Conference oass::racers

    Since brake balance is most important at high speed (who cares if the
    rears lock a bit at 20 mph in a race car, you only see that in a pit
    stop!), you want to do your testing at a race course, paticularly at
    the end of a high speed straight.
    	Have a reliable observer stand where they can observe the car while
    it is braking from high speed. Put some old, but still good tires on
    the car (you will flat-spot them, so you don't want to use new tires),
    but make sure you don't put old hard tires on one end and race fresh
    sticky tires on the other end - this would foul up the test. Put used
    but sticky tires on both ends. Mark the tires with paint so it will be
    easy to see when they lock/stop rotating.
    	On succeeding laps, brake harder and harder at this section until a
    tire locks up. As soon as it locks, ease off the brakes. Find out from
    your observer which it was. If it was the front, go back out and do
    some more laps, hitting the brakes even harder. You should get the
    rears to lock with just a bit more pressure on the pedal than made the
    fronts lock. If the rears lock first (you may have trouble controling
    the car if this happens!), move the bias towards more front action. If
    the rears never lock, but the fronts do, move the bias toward the
    rear, but not so much that the rears lock first. You want the fronts to
    lock just a bit before the rears.
    	Go home. Throw away the flat-spotted tires. Measure and record the
    position of the bias bar. (Perhaps mark it with a dab of paint, too.)
    	If you make any changes in the brakes or tires, do a check in
    practice to make sure the fronts still lock first (you may want to save
    the flat-spotted tires for this.)
    	While you are doing this excercise, notice how the car feels upon
    brake lock. With experience on the track, you should be able to feel
    too much front or rear bias without locking up tires - the car gets a
    bit squirrly on one end.  - Chris (who had too much rear bias on his FVee
    when first built)
    ps. The squirrly feel will not occur if you aren't using the brakes
    very very hard. This excercise may improve your driving by showing you
    that you can brake deeper than you had thought. - C

I've just gone from too much rear to too much front and spun it last
weekend. Luckily no damage but my luck wont hold out for ever.

I set the bias towards the front and then add a little more rear bias each
lap until I feel the back start to get loose under heavy braking then 
back off a touch.

    
    Input through the steering wheel should also help you determine which
    end is locking;  front wheel lock the wheel "feels light" as the tire
    is running over burning rubber, not pavement.  Movement of the steering
    wheel is NOT transferred to the car until braking is released.  By
    comparison, rear lock-up, the wheel will feel normal, UNTIL you add in
    steering input, which, GOOD LUCK!!  The car which be VERY twitchy with
    too much rear bias, and "plow" with too much front bias.  Compare what
    you feel through the wheel with what an observer tells you to confirm
    your thoughts, and intended bias change.  If they DON'T concur, do more
    laps!!
    
    And a story about a "reliable" observer;  I asked a friend to watch as
    I entered a heavy braking zone, and see whether the fronts or rears
    locked.  Went out, did about 10 laps, and came in.  His comment; rears.
    I replied; fronts.  He said he saw tire smoke coming off the REARS. 
    Are you sure, I ask.  Definitely, he assures me.  I give in and we make
    the change towards the front.  This is during a one day regional, so
    the next track session is a RACE.  First FLYING lap into the braking
    zone, I just had to THINK about hitting the brakes and the fronts were
    locked.  Straight off the escape road, fell from 5th to last, got back
    on and now have 16 of 18 laps STILL TO GO.  Learning experience, in a
    number of ways!!!  When I asked my observer to tell mre again that he
    saw the rears lock, he said:  It was hard to tell FROM THE PITS!!!!!
    Luckily for him, no tire irons were within reach.  (Although I was not
    blameless either, but that makes for bad press!!!)
    
    Good Luck.
    
    Bob R.
    

    hmmm, I really am surprised at the discussion about observers and how
    to figure out which end locks first, because I've always found it
    trivially easy to identify the locking corner (not just end) simply
    from the dynamic effects on car balance.  Basically, when you lock a
    wheel the tire is sliding over burning rubber rather than gripping
    pavement, as Bob Roth mentions in .4, and as a result the adhesion is
    reduced.  I find this gives an extremely noticable change in the 
    acceleration produced by that corner, and it's real easy to identify
    the situation.  It might be less pronounced when both sides of the same
    end of the car lock up simultaneously, but since I seem to specialize
    in locking just one corner I can't say for sure.
    
    In fact, I seem to specialize in locking one particular corner, it's
    always the inside front for some strange reason that probably has to do
    with trail braking and weight transfer on turn-in...
    Anyway, that particular scenario is an easy way to become acquainted
    with the sensation of locking a wheel (and quickly following you may
    get acquainted with the sensation known as "swapping ends" :-).  That
    will at least help the outside observers with their reports, they can
    concentrate on the lurid details you already remember vividly with a
    great excuse for overlooking the subtle details that would help you
    avoid such fun in the future!

    What Bob also forgot to say was that it was his CREW member in the
    pits who told him, not the pit worker.  :-)
    
    jim e - who was working the pits

    	That's what's nice about open wheels.  You can look at them
    yourself and tell what's goin on.
    					John
    

I put it back to the front wheels and NO SPIN at BH