2WD w/posi vs 4WD with open diffs in snow

[Donald]

Originally Posted By: ledslinger
A friend of mine had a 1990s 2WD posi Suburban and he saw another friend's Tahoe 4WD with open diffs get stuck in snow. He thinks a 2WD with posi is better in snow than a 4WD with open diff. I think he's nuts. What do you think?


My 2WD pickup w/posi is stuck in almost no snow today. My Suburban would get out of almost any condition.

 

[dlundblad]

If there's only a few inches of snow on the ground, his 2WD truck will do just fine. Plus, since its a suburban, it has the extra weight in the back too. If the snow depth starts reaching say the lugs on the rims, I imagine he'd be hosed. Lol.

Also say your friend had to drive up a snow covered incline like a driveway in a housing addition.. 2WD with LSD wont help one bit.

 

[rjundi]

Situation dependent.

I will state nothing more annoying then open diff and spinning tires on the ice on one side while your other are sitting on pavement.

 

[meep]

in my experience, 4wd open beats 2WD LSD. Some of it's due to LSD in a rear-drive vehicle is putting the "other" traction still beneath a light rear end. FWD with a real LSD would be a different animal. The van has FWD eLSD/trac control (not a fan of the tech) but I've never tried it in the snow. I can attest that it is still thoroughly capable of getting well-stuck in mud, and based on what I saw the eLSD would not be very good in snow.... because... it needs to see a certain mph before the system appears to activate. You can't feather it like a mechanical LSD allows, it's either all-or-nothing. It is extremely effective, however, in the rain, or (gosh) even leaving two dark strips on dry pavement. (Hard to believe the van will do that, but it can if you ask it to).

agree with above--- in a RWD with LSD over a light rear, once one breaks loose, it often sends the torque over and breaks the other loose as well. I learned that the hard way but thankfully the east-TN redneck reflexes kicked in quickly and we just went down the road sideways in rush-hour traffic until it tucked in. The /amount/ of limited slip additive plays a role in how quickly that happens, I have found. More additive = less aggressive.

I have yet to try the LSD rear in my truck in any real snow. We just don't get that much. The 1/2" we had yesterday was not a challenge.

 

[PhillipM]

Depends entirely on weight bias tbh, my racer is 2wd and shows a lot of 4wds up even when they have LSD's/lockers - but then 2/3rds of it's weight is over the driven wheels.

 

[OVERKILL]

Originally Posted By: Clevy
Originally Posted By: OVERKILL
Every 4x4 I've ever owned has had a limited slip rear

The Charger is a "peg leg" whilst the M5 has a limited slip rear.


What's a peg leg?
When I roasted off my old set on my charger I had 2 equal length burn outs however normal driving one tire or the other spins til I lose traction then both do.
My 99 and 01 chev's both have posi rears. The C3 is awd so the front is limited slip and the silverado has all 4 lock up when 4wd is engaged.
My 04 ram had a rear locker and the fronts locked when 4wd was engaged however my old cummins 98,3/4 ton was limited slip front and rear.


Yours has a peg-leg too. Basically, there isn't a limited slip unit in the diff. I'm going to see how much it is going to cost me to install one.

 

[95busa]

I can answer this one with one truck. I have an F250 with a posi. Without the 4WD engaged, it gets stuck or spins. With the 4WD, it goes pretty much anywhere. Two pushing does not equal one pulling and one pushing.

 

[exranger06]

Originally Posted By: 95busa
I can answer this one with one truck. I have an F250 with a posi. Without the 4WD engaged, it gets stuck or spins. With the 4WD, it goes pretty much anywhere. Two pushing does not equal one pulling and one pushing.

+1. My Ranger is 4wd and had a limited slip. The pinion bearings went bad on that axle, so I swapped in a junkyard rear that's a regular open diff (temporary, until I get my original rear fixed). So, I have experience with 2wd open rear, 2wd limited slip rear, 4wd with limited slip rear, and 4wd open rear, all on the same truck. 4wd with open diffs is way better than 2wd with limited slip, no comparison. 4wd with limited slip rear is even better.

 

[Rhymingmechanic]

Originally Posted By: rjundi
Situation dependent.


I learned to drive on snow with peg-leg RWD cars, and don't have much experience with 4WD. I currently have a 2WD Silverado shortbox with the gov-lock rear, and drive accordingly on snow. What really makes a difference is the much-maligned-on-BITOG traction control, plus a bed full of snow. If I can get started, I can usually keep going.

