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Clare Snyder Clare Snyder is offline
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Default Need help INTERPRETING these test results police cruiser SAE J866a Chase Test

On Tue, 16 Jan 2018 02:10:28 -0000 (UTC), Mad Roger
wrote:

On Mon, 15 Jan 2018 17:01:47 -0500,
Tekkie+AK4- wrote:

To Madman: When I was early in emergency services I used to run my private
vehicle. I had to pay attention to braking because after 3 stops there were
NO brakes.


I've never experienced such fade in my life, and I drive a performance car,
where I've driven down many a long hill. I don't know why I have never
experienced brake fade, but I know it exists. I just have never felt it.

But I've never put in less than FF pads either.

That may or may not be related - we can't tell. It's just a datum.

I got the police shoes because I was all into it.


What's a "police shoe"?

The police report from Michigan tested "regular" shoes only.

The shoes they tested were premium and heavy duty (all of the FF and
FG were "heavy duty" pads.

On Persuit rated vehicles they oftern also have larger rotors and
drums - as well as different tires, and even different RIMS to allow
bwtter brake cooling. Never wondered why cruisers have "dog dish" hub
caps instead of full wheel covers??? To allow the brakes to "breath"
better.

What a difference!


If there was a difference, it's hard to tell because nobody (except the
police in Michigan it seems) tests *new* pads against *new* pads (after
burnishing).

You probably didn't as nobody does.

You probably tested *old* pads against *new* pads, and even if you did test
apples to apples, it's not extensible to "my" car or to anyone else's car.


I can say without reservation that the "police duty" and severe duty
brakes were MUCH better at high speeds than standard brakes (and
sometimes not nearly as good when cold/low speed) 1 1966 Dodge Polara
Pursuit Special I drove for a short time went like a scalded cat, and
stopped like you had jammed a stick into a hole in the pavement.


That's the problem with tiny experiments of a single datapoint.

When I got a pursuit certified vehicle it was wonderful.


What the heck is a "pursuit certified vehicle"?
I drove an EMT vehicle many times. It drove like a truck.

They are designed and built to endure punishment.


Like any performance vehicle on the road today?

Try and go to the dealer and
get the model, good luck with that.


Don't even know what it is.
Is it a souped up police cruiser?


Yes.

Watch what happens on one of the police
shows. See which car is destroyed or smoking at the end.


That's not a good scientific test.

The actors can't
make the corner because they got no brakes. Or the engine expires. Something
is to be said when one goes from 0 to 40 then 40 to 0 repeatedly and sit
there idling for the next 1/2 hour then going to the next call. Then there
were the ambulances and fire trucks. *Training*


I have been trained to drive an ambulance.
Know what they taught me?

a. Defensive driving
b. Noise pollution is bad
c. Laws (nobody is allowed to break the law in that state, not even
ambulances)

I think in some states emergency vehicles *are* allowed to break the law,
but not in that state where I drove the ambulance. Of course, nobody is
going to give you a ticket either, but if you kill someone while breaking
the law, the onus is on you.



Todays persuit special vehicles are often the big ecoboost engine on
fords, and Hemis on Chargers. Often with a "special tune" that raises
the rev limiter setting and reprograms the tranny shift points - as
well as having bigger rads, bigger alternators, honking big sway bars
and super-duty shocks and springs.