"Steven Campbell" wrote in message
...

"Roger Mills" wrote in message
...
In an earlier contribution to this discussion,
Steven Campbell wrote:


Thanks everyone for the hints and tips.
I slackened the wheel nuts off and drove round my housing estate for
a few minutes, hitting every pot hole on the way but still the wheel
refused to budge.
In the end I squirted some super glue into the hole and loads on top
of it. Left it to cure for a couple of hours and then blew the tyre
back up. Left it over night and no air escaped at all.
So managed to drive the 10 miles or so to the nearest tyre place this
morning, again with no air escaping.

Job done. Great stuff that super glue ;o)


So how they *they* get the wheel off?

Haven't a clue.
By the time I'd went in to the office and told them what price of tyre
etc, my car had been moved and the offending wheel removed.
I'd guess it was a great big hammer although I never heard them
hammering!!

Judicious application of a hefty right foot usually. You need decent leather
boots on rather than trainers or the like and then you just kick the ****
out of one side of the tyre, then the other until it decides to part company
with the hub. All done from the outward facing side of the tyre btw not from
the back. It's the twisting force between the edge of the tyre and the hub
as you kick the tyre that starts to loosen the corrosion. You can't use
metal hammers or you'll damage the rim and rubber mallets are useless
anyway. The most force you can apply without damaging anything turns out to
be with your foot.

I recently struggled for about half an hour with a rear wheel on my Focus
which hadn't been off for at least six years until finally phoning a mate
for advice and he told me to put bigger boots on and kick it harder. Up till
then I'd tried swinging at it from behind with lumps of wood, hammering on
lumps of wood with a 4lb lump hammer, levering at it with a crowbar and
kicking it with trainers on to no good effect other than hurting my foot. A
good kicking with my hiking boots on had it off fairly smartly. As soon as
you see it move even 1mm or so you can generally then grab it and wiggle it
free.
--
Dave Baker

On Mon, 18 May 2009 00:04:35 +0100, Steve Firth wrote:

Steve Walker wrote:

Bloody Kwikfit - they wouldn't adjust the tracking on my car, as it wasn't
in their book.

Narrow escape for you then. Never, ever, ever, get the tracking adjusted
at Kwik Fit. You stand a chance of getting a dork like Toomy doing it.

Find a decent independent in your area. If you know anyone who does
track days, take their advice.

In the end I did go elsewhere, but even though I was legal, I wanted to
avoid the hassle of being pulled in an unregistered car (insured on the
VIN) and having to try and persuade them that all was legit, hence wanting
to use the nearest place.

SteveW

Steve Firth wrote:
Steve Walker wrote:

Bloody Kwikfit - they wouldn't adjust the tracking on my car, as it wasn't
in their book.

Narrow escape for you then. Never, ever, ever, get the tracking adjusted
at Kwik Fit. You stand a chance of getting a dork like Toomy doing it.

Find a decent independent in your area. If you know anyone who does
track days, take their advice.


Took one of my Rover 45's down to the garage that the ex Rover foreman
had set up after they went bust, He put a scale on the floor and pushed
the car over it and declared that it was OK.
I have not seen one of these scales in more than 40 years, but he was
right, the tracking was perfet, except for a slight steering wheel mis-
alignment that is not big enough to worry about yet.

He can do 4 wheel alignment, but this was much quicker for him.

Dave

Dave Baker wrote:
"Steven Campbell" wrote in message
...
"Roger Mills" wrote in message
...
In an earlier contribution to this discussion,
Steven Campbell wrote:

Thanks everyone for the hints and tips.
I slackened the wheel nuts off and drove round my housing estate for
a few minutes, hitting every pot hole on the way but still the wheel
refused to budge.
In the end I squirted some super glue into the hole and loads on top
of it. Left it to cure for a couple of hours and then blew the tyre
back up. Left it over night and no air escaped at all.
So managed to drive the 10 miles or so to the nearest tyre place this
morning, again with no air escaping.

Job done. Great stuff that super glue ;o)

So how they *they* get the wheel off?
Haven't a clue.
By the time I'd went in to the office and told them what price of tyre
etc, my car had been moved and the offending wheel removed.
I'd guess it was a great big hammer although I never heard them
hammering!!

