Shudder at very low speed during sharp turning

[Yousuf Khan]

My 2000 OBW w/ 5MT has recently developed a slight shudder during sharp
cornering at low speeds. I'm talking about parking maneuver type
situations. It seems to occur whether I'm turning left or right, just as
long as it's slow and sharp.

I've seen this type of shuddering before on this car, but those were
during cold winter days when there was a bit of ice that built up on the
joints, and they go away if you let the ice melt away. But it's nowhere
near winter yet, and there isn't a flake of snow on the ground right now.

What could this be? CV joints, or differentials (i.e. front to rear)?

Yousuf Khan

 

[1 Lucky Texan]

My 2000 OBW w/ 5MT has recently developed a slight shudder during sharp
cornering at low speeds. I'm talking about parking maneuver type
situations. It seems to occur whether I'm turning left or right, just as
long as it's slow and sharp.

I've seen this type of shuddering before on this car, but those were
during cold winter days when there was a bit of ice that built up on the
joints, and they go away if you let the ice melt away. But it's nowhere
near winter yet, and there isn't a flake of snow on the ground right now.

What could this be? CV joints, or differentials (i.e. front to rear)?

        Yousuf Khan

d@mn - most likely 'torque bind' . From mis-matched tires if you're
lucky, if not - center diff.

Some folks have found bad U joints on the drive shaft.

Carl

 

[.._..]

Usually it's air pressure in the tires.

My 2000 OBW w/ 5MT has recently developed a slight shudder during sharp
cornering at low speeds. I'm talking about parking maneuver type
situations. It seems to occur whether I'm turning left or right, just as
long as it's slow and sharp.

I've seen this type of shuddering before on this car, but those were
during cold winter days when there was a bit of ice that built up on the
joints, and they go away if you let the ice melt away. But it's nowhere
near winter yet, and there isn't a flake of snow on the ground right now.

What could this be? CV joints, or differentials (i.e. front to rear)?

Yousuf Khan

d@mn - most likely 'torque bind' . From mis-matched tires if you're
lucky, if not - center diff.

Some folks have found bad U joints on the drive shaft.

Carl

 

[S]

Hi Yousuf!

My 2000 OBW w/ 5MT has recently developed a slight shudder during sharp
cornering at low speeds. I'm talking about parking maneuver type
situations. It seems to occur whether I'm turning left or right, just as
long as it's slow and sharp.

I've seen this type of shuddering before on this car, but those were
during cold winter days when there was a bit of ice that built up on the
joints, and they go away if you let the ice melt away. But it's nowhere
near winter yet, and there isn't a flake of snow on the ground right now.

What could this be? CV joints, or differentials (i.e. front to rear)?

I'll assume you have done the obvious; check tires for wear/proper
inflation, check for visible damage (torn boots of whatever) on front
axles.

When was the last time you changed the fluid in the transmission? I
ask because we experienced a similar issue in my wife's '02 Forester.

After replacing both front axles without eliminating the torque bind,
I determined that it was being generated in the 5spd transmission,
specifically the "viscous coupling/center differential".

I was told various stories about repairing this, and finally ended up
replacing the transmission with a low miles junkyard box. At the time
this appeared to be the quickest and easiest approach, and did cure
the torque bind issue.

Subsequently, I disassembled the rear case of the original
transmission. It was kind of a b____ getting the cases to separate,
but otherwise fairly easy, and could undoubtedly have been
accomplished with the tranny in the car. Getting the center
differential assembly out was likewise easy (it sorta fell out into my
hands), and there didn't appear to be any special shimming or
alignment involved in putting it back together.

The "viscous coupling" part of the center differential was severely
gummed up, and couldn't be turned by hand. I tossed the entire thing
into my solvent tank for a couple days before taking it apart as far
as possible, cleaning, re-assembling, lubricating, and re-installing
it into the transmission.

Just out of curiosity, I swapped this transmission into my '99 Forry
(I needed to service the clutch anyway), where it appears to be
working just fine. Haven't put but about 1000 miles on it yet, tho, so
time will tell.

In any event, because of where the center diff lives (at the back of
the transmission in it's own chamber), it doesn't appear to get much
fluid circulation. This suggests to me that frequent fluid changes in
the transmission are probably indicated, and may well prevent the
viscous coupling from becoming gummed up.

