Questions for a friend purchasing an '02 Forrester.

[Jim Whall]

Howdy all!

I have a friend who is looking into getting an '02 Forester, or
possibly an '02 Impreza. He is going to be using them for mainly
cruising around northern Michigan roads, and it is down to them and a
CR-V. As I am the more usenet literate of either of us, it came to me
to ask the questions. I'm a Jeep guy so please forgive me if I butcher
some terms.

Q: The Subaru AWD system seems alot better than the Hondas, but there
are a couple things that are confusing. Subaru says it has
'symmetrical AWD'which would imply that it distributes power across
axles as well as between axles (cool!). My question is how? I have
done a couple hours of searching but the most I can get on Subaru AWD
systems is a few years old. I have read that Subaru uses a viscous
coupling for what I think of as its center diff, but what about across
the axle itself? Does it use another VC? The ABS?

Q: Is the 2.5 litre engine an interference motor?

Q: Is there any advantage to getting the stick vs. the Auto? And does
that change the AWD system?

Q: Any huge advantage to getting the Forester vs. the Impreza? (Other
than the WRX which, try as I might, I wasn't able to talk him into).

Q: Is the VC center diff sensitive to tire pressure differences; i.e.
if he doesn't keep his tires at similar pressures damage can result. I
know that some of the earlier JGC's that used this had some problems
along this line.

Q: Is the AWD system a full time variable split between the front and
rear, or is it more of a reactive system with the power favoring one
side, like the Hondas?

Thanks!

Jimbo

(e-mail address removed)

 

[Sparky Polastri]

http://www.subaru-global.com/about/awd/1000.html

 

[S]

Hi Jim!

Q: The Subaru AWD system seems alot better than the Hondas, but there
are a couple things that are confusing. Subaru says it has
'symmetrical AWD'which would imply that it distributes power across
axles as well as between axles (cool!). My question is how? I have
done a couple hours of searching but the most I can get on Subaru AWD
systems is a few years old. I have read that Subaru uses a viscous
coupling for what I think of as its center diff, but what about across
the axle itself? Does it use another VC? The ABS?

Mmmmm, I think all that they mean by "symmetrical", is that the half
shafts are the same length on either side. The AWD, at least as found
on the '02 Forester/Impreza, has a sealed viscous coupling between the
front and back, a mechanical limited-slip of some description
(probably also viscous coupled, but I wouldn't swear to it) in the
rear. The front diff is open.

Q: Is the 2.5 litre engine an interference motor?
No.

Q: Is there any advantage to getting the stick vs. the Auto? And does
that change the AWD system?

Folks I know that have AT Soobies seem to like them. I prefer a stick,
as I feel it gives me better control of power delivery to the wheels,
and more options as to where in the engines RPM range I am operating.
In the end, I'm sure it's mostly a matter of personal preference. I
will comment that if you spend much time in stop and go traffic, the
AT is less tiring to drive, and probably less wear-n-tear on the
drive-train as well. The '02 Forester clutch is known to have some
issues; the one in m'ladys Forester started getting "shuddery" (that a
word d'ya suppose?) at around 25K. It's no worse, really, now at 60K,
but I'll probably put a new one in before winter hits, just to be on
the safe side.

Q: Any huge advantage to getting the Forester vs. the Impreza? (Other
than the WRX which, try as I might, I wasn't able to talk him into).

The Forester has a bit more cargo room than the Impreza (as compared
to my WRX wagon; considerably more than the RS sedan), but only a bit.
Also a bit more headroom, and better ground clearance. Other than
that, they share a common chassis, engine, and drive-train. The
seating position in the Forester seems a bit more upright than that in
the Impreza, but they feel remarkably similar other than that.

Q: Is the VC center diff sensitive to tire pressure differences; i.e.
if he doesn't keep his tires at similar pressures damage can result. I
know that some of the earlier JGC's that used this had some problems
along this line.

You have to run tires with the same rolling diameter, +/- some small
amount. Unless one tire is very nearly deflated, tho, I doubt
differences in inflation would cause problems.

Q: Is the AWD system a full time variable split between the front and
rear, or is it more of a reactive system with the power favoring one
side, like the Hondas?

Don't know. Anyone?

ByeBye! S.
Steve Jernigan KG0MB
Laboratory Manager
Microelectronics Research
University of Colorado
(719) 262-3101