Slow Speed Surging

On Sat, 01 Sep 2007 00:53:48 -0700, houndman DeleteThis @phonom.net wrote:

> I call it Chugging, but at low speeds the car isn't smooth. I read
>that the variable valve timing could be the cause, or the drive by
>wire throttle. Seems like being in a lower gear which would get the
>revs up might help, but haven't tried it yet. I've seen the revs go up
>right after stoping, which looks like the car has a mind of its own.((
>
>VF

The valves don't change until you are cruising. If you are engine
braking and it surges add a little mechanical brake pressure, that
should smooth it out. The differentials like some steady bias.
 >> Stay informed about: Slow Speed Surging 

On 1 Sep, 14:06, David wrote:
> On Sat, 01 Sep 2007 00:53:48 -0700, hound....DeleteThis@phonom.net wrote:
> > I call it Chugging, but at low speeds the car isn't smooth. I read
> >that the variable valve timing could be the cause, or the drive by
> >wire throttle. Seems like being in a lower gear which would get the
> >revs up might help, but haven't tried it yet. I've seen the revs go up
> >right after stoping, which looks like the car has a mind of its own.((
>
> >VF
>
> The valves don't change until you are cruising. If you are engine
> braking and it surges add a little mechanical brake pressure, that
> should smooth it out. The differentials like some steady bias.

It Does feel like it or some of it is in the drive train. I feel a
little vibration when the clutch starts to grab mainly when just
letting it start to grab.
What about a Little hand brake applied?

Changing the tire pressures, lowering the rears seems to have
helped. Maybe it causes a bit of friction that smoothes or drags.

VF
 >> Stay informed about: Slow Speed Surging 

On 1 Sep, 13:24, Carl 1 Lucky Texan wrote:
> hound... RemoveThis @phonom.net wrote:
> > On 1 Sep, 11:31, Carl 1 Lucky Texan wrote:
>
> >>hound...@phonom.net wrote:
>
> >>> I call it Chugging, but at low speeds the car isn't smooth. I read
> >>>that the variable valve timing could be the cause, or the drive by
> >>>wire throttle. Seems like being in a lower gear which would get the
> >>>revs up might help, but haven't tried it yet. I've seen the revs go up
> >>>right after stoping, which looks like the car has a mind of its own.((
>
> >>>VF
>
> >>TRy sliding the seat one notch back. It might help. Took me a while to
> >>get the right seat position to be able to get the clutch to the floor
> >>without being 'early' on the release. I dunno.
>
> >>While i don't quite rev the sube like I did my '81 civic wagon, I
> >>frequently got to 4 k in everyday driving and will go to redline without
> >>hesitaion if I need (or 'want') to.
>
> >>One problem carmakers have nowadays is marketing. We seem to be stuck
> >>with 0-60mph as a 'benchmark' and sometimes an engine/tranny/final ratio
> >>is tailored to get that number low - regardless if a different
> >>combination would be easier to actually drive! Try using first to near
> >>redline, then a little lower rpm shift in second (second is 'TALL' in
> >>my WRX - though my old 69 Datsun 2000 was worse. I was doing 70 at the
> >>top of 2nd in it!) even lower in third - like that. Sometimes I will use
> >>second to 90% of intended cruising speed then skip to 4th or even 5th.
> >>You know - just depends on the road and your 'style' I guess.
>
> >>My wrx has plenty of torque but the curve is 'peaky' and comes on quick.
> >>So I will accelerate using a high enough rpm to use that torque most of
> >>the time. Lugging an engine can be bad I guess (overheating, carbon
> >>buildup ????) and lower gears help it work easy.
>
> >>Carl
>
> >>--
> >>to reply, change ( .not) to ( .net)
>
> > I'm trying a lot of different things, like seating position. The
> > clutch grabs a bit low for comfort. Feel like I'm gona grind the gears
> > not disengaging it completely, but haven't yet. Have to get my left
> > leg to hang in the air more, to release the clutch smoothly. Guess
> > I'll get it right soon. I'm practicing enough.
>
> > Trying not to rev it too high just yet with only 200mi on it, though
> > I probably have.
>
> > Playing with tire pressures, and getting the ride better. It was
> > bumpy feeling. I dropped them all down to the high 20's, and the
> > fronts looked too low. I wound up pumping the fronts up to 34, and
> > dropped the rears to 24, and they Look right, and feel a Lot better.
> > I'm figuring the weight distribution of the car is about 60/40 and a
> > rough calc looks like those pressures are the same.
>
> > It's taking more time than I imagined, but things are coming together
>
> > VF
>
> Don't get TOO far away from the 'ratio' of F/R pressure as recommended
> by Subaru - could lead to center diff problems.
>
> Carl
>
> --
> to reply, change ( .not) to ( .net)- Hide quoted text -
>
> - Show quoted text -