Judicious application of a hefty right foot usually. You need decent leather
boots on rather than trainers or the like and then you just kick the ****
out of one side of the tyre, then the other until it decides to part company
with the hub. All done from the outward facing side of the tyre btw not from
the back. It's the twisting force between the edge of the tyre and the hub
as you kick the tyre that starts to loosen the corrosion. You can't use
metal hammers or you'll damage the rim and rubber mallets are useless
anyway. The most force you can apply without damaging anything turns out to
be with your foot.

What about a leather faced hammer?

I recently struggled for about half an hour with a rear wheel on my Focus
which hadn't been off for at least six years until finally phoning a mate
for advice and he told me to put bigger boots on and kick it harder. Up till
then I'd tried swinging at it from behind with lumps of wood, hammering on
lumps of wood with a 4lb lump hammer, levering at it with a crowbar and
kicking it with trainers on to no good effect other than hurting my foot. A
good kicking with my hiking boots on had it off fairly smartly. As soon as
you see it move even 1mm or so you can generally then grab it and wiggle it
free.

Dave

In article ,
Dave wrote:
Took one of my Rover 45's down to the garage that the ex Rover foreman
had set up after they went bust, He put a scale on the floor and pushed
the car over it and declared that it was OK.
I have not seen one of these scales in more than 40 years, but he was
right, the tracking was perfet, except for a slight steering wheel mis-
alignment that is not big enough to worry about yet.

With R&P steering if the wheel ends up off centre the tracking isn't
correctly done - the geometry will vary as the wheels turn. Unless the
steering wheel has been moved on its splines.

--


Dave Plowman London SW
To e-mail, change noise into sound.

Dave Plowman (News) wrote:
In article ,
Dave wrote:
Took one of my Rover 45's down to the garage that the ex Rover foreman
had set up after they went bust, He put a scale on the floor and pushed
the car over it and declared that it was OK.
I have not seen one of these scales in more than 40 years, but he was
right, the tracking was perfet, except for a slight steering wheel mis-
alignment that is not big enough to worry about yet.

With R&P steering if the wheel ends up off centre the tracking isn't
correctly done - the geometry will vary as the wheels turn.

Can you expand on that, please? I assume that is because the steering
geometry varies from neutral to off set when the steering wheel turns
fron neutral, but that the RAP will be in neutral if the steering wheel
does not match it, or have I got that horribly wrong?

Unless the
steering wheel has been moved on its splines.

No, steering wheel has been there since birth :-)

The different angle is barely noticable

Dave

In article ,
Dave wrote:
Dave Plowman (News) wrote:
In article ,
Dave wrote:
Took one of my Rover 45's down to the garage that the ex Rover
foreman had set up after they went bust, He put a scale on the floor
and pushed the car over it and declared that it was OK. I have not
seen one of these scales in more than 40 years, but he was right,
the tracking was perfet, except for a slight steering wheel mis-
alignment that is not big enough to worry about yet.

With R&P steering if the wheel ends up off centre the tracking isn't
correctly done - the geometry will vary as the wheels turn.

Can you expand on that, please? I assume that is because the steering
geometry varies from neutral to off set when the steering wheel turns
fron neutral, but that the RAP will be in neutral if the steering wheel
does not match it, or have I got that horribly wrong?

The rack forms part of the link between the wheels and has balljoints on
either end. If it were part of a rigid link - as on cars with a steering
box - it wouldn't make any difference to the geometry if off centre. But
because it isn't, the geometry won't be accurate when the suspension moves
or the wheels turn. May not in practice be a big error, but best avoided.
But it requires more accurate equipment - and skill - than the likes of
Kwikfit possess.

Unless the steering wheel has been moved on its splines.

No, steering wheel has been there since birth :-)

The different angle is barely noticable

*If* the tracking is correct in the straight ahead on a level surface,
adjusting each track rod end by the same amount to bring the wheel
straight should do it. But best to have it checked again afterwards.

--
*60-year-old, one owner - needs parts, make offer

Dave Plowman London SW
To e-mail, change noise into sound.

"Dave Plowman (News)" wrote in message
...
In article ,
Dave wrote:
Took one of my Rover 45's down to the garage that the ex Rover foreman
had set up after they went bust, He put a scale on the floor and pushed
the car over it and declared that it was OK.
I have not seen one of these scales in more than 40 years, but he was
right, the tracking was perfet, except for a slight steering wheel mis-
alignment that is not big enough to worry about yet.

With R&P steering if the wheel ends up off centre the tracking isn't
correctly done - the geometry will vary as the wheels turn.

