A Cars forum. AutoBanter

If this is your first visit, be sure to check out the FAQ by clicking the link above. You may have to register before you can post: click the register link above to proceed. To start viewing messages, select the forum that you want to visit from the selection below.

Go Back   Home » AutoBanter forum » Auto newsgroups » Technology
Site Map Home Register Authors List Search Today's Posts Mark Forums Read Web Partners

Clare - are smaller car tires easier to balance than SUV tires?



 
 
Thread Tools Display Modes
  #1  
Old June 13th 19, 05:32 AM posted to alt.home.repair,rec.autos.tech
Arlen G. Holder
external usenet poster
 
Posts: 51
Default Clare - are smaller car tires easier to balance than SUV tires?

On Wed, 12 Jun 2019 21:37:49 -0400, Clare Snyder wrote:

> Yes and no. The smaller tire has less total mass so a small amount
> of weight has more effect than it would on a bigger tire - but it is
> not as far from the center (shorter moment arm) so it has less effect.


Thanks Clare as I never mounted and balanced a tire so fast on purpose, not
even taking time to clean the wheel or even remove the old weights until
AFTER I put it on the static balance stand.

These tires are Lexani LXTR 203 model tires, of size P185/65R14 with load
range 86 and speed range H (traction A, temperature A, and treadwear 500),
where I don't know WHAT specific thing makes these so easy to balance, but
they're so easy that something is very different.

I was surprised that I skipped a bunch of steps, and yet, the wheel _still_
didn't cause any perceptible vibration, according to the driver, even as
it's a front wheel drive vehicle with the tire being the driver side front
tire.

I had told the owner to take it to Costco for the $5 wheel balancing, but
that wasn't even necessary, even as I skipped a bunch of balancing steps.

The old tires on her car were model "Grand Prix" of size P185/65R14 load
range 86 and speed of T (traction A, temperature B, and treadwear 500)
which seem to be wearing on both edges, where here are the front two tires
of this FWD vehicle with the tires set up in the appropriate position.
<https://i.postimg.cc/JzvTyjKg/mount18.jpg>

I had previously replaced her passenger front tire due to this gouge
<https://i.postimg.cc/4dTBPZDQ/mount19.jpg>

Where the driver front tire wore into the steel belts which jutted out
<https://i.postimg.cc/85Bwn9DQ/mount20.jpg>

She needed to be somewhere so I was in such a rush, that I didn't even
_see_ the yellow (weight) dot when I mounted the valve stem to the red
(uniformity) dot:
<https://i.postimg.cc/7L8HPbtb/mount16.jpg>

Where I only noticed the yellow dot when I looked at this picture!
<https://i.postimg.cc/kG1M7cLd/mount15.jpg>

Back to how easy it was to statically balance these tires, not only did
this tiny car have the only four-lug wheel I've ever worked on, but popping
the first bead of this tiny 14-inch P185 tire was so simple that it took
only a couple of pumps and about triple that to break the second bead.

Removing the third bead and fourth bead was, likewise, surprisingly simple.
Popping on the fifth bead was almost entirely done by hand, it was that
easy, where only the sixth bead took any effort whatsoever that required a
force that any teenager could exert.

With two wheel weights already on the rim, and by match mounting the red
dot (I didn't even _see_ that yellow dot until I looked at the picture
afterward), the balance was spot on in the middle of the bubble level.

So I didn't even remove the _old_ wheel weights, which I normally would
have done as part of the wheel prep after breaking the bead and removing
the old tire. I didn't even replace the valve stem, as I recently used up
the four valve stems I had bought after speaking to you about getting the
bolt-in kind so I didn't have any available.

The tires have been waiting for her outside in the mud and rain, so I
simply bounced and blew out the leaves and crud where I would have cleaned
the tires more had I more time, where I might have noticed that yellow dot
which was slightly worn away from being outside all winter.

> GOOD tires of any size are easier to ballance than crappy tires. Ealy
> Hankooks were a real pain to ballance. Apparentlythey have gotten
> better.


Funny you mention the Hankook's where I just snapped this for you!
<https://i.postimg.cc/zGVtXxwK/mount17.jpg>

Those are Hancook Optimo H724 model tires of size P225/75R15, with the load
range of 102 and speed range of S (traction A, temperature B, and treadwear
500), which were MUCH HARDER to mount and dismount and harder to balance
too, it seems.

