On Thu, Jul 2, 2015 at 7:55 PM, John T. Blair <jblair1948@cox.net> wrote:
> I inadvertantly sent the reply to Jim only. So I'm reposting for the group.
>
>
> At 03:33 PM 7/2/2015, you wrote:
>
> >Thanks John. My follow-up question was going to be on the value of
> inexpensive
> >rotors. :)
>
> >The only reason for wanting to avoid replacing the rotors (besides just
> being
> >cheap) is because they are held on with two screws that seems to
> almost always
> >rust in place. From all that I have read, those two screws turn this from a
> >quick simple job to one that can take a day.
>
> While this is true, here are some comments:
>
> 1. These screws aren't required. They are there to hold the rotor on
> the hub while
> the car is on the assembly line.
>
If that is the only purpose, manufacturers would have come up with
someting substantially cheaper than drilling and tapping holes in the
hubs. The screws serve to properly locate the rotor against the hub.
Without the screws, the first lug nut you install does that, and isn't
properly torqued for holding the wheel on. The later lugs are
relatively over torqued, which bends the rotor, which leads to wear or
pad deposits (depends on the pads: semi-metallics tend to wear the
rotor away, ceramics tend to leave deposits), which leads to pedal
pulsation and "warped rotors" (which aren't warped at all.). This
problem is exacerbated by using an impact wrench to install wheels,
and by improper order of tightening.
One additonal step: clean the surface of the hub that the rotor bears
on. If there's rust or crud, the rotor won't be square to the
calipers, and it will "warp".
--
David Scheidt
dmscheidt@gmail.com
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