On Thu, 12 Feb 2009 10:55:08 +0100, scott wrote:

>> Um, no, the brakes don't do the same - if you have disc brakes, the
>> brakes stop the wheels when fully engaged
> 
> Of course, because through the brakes you are applying more torque than
> the tyre/road surface can provide, so the wheel locks.

Exactly my point.

>> Conversely, by downshifting, you increase the engine revs and the
>> wheels are not locked - they still turn.
> 
> Only because *usually* the negative torque applied from the engine is
> not enough to overcome the grip between the tyre/road.  Try downshifting
> on ice or even on wet tarmac violently (eg 4th to 2nd at 40mph) and you
> will lock the wheels (certainly audible on wet/dry tarmac).

I wouldn't do 4th to 2nd.  Always one gear at a time, otherwise as you 
state, you can cause the wheels to lock up.  What you're looking to do is 
*gradually* slow down, so doing things that work contrary to that goal 
like downshifting two gears are obviously going to not achieve that goal.

> BTW the two effects add up, so if you are already braking hard with the
> pedal, downshifting hard at the same time will likely lock the wheels
> easily, this is why racing drivers always "blip" the throttle while
> braking and changing down, to avoid the engine braking that could lock
> the wheels.

Well, see my above paragraph.  Sure, if you do things that are contrary 
to the goal of gradually slowing the vehicle down, you're going to wind 
up in trouble.

>> Now, when you're on dry pavement, the wheels normally don't lock
>> because the car's momentum overcomes the friction on the brakes,
>> bringing you to a gentle (or sometimes less-than-gentle) stop.  On ice,
>> though, it takes less friction of the brake pads against the wheel to
>> stop the wheels because it takes less to overcome the friction of the
>> wheel against the ground.
>>
>> So it's easier to lock the wheels up and skid.
> 
> Yes, and the same applies to engine braking.  Next time it's wet or
> snowy try changing down (a couple of) gear(s) and letting the clutch out
> quickly, you'll hear/feel the driven wheels lock until the car slows
> enough for the wheels to grip again.  Obviously on snow and ice this
> happens easier.

I've used engine braking enough that I don't need to "try it", and like I 
said, of course you can *make* it do it, but that's not the goal.  The 
goal is to use the tools available in a way that is appropriate to get a 
gradual slowdown in speed, not a sudden change that's going to send you 
out of control.

Jim

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On Thu, 12 Feb 2009 11:27:03 +0000, Stephen wrote:

> On 11 Feb 2009 17:52:18 -0500, Jim Henderson <nos### [at] nospamcom> wrote:
> 
>>On Wed, 11 Feb 2009 20:23:40 +0000, Stephen wrote:
>>
>>> On 11 Feb 2009 15:02:24 -0500, Jim Henderson <nos### [at] nospamcom>
>>> wrote:
>>> 
>>> 
>>>>At least when I drove in England, I was driving an automatic.  I don't
>>>>know that I'd get used to shifting with the lever on the wrong side
>>>>(Yes, Stephen, the left side is the WRONG side <g>).
>>>>
>>>>
>>> Of course it is, it isn't the American Way ;)
>>
>><Grumble> I shoulda expected THAT. ;-)
>>
>>(Haven't you noticed my spelling?)
>>
>>
> No, you are asking a dyslectic about spelling? :)

LOL, arguably, the question comes up if a dyslexic person wouldn't in 
fact describe themselves as "lysdexic"....?

> Anyway I am used to reading American spelling now and translate into
> proper English, automatically. It is BTW one way. :)

So all my automated typing of things into UK English (I usually have to 
correct for an American audience, in fact, because it is automatic for me 
99% of the time) has just gone right past?

Jim

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On 12 Feb 2009 14:37:59 -0500, Jim Henderson <nos### [at] nospamcom> wrote:

>>>(Haven't you noticed my spelling?)
>>>
>>>
>> No, you are asking a dyslectic about spelling? :)
>
>LOL, arguably, the question comes up if a dyslexic person wouldn't in 
>fact describe themselves as "lysdexic"....?
>

No.

I often type it dislyxic, I know that there is a "y" in there somewhere. I can
see that it is not right but have never been able to remember the spelling.


>> Anyway I am used to reading American spelling now and translate into
>> proper English, automatically. It is BTW one way. :)
>
>So all my automated typing of things into UK English (I usually have to 
>correct for an American audience, in fact, because it is automatic for me 
>99% of the time) has just gone right past?