OK, but would lowering pressure change the diameter of the tire and
distance it will cover? Seems like would have to go really low to do
that.

IF both Fr and Rr tires have the same shape/bulge, wouldn't they
cover the same ground, not making the center diff work like one axel
was slipping? I Think that is what you are talking about, like the
center diff is working all the time, and can burn it up or damage it.

What have you heard? I have heard that different sized tires Fr/Rr
will make the diff constantly work and damage it, like new and worn
tires on a Sube.

VF
 >> Stay informed about: Slow Speed Surging 

houndman.RemoveThis@phonom.net wrote:

> I call it Chugging, but at low speeds the car isn't smooth. I read
> that the variable valve timing could be the cause, or the drive by
> wire throttle. Seems like being in a lower gear which would get the
> revs up might help, but haven't tried it yet. I've seen the revs go up
> right after stoping, which looks like the car has a mind of its own.((
>
> VF
>

TRy sliding the seat one notch back. It might help. Took me a while to
get the right seat position to be able to get the clutch to the floor
without being 'early' on the release. I dunno.

While i don't quite rev the sube like I did my '81 civic wagon, I
frequently got to 4 k in everyday driving and will go to redline without
hesitaion if I need (or 'want') to.

One problem carmakers have nowadays is marketing. We seem to be stuck
with 0-60mph as a 'benchmark' and sometimes an engine/tranny/final ratio
is tailored to get that number low - regardless if a different
combination would be easier to actually drive! Try using first to near
redline, then a little lower rpm shift in second (second is 'TALL' in
my WRX - though my old 69 Datsun 2000 was worse. I was doing 70 at the
top of 2nd in it!) even lower in third - like that. Sometimes I will use
second to 90% of intended cruising speed then skip to 4th or even 5th.
You know - just depends on the road and your 'style' I guess.

My wrx has plenty of torque but the curve is 'peaky' and comes on quick.
So I will accelerate using a high enough rpm to use that torque most of
the time. Lugging an engine can be bad I guess (overheating, carbon
buildup ????) and lower gears help it work easy.

Carl


--
to reply, change ( .not) to ( .net)
 >> Stay informed about: Slow Speed Surging 

houndman RemoveThis @phonom.net wrote:

> On 1 Sep, 11:31, Carl 1 Lucky Texan wrote:
>
>>hound...@phonom.net wrote:
>>
>>> I call it Chugging, but at low speeds the car isn't smooth. I read
>>>that the variable valve timing could be the cause, or the drive by
>>>wire throttle. Seems like being in a lower gear which would get the
>>>revs up might help, but haven't tried it yet. I've seen the revs go up
>>>right after stoping, which looks like the car has a mind of its own.((
>>
>>>VF
>>
>>TRy sliding the seat one notch back. It might help. Took me a while to
>>get the right seat position to be able to get the clutch to the floor
>>without being 'early' on the release. I dunno.
>>
>>While i don't quite rev the sube like I did my '81 civic wagon, I
>>frequently got to 4 k in everyday driving and will go to redline without
>>hesitaion if I need (or 'want') to.
>>
>>One problem carmakers have nowadays is marketing. We seem to be stuck
>>with 0-60mph as a 'benchmark' and sometimes an engine/tranny/final ratio
>>is tailored to get that number low - regardless if a different
>>combination would be easier to actually drive! Try using first to near
>>redline, then a little lower rpm shift in second (second is 'TALL' in
>>my WRX - though my old 69 Datsun 2000 was worse. I was doing 70 at the
>>top of 2nd in it!) even lower in third - like that. Sometimes I will use
>>second to 90% of intended cruising speed then skip to 4th or even 5th.
>>You know - just depends on the road and your 'style' I guess.
>>
>>My wrx has plenty of torque but the curve is 'peaky' and comes on quick.
>>So I will accelerate using a high enough rpm to use that torque most of
>>the time. Lugging an engine can be bad I guess (overheating, carbon
>>buildup ????) and lower gears help it work easy.
>>
>>Carl
>>
>>--
>>to reply, change ( .not) to ( .net)
>
>
> I'm trying a lot of different things, like seating position. The
> clutch grabs a bit low for comfort. Feel like I'm gona grind the gears
> not disengaging it completely, but haven't yet. Have to get my left
> leg to hang in the air more, to release the clutch smoothly. Guess
> I'll get it right soon. I'm practicing enough.
>
> Trying not to rev it too high just yet with only 200mi on it, though
> I probably have.
>
> Playing with tire pressures, and getting the ride better. It was
> bumpy feeling. I dropped them all down to the high 20's, and the
> fronts looked too low. I wound up pumping the fronts up to 34, and
> dropped the rears to 24, and they Look right, and feel a Lot better.
> I'm figuring the weight distribution of the car is about 60/40 and a
> rough calc looks like those pressures are the same.
>
> It's taking more time than I imagined, but things are coming together
>
> VF
>

Don't get TOO far away from the 'ratio' of F/R pressure as recommended
by Subaru - could lead to center diff problems.

Carl


--
to reply, change ( .not) to ( .net)
 >> Stay informed about: Slow Speed Surging 

On Sat, 01 Sep 2007 10:08:31 -0700, houndman DeleteThis @phonom.net wrote:

>On 1 Sep, 14:06, David wrote:
>> On Sat, 01 Sep 2007 00:53:48 -0700, hound... DeleteThis @phonom.net wrote:
>> > I call it Chugging, but at low speeds the car isn't smooth. I read
>> >that the variable valve timing could be the cause, or the drive by
>> >wire throttle. Seems like being in a lower gear which would get the
>> >revs up might help, but haven't tried it yet. I've seen the revs go up
>> >right after stoping, which looks like the car has a mind of its own.((
>>
>> >VF
>>
>> The valves don't change until you are cruising. If you are engine
>> braking and it surges add a little mechanical brake pressure, that
>> should smooth it out. The differentials like some steady bias.
>
>It Does feel like it or some of it is in the drive train. I feel a
>little vibration when the clutch starts to grab mainly when just
>letting it start to grab.
>What about a Little hand brake applied?
>
> Changing the tire pressures, lowering the rears seems to have
>helped. Maybe it causes a bit of friction that smoothes or drags.
>
>VF
Either gently apply foot braking or shift to the next higher gear.
Don't worry about the automatic stuff doing its thing.
 >> Stay informed about: Slow Speed Surging 

On Sat, 01 Sep 2007 10:08:31 -0700, houndman.RemoveThis@phonom.net wrote:

>On 1 Sep, 14:06, David wrote:
>> On Sat, 01 Sep 2007 00:53:48 -0700, hound....RemoveThis@phonom.net wrote:
>> > I call it Chugging, but at low speeds the car isn't smooth. I read
>> >that the variable valve timing could be the cause, or the drive by
>> >wire throttle. Seems like being in a lower gear which would get the
>> >revs up might help, but haven't tried it yet. I've seen the revs go up
>> >right after stoping, which looks like the car has a mind of its own.((
>>
>> >VF
>>
>> The valves don't change until you are cruising. If you are engine
>> braking and it surges add a little mechanical brake pressure, that
>> should smooth it out. The differentials like some steady bias.
>
>It Does feel like it or some of it is in the drive train. I feel a
>little vibration when the clutch starts to grab mainly when just
>letting it start to grab.
>What about a Little hand brake applied?
>
> Changing the tire pressures, lowering the rears seems to have
>helped. Maybe it causes a bit of friction that smoothes or drags.
>
>VF
It's symmetrical all-wheel drive, especially in the manual
transmission version. All tires should be within a pound of each
other.
 >> Stay informed about: Slow Speed Surging 