I'm planning on mounting and balancing them this weekend on an SUV which
keeps wearing out the front tires which I have to get alignment tools to
check the camber mostly since they're wearing on the outside edge.

When I mount those thick-sided Hancooks, on steel wheels, I will mount by
the _yellow_ (minimum weight) dot for the first time, instead of by the red
(maximum runout) dot, as I recall you recommended for when there's no match
mounting mark on the rims.

Thanks for being helpful where you're just about the only guy on this
newsgroup who knows anything about this subject matter, which I greatly
appreciate your advice, and where I try to remember it all over the years,
where I'm starting to lose count of how many tires I've done in the past
five years with the crappy Harbor Freight tools (they work, but they suck).
Ads
  #2  
Old June 13th 19, 08:11 AM posted to alt.home.repair,rec.autos.tech
Xeno
external usenet poster
 
Posts: 363
Default Clare - are smaller car tires easier to balance than SUV tires?

On 13/6/19 2:32 pm, Arlen G. Holder wrote:
> On Wed, 12 Jun 2019 21:37:49 -0400, Clare Snyder wrote:
>
>> Yes and no. The smaller tire has less total mass so a small amount
>> of weight has more effect than it would on a bigger tire - but it is
>> not as far from the center (shorter moment arm) so it has less effect.

>
> Thanks Clare as I never mounted and balanced a tire so fast on purpose, not
> even taking time to clean the wheel or even remove the old weights until
> AFTER I put it on the static balance stand.
>
> These tires are Lexani LXTR 203 model tires, of size P185/65R14 with load
> range 86 and speed range H (traction A, temperature A, and treadwear 500),
> where I don't know WHAT specific thing makes these so easy to balance, but
> they're so easy that something is very different.
>
> I was surprised that I skipped a bunch of steps, and yet, the wheel _still_
> didn't cause any perceptible vibration, according to the driver, even as
> it's a front wheel drive vehicle with the tire being the driver side front
> tire.
>
> I had told the owner to take it to Costco for the $5 wheel balancing, but
> that wasn't even necessary, even as I skipped a bunch of balancing steps.
>
> The old tires on her car were model "Grand Prix" of size P185/65R14 load
> range 86 and speed of T (traction A, temperature B, and treadwear 500)
> which seem to be wearing on both edges, where here are the front two tires
> of this FWD vehicle with the tires set up in the appropriate position.
> <https://i.postimg.cc/JzvTyjKg/mount18.jpg>
>
> I had previously replaced her passenger front tire due to this gouge
> <https://i.postimg.cc/4dTBPZDQ/mount19.jpg>
>
> Where the driver front tire wore into the steel belts which jutted out
> <https://i.postimg.cc/85Bwn9DQ/mount20.jpg>
>
> She needed to be somewhere so I was in such a rush, that I didn't even
> _see_ the yellow (weight) dot when I mounted the valve stem to the red
> (uniformity) dot:
> <https://i.postimg.cc/7L8HPbtb/mount16.jpg>
>
> Where I only noticed the yellow dot when I looked at this picture!
> <https://i.postimg.cc/kG1M7cLd/mount15.jpg>
>
> Back to how easy it was to statically balance these tires, not only did
> this tiny car have the only four-lug wheel I've ever worked on, but popping
> the first bead of this tiny 14-inch P185 tire was so simple that it took
> only a couple of pumps and about triple that to break the second bead.
>
> Removing the third bead and fourth bead was, likewise, surprisingly simple.
> Popping on the fifth bead was almost entirely done by hand, it was that
> easy, where only the sixth bead took any effort whatsoever that required a
> force that any teenager could exert.
>
> With two wheel weights already on the rim, and by match mounting the red
> dot (I didn't even _see_ that yellow dot until I looked at the picture
> afterward), the balance was spot on in the middle of the bubble level.
>
> So I didn't even remove the _old_ wheel weights, which I normally would
> have done as part of the wheel prep after breaking the bead and removing
> the old tire. I didn't even replace the valve stem, as I recently used up
> the four valve stems I had bought after speaking to you about getting the
> bolt-in kind so I didn't have any available.
>
> The tires have been waiting for her outside in the mud and rain, so I
> simply bounced and blew out the leaves and crud where I would have cleaned
> the tires more had I more time, where I might have noticed that yellow dot
> which was slightly worn away from being outside all winter.
>
>> GOOD tires of any size are easier to ballance than crappy tires. Ealy
>> Hankooks were a real pain to ballance. Apparentlythey have gotten
>> better.

