[s-cars] Big Reds making Sandy red in the face...

[Mark Strangways]

Also note, that truing is suggested once  the rotors get a few good initial
heat sets in them.
I tried and tried to trace a problem I had with my 996tt over 993 set-up, it
was a very similar situation.
A bit of vibration at very high speeds, and some pulsing in the pedal when
braking...
I turned out to be a bent rim believe it or not.

But I tried the indexing and had them turned prior to making the discovery
that my rims where bent.

Mark S
----- Original Message ----- 
From: "Mark Strangways" <strangconst at rogers.com>
To: "Sandy Sligh" <sdslig at yahoo.com>; <s-car-list at audifans.com>
Sent: Wednesday, February 11, 2004 6:48 PM
Subject: Re: [s-cars] Big Reds making Sandy red in the face...


> The rotor is designed to float on the hat.
> So, torque is a very important factor. So are the many small bolts and
funny
> looking nuts that allow you to reach torque but still allow the rotors to
> float.
> I don't know if you used the new ones with the rotors you bought, I assume
> you got your rotors complete with the Porsche hats from the factory. I
would
> strongly suggest you don't re-use the old fasteners, use  the new ones
that
> shipped with the rotors.
> Second, you will need to index the rotors on the hat. Try placing the
rotor
> on the hat 180 degrees from what it is now.
>
> There is a factory porches sheet that is on the bira site that gives the
> proper torque values and sequences.
>
> Mark S
> ----- Original Message ----- 
> From: "Sandy Sligh" <sdslig at yahoo.com>
> To: <s-car-list at audifans.com>
> Sent: Wednesday, February 11, 2004 6:20 PM
> Subject: [s-cars] Big Reds making Sandy red in the face...
>
>
> > Ok, this email will be part Sandy's-an-idiot and
> > Sandy's-a-newb. Whichever is worse, who knows.
> >
> > SO. The S4 fails tech inspection due to worn-out front
> > rotors (993tt). No problem, I'll go pick up a new set
> > and put them on myself. How hard could it be really.
> >
> > I get the rotors in my hot little hands, pull off the
> > old rotors which are cracked inside edge to outside
> > (nice work, Bruce!! Thats some hard drivin!)  Pop the
> > rotor hats out and install said rotor hats onto brand
> > new rotors. WHee!!! Going pretty good.
> >
> > A week or so later I develop two vibrations. One felt
> > through the steering wheel (small amplitude) when
> > cruising at 120kph and higher, the second(medium
> > amplitude) when lightly braking from 100kph and down
> > to about 40kph. This second one I feel much more in
> > the steering wheel and also through the brake pedal.
> > With the hands off the wheel and braking, the steering
> > wheel noticably rocks back and forth rapidly, maybe
> > 3/4" to 1" in each direction.
> >
> > "There is no WAY I've warped these rotors!", Sandy
> > cries.
> >
> > I pull them off, pull out the hats and clean up the
> > mating surfaces considerably, mostly scraping off what
> > I assume was built up pad material.  Reinstall the
> > rotors.. same deal, vibrations are unchanged. (BTW,
> > I've been very methodically about torquing my wheels
> > correctly.  In a star pattern, first to 45ft-lbs and
> > then to 90. )
> >
> > Off they come again and I notice outlines of the brake
> > pads imprinted on the new rotors.. AH HA! Stoptech's
> > brake FAQ tells me what that is! I remove those rotors
> > and reserve them for later scrubbing with garnet paper
> > per Stoptech's suggestions (hopefully a new set is not
> > in order. $$$$)  In the meantime, I reinstall the old
> > rotors and plan on babying them until I either am
> > ready to try the new set again or break down and buy
> > another set.
> >
> > Well, low and behold, the old rotors are displaying
> > similar albeit slightly better symptoms.
> >
> > Questions:
> >
> > A) Do the sources of my vibrations reside elsewhere?
> >
> > B) Am I missing a crucial installation step, i.e. a
> > specific torque pattern on the rotor hat bolts? (I
> > devised a type of star pattern and just cranked them
> > down till they all felt equally tight)
> >
> > C) Do I need to go back over the mating surfaces again
> > and damn well make sure they are clean and flat?
> >
> > D) Maybe because I didnt' change the pads at the same
> > time? (why would this affect running the old rotors..
> > )
> >
> > E) Something else entirely?
> >
> > Please, anyone with BTDTs or suggestions unleash them
> > upon me.  I've spent more than a few nights in my
> > parking garage pulling wheels, pulling calipers,
> > pulling rotors, cleanings, tightening, reinstalling,
> > wash, rinse, repeat. Help make me smarter and the ride
> > out the the shop.
> >
> >
> > Thanks in advance
> >
> >
> > Sandy
> >
> > __________________________________
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> > http://taxes.yahoo.com/filing.html
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