On 1 Sep, 19:40, David wrote:
> On Sat, 01 Sep 2007 10:08:31 -0700, hound... RemoveThis @phonom.net wrote:
> >On 1 Sep, 14:06, David wrote:
> >> On Sat, 01 Sep 2007 00:53:48 -0700, hound... RemoveThis @phonom.net wrote:
> >> > I call it Chugging, but at low speeds the car isn't smooth. I read
> >> >that the variable valve timing could be the cause, or the drive by
> >> >wire throttle. Seems like being in a lower gear which would get the
> >> >revs up might help, but haven't tried it yet. I've seen the revs go up
> >> >right after stoping, which looks like the car has a mind of its own.((
>
> >> >VF
>
> >> The valves don't change until you are cruising. If you are engine
> >> braking and it surges add a little mechanical brake pressure, that
> >> should smooth it out. The differentials like some steady bias.
>
> >It Does feel like it or some of it is in the drive train. I feel a
> >little vibration when the clutch starts to grab mainly when just
> >letting it start to grab.
> >What about a Little hand brake applied?
>
> > Changing the tire pressures, lowering the rears seems to have
> >helped. Maybe it causes a bit of friction that smoothes or drags.
>
> >VF
>
> It's symmetrical all-wheel drive, especially in the manual
> transmission version. All tires should be within a pound of each
> other.- Hide quoted text -
>
> - Show quoted text -

sounds like I'm gona have a problem then, and I have the base model,
because the WRX suspension and or tires beat me up.

Why wouldn't the inflated shape of the tires being equal make them
cover the same distance in a rotation?

VF
 >> Stay informed about: Slow Speed Surging 

On 1 Sep, 19:40, David wrote:
> On Sat, 01 Sep 2007 10:08:31 -0700, hound....RemoveThis@phonom.net wrote:
> >On 1 Sep, 14:06, David wrote:
> >> On Sat, 01 Sep 2007 00:53:48 -0700, hound....RemoveThis@phonom.net wrote:
> >> > I call it Chugging, but at low speeds the car isn't smooth. I read
> >> >that the variable valve timing could be the cause, or the drive by
> >> >wire throttle. Seems like being in a lower gear which would get the
> >> >revs up might help, but haven't tried it yet. I've seen the revs go up
> >> >right after stoping, which looks like the car has a mind of its own.((
>
> >> >VF
>
> >> The valves don't change until you are cruising. If you are engine
> >> braking and it surges add a little mechanical brake pressure, that
> >> should smooth it out. The differentials like some steady bias.
>
> >It Does feel like it or some of it is in the drive train. I feel a
> >little vibration when the clutch starts to grab mainly when just
> >letting it start to grab.
> >What about a Little hand brake applied?
>
> > Changing the tire pressures, lowering the rears seems to have
> >helped. Maybe it causes a bit of friction that smoothes or drags.
>
> >VF
>
> It's symmetrical all-wheel drive, especially in the manual
> transmission version. All tires should be within a pound of each
> other.- Hide quoted text -
>
> - Show quoted text -

the manual lists 1 lb difference in the 215 17" tires, 3 in the 16"
ones, and 6 in the 225 17"'s