Yes.

Occasionally I notice as I know that you are an American but generally I just
read it and think nothing of it. Actually since you mention it, why and what do
other Americans think of you writing like a limey?
-- 

Regards
     Stephen

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On Thu, 12 Feb 2009 21:47:11 +0000, Stephen wrote:

> On 12 Feb 2009 14:37:59 -0500, Jim Henderson <nos### [at] nospamcom> wrote:
> 
>>>>(Haven't you noticed my spelling?)
>>>>
>>>>
>>> No, you are asking a dyslectic about spelling? :)
>>
>>LOL, arguably, the question comes up if a dyslexic person wouldn't in
>>fact describe themselves as "lysdexic"....?
>>
> No.

Well, I was making a joke - if it touched too close to home, please 
accept my most sincere apologies.

> I often type it dislyxic, I know that there is a "y" in there somewhere.
> I can see that it is not right but have never been able to remember the
> spelling.

I could see that.  I often will spell something the way I think it's 
spelt and it doesn't look right.  In my newsreader, of course, it doesn't 
look right because of the squiggly red line underneath the word.

>>> Anyway I am used to reading American spelling now and translate into
>>> proper English, automatically. It is BTW one way. :)
>>
>>So all my automated typing of things into UK English (I usually have to
>>correct for an American audience, in fact, because it is automatic for
>>me 99% of the time) has just gone right past?
> 
> Yes.

I guess since it's normal spelling for you, it would - that makes sense.
 
> Occasionally I notice as I know that you are an American but generally I
> just read it and think nothing of it. Actually since you mention it, why
> and what do other Americans think of you writing like a limey?

I occasionally get grief from people about it, or light joking about it.  
One of my coworkers noticed it a few years ago and asked me about it - 
not because he was anything other than curious, though - his background 
is linguistics.

I don't know why I started using Queen's English spellings, though - just 
became a habit.  Possibly because I spent a lot of my time writing to 
brits. :-)

Jim

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On 12 Feb 2009 17:43:38 -0500, Jim Henderson <nos### [at] nospamcom> wrote:

>On Thu, 12 Feb 2009 21:47:11 +0000, Stephen wrote:
>
>> On 12 Feb 2009 14:37:59 -0500, Jim Henderson <nos### [at] nospamcom> wrote:
>> 
>>>>>(Haven't you noticed my spelling?)
>>>>>
>>>>>
>>>> No, you are asking a dyslectic about spelling? :)
>>>
>>>LOL, arguably, the question comes up if a dyslexic person wouldn't in
>>>fact describe themselves as "lysdexic"....?
>>>
>> No.
>
>Well, I was making a joke - if it touched too close to home, please 
>accept my most sincere apologies.
>

No you didn't, I'm long past caring what people think 'cause I can't spell or
read big books. :)
I do get pissed off with people who don't take the trouble to check their
spelling especially when they know they can't spell. I even use "Word" when I'm
writing a hand written note or letter. But then I'm from a generation where it
was considered important U no wat I meen?

>> I often type it dislyxic, I know that there is a "y" in there somewhere.
>> I can see that it is not right but have never been able to remember the
>> spelling.
>
>I could see that.  I often will spell something the way I think it's 
>spelt and it doesn't look right.  In my newsreader, of course, it doesn't 
>look right because of the squiggly red line underneath the word.
>

I've switched that feature off in my newsreader. It would drive me mad seeing
other posts :lol:

>>>> Anyway I am used to reading American spelling now and translate into
>>>> proper English, automatically. It is BTW one way. :)
>>>
>>>So all my automated typing of things into UK English (I usually have to
>>>correct for an American audience, in fact, because it is automatic for
>>>me 99% of the time) has just gone right past?
>> 
>> Yes.
>
>I guess since it's normal spelling for you, it would - that makes sense.
> 

It does :)


>I occasionally get grief from people about it, or light joking about it.  
>One of my coworkers noticed it a few years ago and asked me about it - 
>not because he was anything other than curious, though - his background 
>is linguistics.
>
>I don't know why I started using Queen's English spellings, though - just 
>became a habit.  Possibly because I spent a lot of my time writing to 
>brits. :-)
>

If you can't beet them, join them ;)

Did you know that the term "Brit" used to be offensive? It was used by the Irish
republicans during the troubles and was not complimentary ;) Nowadays the word
is in favour.
-- 

Regards
     Stephen

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Jim Henderson wrote:
> 
> Um, no, the brakes don't do the same - if you have disc brakes, the 
> brakes stop the wheels when fully engaged (I don't have drum brakes so I 
> can't comment on those).  

