Pushing The AWD Limit (sorta)

[rweddy]

Excuse my ignorance, but what do you mean by high centered?

 

Charles

All four wheels off the ground. When snow gets really deep you can get a vehcile up off the ground.

[cannonball]

All four wheels off the ground. When snow gets really deep you can get a vehcile up off the ground.

I think I've read that the OB can handle up to 13" of snow. I wouldn't know here. We never get that much. We do get the ice though and this car rocks on ice.

[ron917]

I think I've read that the OB can handle up to 13" of snow. I wouldn't know here. We never get that much. We do get the ice though and this car rocks on ice.

Depends on what kind of snow. We get all kinds here in NJ.

 

Dry, fluffy snow can be pretty deep (over the bumpers). It just kind of blows away.

 

Wet, sticky snow isn't bad until it gets deep enough that you start "plowing" it with the subframe, or whatever. Then it will pack up under the car, and eventually you are high-centered. It doesn't matter how may wheels are driven, or what kind of tires you have, when they don't touch the ground, you don't move. Time to grab a shovel and start digging.

 

If you're REALLY un-lucky, and the temperature is just right, the packed, wet, sticky, snow will freeze solid before you can dig it out. Not fun. Those are the times when you wish you had a winch.

[cannonball]

 

. Those are the times when you wish you had a winch.

Or lived in the South.

[blitz]

Just wanted to add my two cents here. I have a '90 legacy w/ auto trans where the AWD has been broken since I bought it. Something's wrong with the electrical connections to the tranny, and the computer won't lock up the rear wheels. So I spliced a switch in to force the transfer case to lock it up. It works great - with the switch connected I have front wheel drive, and disconnected it's four wheel drive. And yes, it does lock up the transfer case. I will only get stuck if one front wheel and one rear wheel lose traction at the same time. And by the way - it's a blast offroad and in the snow. Always locked up and goes like crazy. Dave

 

I've wanted to install something like that in my car. A three-position switch:

 

Forward position: Manual FWD

Center position: Computer AWD

Rear position: Manual AWD

 

My only concern has been whether or not the solenoid can withstand long periods of forced FWD operation (solenoid on). Based on what you're saying Dave, it appears as though it can?

[wrxsubaru]

I have a lot of experience off-roading vehicles. Jeeps, Landcruiser, etc.

AWD vehicles are not made for this use. It is not a failure of the VC is is the way it works period. You will not be able to get three wheels spinning on a Subaru in a off-road situation. You live where it snows. Get your AWD subaru High centered and only one wheel front left or right will spin. Without a center diff lock this is a matter of physics.

 

 

The VC can transfer enough power to get the wheels to spin on both ends, i had my legacy high centered many times when i was off roading it and every time either all 4 wheels would spin, or 2 one fron one rear would. Its like a limited slip diferintal a lockler is beeter but a liitem slip can still transfer power.

 

If you have a limited slip differintal, it can lock the front wheel and back togher its simple physiscs.

[rweddy]

The VC can transfer enough power to get the wheels to spin on both ends, i had my legacy high centered many times when i was off roading it and every time either all 4 wheels would spin, or 2 one fron one rear would. Its like a limited slip diferintal a lockler is beeter but a liitem slip can still transfer power.

 

If you have a limited slip differintal, it can lock the front wheel and back togher its simple physiscs.

You have not had your vehicle in a hard core off-road situation. There even a LSD becomes overpowered. If you try to climb an AWD subaru up a very steep lose section you will not go and if one wheel is in a hole that wheel will spin. Or it will try to claw its way up with one tire. The VC can transfer power but is 90% to the path of least resistance.

Same concept as a 4wd vehicle with lsd, if you get one tire in a hole or up in the air on both front and rear the wheel up spins. That is why they sell locking differentials. And to get one wheel to spin on the front and rear you need to have a way to lock the VC so it will distribute 50% power front and rear.

 

[cannonball]

You have not had your vehicle in a hard core off-road situation. There even a LSD becomes overpowered. If you try to climb an AWD subaru up a very steep lose section you will not go and if one wheel is in a hole that wheel will spin. Or it will try to claw its way up with one tire. The VC can transfer power but is 90% to the path of least resistance.