>
> Funny you mention the Hankook's where I just snapped this for you!
> <https://i.postimg.cc/zGVtXxwK/mount17.jpg>
>
> Those are Hancook Optimo H724 model tires of size P225/75R15, with the load
> range of 102 and speed range of S (traction A, temperature B, and treadwear
> 500), which were MUCH HARDER to mount and dismount and harder to balance
> too, it seems.
>
> I'm planning on mounting and balancing them this weekend on an SUV which
> keeps wearing out the front tires which I have to get alignment tools to
> check the camber mostly since they're wearing on the outside edge.


You can check the camber all you like but the answer is more likely in
the SAI angles and you will be able to do SFA about that. Quiz the owner
about type of use instead. If it is all city and suburban driving, tyre
wear on the outside of the tread can be considered 100% normal.
Turn the wheels to a high level of lock and the obvious will confront
you. The type of feathering will tell you what the actual cause is.
>
> When I mount those thick-sided Hancooks, on steel wheels, I will mount by
> the _yellow_ (minimum weight) dot for the first time, instead of by the red
> (maximum runout) dot, as I recall you recommended for when there's no match
> mounting mark on the rims.
>
> Thanks for being helpful where you're just about the only guy on this
> newsgroup who knows anything about this subject matter, which I greatly
> appreciate your advice, and where I try to remember it all over the years,
> where I'm starting to lose count of how many tires I've done in the past
> five years with the crappy Harbor Freight tools (they work, but they suck).
>



--

Xeno


Nothing astonishes Noddy so much as common sense and plain dealing.
(with apologies to Ralph Waldo Emerson)
  #3  
Old June 13th 19, 09:28 PM posted to alt.home.repair,rec.autos.tech
Arlen G. Holder
external usenet poster
 
Posts: 51
Default Clare - are smaller car tires easier to balance than SUV tires?

On Thu, 13 Jun 2019 17:11:14 +1000, Xeno wrote:

> You can check the camber all you like but the answer is more likely in
> the SAI angles and you will be able to do SFA about that.


Hi Xeno,

Thanks for your purposefully helpful advice on kingpin inclination angle
(aka steering axis inclination), and perhaps included angle, neither of
which have I delved into yet (as I'm starting with camber, which is the
basis for caster calculations, and where toe is relatively simple).
<http://www.valleyofhastings.com/WheelAlignment2.pdf>

Other than Clare, you and maybe one or two other folks here are
knowledgeable in the important details of home alignment checks &
adjustments, where I don't usually disagree with anything you guys say, as
you know more than I do.

We have to remember a home DIY alignment check & adjust is sort of like
doing a DIY tuneup versus a complete engine overhaul
o A DIY caster/camber/toe check/adjust is to a professional alignment
o as a DIY tuneup is to a professional engine blueprinting overhaul

The fact is that the SIA is a "non adujstable" angle:
<https://www.freeasestudyguides.com/included-angle.html>

The fact it's not adjustable means it is in a different category than
o caster
o camber
o toe

While SIA is not normally adjustable, looking this up anyway for more
insight, it seems SIA checks generally simply need yet _another_ magnetic
bubble gauge, much like the camber gauge apparently, but offset by 90
degrees, according to this cite:
o Checking the Steering Axis Inclination Angle
<http://route66hotrodhigh.com/Inclination.html>
Which says:
"To measure steering axis inclination, the method is identical to caster
measurement except that you use the steering axis inclination guage [sic]
which is at a 90 deg angle to the caster gauge. The wheel is turned 20 deg
inward. The steering axis inclination gauge is centered for 0 deg caster.
There is an adjustment screw on the back of the gauge that allows you to
set it for 0 deg. The wheel is then turned to 20 deg outward for a total
movement of 40 degrees. The steering axis inclination angle is read off the
gauge."

The key question is where to get that SIA gauge, which, apparently, can be
replaced with a normal magnetic caster gauge according to this patent:
o Device & method for measuring SAI on a steerable wheel (#4,546,548)
<http://www.freepatentsonline.com/4546548.pdf>

In short, if we're aligning a vehicle that we own and drive often, then we
don't have any reason to suspect SIA changes (which will only occur with
bent or worn parts), and hence, they aren't part of what typically changes
(which is caster, camber, and toe).
<https://www.motor.com/magazinepdfs/062002_05.pdf>

> about type of use instead. If it is all city and suburban driving, tyre
> wear on the outside of the tread can be considered 100% normal.