VF.
 >> Stay informed about: Slow Speed Surging 

On 1 Sep, 20:49, Carl 1 Lucky Texan wrote:
> hound... DeleteThis @phonom.net wrote:
> > On 1 Sep, 13:24, Carl 1 Lucky Texan wrote:
>
> >>hound...@phonom.net wrote:
>
> >>>On 1 Sep, 11:31, Carl 1 Lucky Texan wrote:
>
> >>>>hound...@phonom.net wrote:
>
> >>>>>I call it Chugging, but at low speeds the car isn't smooth. I read
> >>>>>that the variable valve timing could be the cause, or the drive by
> >>>>>wire throttle. Seems like being in a lower gear which would get the
> >>>>>revs up might help, but haven't tried it yet. I've seen the revs go up
> >>>>>right after stoping, which looks like the car has a mind of its own.((
>
> >>>>>VF
>
> >>>>TRy sliding the seat one notch back. It might help. Took me a while to
> >>>>get the right seat position to be able to get the clutch to the floor
> >>>>without being 'early' on the release. I dunno.
>
> >>>>While i don't quite rev the sube like I did my '81 civic wagon, I
> >>>>frequently got to 4 k in everyday driving and will go to redline without
> >>>>hesitaion if I need (or 'want') to.
>
> >>>>One problem carmakers have nowadays is marketing. We seem to be stuck
> >>>>with 0-60mph as a 'benchmark' and sometimes an engine/tranny/final ratio
> >>>>is tailored to get that number low - regardless if a different
> >>>>combination would be easier to actually drive! Try using first to near
> >>>>redline, then a little lower rpm shift in second (second is 'TALL' in
> >>>>my WRX - though my old 69 Datsun 2000 was worse. I was doing 70 at the
> >>>>top of 2nd in it!) even lower in third - like that. Sometimes I will use
> >>>>second to 90% of intended cruising speed then skip to 4th or even 5th.
> >>>>You know - just depends on the road and your 'style' I guess.
>
> >>>>My wrx has plenty of torque but the curve is 'peaky' and comes on quick.
> >>>>So I will accelerate using a high enough rpm to use that torque most of
> >>>>the time. Lugging an engine can be bad I guess (overheating, carbon
> >>>>buildup ????) and lower gears help it work easy.
>
> >>>>Carl
>
> >>>>--
> >>>>to reply, change ( .not) to ( .net)
>
> >>>I'm trying a lot of different things, like seating position. The
> >>>clutch grabs a bit low for comfort. Feel like I'm gona grind the gears
> >>>not disengaging it completely, but haven't yet. Have to get my left
> >>>leg to hang in the air more, to release the clutch smoothly. Guess
> >>>I'll get it right soon. I'm practicing enough.
>
> >>> Trying not to rev it too high just yet with only 200mi on it, though
> >>>I probably have.
>
> >>> Playing with tire pressures, and getting the ride better. It was
> >>>bumpy feeling. I dropped them all down to the high 20's, and the
> >>>fronts looked too low. I wound up pumping the fronts up to 34, and
> >>>dropped the rears to 24, and they Look right, and feel a Lot better.
> >>>I'm figuring the weight distribution of the car is about 60/40 and a
> >>>rough calc looks like those pressures are the same.
>
> >>> It's taking more time than I imagined, but things are coming together
>
> >>>VF
>
> >>Don't get TOO far away from the 'ratio' of F/R pressure as recommended
> >>by Subaru - could lead to center diff problems.
>
> >>Carl
>
> >>--
> >>to reply, change ( .not) to ( .net)- Hide quoted text -
>
> >>- Show quoted text -
>
> > OK, but would lowering pressure change the diameter of the tire and
> > distance it will cover? Seems like would have to go really low to do
> > that.
>
> > IF both Fr and Rr tires have the same shape/bulge, wouldn't they
> > cover the same ground, not making the center diff work like one axel
> > was slipping? I Think that is what you are talking about, like the
> > center diff is working all the time, and can burn it up or damage it.
>
> > What have you heard? I have heard that different sized tires Fr/Rr
> > will make the diff constantly work and damage it, like new and worn
> > tires on a Sube.
>
> > VF
>
> There was a 'heated' discussion atwww.ultimatesubaru.orgabout this
> issue. The distance the axle hub is from the ground determines the
> radius, regardless of 'bulge size' or tire wear. Since the fron to of
> the car is heavier (as you say, 60/40 or 55/45 distribution) the tires
> get more pressure to maintain the correct 'contact patch'. In my
> experience, maunfacturers tend to suggest somewhat too low tire
> pressures, this may have been more prevalent in the past. If the
> front/rear pressure difference is 2 pounds, I doubt going up 2 or down 2
> front and rear is gonna be a problem. But your post seemed to show a
> difference of 10 lbs which just seemed a little excessive. Of course. if
> the rear of a wagon is heavily loaded I'd feel boosting the pressure
> would be a good idea. Also, too low pressures can lead to the bead
> rolling off the rim in high speed cornering too. That could lead to
> having a 'bad day'.
>
> Carl
>
> --
> to reply, change ( .not) to ( .net)- Hide quoted text -
>
> - Show quoted text -

