Re: Most dangerous braking situation...

[Doug Rasmussen <DougRasmussen@domain.elided>]

Joel B wrote:
>  I'm not in agreement with the rear wheel lockup being the most 
     dangerous situation.  I'd have to say that a front wheel lockup 
     is more hazardous, and second to a four wheel lockup.  How about 
     a one front lockup?  Really, the rear wheel lockup is predictable 
     and the easiest to cure by a quick release and bite of the pedal. <

Joel,
  I got that info from engineers at Wilwood Company.  I don't recall
all of the theoretical basis behind it.  The front wheel lockup is not
considered as dangerous cause you can still steer the vehicle.

  I seem to remember something about tire dealers putting your
worst tread tires (most likely to blowout) on the front rather than
the rear.  They contend it's easier to handle a high speed blowout
on the front than the rear.  Maybe that's somewhat analogous to
the front/rear lockup theory.

  I agree a one front wheel only lockup might be a deadly situation, but
I only meant to comment on lockups that might occur with correctly
functioning brake sytems that were not properly biased.  A system
that would lock up only one wheel would have problems not related
to biasing, wouldn't it?

  In a panic stopping situation with rear lockup I don't think it's that
easy or predictable to cure.  On my 800, I put 11" Scout II rear drums
on.  Right after that conversion I took it out for a neighborhood test 
drive.  35 mph on a city arterial, dry pavement, some idiot pulls out
from a side street right in front of me.  My only option was to hit the
brakes 
*hard*.  Of course, having the oversized drums, the rear wheels locked
up and I spun around almost 180 degrees.  I didn't have any time 
for a quick pedal release to cure the lockup.  Until I looked at the
skid marks I didn't even realize what had happened.

  Turned out there was a cop behind me.  He cited the other guy
for reckless driving and complimented me on my driving skills.   I
appreciated the complements from the cop, but I didn't deserve
them cause I was totally out of control for the second or so
the rears were locked up.

  That incident got me thinking about brake biasing.  The engineers
at Wilwood explained my rear lockup caused the loss of control
and that my improperly biased system was dangerous.  With lots
more calls and questions for the guys at Wilwood I got a
passing education in braking systems theory.  But I've still got a
lot to learn.

Doug