Yes, also on drum brakes. But why on earth would you engage brakes
fully, if you're not trying to stop the car as quickly as possible?

> Conversely, by downshifting, you increase the 
> engine revs and the wheels are not locked - they still turn.

Yes, if you'll do it carefully enough (see the similarity to brakes?)
:). It's possibly a bit easier to be carefully enough, since the maximum
braking power is very limited.

And yes, I actually managed to found one +point to engine braking - with
FWD car it practically ever won't spin the car, since rear wheels won't
lock.

> Now, when you're on dry pavement, the wheels normally don't lock because 
> the car's momentum overcomes the friction on the brakes, bringing you to 
> a gentle (or sometimes less-than-gentle) stop.  

Either you're having really bad brakes (repair them!) or you're not
anymore engaging them fully, when driving on dry pavement (so why to do
it on ice?).

> On ice, though, it takes 
> less friction of the brake pads against the wheel to stop the wheels 
> because it takes less to overcome the friction of the wheel against the 
> ground.

Yes, the scale is smaller, but it's still there.

> So it's easier to lock the wheels up and skid.

Definedly.

> Jim

-Aero

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Jim Henderson wrote:
> 
> I wouldn't do 4th to 2nd.  Always one gear at a time, otherwise as you 
> state, you can cause the wheels to lock up.  

I do that (downshifting 2-3 gears at once) every day while slowing down
from the motorway - either 6-5-3-2, 6-4-2 or 6-3-2, depending on place,
traffic etc.

And I've managed to lock driving wheels up even without downshifting, by
just lifting the gas pedal (icy, Volvo 740 and Nokian HKPL4 (studded and
very good winter tires)). Pressing clutch to get traction back and using
brakes (=braking with front wheels) were the savior of that situation.

But yes, usually with FWD car it's pretty hard to mess up with engine
braking, we certainly agree on that.

> Jim

-Aero

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scott wrote:
> 
> Maybe in some cars with sensitive brake pedals it's easier to control
> the small amount of negative acceleration through the
> clutch/gears/accelerator than through the brake pedal?
> 

Language barrier again :), I'd think sensitive brake pedal as the ones
that give you the most information. But yes, that's true. Top on that,
engine braking is more economical than using the brakes.

-Aero

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Jim Henderson wrote:
> 
> It depends on the road conditions.  For example, this morning as I turned 
> left into the parking lot at the office, the car's momentum overcame the 
> friction of the tires on the ice, and I ended up not turning as per usual 
> but sliding instead.  In that case, pumping the breaks was an effective 
> way to slow the car down.  Similar effect to a car with ABS (which I 
> really miss in my current car, my last one had ABS but the new one 
> doesn't), but the pulsing isn't rapid.
> 
> If a car has ABS, you can get away with hitting the breaks, because the 
> ABS system will prevent the wheels from locking up.
> 

And if you'd had ESP, it should've braked for you (with just left
wheels, to make the car turn) ;). For some reason (dunno why) Audi's
(tested with B7 and B8 A4's) don't seem to do this - if you turn the
wheels too quickly on ice and slide forwards without turning, the ESP
won't realize it and does nothing.

> Jim


-Aero

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> And if you'd had ESP, it should've braked for you (with just left
> wheels, to make the car turn) ;).

It's funny when my car does this, if you leave all the ESP stuff turned on 
and then try to fishtail the car after approx 0.1 seconds of sliding you can 
feel it pull on the brake on just one wheel that gets the car back in shape.

> For some reason (dunno why) Audi's
> (tested with B7 and B8 A4's) don't seem to do this - if you turn the
> wheels too quickly on ice and slide forwards without turning, the ESP
> won't realize it and does nothing.

My changing-down-on-ice experiments were exactly to see if the ESP system 
could cope with it, but alas it couldn't and I just slid with a wiggly back 
end until it gripped again.  I guess the ESP programmers didn't include a 
function to blip the throttle if it detected engine braking was locking the 
rear wheels :-)

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