[s-cars] G60 Confusion !! (small typo correction)

[Theodore Chen]

--- Keith Maddock <Keith.Maddock at TRW.COM> wrote:
> OK, I go to the Nürburgring for the afternoon and what a mess I return to!!!
>
> A) I made a mistake reading Jimmy's page - its a little confusing since G60's
> are only front brakes, not the rears, I interpreted the 45mm and 36mm as the
> leading/trailing piston sizes.
>
> B) G60's do NOT have dual 45mm pistons - I doubt any sliding 2-piston or any
> fixed 4-pistons have the same size leading and trailing pistons.

various PBR twin-piston calipers, such as those used on the corvette and
mustang.  i use corvette calipers on my mustang.  they're twin 38mm pistons.
these calipers are aluminum and quite light.  they're also good enough
for showroom stock corvettes, mustangs, and camaros/firebirds.

these calipers do not use the standard floating caliper design.  rather,
they use PBR's patented pad-guided caliper design, in which the pads are
anchored to the bracket, and the caliper attaches to the pads.  the caliper
has no other connection to the mounting bracket.  works pretty well.

there's still some tapered wear, but not too bad.  most of the uneven
wear seems to be from the caliper cocking sideways.

according to the BIRA archives (we had a big discussion about G60 versus
brembo calipers a few years ago), the G60 pistons are 44mm and 41mm.

the boxster caliper has a 40mm and 38mm piston on one side.  don't know
about the big reds or the 996 calipers.

> D) When comparing fixed piston calipers (Brembo/Porsche) to sliding piston
> calipers, multiply the number of pistons in the sliding caliper  by 2

this implicitly assumes that the pistons in the sliding caliper are on
the same side.  you can also divide the number of pistons in the fixed
caliper by 2, in order to compare it to the sliding caliper.

glad we agree on this point.  you wouldn't believe the lengthy discussions
we had on BIRA.

> E) Big reds have 2  36mm and 2 44mm pistons, therefore they have LESS
> effective piston area than a G60. (effictive sliding caliper single piston
> diameter of 56.85)

in case anybody starts wondering, a conversion to big reds from G60s
could easily result in more front brake bias, despite the lower effective
piston area, because they work on larger rotors.  pad selection also
plays a role, and to a lesser extent, so does caliper stiffness.

-teddy


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