On this mountain, everyone wears tires sooner than people who drive in
flatland do, where there is just "something" horrific about five miles of
steep driving,

Most seem to wear on the outside edge, which I still haven't figured out
exactly why. The road is about 5 miles at about a 9 percent angle with very
many 180 degree and even 270 degree switchbacks, but the speeds are rather
slow, where the road is too narrow to even have panted centerlines and
where the nominal speed limit for such roads is 25mph.

Given nobody drives 25 mph anywhere, we can figure it's something like 30
mph to 40 mph top speed but there's a lot of braking in between. Me? I just
put the tranny in neutral and roll down the entire five miles by giving up
potential energy, where I only brake when I must and I take the turns very
wide (as most people do) which helps maintain speed.

Somehow, _that_ process (which most people do, I think, but in gear most
likely), wears tires out like you can't believe, where tires get half the
stated mileage, as far as I can tell by aggregate conversations.

> Turn the wheels to a high level of lock and the obvious will confront
> you. The type of feathering will tell you what the actual cause is.


I do admit that I can't 'read' a tire very well. I've tried, but rotations
screw up the readings, and certainly there can be multiple causes.

The type of feathering I mostly see is the kind you can feel after only
about 1000 miles on the outside edge, for about 3 inches of tread, where
there is a sharp lip that is feathered into that outside tread that you can
only feel moving your hand clockwise over the front tire tread on the
outside 3 inches.

I need to learn more, but I think that's "normal" since it happens even
after I get a professional alignment. I'm due for one soon for a couple of
cars, which is why, instead of paying the $150 per vehicle, which for the 3
cars I want to do first, will be almost five hundred bucks, I'd rather buy
the tools to do it myself for that same five hundred bucks.
o Caster gauge (to measure caster & calculate camber)
o Caster jig (to lock onto the wheel for the caster gauge to be accurate)
o Wheel plates (to move the wheels for adjustment under suspension loading)
o Toe plates (to enable single-person linear measurement to centerline)

After having discussed this with Clare in the past, I know we can redneck
some of that, but overall, those four items seem to be the key items needed
for a home DIY check/change of caster, camber, & toe, do you agree?
  #4  
Old June 14th 19, 03:58 AM posted to alt.home.repair,rec.autos.tech
Xeno
external usenet poster
 
Posts: 363
Default Clare - are smaller car tires easier to balance than SUV tires?

On 14/6/19 6:28 am, Arlen G. Holder wrote:
> On Thu, 13 Jun 2019 17:11:14 +1000, Xeno wrote:
>
>> You can check the camber all you like but the answer is more likely in
>> the SAI angles and you will be able to do SFA about that.

>
> Hi Xeno,
>
> Thanks for your purposefully helpful advice on kingpin inclination angle
> (aka steering axis inclination), and perhaps included angle, neither of
> which have I delved into yet (as I'm starting with camber, which is the
> basis for caster calculations, and where toe is relatively simple).
> <http://www.valleyofhastings.com/WheelAlignment2.pdf>


Use the term Steering Axis Inclination (SAI) as your vehicle likely does
not have kingpins. They are only found on trucks these days. I am of the
old school so I still use KPI but I found, when teaching apprentices,
the term is meaningless to them because most have never seen kingpins
much less worked on a vehicle so equipped.
>
> Other than Clare, you and maybe one or two other folks here are
> knowledgeable in the important details of home alignment checks &
> adjustments, where I don't usually disagree with anything you guys say, as
> you know more than I do.
>
> We have to remember a home DIY alignment check & adjust is sort of like
> doing a DIY tuneup versus a complete engine overhaul
> o A DIY caster/camber/toe check/adjust is to a professional alignment
> o as a DIY tuneup is to a professional engine blueprinting overhaul
>
> The fact is that the SIA is a "non adujstable" angle:
> <https://www.freeasestudyguides.com/included-angle.html>
>
> The fact it's not adjustable means it is in a different category than
> o caster
> o camber
> o toe