Ummm no it won't. The straight-ahead position of the steering wheel has no
effect on Ackermann steering geometry which is created by the angles of the
steering pivots and tie rod.

http://en.wikipedia.org/wiki/Ackerma...ering_geometry

Imagine with tracking set correctly you move the steering wheel slightly off
centre and then recheck the tracking. The tie rod ends will now be too long
at one side and too short at the other. So you undo the locking nuts and
adjust everything until the wheels are straight again. All you've actually
changed is to lose a little steering lock on one side and gain a little on
the other. The steering geometry hasn't altered. The total length of the tie
rod (rack) is still the same, the steering pivot angles are still the same,
the wheels are still pointing straight, the steering wheel and pinion have
just moved relative to the rack is all.

A rack and pinion system has a completely linear mode of operation. A little
logical thought ought to make it apparent that it can't be the movement of
the pinion relative to the rack or their initial starting positions that
creates a non-linear steering output on opposite sides of the car which
indeed is created solely by the movement of the rack relative to the
steering pivots.

Unless the
steering wheel has been moved on its splines.

Again utterly irrelevant other than you lose steering lock on one side and
gain it on the other. I once had a Fiesta XR2 which I ran for years until it
gradually dawned on me that if I turned into my driveway from the usual
direction I approached the house in I had no difficulty but if I came back
home from the other direction which was pretty rare I struggled to get
enough steering lock on to make the turn. In normal driving there was no
other apparent fault or difficulty. After pondering this for a while I
started checking everything and finally found that from the straight ahead
position I had a lot less steering lock on one side than the other. In fact
after marking the steering wheel with a bit of masking tape and counting the
turns either way to the stop I calculated that I had one third of a turn
more on one side than the other which was a massive error. Turns out that at
some time in the past the steering wheel had been taken off and moved round
a notch on the steering column which had a hexagonal fitting rather than a
spline on this model. So I'd lost a sixth of a turn on one side and gained a
sixth on the other.

Checking the tie rod ends one side was indeed wound almost fully in and the
other side almost fully out. God knows how anyone had managed to screw this
up so badly and not realise. The garage I'd got the car from was run by
complete numpties though so that probably explains it. Anyway, with the
steering wheel back in the right place I had to make a massive tie rod end
correction and finally got everything back as it should have been. However
at no time was there any unusual tyre wear or strange steering or handling
behaviour. The steering wheel position simply makes no difference to this.
--
Dave Baker
(Correcting errors and misconceptions on the internet for over 11 years now)

"Dave Baker" wrote in message
...

"Dave Plowman (News)" wrote in message
...
With R&P steering if the wheel ends up off centre the tracking isn't
correctly done - the geometry will vary as the wheels turn.

Ummm no it won't. The straight-ahead position of the steering wheel has no
effect on Ackermann steering geometry which is created by the angles of
the steering pivots and tie rod.

http://en.wikipedia.org/wiki/Ackerma...ering_geometry

Imagine with tracking set correctly you move the steering wheel slightly
off centre and then recheck the tracking. The tie rod ends will now be too
long at one side and too short at the other. So you undo the locking nuts
and adjust everything until the wheels are straight again. All you've
actually changed is to lose a little steering lock on one side and gain a
little on the other. The steering geometry hasn't altered. The total
length of the tie rod (rack) is still the same, the steering pivot angles
are still the same, the wheels are still pointing straight, the steering
wheel and pinion have just moved relative to the rack is all.

A rack and pinion system has a completely linear mode of operation. A
little logical thought ought to make it apparent that it can't be the
movement of the pinion relative to the rack or their initial starting
positions that creates a non-linear steering output on opposite sides of
the car which indeed is created solely by the movement of the rack
relative to the steering pivots.

Unless the
steering wheel has been moved on its splines.

Again utterly irrelevant other than you lose steering lock on one side and
gain it on the other. I once had a Fiesta XR2 which I ran for years until
it gradually dawned on me that if I turned into my driveway from the usual
direction I approached the house in I had no difficulty but if I came back
home from the other direction which was pretty rare I struggled to get
enough steering lock on to make the turn. In normal driving there was no
other apparent fault or difficulty. After pondering this for a while I
started checking everything and finally found that from the straight ahead
position I had a lot less steering lock on one side than the other. In
fact after marking the steering wheel with a bit of masking tape and
counting the turns either way to the stop I calculated that I had one
third of a turn more on one side than the other which was a massive error.
Turns out that at some time in the past the steering wheel had been taken
off and moved round a notch on the steering column which had a hexagonal
fitting rather than a spline on this model. So I'd lost a sixth of a turn
on one side and gained a sixth on the other.

