2wd-4wd-posi......

mrvette

Phantom of the Opera
Joined
Mar 24, 2008
Messages
15,207
Location
NE Florida
Question for you 4wd guys, something I have never understood, the typical 4 wd vehicle has a open diffy at each end...so in fact you have only a 2 wd vehicle at any given time, given you CAN break the tires loose for any number of reasons.....traction brakes and you have one tire smoking on each end....

what in hell is supposed to be so great about that setup that the simple additon of posi in the rear will not cure??? for instance, in a vette with 50-50 weight dist.....or like my 3/4 ton work vans....a large % on the rear especially with 500000 lbs of junk in it.....

I always had that basic question I don't understand the usefullness of the typical 4 wd setup, I can understand for like mountaineering but for typical flatter land use, I can't.....

and a huge for instance, was a guy ;pulling his boat at a ramp, had a typical 4 wd pickup, and could not get his boat outta the water, one on each end a smoking, and just setting there, had to get someone else to hitch him up and pull him outta there.....
while without even a pier between us, me and my old Goat convertible got up the same ramp with similar boat and posi.....no sweat, not even spun a wheel....

which made me wonder, WTF????


:lol:
 
Have you been drinking water from the pottsburg creek again ?

GEE
 
A posi is an option for the rear of a 4wd. For some reason most don't order it- I didn't when I ordered my pickup. If I had to do it again, I'd get it. The front has to be an open diffy so you can steer it in 4wd and not break anything. If I'm in 4wd and make a tight turn on dry pavement it "skips" anyway.
I'm still a little worried about breaking a rear axle if it hooks up suddenly- the duals are heavy.
 
well if your rear tires are both on ice your screwed.... you at best have aprox 45% weight on the rear so you are only at best using that 45% to push the rest of the weight.... now if you have the front PULLING too then you have 100% of the weight pushing and pulling. yes you can have one one front and one rear doing the work but really even when you have less traction on one side you will still have some (small %) of drive from the other side.
 
My experience is the rear of most (pre '87 4x4 chevy) pick-ups is so light you
can get stuck in a wet parking lot. The front wheels have the added benefit
of having the weight of the engine and accessories to aid traction.

So why did your car pull the boat? Probably because under the conditions
it had better weight transfer to rear wheels and the fact I'm sure it set much
lower than the 4x4 which resulted in positive tongue weight from the boat trailer. "Double Bonus"

If the 4x4 set high enough it may have been experiencing negative tongue
weight. It was trying to put the same weight but with a now 20% lighter
rear end than if pulling no boat at all. And weight transfer was None.

Make sense. :nuts:



:wink:
 
My experience is the rear of most (pre '87 4x4 chevy) pick-ups is so light you
can get stuck in a wet parking lot. The front wheels have the added benefit
of having the weight of the engine and accessories to aid traction.

So why did your car pull the boat? Probably because under the conditions
it had better weight transfer to rear wheels and the fact I'm sure it set much
lower than the 4x4 which resulted in positive tongue weight from the boat trailer. "Double Bonus"

If the 4x4 set high enough it may have been experiencing negative tongue
weight. It was trying to put the same weight but with a now 20% lighter
rear end than if pulling no boat at all. And weight transfer was None.

Make sense. :nuts:



:wink:

Good explanation, I always had a decent amount of tongue weight on my boat, I would barely be able to lift it....and not so far at that....

they guy didn't have his boat far enough forward on the trailer....:clobbered:
 
my 02 S10 4x4 has posi in the rear,came with it. The truck will fish tail or get stuck in the snow with just the posi. Once the frt end is engaged it pulls right out. It's nice to have it up here but it also failed 4 winters so far! Turning radius is much too wide and MPG is lower, but sure beats the 4x2 when leaving the shop when there's 6+ inches of snow on the ground.
 
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