 

[rslifkin]

2WD with posi will drive better in the snow, up until the point where getting it stuck is a concern. However, the 4wd with open diffs will go through more before it gets stuck.

 

[Traction]

After having 2 different Chevy 4WD trucks running Blizzaks I found 4WD not needed most of the time, although fun. So, I went back to 2WD with 4 Bizzaks, and locking diff that the 4WD trucks didn't have. Sure it would be nice to have 4WD once in a while, but the 2WD works great with 4 winter tires. I would take a 2WD with winter tires over 4WD with regular tires any day in the snow. I can pull away from most 4WD vehicles running all seasons in the snow. Plus 4WD is no advantage for stopping and turning, which is half the battle in the winter. I like 2WD even more when the roads are clear. It mostly comes down to the right tires for the conditions, and after using winter tires every year for 20 years now, it is the ONLY way in winter!

 

[HangFire]

I've had enough of getting stuck.

Within a year of buying my new 4WD Dakota, I had an LSD put in the rear. I tried different tires and now I run tires with the Severe Snow Service Standard rating (the mountain/snowflake symbol), BFG T/A KO's. The KO's besides being good Winter Tires, are also great Snow Tires.

I hear the guys crowing about how fantastic their Winter tires on FWD/2WD are in the snow, yeah, I know, I have a great set on my FWD Corolla. But it ain't no LSD 4WD with Winter tires. Sorry.

 

[ledslinger]

Thanks for your input, It has helped me form some observations about the differences which I will attempt to break down.

I think it is established that front wheel drive cars are better in snow than RWD cars. So adding just the front wheels gives an advantage over an open diff RWD. In the worst conditions both 2WD posi and 4WD with open diffs are effectively 2 wheel drive. The 2WD will never have better traction than two wheels driving at 100 percent. The open diff 4WD can experience conditions worse than 2 wheels driving at 100 percent.

These conditions are rare, but the traction of a tire on either axle of an open diff is equal to the tire with the worst traction. If a tire of each axle sit on ice, even if the other tire on that axle sits on dry pavement, the total traction force of that axle is 2X the worst tire's traction. If one sits on ice, the traction is close to zero, so the total traction of that axle is 2 X 0, or zero.

I think that is a rare situation to see a 4WD open diff vehicle experience, I've seen it once in mud. It can only happen in a vehicle that is static, and in that situation it is possible a 2WD posi could have an advantage. If you are unlucky enough to have seen an open diff 4WD vehicle in this unfortunate situation, it could cause you to be biased toward your 2WD posi vehicle you've never seen stuck.

Faced with the rare situation where an open diff 4WD is stuck while stopped, vs its likely ability to have more than two wheels driving with maximum traction available, I'll take my chances with the open diff 4WD over a 2WD posi.

 

[hattaresguy]

They both suck, 4wd with lockers and snow tires.

I'm so done with 2wd trucks, I won't buy another in New England.

 

[hattaresguy]

Originally Posted By: OVERKILL
Every 4x4 I've ever owned has had a limited slip rear

The Charger is a "peg leg" whilst the M5 has a limited slip rear.


On the new Ram's an LSD is an option and a lot of the bone headed dealers don't order it. I don't get why someone would spend the money on 4wd to basically still get a 2wd truck.

 

[95busa]

Originally Posted By: Traction
After having 2 different Chevy 4WD trucks running Blizzaks I found 4WD not needed most of the time, although fun. So, I went back to 2WD with 4 Bizzaks, and locking diff that the 4WD trucks didn't have. Sure it would be nice to have 4WD once in a while, but the 2WD works great with 4 winter tires. I would take a 2WD with winter tires over 4WD with regular tires any day in the snow. I can pull away from most 4WD vehicles running all seasons in the snow. Plus 4WD is no advantage for stopping and turning, which is half the battle in the winter. I like 2WD even more when the roads are clear. It mostly comes down to the right tires for the conditions, and after using winter tires every year for 20 years now, it is the ONLY way in winter!

I disagree on the turning. You can use the throttle to pull you around turns in the snow in control with a 4wd, where a 2wd would spin (literally).

 

[Cujet]

Originally Posted By: DoubleWasp
2WD with a spool won't beat 4WD with open diffs.