The axle hub distance to the ground determining the radius makes
sense. My idea and liking is to make the contact patch the same. I
like a little bulge in the sidewalls, but not so much it looks like it
is hanging over the side of the tread. When carrying a heavy load, the
pressures would be increased. I always looked at the load capacity of
the tire, and liked a nice margin where the tire was rated for more
than it was holding up. I didn't think cars that came through with a
tire sizes that were less than the car weight was very safe. Figure
the tire is being overly stressed in normal driving. Always liked
oversized tires.

Will have to give the tires a good look. Maybe after driving it
after the tires will look different, but wouldn't think so. I drove
home after changing the pressures, and looking out the window at them,
they look equal.

VF
 >> Stay informed about: Slow Speed Surging 

houndman DeleteThis @phonom.net wrote:

> On 1 Sep, 13:24, Carl 1 Lucky Texan wrote:
>
>>hound...@phonom.net wrote:
>>
>>>On 1 Sep, 11:31, Carl 1 Lucky Texan wrote:
>>
>>>>hound...@phonom.net wrote:
>>
>>>>>I call it Chugging, but at low speeds the car isn't smooth. I read
>>>>>that the variable valve timing could be the cause, or the drive by
>>>>>wire throttle. Seems like being in a lower gear which would get the
>>>>>revs up might help, but haven't tried it yet. I've seen the revs go up
>>>>>right after stoping, which looks like the car has a mind of its own.((
>>
>>>>>VF
>>
>>>>TRy sliding the seat one notch back. It might help. Took me a while to
>>>>get the right seat position to be able to get the clutch to the floor
>>>>without being 'early' on the release. I dunno.
>>
>>>>While i don't quite rev the sube like I did my '81 civic wagon, I
>>>>frequently got to 4 k in everyday driving and will go to redline without
>>>>hesitaion if I need (or 'want') to.
>>
>>>>One problem carmakers have nowadays is marketing. We seem to be stuck
>>>>with 0-60mph as a 'benchmark' and sometimes an engine/tranny/final ratio
>>>>is tailored to get that number low - regardless if a different
>>>>combination would be easier to actually drive! Try using first to near
>>>>redline, then a little lower rpm shift in second (second is 'TALL' in
>>>>my WRX - though my old 69 Datsun 2000 was worse. I was doing 70 at the
>>>>top of 2nd in it!) even lower in third - like that. Sometimes I will use
>>>>second to 90% of intended cruising speed then skip to 4th or even 5th.
>>>>You know - just depends on the road and your 'style' I guess.
>>
>>>>My wrx has plenty of torque but the curve is 'peaky' and comes on quick.
>>>>So I will accelerate using a high enough rpm to use that torque most of
>>>>the time. Lugging an engine can be bad I guess (overheating, carbon
>>>>buildup ????) and lower gears help it work easy.
>>
>>>>Carl
>>
>>>>--
>>>>to reply, change ( .not) to ( .net)
>>
>>>I'm trying a lot of different things, like seating position. The
>>>clutch grabs a bit low for comfort. Feel like I'm gona grind the gears
>>>not disengaging it completely, but haven't yet. Have to get my left
>>>leg to hang in the air more, to release the clutch smoothly. Guess
>>>I'll get it right soon. I'm practicing enough.
>>
>>> Trying not to rev it too high just yet with only 200mi on it, though
>>>I probably have.
>>
>>> Playing with tire pressures, and getting the ride better. It was
>>>bumpy feeling. I dropped them all down to the high 20's, and the
>>>fronts looked too low. I wound up pumping the fronts up to 34, and
>>>dropped the rears to 24, and they Look right, and feel a Lot better.
>>>I'm figuring the weight distribution of the car is about 60/40 and a
>>>rough calc looks like those pressures are the same.
>>
>>> It's taking more time than I imagined, but things are coming together
>>
>>>VF
>>
>>Don't get TOO far away from the 'ratio' of F/R pressure as recommended
>>by Subaru - could lead to center diff problems.
>>
>>Carl
>>
>>--
>>to reply, change ( .not) to ( .net)- Hide quoted text -
>>
>>- Show quoted text -
>
>
> OK, but would lowering pressure change the diameter of the tire and
> distance it will cover? Seems like would have to go really low to do
> that.
>
> IF both Fr and Rr tires have the same shape/bulge, wouldn't they
> cover the same ground, not making the center diff work like one axel
> was slipping? I Think that is what you are talking about, like the
> center diff is working all the time, and can burn it up or damage it.
>
> What have you heard? I have heard that different sized tires Fr/Rr
> will make the diff constantly work and damage it, like new and worn
> tires on a Sube.
>
> VF
>