Same concept as a 4wd vehicle with lsd, if you get one tire in a hole or up in the air on both front and rear the wheel up spins. That is why they sell locking differentials. And to get one wheel to spin on the front and rear you need to have a way to lock the VC so it will distribute 50% power front and rear.

 

 

So from what you are saying a continous AWD system that is roughly (according to Subaru) 50/50 will take the energy from the rear axle in a front slippage scenario and deliver it all to the front tire that is slipping which in turn by definition of torque distribution means all torque goes to zero. This kinda goes against what Subaru is preaching. Or are you saying that if the hill is steep enough and the rear tires have traction that the VC could be overwhelmed because the force to go up the hill is just to much. Thus the silicone in the VC can't keep the plates locked together causing the rear to lose all of it power transfer? Which in turn means that the stiction(for lack of better terms) of the rear tires is greater than the stiction of the VC. Or are you saying that a little slippage is ok, but a lot is not?:-\

[MorganM]

Next time straddel the rut instead; I think you'll make it farther up the hill then!

 

Picking a line and a little momentum is just as important in a situation like this as having AWD.

[cannonball]

Next time straddel the rut instead; I think you'll make it farther up the hill then!

 

Picking a line and a little momentum is just as important in a situation like this as having AWD.

 

If only I had more time to play. Life would be sooo much easier. Work is almost over and I'm ready to jump in the OB go home and drink some beer. Maybe I'll play tommorrow.

[rweddy]

So from what you are saying a continous AWD system that is roughly (according to Subaru) 50/50 will take the energy from the rear axle in a front slippage scenario and deliver it all to the front tire that is slipping which in turn by definition of torque distribution means all torque goes to zero. This kinda goes against what Subaru is preaching. Or are you saying that if the hill is steep enough and the rear tires have traction that the VC could be overwhelmed because the force to go up the hill is just to much. Thus the silicone in the VC can't keep the plates locked together causing the rear to lose all of it power transfer? Which in turn means that the stiction(for lack of better terms) of the rear tires is greater than the stiction of the VC. Or are you saying that a little slippage is ok, but a lot is not?:-\

These are things you do not find out or will not find out until you truly off-road a vehicle. AWD is great for on the road and minor off-road use.

 

 

Limit slip and VC are traction aid devices. LS uses clutch packs, VC Fluid. When you really start pushing these, put them in extreme situations they will and do get defeated. When I first started taking my Jeep CJ on trials I would get the vehicle crossed up going up hill and only one wheel would spin on the front and rear even though I had LS in both axles. So to get a truck lock up you need to have a mechanical devices that locks them mechanically together. ARB, Detriot lockers, etc makes devices like these. They cannot be used on the street or are not very good because the do not allow for wheels to turn at different speeds since they are designed to make both wheels turn at the same rate all the time. So when you go around a turn there is issues. The inside tire turns slower than the outside tire when you make a turn.

 

 

I am not bashing subaru’s AWD system at all. This thread was started asking why when going up a steep lose hill not all four wheels were spinning. And I was just explaining why they wont in this situation.

[rweddy]

So from what you are saying a continous AWD system that is roughly (according to Subaru) 50/50 will take the energy from the rear axle in a front slippage scenario and deliver it all to the front tire that is slipping which in turn by definition of torque distribution means all torque goes to zero. This kinda goes against what Subaru is preaching. Or are you saying that if the hill is steep enough and the rear tires have traction that the VC could be overwhelmed because the force to go up the hill is just to much. Thus the silicone in the VC can't keep the plates locked together causing the rear to lose all of it power transfer? Which in turn means that the stiction(for lack of better terms) of the rear tires is greater than the stiction of the VC. Or are you saying that a little slippage is ok, but a lot is not?:-\

 

Limit slip and VC are traction aid devices. LS uses clutch packs, VC Fluid. If they could not be defeated, defeated, slip, etc the car would be un-drivable. When you go around a corner they must allow the inside tire to turn at a slower rate then the outside tire that has more ground to cover.

 

These are things you do not find out or will not find out until you truly off-road a vehicle. AWD is great for on the road and minor off-road use.When you really start pushing these, put them in extreme situations they will and do get defeated. When I first started taking my Jeep CJ on trials I would get the vehicle crossed up going up hill and only one wheel would spin on the front and rear even though I had LS in both axles. So to get a truck lock up you need to have a mechanical devices that locks them mechanically together. ARB, Detriot lockers, etc makes devices like these.

