cross drilled rotors [Round Two]

[jason@scirocco.org (16V Jason)]

At 07:45 PM 3/25/2002, Larry wrote:
>Jason-
>   I was right wicha'...right up until the part about the rear axle.  After
>that, I think your meds kicked in.  :)

Oooooohhhhh rreeee-aaaaa-lllllllly. :)

My meds haven't kicked "out" in years.  That's the reason I'm always right. :)
Jason





>Larry  sandiego16V
>
> >
> > But you didn't do shit to the rear axle, did you?
> >
> > So what you did was tilt the car's front/rear brake bias further towards
> > the front.  You just *increased* your braking distance.  Say before your
> > brakes were proportioned "ideally", meaning that you were able to easily
> > hold all 4 wheels at impending lockup.  Now, you'll be able to keep the
> > fronts at impending lockup, but not your rears.  Regardless of how badly
> > your brakes were proportioned in the first place (unless you had a
> > rear-bias, which you don't or you'd be dead), you have just increased the
> > maximum braking distance of your car.  Sorry, that 11" brake conversion
> > just cost you your insurance deductible.
> >
> > OH!  Wait!!  Something else just popped up!  Since we all know that you
> > will get your best braking at impending lockup (hence the reason
> > ABS-equipped cars that keep all 4 wheels at/near impending lockup under
>any
> > conditions stop more quickly almost all the time), we know that we have to
> > modulate our brakes to keep them on the edge.  But since the pressure
> > exerted on your brake pedal is now amplified more, modulation becomes even
> > more difficult:  A smaller difference in pressure on the pedal now defines
> > the difference between impending lockup (100% braking ability) and full
> > lockup (only about 80% of full braking ability).
> >
> > So not only did you increase your theoretical minimum stopping distances,
> > you also made it harder to reach that theoretical minimum.
> >
> > And at the same time, you increased unsprung and unspring-reciprocating
> > weight.  That means your car is now slower, handles worse, and doesn't
> > brake as well.  COOL!
> >
> > :)
> > Jason
> >
> >
> >
> > modulation
> >
> >
> >
> > >DOnt belive me. What about your front wheel axle
> > >nuts. while brakeing does turn KE into heat there are more effienect ways
> > >to do it so you get less heat. (you thermo ppl can help here). (my
> > >connection is startign to suck again so typos will start up again). SO if
> > >you still have the problem of you want to stop quicker and your tires are
> > >NOT sliding if you are sliding.. get BETTER tires or stop pressing on the
> > >brakes so hard. as the tire starts to slide your coefficent of friction
> > >goes waaaay doen its very inefficeint. a sliding stop takes as much as
>50%
> > >longer to stop in as a non sliding stop all things being equal.. thats
>why
> > >new cars and some motorcycles have ABS brakes. . increasing diameter adn
> > >the swept area remaining constant will result in less heat or equal heat
> > >generated. Increasing the swept area
> > >will integrate the heat over a larger area overall reducing the average
> > >temperature.
> > >
> > >Holes and slots. <-- in some extreme conditions they may actually help.
> > >but getting larger dia disks with holes or slots is still better than
> > >smaller ones. (more swept area lewer temp not less heat).
> > >
> > >tired of hearing this argument... rage for days.
> > >basically slots and drilled rotors unless you are RACING for long periods
> > >of time or in extreme conditions (mud, snow, rain, desert) it deos do
> > >shit. So there.
> > >no vented vs. not vented is an easy one. more Surface area  means more
> > >convection. means lower temperature NOT lower heat. you basically dOuble
> > >the surface area and increas the mass of the rotor so yes that is a good
> > >upgrade. but if you drive like my wife or an old lady ... dont bother.
> > >unless you wanna look cool.....or they come on the car already installed
> > >by the PO... <-- my case!
> > >
> > >brian
> > >2.0L Topless bunny
> > >Brakes.
> > >Stock booster -- bad sticky brake pedal syndrome manual return often
> > >required
> > >Stock master clyn new
> > >10.1's in the front zimmerman xdrills PO of 16v bought them
> > >drums in the rear
> > >one new wheel clyn in the rear.
> > >
> > >
> > >On Sat, 23 Mar 2002, Brett Van Sprewenburg wrote:
> > >
> > > > >Bigger rotors do give the caliper much more leverage to work against
> > > > >the spinning wheel. You can easily set up your own experiment with a
> > > > >spinning bike wheel and see what I mean. What do you think is easier
> > > > >to grab and stop, near the hub or near the rim? Also the rotor and
> > > > >pad material used in F1 is so exotic we cant even begin to relate a
> > > > >tenth of the physics going on there and apply it to our street cars.
> > > >
> > > > I'm going to scan the article now, as I just can't stand this
> > > > anymore..The physics of
> > > > turning kinetic energy into heat works exactly the same between our
> > > > cars and an F1 car.  You are of course correct that
> > > > they can use exotic materials to increase their heat handling and
> > > > transfer...you are also correct that it's easier to stop
> > > > something spinning near the rim, then near the center.  Here's how to
> > > > generate the same effect with a smaller rotor:
> > > >
> > > > Press On The Brake Pedal Harder.  No kidding. :)  In other words
> > > > create higher clamping load, which may generate more
> > > > heat, but then we're back into the heat issues previous discussed.
> > > >
> > > > Once you reach the point of tire lock up (and if you cannot, then you
> > > > DO need brake work) you will NOT generate any
> > > > more braking force, no matter how far 'out' your caliper is away from
> > > > the hub.  Just physics.
> > > >
> > > > >
> > > > >While watching some Tarmac rally last year I remember in a tech
> > > > >sidebar they were talking about putting the largest brakes they
> > > > >could fit under the wheel in order to cope with the extra braking
> > > > >needed. I put more stake in a WRC engineer than a guy racing most
> > > > >anything in the US let alone a Saturn.
> > > > >
> > > > >Jasin
> > > > >one cents worth
> > > >
> > > > That 'guy' racing a Saturn is (as I wrote) an engineer creating
> > > > braking systems for the Robert
> > > > Bosch corporation (we've all probably heard of them) and I only threw
> > > > out the fact he was
> > > > also a racer as a point to his practical experience.
> > > >
> > > > Yes, this is info on how braking actually works can be suprising and
> > > > offensive, as it upsets
> > > > several beliefs and notions we (including myself) have had...
> > > >
> > > > ==Brett
> > > >
> > > >  \/  '84 Scirocco (ITB racer 2B) | "Hot VW's, take two home. They're
>small"
> > > > \/\/ '88 Scirocco 16v (Show), '92 Passat 16v (Winter+) | -
>brett@netacc.net
> > > >
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