If torque bind is starting to become evident, however, flushing the
tranny with light weight motor oil, or even Stoddard solvent
(kerosene) just might clean things up for you. Worth a try in any
event, as a new center differential assembly (you can't get just the
viscous coupling part) will set you back $550, while a new tranny is
$3500. I _only_ spent $500 on the junkyard transmission, but if I ever
have to do it again, I will try a flush as detailed below, followed by
replacing the center diff if the flush doesn't help. Live and learn.

My plan to flush the tranny would look like this:

Drain the existing fluid and re-fill with a light weight motor oil.
(10W30, or maybe some of the "Marvel Mystery Oil" stuff)(or Stoddard
solvent) Drive the car around a bit to circulate the oil. including
some tight "parking lot" maneuvers to work the viscous coupling. If
things appear to be improving, drain and repeat as desired. Finally
drain and refill with proper gear lube. If you use solvent, a final
flush with motor oil or gear lube is probably advisable to be sure you
get most of the solvent out of the transmission.

If you try this, do post a follow-up to let us know if it helped at
all.

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

 

[XR650L_Dave]

Hi Yousuf!





I'll assume you have done the obvious; check tires for wear/proper
inflation, check for visible damage (torn boots of whatever) on front
axles.

When was the last time you changed the fluid in the transmission? I
ask because we experienced a similar issue in my wife's '02 Forester.

After replacing both front axles without eliminating the torque bind,
I determined that it was being generated in the 5spd transmission,
specifically the "viscous coupling/center differential".

I was told various stories about repairing this, and finally ended up
replacing the transmission with a low miles junkyard box. At the time
this appeared to be the quickest and easiest approach, and did cure
the torque bind issue.

Subsequently, I disassembled the rear case of the original
transmission. It was kind of a b____ getting the cases to separate,
but otherwise fairly easy, and could undoubtedly have been
accomplished with the tranny in the car. Getting the center
differential assembly out was likewise easy (it sorta fell out into my
hands), and there didn't appear to be any special shimming or
alignment involved in putting it back together.

The "viscous coupling" part of the center differential was severely
gummed up, and couldn't be turned by hand. I tossed the entire thing
into my solvent tank for a couple days before taking it apart as far
as possible, cleaning,  re-assembling, lubricating, and re-installing
it into the transmission.

Just out of curiosity, I swapped this transmission into my '99 Forry
(I needed to service the clutch anyway), where it appears to be
working just fine. Haven't put but about 1000 miles on it yet, tho, so
time will tell.

In any event, because of where the center diff lives (at the back of
the transmission in it's own chamber), it doesn't appear to get much
fluid circulation.  This suggests to me that frequent fluid changes in
the transmission are probably indicated, and may well prevent the
viscous coupling from becoming gummed up.

If torque bind is starting to become evident, however, flushing the
tranny with light weight motor oil, or even Stoddard solvent
(kerosene) just might clean things up for you. Worth a try in any
event, as a new center differential assembly (you can't get just the
viscous coupling part) will set you back $550, while a new tranny is
$3500. I _only_ spent $500 on the junkyard transmission, but if I ever
have to do it again, I will try a flush as detailed below, followed by
replacing the center diff if the flush doesn't help. Live and learn.

My plan to flush the tranny would look like this:

Drain the existing fluid and re-fill with a light weight motor oil.
(10W30, or maybe some of the "Marvel Mystery Oil" stuff)(or Stoddard
solvent) Drive the car around a bit to circulate the oil. including
some tight "parking lot" maneuvers to work the viscous coupling.  If
things appear to be improving, drain and repeat as desired. Finally
drain and refill with proper gear lube. If you use solvent, a final
flush with motor oil or gear lube is probably advisable to be sure you
get most of the solvent out of the transmission.

If you try this, do post a follow-up to let us know if it helped at
all.

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

I believe the center diff viscous coupling is sealed from the
transmission fluid, so changing the trans fluid will not have any
effect on manual-transmission torque bind.

Cleaning out the gummy silicone fluid will leave you with AWD as long
as no wheels slip, a wheel starts to slip and the center diff will
send all the power to the slipping wheel.

Still better than just front-wheel-drive, but not as good as a 50/50
front/rear torque split when a wheel slips.