 

They cannot be used on the street or are not very good because the do not allow for wheels to turn at different speeds since they are designed to make both wheels turn at the same rate all the time. So when you go around a turn there is issues. The inside tire turns slower than the outside tire when you make a turn.

 

I am not bashing subaru’s AWD system at all. This thread was started asking why when going up a steep lose hill not all four wheels were spinning. And I was just explaining why they wont in this situation.

[coloradosubarules]

I took my 90 legacy L AWD Wagon up the Ute creek and Clear Creek Pass in Idaho springs, CO followed by a 2000 Dodge Durango 4X4 and let me tell you the Durango had a hard time keeping up. My cousins exact words were, "this gets out to nobody!"

 

I can't recall one time that my tires ever slipped the enitre trip. Maybe you should use a little more torque and less speed. I was running M+S tires (nothing special) but you might want to look at your tires. Were the lugs clogged with dirt or mud?

 

just my two cents.....

[cookie]

at least six of them. I had a Dodge Durango a couple of years ago off road in Maine. My opinion is that under certain conditions different vehicles will do better. There is no great one for all conditions that I have seen. If you were rock climbing, or nasty mud off roading it is hard to beat a lifted Jeep or Toyota with lockers.

On the other hand if you keep a Subie going with enough speed it just might get furthur under some conditions than the Jeep.

The Subie is very light and if lightness counts, like on snow where you don't want to break though the crust, the Subie might surprise you.

As for the Durango note that I am on this board not the Durango board.

[Ranger83]

The OBW is not an off-road vehicle. It is a pretty good bad road vehicle. The advantage the Subaru has over 4WD pickups and SUV's is that most of those had beam rear axles at both ends. The independently suspended wheels of the Subaru spend a lot more time in contact with the ground on rough uphill sections, whether they be mud, ice, or snow. It is NOT fun to be driving a 4WD truck around a corner, hit a couple of bumps, and have it slide two feet sideways. The new Ford SUVs and others are starting to offer all independent AWD, although most of those are far too heavy to go off road.

 

I am fortunate to have spent several years in an Armored Cavalry Squadron, patrolling the Iron Curtain in everything from M151 Jeeps to M113 Armored Personnel Carriers and tanks. We also did some manuevers with the Germans and I've been down the same trails with the German Iltus (aka VW190). Wheeled vehicles can't hold a candle to tracks off road. The Subaru does a great job on bad roads, making tradeoffs in off-road performance for greatly improved handling and economy.

[rweddy]

The advantage the Subaru has over 4WD pickups and SUV's is that most of those had beam rear axles at both ends. The independently suspended wheels of the Subaru spend a lot more time in contact with the ground on rough uphill sections, whether they be mud, ice, or snow. It is NOT fun to be driving a 4WD truck around a corner, hit a couple of bumps, and have it slide two feet sideways. The new Ford SUVs and others are starting to offer all independent AWD, although most of those are far too heavy to go off road.

Yep this is why the subaru is such a great on-road vehicle in snow ice etc.

But off road a solid axle is much better since it affords great articulation and power to be put to the road.

 

I can also tell you that I have had several of my 4wd subarus w/lo range in some very hairy off-road situations and they do great!

[WoodsWagon]

Well, the only way i can see to settle this argument is for someone to plug one of their brake lines with a box nail, jack that wheel up, and hold the brake while letting the clutch out. According to Rweddy, this wheel will just spin instead of the engine stalling out. If the wheel spins for a second, then the engine stalls, then the viscious coupling has worked effectively, and it has been designed to handle the power of the engine. If the wheel spins for 3 seconds plus, then rweddy is right and the coupling cannot handle the power and the car is basically 1 wheel drive. I don't dare try this with my car, i would if my clutch had more life to it, but as it is it slips in anything over 2nd gear. Now my mind recovers its functions! Pull the E brake full on, jack up one of the front wheels, and do the same test, just simplified.