Checking the tie rod ends one side was indeed wound almost fully in and
the other side almost fully out. God knows how anyone had managed to screw
this up so badly and not realise. The garage I'd got the car from was run
by complete numpties though so that probably explains it. Anyway, with the
steering wheel back in the right place I had to make a massive tie rod end
correction and finally got everything back as it should have been. However
at no time was there any unusual tyre wear or strange steering or handling
behaviour. The steering wheel position simply makes no difference to this.

BTW it should also be apparent from the above that just because the car
tracks straight and the steering wheel is in the right position while it's
doing that is no indication that everything is correct. Before checking the
tracking you need to check the turns lock to lock either side of the
straight up position. If this is the same both ways then the steering wheel
is on correctly and the rack is properly centred. If not then the steering
wheel needs to be moved on its spline before the track rod ends are adjusted
to set the tracking.
--
Dave Baker

"Dave" wrote in message
...
Dave Plowman (News) wrote:
In article ,
Dave wrote:
Took one of my Rover 45's down to the garage that the ex Rover foreman
had set up after they went bust, He put a scale on the floor and pushed
the car over it and declared that it was OK.
I have not seen one of these scales in more than 40 years, but he was
right, the tracking was perfet, except for a slight steering wheel mis-
alignment that is not big enough to worry about yet.

With R&P steering if the wheel ends up off centre the tracking isn't
correctly done - the geometry will vary as the wheels turn.

Can you expand on that, please? I assume that is because the steering
geometry varies from neutral to off set when the steering wheel turns fron
neutral, but that the RAP will be in neutral if the steering wheel does
not match it, or have I got that horribly wrong?

On modern cars the steering geometry changes by design.
I can't see how the steering rack makes any difference though.
Its controlled by the top and bottom bearings of the hub and the direction
the wheel is facing, not how much rack is hanging out of each side.
What you do get is different turning circles on LH and RH corners but even
that doesn't effect normal driving.

Unless the
steering wheel has been moved on its splines.

No, steering wheel has been there since birth :-)

The different angle is barely noticable

Dave

In an earlier contribution to this discussion,
dennis@home wrote:


On modern cars the steering geometry changes by design.
I can't see how the steering rack makes any difference though.
Its controlled by the top and bottom bearings of the hub and the
direction the wheel is facing, not how much rack is hanging out of
each side.

That's not quite true! If the links from the ends of the rack to the
steering arms on the hubs are of unequal length, there is a strong
likelihood of bump steer. When correcty adusted, those links should shadow
the wishbones - allowing the wheel the move up and down without steering.
But if you make one too long and the other too short, that no longer
applies.
--
Cheers,
Roger
______
Email address maintained for newsgroup use only, and not regularly
monitored.. Messages sent to it may not be read for several weeks.
PLEASE REPLY TO NEWSGROUP!

In article ,
Dave Baker wrote:
With R&P steering if the wheel ends up off centre the tracking isn't
correctly done - the geometry will vary as the wheels turn.

Ummm no it won't. The straight-ahead position of the steering wheel has
no effect on Ackermann steering geometry which is created by the angles
of the steering pivots and tie rod.

I did also say the rack had to be central too. Which it will usually be
from the factory with the wheel in the straight ahead postion.

http://en.wikipedia.org/wiki/Ackerma...ering_geometry

That shows a simple system.

Imagine with tracking set correctly you move the steering wheel slightly
off centre and then recheck the tracking. The tie rod ends will now be
too long at one side and too short at the other. So you undo the
locking nuts and adjust everything until the wheels are straight again.
All you've actually changed is to lose a little steering lock on one
side and gain a little on the other.

That might be true if the ball joints on the end of the rack were exactly
in line with the suspension pivots. But move it to one side or the other
and the geometry changes with suspension movement, as you're moving that
pivot point.

The steering geometry hasn't altered. The total length of the tie rod
(rack) is still the same, the steering pivot angles are still the same,
the wheels are still pointing straight, the steering wheel and pinion
have just moved relative to the rack is all.

Sorry but you're wrong.

A rack and pinion system has a completely linear mode of operation. A
little logical thought ought to make it apparent that it can't be the
movement of the pinion relative to the rack or their initial starting
positions that creates a non-linear steering output on opposite sides
of the car which indeed is created solely by the movement of the rack
relative to the steering pivots.

You're forgetting that the rack isn't rigidly connected to the track rods.
If it were you'd be correct.