Dave

 

[YKhan]

d@mn - most likely 'torque bind' . From mis-matched tires if you're
lucky, if not - center diff.

I did recently change the tires on this thing, about a month back, but
they are all brand new and exactly the same model. I'll see if there
is a tire pressure difference somewhere.

Yousuf Khan

 

[OptoOne]

My 2000 OBW w/ 5MT has recently developed a slight shudder during sharp
cornering at low speeds. I'm talking about parking maneuver type
situations. It seems to occur whether I'm turning left or right, just as
long as it's slow and sharp.

I've seen this type of shuddering before on this car, but those were
during cold winter days when there was a bit of ice that built up on the
joints, and they go away if you let the ice melt away. But it's nowhere
near winter yet, and there isn't a flake of snow on the ground right now.

What could this be? CV joints, or differentials (i.e. front to rear)?

        Yousuf Khan

Can you feel the shudder in the steering wheel? If so, then you may
be suffering from a problem that was inherent in Legacies and OBs of
that era. I had it in my 2000 Legacy Brighton wagon. The power
steering lines were too small in diameter, so at low speed there was
not enough pressure in the system and it shuddered. This was
especially true turning left.

For this problem Subaru sells an upgrade kit with larger diameter
lines, although they do not guarentee that it would fix the probelm
completely. I had the kit installed 5 or 6 years ago and the problem
pretty much went away. Only happens now in extreme cold when
pressure is low.

Gook luck.

 

[YKhan]

Can you feel the shudder in the steering wheel?  If so, then you may
be suffering from a problem that was inherent in Legacies and OBs of
that era.  I had it in my 2000 Legacy Brighton wagon.  The power
steering lines were too small in diameter, so at low speed there was
not enough pressure in the system and it shuddered.  This was
especially true turning left.

For this problem Subaru sells an upgrade kit with larger diameter
lines, although they do not guarentee that it would fix the probelm
completely.  I had the kit installed 5 or 6 years ago and the problem
pretty much went away.  Only happens now in extreme cold  when
pressure is low.

Yes, I can feel it in the steering wheel. It's very slight, it's not
like as if the wheel shakes visibly, just something I can feel through
the hands.

Interesting, I'll probably look into this if the tire pressures don't
fix it.

Yousuf Khan

 

[YKhan]

Hi Yousuf!





I'll assume you have done the obvious; check tires for wear/proper
inflation, check for visible damage (torn boots of whatever) on front
axles.

I have checked the tire wear situation, but since these tires are so
brand new (a month or two), not a lot of wear patterns are visible
yet.

I haven't noticed anything wrong with the boots while the tires were
turned to one side or the other. But I haven't checked from under
since I don't have a car lift.

When was the last time you changed the fluid in the transmission? I
ask because we experienced a similar issue in my wife's '02 Forester.

That was done earlier this year. The front diff and transmission are
the same unit, so they both get changed at the same time. I think the
rear diff was also done at the same time.

After replacing both front axles without eliminating the torque bind,
I determined that it was being generated in the 5spd transmission,
specifically the "viscous coupling/center differential".

That's a possibility, that's why I asked in here.

The "viscous coupling" part of the center differential was severely
gummed up, and couldn't be turned by hand. I tossed the entire thing
into my solvent tank for a couple days before taking it apart as far
as possible, cleaning,  re-assembling, lubricating, and re-installing
it into the transmission.

Just out of curiosity, I swapped this transmission into my '99 Forry
(I needed to service the clutch anyway), where it appears to be
working just fine. Haven't put but about 1000 miles on it yet, tho, so
time will tell.

In any event, because of where the center diff lives (at the back of
the transmission in it's own chamber), it doesn't appear to get much
fluid circulation.  This suggests to me that frequent fluid changes in
the transmission are probably indicated, and may well prevent the
viscous coupling from becoming gummed up.

It is my understanding that the "viscous coupling" part of central
diff is a sealed unit, and its fluid is never replaceable. Only the
outer gearing of the central diff gets lubed by transmission oil in
the normal way.

Yousuf Khan

 

[S]

Hi Dave!

I believe the center diff viscous coupling is sealed from the
transmission fluid, so changing the trans fluid will not have any
effect on manual-transmission torque bind.

Lightning McQueen: "What are you talking about?"
Mater: "I dunno."

