[geeks] Drum versus disk brakes vs. rear-wheel anti-lock

[Kris Kirby]

On Tue, 12 Mar 2002, Kurt Huhn wrote:
> This is a parking brake - it has been mistakenly called an "emergency"
> brake in modern vehicles.  It should be used for nothing else except
> ensuring your vehicle won't move when it is parked.  This is not (on
> modern vehicles anyway) an effective braking mechanism and should never
> be used as such.

I have had a parking brake in both of the last two cars I have driven,
both automatics with floor shifters and the parking brake right behind
them. I put the Tempo ('87, 4500 lbs) into a nifty slide once, but when I
attempted that trick in my Sentra ('85, 3500 lbs), I wound up in a spin,
turning in the opposite direction I had started in.

The slide was locking the rear wheels with the parking brake and turning
the wheel and gunning it (both cars are front wheel drive). Pretty neat,
making a 90 degree turn faster than your buddies who are following you.

I need to get better at dealing with slides and such. I feel that will be
my undoing.

> Not in my experience.  A pickup truck will actually brake *better* with
> more weight over the rear axle - that's why you see pickup owners
> tossing cinderblocks in the bed of their trucks during winter - to try
> to increase the weight over the rear axle.  Again - simple physics takes
> over - more weight with the coefficient of friction (which remains
> realtively constant) equals better stopping power.  If we all drove
> around with half a ton of weight in our beds, ther rears would rarely
> (if ever) lock under straight line braking.  But we don't, we usually
> drive around with empty beds.  If the weight distribution of a truck was
> equal front/rear, then RWOAL wouldn't be necessary - but most trucks
> have a front/rear weight distribution of 60/40 (or thereabouts).  Add
> chassis dynamics, and you get the *radically* different handling
> characteristics for pickups.  And locking the front wheels before the
> rears wheels, isn't one of those differences.

My brother is having an aftermarket towing package installed on his 2001
Sonoma (10k, 4.3L). The package includes a rear anti-sway bar; he can't
wait to get it on. He was jumping lanes the other day (not something he
normally does) and felt the rear start to misbehave.

I need to get my car weighed again; I've always felt it seemed lighter
than 3500 lbs. Too high a center of gravity; no suspension.

--
Kris Kirby, KE4AHR          | TGIFreeBSD... 'Nuff said.
<kris at nospam.catonic.net>   | IM: KrisBSD | HSV, AL.
-------------------------------------------------------
"Fate, it seems, is not without a sense of irony."