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Radio
01-01-2013, 05:14 PM
The roads are slicker than snot on a door knob...

Radio
01-01-2013, 05:16 PM
On a more serious note, why would you 'not' drive in 4 wheel drive?

Andy N1ORK
01-01-2013, 06:53 PM
On a related note, what's the difference between AWD and 4WD? My wife drives a Honda CRV AWD.

NN5I
01-01-2013, 07:16 PM
Typically an all-wheel-drive (AWD) vehicle is intended to be in 4WD all the time, and has a transfer case that includes a differential gearset between the front and rear axles so that the front and rear axles can turn at slightly different rotational speeds -- in the same way that the differential gears in each axle allow the port and starboard wheels to turn at different speeds.

Vehicles called 4WD rather than AWD usually don't have this third differential nowadays, and should be in 2WD and not 4WD when they're on dry pavement. Ever-so-slight differences in rotational speed, front and rear (which might be due to tiny differences between tires, for example, or even caused by a heavier load on the front than on the rear) could cause the front wheels to try to roll one mile plus 1/2 inch while the rears were rolling only a mile. With no differential gears between front and rear, that can develop forces in the drivetrain sufficient to break teeth in the transmission and axles, or to cause rapid wear. So 4WD vehicles should be in 4WD only when the road surface is at least a little bit slippery; OK on wet pavement, not OK on dry pavement.

Having said all that, many modern AWD vehicles have complex couplings, sometimes hydraulic, that measure slip at each wheel and vary the power sent to each wheel (sending less power to a wheel that is slipping). Such a system often has a dedicated computer that also includes handling assistance and the like. Too complicated for me.

I once owned a 1978 Chevy 4WD pickup that had what was then called "full-time four wheel drive" -- its transfer case did have a differential gear, and you could drive in 2WD or in 4WD regardless of what surface you were on. It worked well.

As for why they'd say don't use 4WD on snow and ice, I think they're wacky. But what would you expect of people who don't proofread what they write?

N3LYT
01-01-2013, 07:25 PM
On a more serious note, why would you 'not' drive in 4 wheel drive?
I don't think I would want to drive my 4X4 in snot either!

Andy N1ORK
01-02-2013, 06:09 AM
Thanks for the explanation Carl.
73

TXiceman
01-02-2013, 06:50 AM
Rather drive in snot than sh---poop.

Ken

N3LYT
01-02-2013, 07:06 AM
Rather drive in snot than sh---poop.

Ken

I guess if it gets that bad out I'll stay home.

wa8yxm
01-02-2013, 08:54 AM
ON ice,,,, Well the only things that work is SLOW DOWN and Skill. On snow or other poor conditons there is one other thing that helps.. TIRES.

For many years I could safely handle a car at nearly 2x the average speed (If I could find an open road to do it on) because I bought tires that were 4x better than average. NO slipping, NO sliding, No spinning tires, because they were very good tires. Many times I was "mobile" while others were stuck.

Part skill, I did not push the envelope ever. If the roads were bad I slowed down to improve control rather than risk it.

Part tires. For example one time we had a co-worker talking about how much fun it was going to be to watch the kid with the new ford Pickup (Light on the drive axle, like all ford pickups) with the super wide tires (Way worse in snow) go up the hill.. I have to admit he was right.. What was even more fun was watching HIM go up the hill. (Same way the kid did).

What was not so much fun was watching me and my Kelly Navigators go up that hill like it was the middle of August. (Which by the way was when I bought the Kelly's)

Still, on Ice.. Well, I've been known to drive all ahead full idle.

TXiceman
01-02-2013, 07:07 PM
The twp years we lived in Toronto, all we had were summer radials...good ones with an open thread. we never had any issues. But if you went out in the rural areas, you needed snow tires by law.

Ken

NN5I
01-03-2013, 12:11 AM
It was probably a bit colder in Toronto than some other places. Snow & ice are much more slippery when the temperature is near freezing than when it is way below freezing. At, say, 10 below zero, ice isn't particularly slippery compared to wet pavement in summer. But at 30 above zero, you can't even stand on the stuff, much less drive on it.

wa8yxm
01-03-2013, 10:08 AM
On a more serious note, why would you 'not' drive in 4 wheel drive?

Ok the difference between 4WD and AWD is the transfer case.

On many 4wd Vehicles the transfer case is a collection of simple spline cluthes (Gears or toothed plates that either engage or don't) thus both the front and rear drive shaft turn at teh same rate, as though they were one.

On an AWD, the transfer case is itself a differential, so it is possible for one shaft to turn at a different speed.

Now going straight down the road, and I do mean straight, makes no difference,

But in a curve teh front wheels (epically the inside front) turn at different speeds than the rear (Even the inside) the result is the front and rear drive shafts turn at different speeds.

In a 4wd vehicle on slippery roads, Mud, Ice, Sand, Gravel, Dirt, no problem

On concrete or asphalt, (Clear and dry in both cases) this puts a whole lot of strain on the drive systems.. Which is why it's not to be done.

KF5BET
01-05-2013, 11:45 AM
we used to go around and pull people out of ditches when I was a kid and the snow came. Had a S-15 Jimmy which was a work horse (would climb a tree in 4 lo and 1st).

Don't have a 4wd here in the south (don't need it anymore). Done with the off road stuff!

I have told everyone at work, that if it snows here I will NOT be coming in to work. They Look at me all funny and ask "didn't you grow up in the snow"?

I reply "yes I did but noone here did and you will all be out trying to drive in it. Thank you, but I will stay home and let all of you you play bumper cars..."

One Country Boy
01-07-2013, 01:23 PM
Well I'm not too sure I wish to rely upon someone who entitles there message "Driving on Snot and Ice". ;)

I've always heard and been taught that on slick surface, in a 4WD vehicle that it was best to drive very slowly, in 4WD to maintain the best traction. Maybe I'm old fashioned, but I think I'll stick with that thought.

NN5I
01-07-2013, 01:28 PM
A girlfriend taught me this elegant song a long time ago --

Old Man Lucas
Has a lot of mucus
Comin' out of his nose.
He'll pick and pick
'Til it'll make you sick
And it just grows and grows ...

I'm kind of that way myself, at the moment. I've had the flu for a week plus (despite having had this year's flu shot) and it still has me in its, uh, grippe --

As for driving in snow and ice, I'm with you, Jim -- that's what 4WD is for.