There was a 'heated' discussion at www.ultimatesubaru.org about this
issue. The distance the axle hub is from the ground determines the
radius, regardless of 'bulge size' or tire wear. Since the fron to of
the car is heavier (as you say, 60/40 or 55/45 distribution) the tires
get more pressure to maintain the correct 'contact patch'. In my
experience, maunfacturers tend to suggest somewhat too low tire
pressures, this may have been more prevalent in the past. If the
front/rear pressure difference is 2 pounds, I doubt going up 2 or down 2
front and rear is gonna be a problem. But your post seemed to show a
difference of 10 lbs which just seemed a little excessive. Of course. if
the rear of a wagon is heavily loaded I'd feel boosting the pressure
would be a good idea. Also, too low pressures can lead to the bead
rolling off the rim in high speed cornering too. That could lead to
having a 'bad day'.

Carl


--
to reply, change ( .not) to ( .net)
 >> Stay informed about: Slow Speed Surging 

On Sat, 01 Sep 2007 14:19:58 -0700, houndman DeleteThis @phonom.net wrote:

>On 1 Sep, 19:40, David wrote:
>> On Sat, 01 Sep 2007 10:08:31 -0700, hound... DeleteThis @phonom.net wrote:
>> >On 1 Sep, 14:06, David wrote:
>> >> On Sat, 01 Sep 2007 00:53:48 -0700, hound... DeleteThis @phonom.net wrote:
>> >> > I call it Chugging, but at low speeds the car isn't smooth. I read
>> >> >that the variable valve timing could be the cause, or the drive by
>> >> >wire throttle. Seems like being in a lower gear which would get the
>> >> >revs up might help, but haven't tried it yet. I've seen the revs go up
>> >> >right after stoping, which looks like the car has a mind of its own.((
>>
>> >> >VF
>>
>> >> The valves don't change until you are cruising. If you are engine
>> >> braking and it surges add a little mechanical brake pressure, that
>> >> should smooth it out. The differentials like some steady bias.
>>
>> >It Does feel like it or some of it is in the drive train. I feel a
>> >little vibration when the clutch starts to grab mainly when just
>> >letting it start to grab.
>> >What about a Little hand brake applied?
>>
>> > Changing the tire pressures, lowering the rears seems to have
>> >helped. Maybe it causes a bit of friction that smoothes or drags.
>>
>> >VF
>>
>> It's symmetrical all-wheel drive, especially in the manual
>> transmission version. All tires should be within a pound of each
>> other.- Hide quoted text -
>>
>> - Show quoted text -
>
>the manual lists 1 lb difference in the 215 17" tires, 3 in the 16"
>ones, and 6 in the 225 17"'s
>
>VF.
I have 16s and my manual says 28 front 29 rear. I think it's
important to have equal rolling resistance on hard pavement.