I was gonna say "The center differential lives in the same fluid as
the gear train . . ." But when I thought about it, there was an O-ring
.. . .
So I looked back thru some fotos I took after I disassembled the
center diff/viscous coupling.

Darn it, Dave, that VC was a sealed unit. Wonder why I didn't notice
that; sometimes I'm kinda slow

Anyway, 'taint no mo; it's been reworked with good ol' 90WT in place
of the silicone. What's the saying? "A little knowledge is a dangerous
tool."

Wonder if I should put the original transmission back in now, or wait
'til it fails on the snowiest day of the season? Sigh.

Er, um, Yousuf, a.a.s gang, please ignore the part about flushing the
transmission; as Dave suggests, it won't do a bit of good.

If anyone's curious what the internals of one of these things looks
like, email me directly and I'll send along a couple of fotos.

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

 

[XR650L_Dave]

Hi Dave!



Lightning McQueen: "What are you talking about?"
Mater: "I dunno."

I was gonna say "The center differential lives in the same fluid as
the gear train . . ." But when I thought about it, there was an O-ring
. . .
So I looked back thru some fotos I took after I disassembled the
center diff/viscous coupling.

Darn it, Dave, that VC was a sealed unit. Wonder why I didn't notice
that; sometimes I'm kinda slow

Anyway, 'taint no mo; it's been reworked with good ol' 90WT in place
of the silicone. What's the saying? "A little knowledge is a dangerous
tool."

Wonder if I should put the original transmission back in now, or wait
'til it fails on the snowiest day of the season? Sigh.

Er, um, Yousuf, a.a.s gang, please ignore the part about flushing the
transmission; as Dave suggests, it won't do a bit of good.

If anyone's curious what the internals of one of these things looks
like, email me directly and I'll send along a couple of fotos.

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

It wont fail, you just have slightly less-good AWD.

Now too bad we didn't know just what the fluid was, you could just
clean 'em and refill 'em.


Dave

Dave

 

[YKhan]

I did recently change the tires on this thing, about a month back, but
they are all brand new and exactly the same model. I'll see if there
is a tire pressure difference somewhere.

  Yousuf Khan

Just an update, after I checked the tire pressures, I did notice that
one of the tires (the left front) was about 3 psi higher than the
other three, so I've adjusted that one down to the same level as the
others. So far, it seems to be shuddering a bit less. Not totally
stopped shuddering, just not as much as before. Maybe it takes a bit
of time to settle down.

It's interesting, in the past I've had air leak problems on my tires
where after a couple of months, some of the tires may have lost more
pressure than the difference I've seen here, but it never resulted in
a shudder until now.

Yousuf Khan

 

[Chico]

My 2000 OBW w/ 5MT has recently developed a slight shudder during sharp
cornering at low speeds. I'm talking about parking maneuver type
situations. It seems to occur whether I'm turning left or right, just as
long as it's slow and sharp.

I've seen this type of shuddering before on this car, but those were
during cold winter days when there was a bit of ice that built up on the
joints, and they go away if you let the ice melt away. But it's nowhere
near winter yet, and there isn't a flake of snow on the ground right now.

What could this be? CV joints, or differentials (i.e. front to rear)?

        Yousuf Khan

My 2003 OBS 5sp center diff went around 150,000kms. Same symptoms:
parking maneuvers caused a shudder - almost a clunking that goes with
the speed of travel. It happens in neutral, so it's not gear
related. And it happened only once the car was warmed up. That's
what tipped me off. A 10 minute drive down the highway was enough to
warm things up, and then I couldn't park without the shudder.

The dealer scared me into doing it right away by telling me that the
expensive transmission could eventually get damaged by leaving the
diff alone. $1600 or something like that.

All is well now, 50k kms later.

 

[1 Lucky Texan]

Just an update, after I checked the tire pressures, I did notice that
one of the tires (the left front) was about 3 psi higher than the
other three, so I've adjusted that one down to the same level as the
others. So far, it seems to be  shuddering a bit less. Not totally
stopped shuddering, just not as much as before. Maybe it takes a bit
of time to settle down.

It's interesting, in the past I've had air leak problems on my tires
where after a couple of months, some of the tires may have lost more
pressure than the difference I've seen here, but it never resulted in
a shudder until now.

