> Subject: IML: why did drums hang around so long?
>
> 1978 VCR:  $1000/20 lbs
> 1999 VCR:  $59 ($20 in 1978 dollars?)/2 lbs
>
> I think it comes down to economies of scale.
>
> That's my pitch on that question.  will be curious to
> hear what others say.

  My understanding is it's a few things. Inertia played a big part, all 
the machinery was already set up for making drums, and drums are easier 
to make than disks.

  I think a large part of it was the way the designers of the time 
thought about things. In a drum system, all the parts are protected 
inside the drum - back in the day, engineers tended to think of that as 
being generally better. Another, related point is that until the '70s, 
the rubber used for the various flexible parts either had to be 
expensive, or protected (like in a drum) to last well. Cheap 
plastic/rubber seals that are extremely durable are a relatively modern 
phenomenon.

  I also sort of suspect that disk brake systems have a higher initial 
cost, even though they have much lower maintenance costs. A caliper 
usually costs a heck of a lot less than a wheel cylinder or two, for 
example, and e-brake systems for 4-wheel disk cars are kind of fiddly.
  Manufacturers are all about initial cost, they don't much care about 
maintenance costs.

   -Kle.
   '69 Crown 4DHT (waiting for the next cash transfusion)

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