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Unstable on Slippery Roads


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You bought a wagon and don't understand why it's not as stable as a sedan? Maybe you should have bought the sedan then.

 

You're joking, right? Since when would having a little extra weight over a car's lighter end (making it closer to a 50/50 weight distribution) make it less stable?

 

Not really sure of the purpose behind this comment. No offense, of course.

 

Tim

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You bought a wagon and don't understand why it's not as stable as a sedan? Maybe you should have bought the sedan then.

 

:lol: :lol:

 

Are you having problems with your head?

 

Wagon is heavier about ~50 lbs. over sedan and the handling is virtually the same, actually theoretically bit better on wagon due to better weight distribution.

 

The issue is tires as others said.

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Wagon is heavier about ~50 lbs. over sedan and the handling is virtually the same, actually theoretically bit better on wagon due to better weight distribution.

Not necessarily. The wagon has a higher COG. Also, weight distribution is carefully calculated and designed into cars and 50/50 front/rear, for eaxmple, is not always the ideal solution for good handling.

 

That aside, I have read of this "squirming" phenomenon before on this site but I think it had to do with an OB. Do the EATs in both turbo models have the same drive system?

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I'm a little bit late to join the conversation but:

 

Last year I bought my LGT in April. It had a brand new set of RE92s. One week later, we had a tiny last bit of snow for the season (2-3cm) and I HATED the way it was going in the snow. I can't imagine how bad they can be when worn. Before that I had a WRX with good studded winter tires and there was a day and night difference. For this winter I've got myself some good winter tires for the LGT and they're kickass. (continental viking contact 3)

 

"All season" means that the tires are a compromise for all seasons which means that they will suck at all season. They actually passed a law in Quebec: Starting next winter, everyone will have to have actual winter tires on their cars, no "all season" allowed. They found out that having all season tires during winter doubled your chances of having an accident due to loss of control/poor traction.

 

And AWD is completely useless if you have inappropriate tires. Correcting the path of your vehicle, keeping it stable or simply turnin/accelerating/braking will be greatly harder if your tires have bad traction. Bad tires are a weak link and AWD cannot compensate for that.

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"All season" means that the tires are a compromise for all seasons which means that they will suck at all season. They actually passed a law in Quebec: Starting next winter, everyone will have to have actual winter tires on their cars, no "all season" allowed. They found out that having all season tires during winter doubled your chances of having an accident due to loss of control/poor traction.

 

Interesting, didn't know Quebec was passing that legislation. I'll have to ask my buddy in Montreal about that.

 

And AWD is completely useless if you have inappropriate tires. Correcting the path of your vehicle, keeping it stable or simply turnin/accelerating/braking will be greatly harder if your tires have bad traction. Bad tires are a weak link and AWD cannot compensate for that.

 

Noted. But in my case (and several others) this problem occurs even with dedicated snow tires.

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Tires within specs?

 

Tires are brand new Dunlop WinterSport M3s. No shimmies, shakes, balance checks out OK. Alignment performed 3 months ago (within spec)... no curb shots or potholes since. Tire pressures are spot on (first thing I checked when I started seeing this problem). On any other surface - dry, wet, snow, gravel... absolutely no indication that anything is amiss. Car tracks true and straight. Problem only occurs when the going gets icy - and I know it's not the road surface.

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Tires are brand new Dunlop WinterSport M3s. No shimmies, shakes, balance checks out OK. Alignment performed 3 months ago (within spec)... no curb shots or potholes since. Tire pressures are spot on (first thing I checked when I started seeing this problem). On any other surface - dry, wet, snow, gravel... absolutely no indication that anything is amiss. Car tracks true and straight. Problem only occurs when the going gets icy - and I know it's not the road surface.

 

I wonder if front to back weight distribution of the OBXT is changing the rolling circumference of the tires and the center diff is unable to deal with it. Perhaps the rear tires are rotating slightly slower than the fronts on very slippery (low friction) surfaces.

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I wonder if front to back weight distribution of the OBXT is changing the rolling circumference of the tires and the center diff is unable to deal with it. Perhaps the rear tires are rotating slightly slower than the fronts on very slippery (low friction) surfaces.