SAI, to the serviceman, is a *diagnosis angle* in much the same way as
*toe out on turns* (TOOT) is a diagnosis angle. If your toe is correct
but TOOT is incorrect, you can be assured that you have something that
is *bent*, usually a steering arm. Note, you cannot *adjust* TOOT in
cars as it is *designed in* as part of the Ackermann Angle.
>
> While SIA is not normally adjustable, looking this up anyway for more
> insight, it seems SIA checks generally simply need yet _another_ magnetic
> bubble gauge, much like the camber gauge apparently, but offset by 90
> degrees, according to this cite:
> o Checking the Steering Axis Inclination Angle
> <http://route66hotrodhigh.com/Inclination.html>
> Which says:
> "To measure steering axis inclination, the method is identical to caster
> measurement except that you use the steering axis inclination guage [sic]
> which is at a 90 deg angle to the caster gauge. The wheel is turned 20 deg
> inward. The steering axis inclination gauge is centered for 0 deg caster.
> There is an adjustment screw on the back of the gauge that allows you to
> set it for 0 deg. The wheel is then turned to 20 deg outward for a total
> movement of 40 degrees. The steering axis inclination angle is read off the
> gauge."
>
> The key question is where to get that SIA gauge, which, apparently, can be
> replaced with a normal magnetic caster gauge according to this patent:
> o Device & method for measuring SAI on a steerable wheel (#4,546,548)
> <http://www.freepatentsonline.com/4546548.pdf>
>
> In short, if we're aligning a vehicle that we own and drive often, then we
> don't have any reason to suspect SIA changes (which will only occur with
> bent or worn parts), and hence, they aren't part of what typically changes
> (which is caster, camber, and toe).
> <https://www.motor.com/magazinepdfs/062002_05.pdf>
>
>> about type of use instead. If it is all city and suburban driving, tyre
>> wear on the outside of the tread can be considered 100% normal.

>
> On this mountain, everyone wears tires sooner than people who drive in
> flatland do, where there is just "something" horrific about five miles of
> steep driving,


Steep driving, urban driving, same thing really. You are at a greater
lock more often, even at slow speed, than when you are out on the
highways and freeways.
>
> Most seem to wear on the outside edge, which I still haven't figured out
> exactly why.


The term is Camber Scrub, and it caused a particular type of feathered
wear (for and aft feather IIRC) on the outside of the tyre, but it isn't
caused by the *camber angle* per se. It is caused by what SAI does to
the camber angles in a turn. Here is a video clip describing *one* of
the reasons for SAI.

https://www.youtube.com/watch?v=IZLiP_37Oso

The narrator focuses on the need to reduce unwanted feedback through the
steering. No mention is made of the other major reasons for SAI and that
is steering self centering and torque steer reduction. There are a
number of factors involved in steering stability and self centering
including; SAI, Caster, Camber, mechanical trail and tyre trail.

In this video clip he mentions the self centering effect at the end. He
states that turning the steering forces the axle (and wheel) down and,
in effect, lifts the front of the car. That provides the self centering
effect as the weight of the car will tend to return the steering to its
central or straight ahead position. That downward force also creates a
change in the *camber angle*.

https://www.youtube.com/watch?v=IUcZ63unEyU

But it is the camber angle the wheel adopts when at the turn position,
caused by SAI, that causes *camber scrub*.

This clip https://www.youtube.com/watch?v=VbReLNi2JP4 provides a very
good description of the steering functions. Skip to 13:50 for a
graphical display of the camber angle change when turning.

> The road is about 5 miles at about a 9 percent angle with very
> many 180 degree and even 270 degree switchbacks, but the speeds are rather
> slow, where the road is too narrow to even have panted centerlines and
> where the nominal speed limit for such roads is 25mph.


Definitely camber scrub territory.
>
> Given nobody drives 25 mph anywhere, we can figure it's something like 30
> mph to 40 mph top speed but there's a lot of braking in between. Me? I just
> put the tranny in neutral and roll down the entire five miles by giving up
> potential energy, where I only brake when I must and I take the turns very
> wide (as most people do) which helps maintain speed.
>
> Somehow, _that_ process (which most people do, I think, but in gear most
> likely), wears tires out like you can't believe, where tires get half the
> stated mileage, as far as I can tell by aggregate conversations.


Do the same distance on straight roads and you will have fairly even
tyre wear.
>
>> Turn the wheels to a high level of lock and the obvious will confront
>> you. The type of feathering will tell you what the actual cause is.

