[DeTomaso] NPC - Brake Drum Wear Limits, does Porterfield R4S material eat drums, etc.

[JEFFREY COBB]

Your guy is correct and the internet is wrong about safe usable size limits.
Minimum thickness or max diameter cast or stamped unto a brake rotor or drum indicates the safe min thickness or max diameter. Depending on your lathes bit size and feed rate, you can take off as little as .004 as a fresh up.

Jeff Cobb- I pad
W-225-343-7525
C-225-907-4514

On Dec 13, 2015, at 8:12 PM, Guido deTomaso <guido_detomaso at prodigy.net> wrote:

>    Have done a little driving with the Porterfield rear pads installed,
>   to match the fronts.  While the fronts made a huge difference, not
>   really feeling a big difference after changing the rears.  Ought to get
>   out in the rain though, make sure the fronts are locking up first.
>   Is there any downside to this R4S material, other than initial cost?
>   Short life?  Eats rotors or drums?  Otherwise seems too good to be
>   true.
>   I also installed the four shoes I had relined, drum brake non-Pantera
>   application, new drums too since the shoes cost so much, not really
>   seeing yet the huge improvement like I saw on the Pantera.
>   The old drums have a max diameter shown as 9.114 inches, mine are at
>   9.095 .  Thought I'd get them turned, swap them back on someday, but my
>   guy says 9.114 is the wear limit, not the machining limit, so he can't
>   take anything off.  Internet research seems to support both positions,
>   both you can and cannot machine/turn to the max diameter cast into the
>   drum.  Any thoughts/experience?
>   Also what's the minimum a brake lathe can take off typically?  If .010
>   on the diameter, that would put me at 9.105 with .009 leftover.
>   Same ideas would apply to rotors ... Pantera rotors too ... is the
>   minimum thickness a "machine to" number, or a "wear to" number?
>   Thanks,
>   GD
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