 

So, not dismissing the obvious "tire" portion of the equation--no one likes my theory that this is being caused/partially caused by the rear LSD shifting torque from side-to-side in situations where neither side has adequate traction to keep the rear end tracking straight? :D

 

Ok, riddle-me-this, Batman: Do we have any folks here who've experieced this anomoly on a Subaru without a rear LSD?

 

Great thread!

 

Tim

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'06 2.5i Legacy Wagon here. Same thing. Snow/ice conditions, the car feels very "funny" at speed (35-50mph). It almost feels like you would have a huge tank of water in the trunk and the water was slushing side to side causing the rear end to wander a bit.
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This is a great thread! I will ask this question again.

 

Does Subaru have someone monitor these forums? Perhaps they can give some meaningful input from their side.

 

It sounds like tires are the first step.

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everybody that says this gets flamed for it but im going to say it anyways. They do make good all season tires. I had a real nice set of goodyear all seasons on my 300m before I got my LGT and they did well summer and winter. Not everybody has a budget for 4 new rims and 8 new tires... much more cost effective to get all seasons. Sure the BEST is two sets but just cause the RE92s suck donkey b*lls doesnt mean there arent very nice all season tires out there.

 

I also agree with the majority though that your instability in the weather is due to your tires...

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There is a lot of very good discussion regarding this and it appears that it happens frequently. I do have the RE92's and the inflation is right on. I am a frim believer in keeping things simple and to find the most logical solution to any problem. I will start with tires!

 

I have another question! On the tailgate of my wagon it says Outback. On the title is says Legacy Outback. What is the deal?

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So, not dismissing the obvious "tire" portion of the equation--no one likes my theory that this is being caused/partially caused by the rear LSD shifting torque from side-to-side in situations where neither side has adequate traction to keep the rear end tracking straight? :D

 

Ok, riddle-me-this, Batman: Do we have any folks here who've experieced this anomoly on a Subaru without a rear LSD?

 

Great thread!

 

Tim

 

I would think that if conditions are slippery enough to cause the tires to break traction that the rear diff isn't really going to register much slip differential. If that is the case, the rear will act like a solid axle (power going equally to both wheels) causing the OBXT to "crab" in relation to the front open diff wheel speed. The viscous center diff might be experiencing enough slip to become active in the process but the slightly different rolling diameters may be fouling up its smooth function.:confused:

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Crap! I posted my original question in the incorrect forum. Man I am an idiot! Sorry!

 

What are you THINKING man! GOSH!!! (Insert Napoleon Dynamite icon here) :p

 

Nah, it's probably better posted here so we can try to see if the same thing is happening in the regular Legacies and not just the OBs.

 

Vimy101 - 2 words: Split Mu. ;)

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If that is the case, the rear will act like a solid axle (power going equally to both wheels) causing the OBXT to "crab" in relation to the front open diff wheel speed. .:confused:

 

...just so I understand: In above scenario when a car is moving in a straight line, isn't the rear end of the car losing all traction and beginning to "tail wag" essentially the same behavior/effect as "crabbing" which occurs when a car which is trying to accelerate from a dead stop?

 

In both situations, there's torque being sent to the rear of the car, but with either zero traction at both wheels--the rear of the car cannot continue moving in the same linear path which the front is moving in.

 

My argument is, if the surface is consistent under both wheels, and slippery enough for 1 wheel to start spinning, the transfer of torque to the other wheel (which is all an LSD does) will cause loss of traction for that wheel, as well. Result is: Unless the dynamics of the situation are reduced or somehow controlled, you will find yourself being passed by your own butt ;)

 

Me thinks we might be saying the same thing but from different "angles" (?)

 

Tim

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^ If the suface is slippery enough and friction equal under both rear tires there will be no relative slip detected. The power to each wheel starts out equally distributed. If both wheels are slipping the at the same rate, no shear is created in the VLSD so no power is transfered.

 

Could be the opposite situation if rear tire rolling diameter is smaller than the front so instead of crabbing ahead they're being dragged along. The center diff is very sensitive to tire circumference.

 

We're on the same page with general rear diff function but I'm leaning to the center diff being the culprit.

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