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Insane speed in german cars... [Maxima] (+ tire slip andstuff)
At 04:51 PM 11/6/2002, Allyn wrote:
>yes, 'slip'. its not as if the tire is actually losing traction, because its
>not. each tread block hits the road and doesnt move till it rolls back
>away with
>the tire. in tech tire talk, the term 'slip' also describes tire
>compliance. as
>each new section of tread comes in contact with the road (initially under no
>load), and is then forced to convey the (whatever) hp that it needs to, that
>section gives a little bit. this continuous 'give' results in the inner
>bead of
>the tire actually spinning faster than the outer tread is spinning (this
>is only
>true at the bottom arc that contacts the road). once the tread leaves contact
>with the road, it goes back to its original position.
This is all news to me, but I'll buy it. Halfway.
You say "This is only true at the bottom arc that contacts the road". Fair
enough -- I don't know enough either way to judge the validity of that, so
I'll take your word for it.
But since the bottom arc of the tire is connected to the rest of the tires,
I have to insist (<g>) that this has a negligible effect on the overall
rotational speed of the tire. I can buy that the individual tread blocks
might be moving slower or faster than the others at any given time, but
since the tire is one solid piece, unless the rubber is slipping against
the pavement, the overall speed of the tire has to be proportional to the
speed of the pavement. i.e the slowdown when the tire first contacts the
road is cancelled 100% by the speedup when the tread separates from the
pavement?
Follow me?
Still thinking about this one...
Jason
>Al
>
>----- Original Message -----
>From: "Jason" <jason@scirocco.org>
>To: "Allyn" <amalventano@sc.rr.com>; "Robert Piwonka"
><tpiwonka@ttacs.ttu.edu>;
><scirocco-l@scirocco.org>
>Sent: Wednesday, November 06, 2002 4:21 PM
>Subject: Re: Insane speed in german cars... [Maxima] (+ tire slip and stuff)
>
>
> > At 04:08 PM 11/6/2002, Allyn wrote:
> > >** an important note is that even with an accurate speedo, going for
> top end
> > >results in increased slip at the driven wheels (due to compliance of the
> > >rolling
> > >rubber itself). speedos are linear, but the effect of slip is exponential
> > >(follows effect of wind resistance). at <85 or so, the slip is still
> > >small, but
> > >becomes large enough at the limit to throw indicated speed off by as
> much as
> > >10-15%, depending on the type of tires.
> >
> > Hey Al,
> > Slip? Not sure I follow you... Slip between pavement and tire? I
> > hope not at 140mph! :)
> > Jason
> >
> >
> >
> >
> >
> > >hth
> > >Al
> > >
> > >
> > >----- Original Message -----
> > >From: "Robert Piwonka" <tpiwonka@ttacs.ttu.edu>
> > >To: <scirocco-l@scirocco.org>
> > >Sent: Wednesday, November 06, 2002 12:48 PM
> > >Subject: RE: Insane speed in german cars... [Maxima]
> > >
> > >
> > > > Ok let em clarify the downhill section was through a turn as well
> and top
> > > > speed was not reached there but in the half mile strait
> following(this was
> > > > flat). Also this was a maxima se... different engine than just the v6
> > > > maximas. I feel the speedometer is more accurate than a scirocco
> one :)
> > > > Maximas are fast cars for those of you who have not ridden or
> driven in an
> > > > se.
> > > >
> > > > Robert Piwonka
> > > >
> > > > -----Original Message-----
> > > > From: scirocco-l-admin@scirocco.org
> > > > [mailto:scirocco-l-admin@scirocco.org]On Behalf Of Jason
> > > > Sent: Wednesday, November 06, 2002 9:46 AM
> > > > To: Robert Piwonka; scirocco-l@scirocco.org
> > > > Subject: RE: Insane speed in german cars... [Maxima]
> > > >
> > > >
> > > > At 12:16 AM 11/6/2002, Robert Piwonka wrote:
> > > > >I have not been following this topic but since we are talking
> about top
> > > > >speed a 92 maxima se 5 spd can do 145MPH stock. This was down
> hill into
>a
> > > > >flat staight and assuming the speedo was correct(no reason it
> shouldn't
> > > > be).
> > > >
> > > > Many speedometers are quite off, and get more so at higher speeds
> > > > unfortunately.... even on new cars with electronics. C&D actually
> did a
> > > > nice report about this a few months ago...
> > > >
> > > > The reason is essentially that the law insists that speedometers do not
> > > > read _low_. They can read up to 7% high up to 85mph IIRC. That would
> > > > probably mean around 12% high at 120mph, or an indicated 134mph FWIW.
> > > >
> > > > I thought the V6 Maximas were limited to 131mph though... (H-Rated
> tires)
> > > >
> > > > Either case, top speed downhill doesn't exactly mean "top speed". :)
> > > > Jason
> > > >
> > > >
> > > >
> > > > _______________________________________________
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> > > >
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