DSTC off..... but is it? The verdict below -->

[Ducatista]

I have been experimenting with DSTC lately on snow covered roads and have come to the following conclusions.

1. With DSTC on you may drive at up to a moderate speed on snow/ice and feel relatively secure. This system hides surface conditions just like a gas mask keeps out dangerous fumes.
You cannot feel whats under you. The moment you push the car to feel the limits of traction, it kicks in cutting you from the sense.
On rutted snow, the moment you push the accelerator to overcome a track wall, DSTC kicks in.
On tight uphill hairpins, where you want to power out, it cuts in.
I guess that if you just want to cruise around and forget what you're doing, it will keep you out of trouble but ...
... I like to drive my car, by the seat of my pants.
So I turned DSTC off.....

2. And here we are, with the indicator showing you are in insurance company territory. DSTC off.
First thing you notice in snow is a mild torque steer that wasnt there before, followed by wheel spin (remember wheel spin?) and the haldex joining the club. Then if you are of the foot down persuasion, you get to actually power the car back on course while it mildly oscillates in and out of aforementioned ruts.
Corners are fun with some powersteering available.
And then you get to reach the switchback.
Now any sensible Volvo driver who has endured my brag sofar and hasnt changed subject already, probably knows not what's coming.
Or does he/she?
If you have ever watched WRC footage you may have noticed that these racing cars rarely run facing forward. Why is this?
This is because in limited grip conditions it is actually better to slide the car sideways into and through a corner than to keep an optimum raceline.
Thus affected, I flick the wheel and tug the handbrake just before the switchback turning point, bringing the full length of my beloved XC at a 45deg angle to the road, with the front wheels at opposite lock.
Just as I'm about to scream and palpitate with excitement at the forthcoming powerslide up the corner, the damn thing cuts in and my line is muffled (ruined) by the crack of antispin!!!
What the....???
I turned it off. I did.
Yes but such behavior is not allowed by our big accounting brother in Volvo headquarters.

Verdict:
DSTC is never totally off. It will sort you out if you are foolish enough, like me, to drive like a maniac in bad conditions and it will allow moderate powersteering to give you the impression of control.
So
If you can handle a 4.7m turbocharged AWD car with brio in snow covered roads, go ahead and "deactivate" it for a little dose of politically correct excitement.
But
If you have no idea what I've been talking about above, d o n o t t o u c h t h a t b u t t o n.

[thumbup]

[Willy]

Hi,
Your diagnosis is correct, DSTC is never off completely.
However, you shouldn't have gone through all the testing (unless, of course, it was for the fun :)), it is explained in the owner's manual, see the attachment.
Willy

[Ducatista]

Yes Willy you're right,

But I cant help it, I'm a classic RTFM (Read The F****** Manual) case.

AYC (Active Yaw Control) is never switched off. That means no WRC driving!!!

Not for me, not for any Volvo driver on the road.
Keeps the insurance guys happy.

Bummer!

[Willy]

Yes, I understand what you mean, it must be frustrating to find out that your car will always try to keep you on the road, whereas you would rather be in full control yourself.
Only one solution: get yourself an RWD model with some power, eg. a 240 turbo if you can still find one, it is sure to give you all the fun you are looking for :D
Willy

[airprakken]

Only one solution: get yourself an RWD model with some power
Actually, a WRX works too. :-)

[Willy]

Hmm, isn't a WRX an AWD car as well? IMHO, a RWD is more fun :D :D
Willy

[budrichard]

DSTC OFF actually turn OFF TRACTION CONTROL. In deep snow you need the wheels to keep spinning to get power down and keep moving. Traction control does the opposite, It brakes a spinning wheel and retards the engine. I was on a snowmobile trail and ran into a deep drift with DSTC ON. The vehicle promptly stopped and efforts to back up were thwarted by DSTC ON. With my door open, I could actually see the front right wheel brake and the engine go to min revs to stop the spinning wheel(s). A barn shovel and about an hour later I dug my self out.
Now whenever I go off road, I turn DSTC OFF. -Dick

[Ducatista]

an old Ford Escort RS2000?

hmmm that reminds me of the days...

Sideways 4ever, that was rallying in the seventies.
Plus you could hillclimb it and with some changes take it to the circuits.
Days long gone.

