question about 993tt rotors

Ed Kellock ekellock at
Mon Apr 24 17:23:43 EDT 2006

As an aside to this topic, my recently acquired '91 Avant has a Movit brake
kit that was installed several years ago by the previous owner.  I don't
seem to have any documentation and would like to figure out what all I have
on there.  I've gone to the website and can only really compare their
pictures to what's on my car which has not yeilded conclusive.


On 4/24/06, Kenneth Keith <auditude at> wrote:
> Hi,
> Some of you may be running brakes using 993tt rotor rings and custom
> hats, and able to help with my question.  I have a Billzcat1 Turn 9
> setup for my 200q20v, which has custom hats and brackets to mount
> 996tt "big bloc" calipers and 993tt rotor rings, and I've got a
> question about the hardware that holds the rings to the hats, which
> consist of "t-lock" fasteners and bolts.  I bought the kit with unused
> rotors from a lister and am sorting things out to install them.
> The t-lock fasteners (sort of a sleeved nut) that attaches the rotor
> rings to the factory hats (which need to be removed and replaced with
> the custom ones, re-using the hardware) are different from left to
> right.  These t-lock fasteners have an internally threaded tube that
> runs through both hat and rotor, and the bolt goes through that from
> inboard.
> One set/side (can't remember left or right) has longer fasteners that
> bottom out against the bolt before the rotors are clamped tightly
> against the hats, leaving the rotor able to float away from the hat
> slightly, and the other set/side has a stepped fastener that is quite
> a bit shorter and when bolted up will put the hat in tight contact
> with the rotor ring with no play.
> The diameter of the holes in one rotor is about 5.0mm and the other is
> 5.5mm, as far as I can tell.  Both t-lock fasteners are 5.5mm towad
> the "head," as are the slots in the billzcat1 hats, and the "shorter"
> set of t-locks has stepped down to go into the 5.0mm holes.
> I think the 5.5mm sections of the shorter ones might be the correct
> length to bolt up to the hat leaving some float, but cinch up against
> the rotor firmly, while the other t-locks are different and would
> leave both rotor and hat able to potentially float along the whole
> fastener (instead of just on the thicker part that goes inside the
> hat, being solidly attached to the thinner part between the bolt and
> "shoulder" created by the 5.5mm-to-5.0mm reduction.  I don't think
> more words will help in describing this, so that's it for now. =)
> In addition to this difference between left and right rotors, I also
> found that one of the rotors had a thin black gasket between the
> factor hat and rotor ring, but the other side didn't have any such
> gasket.  The gasket is way thinner than the difference in t-lock
> length (depth really, as the overall length of the fasteners are the
> same, but the "shorter" ones have a much thicker "head" area).
> I haven't gotten a chance to take pics yet, but I will do that.  My
> basic question is whether there should be a difference between how the
> left and right rotors are attached to the hats.  If one is better than
> the other, such as the shorter ones that bolt up tighter, then should
> I shorten the longer ones?  Right now, if I bolt it all up without
> worrying about it, one rotor/hat combo is completely tight and the
> other has play where the fasteners can slide back and forth (or the
> hat pulled away from the rotor slightly).
> Thanks,
> Ken
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