Give the car a chance. My Forester has saved my life a few times
thanks to its incredible handling characteristics. The vehicle
behaves as though it's on tracks.
 >> Stay informed about: Slow Speed Surging 

On 2 Sep, 04:22, David wrote:
> On Sat, 01 Sep 2007 14:19:58 -0700, hound....RemoveThis@phonom.net wrote:
> >On 1 Sep, 19:40, David wrote:
> >> On Sat, 01 Sep 2007 10:08:31 -0700, hound....RemoveThis@phonom.net wrote:
> >> >On 1 Sep, 14:06, David wrote:
> >> >> On Sat, 01 Sep 2007 00:53:48 -0700, hound....RemoveThis@phonom.net wrote:
> >> >> > I call it Chugging, but at low speeds the car isn't smooth. I read
> >> >> >that the variable valve timing could be the cause, or the drive by
> >> >> >wire throttle. Seems like being in a lower gear which would get the
> >> >> >revs up might help, but haven't tried it yet. I've seen the revs go up
> >> >> >right after stoping, which looks like the car has a mind of its own.((
>
> >> >> >VF
>
> >> >> The valves don't change until you are cruising. If you are engine
> >> >> braking and it surges add a little mechanical brake pressure, that
> >> >> should smooth it out. The differentials like some steady bias.
>
> >> >It Does feel like it or some of it is in the drive train. I feel a
> >> >little vibration when the clutch starts to grab mainly when just
> >> >letting it start to grab.
> >> >What about a Little hand brake applied?
>
> >> > Changing the tire pressures, lowering the rears seems to have
> >> >helped. Maybe it causes a bit of friction that smoothes or drags.
>
> >> >VF
>
> >> It's symmetrical all-wheel drive, especially in the manual
> >> transmission version. All tires should be within a pound of each
> >> other.- Hide quoted text -
>
> >> - Show quoted text -
>
> >the manual lists 1 lb difference in the 215 17" tires, 3 in the 16"
> >ones, and 6 in the 225 17"'s
>
> >VF.
>
> I have 16s and my manual says 28 front 29 rear. I think it's
> important to have equal rolling resistance on hard pavement.
>
> Give the car a chance. My Forester has saved my life a few times
> thanks to its incredible handling characteristics. The vehicle
> behaves as though it's on tracks.- Hide quoted text -
>
> - Show quoted text -

If the tire pressures were critical, I can't see how they can be so
different on different tire sizes or cars. The same tire shape from
inflation should have the same rolling resistance.

I'd like to have optimum handling, comfort, and tire wear. They
should all be related. I passed on getting a WRX because the ride was
too stiff, and the 2.5i power seemed adequite at least for now. With
the factory settinge the ride was unbearable on a certain road around
a park I frequent. Every ripple in the road even where it looked
smooth was felt, and made the car move up and down. Reminded me what a
nephew said his wife said about the 5sp car he bought, she said it
made her feel like she was going to upchuck, and wouldn't ride in it,
so he sold it. I figured the motions when shifting were the reason,
since that's what he implied, but I wonder if it was tire pressures or
a combo?

If the settings were mandatory, I wouldn't enjoy going to the park,
and having to drive the 2 1/2 mi one way road around it, inside it,
and only use my other car. The ride wasn't what I'd call comfortable
on many other roads. If it was the car might be exceptional. I perfer
a firm ride, and always bought cars with heavy duty suspensions, since
prefer feeling a bump and then it is over, as opposed to wallowing and
jiggling. What I was getting was, feeling the bumps, and jiggling on
smooth roads. It felt like the tires were lumpy.

VF
 >> Stay informed about: Slow Speed Surging