So true! 4wd/AWD with open diffs can work amazingly well. The age old trick was to engage/modulate the emergency brake to move torque to the front if necessary

 

[meep]

Originally Posted By: 95busa
Originally Posted By: Traction
After having 2 different Chevy 4WD trucks running Blizzaks I found 4WD not needed most of the time, although fun. So, I went back to 2WD with 4 Bizzaks, and locking diff that the 4WD trucks didn't have. Sure it would be nice to have 4WD once in a while, but the 2WD works great with 4 winter tires. I would take a 2WD with winter tires over 4WD with regular tires any day in the snow. I can pull away from most 4WD vehicles running all seasons in the snow. Plus 4WD is no advantage for stopping and turning, which is half the battle in the winter. I like 2WD even more when the roads are clear. It mostly comes down to the right tires for the conditions, and after using winter tires every year for 20 years now, it is the ONLY way in winter!

I disagree on the turning. You can use the throttle to pull you around turns in the snow in control with a 4wd, where a 2wd would spin (literally).


and this ^^^ is like the most fun in the world for me, ever. Snow-driving, steering a 4wd/awd with the throttle is for me the most fun [driving, that is] I have ever had in a car. Drop the clutch in 2nd, keep the revs up and just go with it. smaller vehicles IMO handle this with better sport than longer or taller vehicles.

 

[rslifkin]

Originally Posted By: 95busa
Originally Posted By: Traction
After having 2 different Chevy 4WD trucks running Blizzaks I found 4WD not needed most of the time, although fun. So, I went back to 2WD with 4 Bizzaks, and locking diff that the 4WD trucks didn't have. Sure it would be nice to have 4WD once in a while, but the 2WD works great with 4 winter tires. I would take a 2WD with winter tires over 4WD with regular tires any day in the snow. I can pull away from most 4WD vehicles running all seasons in the snow. Plus 4WD is no advantage for stopping and turning, which is half the battle in the winter. I like 2WD even more when the roads are clear. It mostly comes down to the right tires for the conditions, and after using winter tires every year for 20 years now, it is the ONLY way in winter!

I disagree on the turning. You can use the throttle to pull you around turns in the snow in control with a 4wd, where a 2wd would spin (literally).


I find walking the tail around a turn under throttle in 2wd more useful than the slightly understeer biased 4 wheel drift that ensues when hammering on it in 4wd around a turn. That definitely has its place and will get you around the turn faster, but it can't be used to tighten up your turns at low speed like the RWD tail kick can be.

As far as braking, a locked center diff 4wd setup, especially with limited slip or locking diffs can slightly help under braking compared to 2wd or other 4wd systems. It makes it harder to lock up the tires at just 1 end, so if your brake proportioning isn't ideal for the available grip and weight in the vehicle, you can sometimes get a little more braking power before you exceed your traction limits (at which point you'll lock up all 4).

 

[IndyIan]

Originally Posted By: rslifkin
Originally Posted By: 95busa
Originally Posted By: Traction
After having 2 different Chevy 4WD trucks running Blizzaks I found 4WD not needed most of the time, although fun. So, I went back to 2WD with 4 Bizzaks, and locking diff that the 4WD trucks didn't have. Sure it would be nice to have 4WD once in a while, but the 2WD works great with 4 winter tires. I would take a 2WD with winter tires over 4WD with regular tires any day in the snow. I can pull away from most 4WD vehicles running all seasons in the snow. Plus 4WD is no advantage for stopping and turning, which is half the battle in the winter. I like 2WD even more when the roads are clear. It mostly comes down to the right tires for the conditions, and after using winter tires every year for 20 years now, it is the ONLY way in winter!

I disagree on the turning. You can use the throttle to pull you around turns in the snow in control with a 4wd, where a 2wd would spin (literally).


I find walking the tail around a turn under throttle in 2wd more useful than the slightly understeer biased 4 wheel drift that ensues when hammering on it in 4wd around a turn. That definitely has its place and will get you around the turn faster, but it can't be used to tighten up your turns at low speed like the RWD tail kick can be.

As far as braking, a locked center diff 4wd setup, especially with limited slip or locking diffs can slightly help under braking compared to 2wd or other 4wd systems. It makes it harder to lock up the tires at just 1 end, so if your brake proportioning isn't ideal for the available grip and weight in the vehicle, you can sometimes get a little more braking power before you exceed your traction limits (at which point you'll lock up all 4).

I do like a nice 4wd drift but for whatever reason I can't be that precise with them. In rwd I can do some nice long drifts on my driveway and I only plow it 20' wide, which gets kind of narrow with the car at a good angle.