  Yousuf Khan

I've read 'rumors' that making figure *s/tight maneuvers IN REVERSE
can alleviate some center diff symptoms.

I've never tried it and it seems weird.

I think I've seen pics/article on-line where some Aussies are
disassembling the center diffs and replacing the fluid to make them
engage more quickly for some kinda off-road use. So, maybe it IS
possible to rebuild one?

good luck (don't forget to check the U joint on the driveshaft)

 

[1 Lucky Texan]

Just an update, after I checked the tire pressures, I did notice that
one of the tires (the left front) was about 3 psi higher than the
other three, so I've adjusted that one down to the same level as the
others. So far, it seems to be  shuddering a bit less. Not totally
stopped shuddering, just not as much as before. Maybe it takes a bit
of time to settle down.

It's interesting, in the past I've had air leak problems on my tires
where after a couple of months, some of the tires may have lost more
pressure than the difference I've seen here, but it never resulted in
a shudder until now.

  Yousuf Khan

I've read 'rumors' that making figure 8s/tight maneuvers IN REVERSE
can alleviate some center diff symptoms.

I've never tried it and it seems weird.

I think I've seen pics/article on-line where some Aussies are
disassembling the center diffs and replacing the fluid to make them
engage more quickly for some kinda off-road use. So, maybe it IS
possible to rebuild one?

good luck (don't forget to check the U joint on the driveshaft)

 

[Yousuf Khan]

My 2003 OBS 5sp center diff went around 150,000kms. Same symptoms:
parking maneuvers caused a shudder - almost a clunking that goes with
the speed of travel. It happens in neutral, so it's not gear
related. And it happened only once the car was warmed up. That's
what tipped me off. A 10 minute drive down the highway was enough to
warm things up, and then I couldn't park without the shudder.

The dealer scared me into doing it right away by telling me that the
expensive transmission could eventually get damaged by leaving the
diff alone. $1600 or something like that.

All is well now, 50k kms later.

Ouch! So far, it doesn't happen in neutral yet. And it's unrelated to
how warm the transmission is: it'll happen warm or cold. So I'm hoping
that this means that mine is not as serious as what happened to you.

I'm still investigating the tire inflation pressures to see if they make
it go away. I've never had to worry about the tire inflation tolerances
this much before. Usually I could keep the tires within 2 psi of each
other.

Yousuf Khan

 

[Yousuf Khan]

I've read 'rumors' that making figure 8s/tight maneuvers IN REVERSE
can alleviate some center diff symptoms.

I've never tried it and it seems weird.

Yeah, that does sound weird. Can't see why that should work, but I'll
keep it in mind.

I think I've seen pics/article on-line where some Aussies are
disassembling the center diffs and replacing the fluid to make them
engage more quickly for some kinda off-road use. So, maybe it IS
possible to rebuild one?

good luck (don't forget to check the U joint on the driveshaft)

Well, I'll play with the tire pressures some more. Maybe these tires are
just more sensitive to tire inflation than any of my previous set?

Yousuf Khan

 

[XR650L_Dave]

I've read 'rumors' that making figure 8s/tight maneuvers IN REVERSE
can alleviate some center diff symptoms.

I've never tried it and  it seems weird.

I think I've seen pics/article on-line where some Aussies are
disassembling the center diffs and replacing the fluid to make them
engage more quickly for some kinda off-road use. So, maybe it IS
possible to rebuild one?

good luck (don't forget to check the U joint on the driveshaft)

"S" on this thread said he took his apart and drained the fluid (which
leaves you with slightly less good AWD), so if you had the fluid to
put in (a bucket of it so you could re-assemble the viscous-clutch
unit submerged) you'd be able to rebuild your own.

Dave

 

[.._..]

One thing I learned while dealing with the torque bind due to tire pressure
is that the "stick" gauges absolutly suck balls.

Get a "dial and needle" type for a few bucks more. (Which should still be
under 20). Then use a sample of five or six tests to get a reading.

 

[Yousuf Khan]

One thing I learned while dealing with the torque bind due to tire pressure
is that the "stick" gauges absolutly suck balls.

Get a "dial and needle" type for a few bucks more. (Which should still be
under 20). Then use a sample of five or six tests to get a reading.

I got a dial'n'needle, but I also got a digital unit, which reads out in
increments of 0.5 psi.

Yousuf Khan