Re: ihc-digest V6 #658

[Ted Borck <tborck@domain.elided>]

> Date: Fri, 19 Mar 1999 19:31:53 GMT
> From: jlandry@domain.elided (John A. Landry)
> Subject: Re: rear disk brakes
> 
> The aliens commander decided jbade@domain.elided would make a perfect
> specimen for dissection, and he yelled...
> 
> >Of course it is best not to lock any up.  But if the rear wheels lock up
> >before the front you will totally loose control of the vehicle and the back
> >end will try to swing around the front..
> >If the front wheels lock up (Yes you will loose steering.. We've all had
> >that happen before) but you will follow the direction the wheels are pointed
> >in.  Have the rear wheels lock up is just inviting a roll over on the
> >highway.
> 
> Jeff,
> 
> I'm going to politely agree to disagree with your statements and I'm going
> to take the time in the next few weeks to research this entire issue via
> the Society of Automotive Engineers and post my findings to the Digest.
> Maybe once we get the truth from a definitive source we can put this
> argument to bed once and for all and post it in the FAQ.
> 
> Best regards,
> 
> John L.


I believe you guys are forgetting:

weight transfers to the front during braking which tends to unload the
rear and increases the tendency of the rear brakes to lock up

this means that the majority of the stopping power should be
concentrated in the front brakes

a skidding tire has less stopping power than just below lockup

rear disk brakes do much more than just increase stopping power, they
are easier to modulate (remain below the threshold of locking up)
than drum brakes.

a lot of vehicle emergencies involve hard braking and attempting to
turn away from what ever is creating the emergency.

if you brake and turn and your rear tires lock up - the loss of
traction in the rear will cause your vehicle to over steer (polar
inertia), get sideways (if you're in the grass or dirt - this means
your SUV will do barrel rolls) or spin.

**when in doubt - Just lock all four**

I recently visited a lot of boneyards in Dade County, FL, getting
parts for my F**D Explorer.  The majority of wrecked Explorers and
other SUVs I saw, had been rolled.



Ted Borck	tborck@domain.elided