>
> I do admit that I can't 'read' a tire very well. I've tried, but rotations
> screw up the readings, and certainly there can be multiple causes.


It takes practice and, since I haven't operated a wheel aligner for a
very long time, I am *out of practice* but I've had the priciples
hammered into me over the decades ably assisted by having taught the
principles for some 20 years.
>
> The type of feathering I mostly see is the kind you can feel after only
> about 1000 miles on the outside edge, for about 3 inches of tread, where
> there is a sharp lip that is feathered into that outside tread that you can
> only feel moving your hand clockwise over the front tire tread on the
> outside 3 inches.


That sounds like camber scrub feathering - if I'm reading your
description correctly.
>
> I need to learn more, but I think that's "normal" since it happens even
> after I get a professional alignment. I'm due for one soon for a couple of


A *professional alignment* cannot fix a *symptom* that is considered
*normal* for the kind of driving you do. Any changes made to mitigate
camber scrub will cause a reduction in handling capability at speed.

> cars, which is why, instead of paying the $150 per vehicle, which for the 3
> cars I want to do first, will be almost five hundred bucks, I'd rather buy
> the tools to do it myself for that same five hundred bucks.
> o Caster gauge (to measure caster & calculate camber)
> o Caster jig (to lock onto the wheel for the caster gauge to be accurate)
> o Wheel plates (to move the wheels for adjustment under suspension loading)
> o Toe plates (to enable single-person linear measurement to centerline)
>
> After having discussed this with Clare in the past, I know we can redneck
> some of that, but overall, those four items seem to be the key items needed
> for a home DIY check/change of caster, camber, & toe, do you agree?
>

Yes, that is basically all the small service station had next door to
where I did my apprenticeship. You have missed the primary requisite
however - a guaranteed dead flat and level garage floor. Also a lock to
lock the steering wheel to the desired centre position;
https://i.ebayimg.com/images/g/sJIAA...58p/s-l225.jpg



--

Xeno


Nothing astonishes Noddy so much as common sense and plain dealing.
(with apologies to Ralph Waldo Emerson)
  #5  
Old June 14th 19, 05:55 PM posted to alt.home.repair,rec.autos.tech
Arlen G. Holder
external usenet poster
 
Posts: 51
Default Clare - are smaller car tires easier to balance than SUV tires?

On Fri, 14 Jun 2019 12:58:31 +1000, Xeno wrote:

> Use the term Steering Axis Inclination (SAI) as your vehicle likely does
> not have kingpins.


Hi Xeno,
I typed up a super detailed response, after viewing every second of those
three videos, where the first and last seem to have the same graphics, and
the middle (whiteboard) one was a bit different - and where that wheelcam
shot of the tire literally bending away from the rim - and the temperature
methods of determining footprint on hard cornering were illuminating.

I hate losing data, but I lost it when the PC rebooted, so suffice to say I
appreciate the videos, from which I learned good stuff, particularly about
that "scrub radius".

I didn't find a lot on the net about "camber scrub", and those videos
didn't cover specific tire wear on the slow speed (less than 40mph)
constantly lock-to-lock turns we perform on the mountain, where the goal
is how to modify the set up for the vehicle in a compromise to minimize
that 'camber scrub' on FWD and RWD vehicles without adversely affecting
straight-line handling.

> Yes, that is basically all the small service station had next door to
> where I did my apprenticeship. You have missed the primary requisite
> however - a guaranteed dead flat and level garage floor. Also a lock to
> lock the steering wheel to the desired centre position;
> https://i.ebayimg.com/images/g/sJIAA...58p/s-l225.jpg



Everyone says you need a perfectly flat garage floor, which, as far as I
know, mine is pretty flat based on putting a level on it - but I don't
really know how flat is flat enough.

Given that a millimeter or two of height adjustment in any one corner might
be necessary for most garages, I guess your suggestion above adds two
nice-to-have tools to the home DIY alignment check mix...
o Steering wheel centering lock
o Some kind of way to put the 4 wheels on a wormscrew-adjusted plate

Googling found the first, but the second was in the thousand dollar range.

Are there good redneck solutions for leveling the four tires?
  #6  
Old June 15th 19, 05:14 AM posted to alt.home.repair,rec.autos.tech
Xeno
external usenet poster
 
Posts: 363
Default Clare - are smaller car tires easier to balance than SUV tires?