[rweddy]

Well, the only way i can see to settle this argument is for someone to plug one of their brake lines with a box nail, jack that wheel up, and hold the brake while letting the clutch out. According to Rweddy, this wheel will just spin instead of the engine stalling out. If the wheel spins for a second, then the engine stalls, then the viscious coupling has worked effectively, and it has been designed to handle the power of the engine. If the wheel spins for 3 seconds plus, then rweddy is right and the coupling cannot handle the power and the car is basically 1 wheel drive. I don't dare try this with my car, i would if my clutch had more life to it, but as it is it slips in anything over 2nd gear. Now my mind recovers its functions! Pull the E brake full on, jack up one of the front wheels, and do the same test, just simplified.

Or you can talk to anyone else with off-road experience. I have been wheeling and wrenching vehicles for a very long time. There is a reason they do not take AWD vehicles off-road.

Or come with me to a off-road trail in Colorado. I will show you there with hurting the vehicle.

[Skip]

I am also skeptical of rweedy's statement repeatedly that only one wheel will spin.

 

I have on my lot a 94 Legacy 4EAT AWD and a 00 2.5 RS 5 speed.

 

If I use a scissors jack to jack one front wheel off the ground

(positioned sideways to make tipping easy),

 

if what he says is true -

 

neither car will push itself off the jack when put in gear.

 

Does this sound like a fair test?

[rweddy]

I am also skeptical of rweedy's statement repeatedly that only one wheel will spin.

 

I have on my lot a 94 Legacy 4EAT AWD and a 00 2.5 RS 5 speed.

 

If I use a scissors jack to jack one front wheel off the ground

(positioned sideways to make tipping easy),

 

if what he says is true -

 

neither car will push itself off the jack when put in gear.

 

Does this sound like a fair test?

Having the vehicle up on jacks does not create enough forces to overwhelm the VC. You need to have it in a situation where there is a lot of pressure on it. IE going up hill in an off-road situation. This is the same as a LSD, if will work on the road or in most situations, but when you exert an extreme amount of torque on the unit it will become overpowered and only one wheel will spin. Like I stated before this is common knowledge by the off-roading community, you can pick up a "How to Off-road" by Mark Peterson (not sure the author is correct) and it has diagrams showing this.

[rweddy]

NO REASON TO YELL!!!

FYI Jeeps had VC and full time AWD in the CJ7 in 78.

A VC is a VC.

Beleive what you wish I have real experience with this and next time we take the outbacks wheeling I will take some video to post when we get crossed up and have one wheel drive.

 

[WoodsWagon]

Grrr. If only I had an E brake and a clutch, I'd go out and settle this right now. Someone please run my simplified test. And video tape it if you can.

[wrxsubaru]

You can over whelm the VC cneter diff on any car that i no of its just not that easy, and on subes there pretty strong, but you can stil have kind of one wheel drive, the other wheel will get power just not engough to spin it or move the car.

 

The 4eat auto on the other hand can basicly lock the wheels togher like a clutch i think, and that is really hard to get one wheel spining, never have.

[rweddy]

You can over whelm the VC cneter diff on any car that i no of its just not that easy, and on subes there pretty strong, but you can stil have kind of one wheel drive, the other wheel will get power just not engough to spin it or move the car.

 

The 4eat auto on the other hand can basicly lock the wheels togher like a clutch i think, and that is really hard to get one wheel spining, never have.

That is all I was trying to explain! Thank you!!

http://auto.howstuffworks.com/differential9.htm

 

The first post was asking if his car was screwed up since he was going up a steep dirt hill and only one wheel was spinning..... wanted to know if it was broken.

[cannonball]

That is all I was trying to explain! Thank you!!

http://auto.howstuffworks.com/differential9.htm

 

The first post was asking if his car was screwed up since he was going up a steep dirt hill and only one wheel was spinning..... wanted to know if it was broken.

 

Richard I didn't mean to get you flamed like that. You are right that I wanted to make sure that something was not screwed up. To settle the matter I went back yesterday. Since this is not to far from my house I did a preride on my mtn bike to make sure that if I made it I the rest of the road was doable. Well I took my notes and headed back out yesterday afternoon. This time I took the turn a little wider and cut across the gully more perpendicular. This time she scooted through and up the short hill with style. What started out as an initial tire spin turned into traction. Well as you can imagine this made my day. I can't say enough how much I love this car.

 

Charles