AWD maintenance

[Hightide]

I have a 2001 Outback, and an 06 Forester. My last car was a 97 Outback
that was replaced by the Forester. At 126k the 97 started "bucking" in a
tight turn. The dealer told me that the transfer case had locked up; they
wanted to charge me $1,500 to make the repair. The also told me that I
should have had the "all wheel drive" service performed. Well, I checked
the owner's manual, and the shop manual; there was no mention of an "all
wheel drive service". So what gives? Is there a periodic AWD service?
Also, my 01 Outback has a transmission filter, but there is no mention in
the manual about service and / or replacement.

After being introduced to Subaru by a friend in 1996, I am one happy puppy.
My dearly departed 97 ran for 126k, and the only problem was a defective
alternator that Subaru replaced "no charge" well after the warranty had
expired. My wife's 01 has had zero problems. I once had a Pontiac company
car that had two engines and four transmissions replaced before the clock
hit 60k. My classic MGA twin cam isn't even that bad, considering the
Prince of Darkness electrics by Lucas.

 

[y_p_w]

I have a 2001 Outback, and an 06 Forester. My last car was a 97 Outback
that was replaced by the Forester. At 126k the 97 started "bucking" in a
tight turn. The dealer told me that the transfer case had locked up; they
wanted to charge me $1,500 to make the repair. The also told me that I
should have had the "all wheel drive" service performed. Well, I checked
the owner's manual, and the shop manual; there was no mention of an "all
wheel drive service". So what gives? Is there a periodic AWD service?
Also, my 01 Outback has a transmission filter, but there is no mention in
the manual about service and / or replacement.

After being introduced to Subaru by a friend in 1996, I am one happy puppy.
My dearly departed 97 ran for 126k, and the only problem was a defective
alternator that Subaru replaced "no charge" well after the warranty had
expired. My wife's 01 has had zero problems. I once had a Pontiac company
car that had two engines and four transmissions replaced before the clock
hit 60k. My classic MGA twin cam isn't even that bad, considering the
Prince of Darkness electrics by Lucas.

You forgot to mention the most important detail. What
transmission? The manual transmissions have a viscous
coupled center differential. Maintenance would be changing
the transmission fluid.

The auto trannies mostly use a transfer case with an
electronically controlled clutch. I don't know if there's
any particular maintenance you can really do for it other
than tire rotations to keep the tires at the same
circumference; the clutch can supposedly wear out early if
the system senses a difference in wheel speeds all the time.
The fluid in the front diff could be serviced though.

 

[bigjim]

fluid changes in diffs couldnt hurt

 

[CL (dnoyeB) Gilbert]

You forgot to mention the most important detail. What
transmission? The manual transmissions have a viscous
coupled center differential. Maintenance would be changing
the transmission fluid.

The auto trannies mostly use a transfer case with an
electronically controlled clutch. I don't know if there's
any particular maintenance you can really do for it other
than tire rotations to keep the tires at the same
circumference; the clutch can supposedly wear out early if
the system senses a difference in wheel speeds all the time.
The fluid in the front diff could be serviced though.

If a difference in wheel speed due to tire sizes or other reason causes
a problem then the car should be called a 4WD not an AWD.


--
Thank you,


CL Gilbert
"Then said I, Wisdom [is] better than strength: nevertheless the poor
man's wisdom [is] despised, and his words are not heard." Ecclesiastes 9:16

 

[Carl 1 Lucky Texan]

If a difference in wheel speed due to tire sizes or other reason causes
a problem then the car should be called a 4WD not an AWD.

If the systems 'interprets' slippage under conditions where no slippage
can occur. It will 'switch' to (essentially) 4WD but be subjected to
stress (torque bind) which COULD lead to failure of one or more
driveline parts. The trick is to prevent conditions which 'trick' the
system into engaging when it shouldn't. Running odd sized tires on
dry/normal/hard road surfaces - particulary at high speeds for great
distances - will likely stress the system. It MAY be possible to - say -
put on one new tire with 3 older ones and run lower air pressure to
compensate. But there would be safety issues with that I suppose.

Carl

 

[y_p_w]

If a difference in wheel speed due to tire sizes or other reason
causes a problem then the car should be called a 4WD not an AWD.

I was always under the assumption that 4WD implied a 50/50
power split. Subaru AWD (automatics) have supposedly been
anywhere from 90/10 to 60/40.

 

[Michael Pardee]

I was always under the assumption that 4WD implied a 50/50
power split. Subaru AWD (automatics) have supposedly been
anywhere from 90/10 to 60/40.

I have experience with 4WD but none with AWD. My personal criterion for 4WD
is that the front and rear are hard-coupled, whether the front and rear
differentials are locked or not. 4WD is the way to go in rough, demanding
terrain but is a terror on slippery streets, since at least one wheel must
give up traction to allow the vehicle to turn. In town I drive my 4WD work
truck in 2WD even when the roads are icy because it gets squirrelly in 4WD
(as I learned the hard way!) If the road gets really slippery and I have to
get up a hill I'll change to 4WD, but chaining up is the proper way to go at
that point..

Mike

 

[CL (dnoyeB) Gilbert]

I was always under the assumption that 4WD implied a 50/50
power split. Subaru AWD (automatics) have supposedly been
anywhere from 90/10 to 60/40.

well im not sure its official anywhere but usually the difference
betweel full time 4wd and AWD is that AWD can handle different tires
turning at different revolutions which happens during turning. 4WD does
not account for/handle this.

--
Thank you,


CL Gilbert
"Then said I, Wisdom [is] better than strength: nevertheless the poor
man's wisdom [is] despised, and his words are not heard." Ecclesiastes 9:16

 

[y_p_w]

well im not sure its official anywhere but usually the difference
betweel full time 4wd and AWD is that AWD can handle different tires
turning at different revolutions which happens during turning. 4WD does
not account for/handle this.

The California Dept of Transportation seems to call any four-
wheeled vehicle where are four wheels are driven "four wheel
drive" for exceptions to chain requirements.

Certainly there's 4wd drive where the differentials can be locked
in tough driving situations. However - most of these vehicles
are driven in situations where there's power to all four wheels
on pavement.

http://www.4x4abc.com/4WD101/diff_locks.html

 

[Carl 1 Lucky Texan]

well im not sure its official anywhere but usually the difference
betweel full time 4wd and AWD is that AWD can handle different tires
turning at different revolutions which happens during turning. 4WD does
not account for/handle this.

here's one explanation;
http://www.cars101.com/subaru_terms.html#awd


Carl
1 Lucky Texan