On 15/6/19 2:55 am, Arlen G. Holder wrote:
> On Fri, 14 Jun 2019 12:58:31 +1000, Xeno wrote:
>
>> Use the term Steering Axis Inclination (SAI) as your vehicle likely does
>> not have kingpins.

>
> Hi Xeno,
> I typed up a super detailed response, after viewing every second of those
> three videos, where the first and last seem to have the same graphics, and
> the middle (whiteboard) one was a bit different - and where that wheelcam
> shot of the tire literally bending away from the rim - and the temperature
> methods of determining footprint on hard cornering were illuminating.


Yes, I learnt a couple of points from those videos too so it seems you
can teach old dogs new tricks. I have found, in order to gain a better
appreciation of steering geometry and suspension systems, one needs to
look at those places that are extreme. In this case, it's in motor racing.
>
> I hate losing data, but I lost it when the PC rebooted, so suffice to say I
> appreciate the videos, from which I learned good stuff, particularly about
> that "scrub radius".
>
> I didn't find a lot on the net about "camber scrub", and those videos


You won't. Information on it is scarce since it is an undesired effect.
However, if you look at what the wheel is doing vis a vis camber during
high angle (note - not high speed) cornering, then you can visualise the
issue. Note too that tread blocks have a limited degree of flexibility
and, as such, are likely to exceed that during high angle cornering
resulting in tread scrubbing.

> didn't cover specific tire wear on the slow speed (less than 40mph)
> constantly lock-to-lock turns we perform on the mountain, where the goal
> is how to modify the set up for the vehicle in a compromise to minimize
> that 'camber scrub' on FWD and RWD vehicles without adversely affecting
> straight-line handling.


The reality is that you are faced with a *compromise* and there are many
such in steering and suspension geometry. Any gain in the tyre wear
scenario will negatively affect high speed. If you happen to see a
Porsche Cayenne in a parking lot with its wheels turned at a high angle,
the camber angle displayed will amaze you. I know it amazed me. Of
course, when you realise that vehicle's suspension is *optimised* for
high speed and high power operation in a very narrow band either side of
straight ahead, it all makes sense.
>
>> Yes, that is basically all the small service station had next door to
>> where I did my apprenticeship. You have missed the primary requisite
>> however - a guaranteed dead flat and level garage floor. Also a lock to
>> lock the steering wheel to the desired centre position;
>> https://i.ebayimg.com/images/g/sJIAA...58p/s-l225.jpg

>
>
> Everyone says you need a perfectly flat garage floor, which, as far as I
> know, mine is pretty flat based on putting a level on it - but I don't
> really know how flat is flat enough.


A level will only give you a localised point. You need something that
can verify any point in the garage floor against a common datum point.
These can be used for that purpose and aren't expensive;
https://www.bosch-do-it.com/au/en/di...898-199931.jsp
Or you could hire one for a day just to verify your garage floor. A
professional one of these should have been used when the floor was
poured and leveled anyway.
>
> Given that a millimeter or two of height adjustment in any one corner might
> be necessary for most garages, I guess your suggestion above adds two
> nice-to-have tools to the home DIY alignment check mix...
> o Steering wheel centering lock
> o Some kind of way to put the 4 wheels on a wormscrew-adjusted plate
>
> Googling found the first, but the second was in the thousand dollar range.
>
> Are there good redneck solutions for leveling the four tires?
>

Most wheel aligners that I have used come with ramps that have the added
benefit of raising the vehicle a couple of feet off the floor. Ramps,
even without the aligner heads, provide a relatively easy means of
leveling the required work area. They don't even need to be raised more
than an inch or two. If the floor area is really out of whack, two or
four ramps made of wood of varying thicknesses might suffice. You can
even check the level easily these days with laser levels as I mentioned
above. My brother has one of the professional units since he is a
concreter but cheaper DIY versions, like the one in the link, should
suffice for this purpose.

--

Xeno


Nothing astonishes Noddy so much as common sense and plain dealing.
(with apologies to Ralph Waldo Emerson)
  #7  
Old June 15th 19, 02:40 PM posted to rec.autos.tech
[email protected]
external usenet poster
 
Posts: 539
Default Clare - are smaller car tires easier to balance than SUV tires?