You know, before I got the Volvo I tested the Subaru Outback 3.0
It was actually a terrific car.
Power, topclass 4WD and gadgets galore.

But I went for the XC because it can carry all of us + the dog, its interior quality is excellent, way better than the Sub's, and it is very fast. Plus the whole car looks more solidly built and, of couse, it offers superior active safety.

One thing I remember of the Sub is that the 4WD was imho better than the Volvo's. In low traction conditions, you never felt the front wheels spin like the Volvo's do. Power is distributed to all wheels simultaneously as opposed to front first.
Haldex is good but the front has to loose traction for the rear to be put to work. It is not seamless in any way.

Sorry to say this in this board but the Sub 4WD system is way superior and if Volvo AB wants to improve these excellent cars in this respect, it should take some Japanese lessons.

[airprakken]

Hmm, isn't a WRX an AWD car as well? IMHO, a RWD is more fun

Depends what you are looking for I guess. I have never had so much fun as a WRX off-pavement in gravel, dirt and snow on mountainous, back-country roads. Also, it is a lot faster than RWD on wet pavement corners -- which I get a lot of here in Oregon.

However, I agree that the XC70 is for different purposes. I'll have one of each soon to directly compare.

[vtie]

One thing I remember of the Sub is that the 4WD was imho better than the Volvo's. In low traction conditions, you never felt the front wheels spin like the Volvo's do. Power is distributed to all wheels simultaneously as opposed to front first.
Haldex is good but the front has to loose traction for the rear to be put to work. It is not seamless in any way.
Sorry to say this in this board but the Sub 4WD system is way superior and if Volvo AB wants to improve these excellent cars in this respect, it should take some Japanese lessons.

It's a design choice. In the subaru, the power is always split between the front and rear wheels (approx. 50/50). In the volvo, default is almost all the power to the front wheels, and the rear ones are only engaged in case of front wheel spinning. There may be several reasons why volvo chose that approach, for example fuel consumption. Or maybe, the clutch in the haldex system isn't sturdy enough to be used all the time?

[Ducatista]

There may be several reasons why volvo chose that approach, for example fuel consumption. Or maybe, the clutch in the haldex system isn't sturdy enough to be used all the time?

I understand fuel consumption. It makes sense to power the front wheels first to save fuel.

But why give a competitor an edge?
Haldex is a very good diff. It can handle the power and torque of the R and thats a lot. But it isnt exactly IT.

If Sub has something to brag about, its their 4x4 system and rightly so.

You know what I'd do, if I were Volvo AB?
I'd do exactly what the Japanese did back in the 60ies and 70ies and 80ies and to some extent the 90ies.
I'd buy an Impreza WRX and copy the 4x4 system bolt for bolt.
Surely they wouldn't mind...! [cool2]

He He

Kampai Fuji san!

Arigato!
:D :D [thumbup]

[vtie]

I understand fuel consumption. It makes sense to power the front wheels first to save fuel.
But why give a competitor an edge?
Haldex is a very good diff. It can handle the power and torque of the R and thats a lot. But it isnt exactly IT.


I don't know, this is pure speculation from my side. Maybe it can handle the torque for a while (a couple of minutes), but would heat up too much if enganged constantly? Is it designed to stand a 5 hours drive at 180km/h if constantly engaged? From what I learned about the haldex system, it is designed to be used on a temporary basis rather than being permanently engaged.

[Ducatista]

Have a look at this link.
Its the official link for HALDEX traction systems.

http://www.haldex-traction.com/technical_information/six_dimensions/six_dimensions.htm

Nice specs but I like the Sub's feel better...

Waidaminute................!

Didn't Saab join forces with Sub to build the large 4x4 suvs they are introducing this year?
Thats interesting.
I saw the SAAB version at an exhibition this year but didn't like its looks. Too bulky. I like my XC better.

http://www.saabusa.com/saabjsp/97x/index.jsp
http://www.subaru.com/shop/overview.jsp?model=B9_TRIBECA&trim=LIMITED_5-PASSENGER&command=overview

[Jack]

I believe the 9-7 is a Chevy Trailblazer mechanically. It would have been a much better vehicle if it was developed with Subaru!

[littlewaywelt]

dstc off only turns off the spin control which brakes a wheel that is slipping rotationally forward. it does not affect or turn off anything else. this feature is useful if travelling in deep mud, sand or snow where you don't want the wheels to be braked.