Here is the skinny on the diffs......I am a driving instructor at a four
wheel driving facility.......
Anyway, a viscous coupling or VC is basically a clutch between your front
and rear drive axles. When all four wheels are spinning at the same speed,
power is transmitted equally (50% front and 50% rear). When you turn a
corner, even if you have good traction, your wheels (all 4) turn at
different speeds. In this situation, the VC will not activate because it is
designed to accomodate a certain amout of "slop" in the system (you would
go through tires very quickly if it were not this way.)
To preface the next part, let it be understood that differentials are lazy
and send power to the wheel or axle with the least amount of traction,
whether it be the front center or rear diff.
When you start to lose traction at the ie front of the car, the front drive
shaft turns faster than the rear and creates friction inside the VC. The
friction then heats up the fluid inside the VC, and forces clutch plates
together to essentially lock the front and rear driveshafts together.
Because the system relies on friction and heat, this lock will unlock as the
fluid then cools. However, keep in mind that this all happens within a
fraction of a second so the user may not even notice. Because of this, the
VC can lock and unlock many times within a very small time frame until good
traction is restored.
As far as I know, there is no LSD on the front of our cars. There is one on
the rear. It works similar to the vc, but does not lock. Instead, there is
a certain amount of slop, meaning difference in wheel speeds built into the
lsd, thus "limited slip". Once the maximum slip is acheived, a percentage
of the power that is being sent to that axle (be it front or rear) will go
to the slower spinning wheel, however no equalization is acheived.
Basically if you have a right wheel spinning, the left will still spin at a
percentage of the right until good traction is restored.
I think all my ducks are in a row, but if anyone can find some fault in this
please let me know.
By the way, the VC is TUNABLE by using different weight fluids. It can as
you may have guessed, be set up more agressively (more traction and tire
wear) or lazier!
KMH
----- Original Message -----
From: <
prostho@netscape.net>
To: <
BC-BFLegacyWorks@egroups.com>
Sent: Sunday, January 21, 2001 1:34 AM
Subject: [BC-BFLegacyWorks] Re: Question about LSDs on US legacy turbo
> from what i heard.. subaru cars have a open center diff with a viscous
> lock.. viscous differential will only result in part time awd while
> subaru has full time AWD...
>
> corrections anyone??
>
> anyways.. i am more interested in rear LSD becoz i don't know if its a
> LSD or not... but i am pretty sure all subarus more moderm subaru with
> full time AWD has the viscous lock center diff system
>
>
> To unsubscribe from this group, send an email to:
>
BC-BFLegacyWorks-unsubscribe@egroups.com
>
>
To unsubscribe from this group, send an email to:
BC-BFLegacyWorks-unsubscribe@egroups.com