Xeno wrote: "number of factors involved in steering stability and self centering
including; SAI, Caster, Camber, mechanical trail and tyre trail. "

One question I have never been able to find an answer for:

Which, per degree of angle, plays a bigger role in
self-centering of the front wheels, and stability: Caster,
or SAI?
  #8  
Old June 15th 19, 04:01 PM posted to rec.autos.tech
Xeno
external usenet poster
 
Posts: 363
Default Clare - are smaller car tires easier to balance than SUV tires?

On 15/6/19 11:40 pm, wrote:
> Xeno wrote: "number of factors involved in steering stability and self centering
> including; SAI, Caster, Camber, mechanical trail and tyre trail. "
>
> One question I have never been able to find an answer for:
>
> Which, per degree of angle, plays a bigger role in
> self-centering of the front wheels, and stability: Caster,
> or SAI?
>

You would need to look at the actual angles to determine that. SAI
angles up there between 9 & 12 degrees are really pulling their weight
in the area of stability. That's typical of FWDs. FWD cars with large
SAI angles tend to rely less on caster. Remember, front wheel drives are
either pushing or pulling the front wheels depending on whether they are
braking or accelerating. Think what happens to caster wheels on a
supermarket trolley when you reverse direction. Caster angles on front
wheel drives tend to be less because of this so reliance on caster is
also reduced and more emphasis placed on SAI.

Rear wheel drive caster angles only have to deal with rolling resistance
and braking forces in the same direction. You can notice that lack of
steering stability in reverse. That said, high angles of caster can
create a high camber gain when cornering and can cause camber scrub as
well as heavy steering. Power steering negates the heavy steering effect.

In summary, in modern cars SAI is the primary means of gaining steering
stability and self centering, therefore reliance on caster is much less.

--

Xeno


Nothing astonishes Noddy so much as common sense and plain dealing.
(with apologies to Ralph Waldo Emerson)
  #9  
Old June 15th 19, 05:33 PM posted to rec.autos.tech
[email protected]
external usenet poster
 
Posts: 539
Default Clare - are smaller car tires easier to balance than SUV tires?

Xeno:

Thanks for that explanation! Makes a lot of sense. So SAI
is more relevant in front-wheel drive, and Caster angle in
rear-wheel drive.

One thing that sticks out in my mind regarding SAI, is that if
it is more than half-degree unequal side-to-side, it tends to
cause vehicular pull to one side at LOWER, vs higher speeds,
where unequal Caster and Camber angles have the most
implications. Interesting!
  #10  
Old June 16th 19, 07:31 AM posted to alt.home.repair,rec.autos.tech
Arlen G. Holder
external usenet poster
 
Posts: 51
Default Clare - are smaller car tires easier to balance than SUV tires?

On Sat, 15 Jun 2019 14:14:27 +1000, Xeno wrote:

> You won't. Information on it is scarce since it is an undesired effect.
> However, if you look at what the wheel is doing vis a vis camber during
> high angle (note - not high speed) cornering, then you can visualise the
> issue. Note too that tread blocks have a limited degree of flexibility
> and, as such, are likely to exceed that during high angle cornering
> resulting in tread scrubbing.


Hi Xeno,

While I don't race, our conditions are "extreme" enough, in that constant
incessant repeated nearly full back-to-back wheel locks are causing
"something" to scrape away rubber, so this "camber scrub" is intriguing.

I snapped this photo of tires that I mounted about a month ago, which only
have about 1000 miles on them, where they clearly show this pattern which
"might" be what you've been referring to as "camber scrub".
<https://i.postimg.cc/zvvyL2tq/mount24.jpg>

Does _that_ feathering look like what you're referring to as "camber scrub"?
 




Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

vB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
can water in your tires make them go out of balance? Nate Nagel[_2_] Technology 7 March 17th 10 01:42 AM
how often to balance tires? [email protected] Honda 6 March 29th 05 06:24 AM
how often to balance tires? [email protected] General 6 March 29th 05 06:24 AM
Balance markings on tires and wheels DBLZOOM Mazda 10 February 19th 05 03:02 AM
Ho much to mount/install/balance tires? kevins_news General 7 January 30th 04 04:20 PM


All times are GMT +1. The time now is 10:51 AM.


Powered by vBulletin® Version 3.6.4
Copyright ©2000 - 2024, Jelsoft Enterprises Ltd.
Copyright ©2004-2024 AutoBanter.
The comments are property of their posters.