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

Tegger wrote:
> jim beam <spamvortex@bad.example.net> wrote in
> news:27ydneh3Kqnl_s3bnZ2dnUVZ_jWdnZ2d@speakeasy.ne t:
>
>
>> 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.]
>
>
>
> 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:
http://www2.partstrain.com/products/....html?index=17
to 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.

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

Tegger wrote:
> jim beam <spamvortex@bad.example.net> wrote in
> news:27ydneh3Kqnl_s3bnZ2dnUVZ_jWdnZ2d@speakeasy.ne t:
>
>
>> 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.]
>
>
>
> 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:
http://www2.partstrain.com/products/....html?index=17
to 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.