Think again of the action on the road wheel position as the suspension
moves up and down. The rack cannot move up and down with it so there is a
pivot at each end of the rack and of course the track rod end. If
everything else remains static the wheel will turn in slightly at either
end of the travel under the influence of the track rod. Using strut
suspension as an example where the wheel moves up and down in a straight
line. If you alter the length of that tie rod the effect will be more or
less apparent - depending on whether it is longer or shorter.

Unless the
steering wheel has been moved on its splines.

Again utterly irrelevant other than you lose steering lock on one side
and gain it on the other.

Just how much it matters in practice varies by suspension design.

--
*Many people quit looking for work when they find a job *

Dave Plowman London SW
To e-mail, change noise into sound.

In article ,
Roger Mills wrote:
That's not quite true! If the links from the ends of the rack to the
steering arms on the hubs are of unequal length, there is a strong
likelihood of bump steer. When correcty adusted, those links should
shadow the wishbones - allowing the wheel the move up and down without
steering. But if you make one too long and the other too short, that no
longer applies.

Yup. I'd also expect heavier tyre wear if things are miles out.

It is actually quite critical on my SD1. The rack on that has a centre
finder - an indent in the rack that a bolt fits into to lock it in the
central position. No need for that if it weren't important.

--
*Why can't women put on mascara with their mouth closed?

Dave Plowman London SW
To e-mail, change noise into sound.

"Dave Plowman (News)" wrote in message
...
In article ,
Dave Baker wrote:
With R&P steering if the wheel ends up off centre the tracking isn't
correctly done - the geometry will vary as the wheels turn.

Ummm no it won't. The straight-ahead position of the steering wheel has
no effect on Ackermann steering geometry which is created by the angles
of the steering pivots and tie rod.

I did also say the rack had to be central too. Which it will usually be
from the factory with the wheel in the straight ahead postion.

http://en.wikipedia.org/wiki/Ackerma...ering_geometry

That shows a simple system.

Imagine with tracking set correctly you move the steering wheel slightly
off centre and then recheck the tracking. The tie rod ends will now be
too long at one side and too short at the other. So you undo the
locking nuts and adjust everything until the wheels are straight again.
All you've actually changed is to lose a little steering lock on one
side and gain a little on the other.

That might be true if the ball joints on the end of the rack were exactly
in line with the suspension pivots. But move it to one side or the other
and the geometry changes with suspension movement, as you're moving that
pivot point.

The steering geometry hasn't altered. The total length of the tie rod
(rack) is still the same, the steering pivot angles are still the same,
the wheels are still pointing straight, the steering wheel and pinion
have just moved relative to the rack is all.

Sorry but you're wrong.

A rack and pinion system has a completely linear mode of operation. A
little logical thought ought to make it apparent that it can't be the
movement of the pinion relative to the rack or their initial starting
positions that creates a non-linear steering output on opposite sides
of the car which indeed is created solely by the movement of the rack
relative to the steering pivots.

You're forgetting that the rack isn't rigidly connected to the track rods.
If it were you'd be correct.

Think again of the action on the road wheel position as the suspension
moves up and down. The rack cannot move up and down with it so there is a
pivot at each end of the rack and of course the track rod end. If
everything else remains static the wheel will turn in slightly at either
end of the travel under the influence of the track rod. Using strut
suspension as an example where the wheel moves up and down in a straight
line. If you alter the length of that tie rod the effect will be more or
less apparent - depending on whether it is longer or shorter.

Unless the
steering wheel has been moved on its splines.

Again utterly irrelevant other than you lose steering lock on one side
and gain it on the other.

Just how much it matters in practice varies by suspension design.

The effect of a slightly off centre steering wheel on the relative lengths
of the tie rod ends at each side of the car is not large enough to make any
significant difference to bump steer or any other steering input. Cars
simply aren't made to that level of accuracy. I bet if you take a tape
measure to each side of your car and measure the wheelbase from front to
rear wheel centres you'll find it's nowhere near the same. 1/4" inch out is
not unusual and if the wheels aren't located to within a fraction of a mm
anyway then a similar sized error in the lengths of bits of steering rack
isn't going to affect them either. Similarly camber and caster can vary each
side, both of which affect track rod end settings.
--
Dave Baker

"Roger Mills" wrote in message
...
In an earlier contribution to this discussion,
dennis@home wrote:


On modern cars the steering geometry changes by design.
I can't see how the steering rack makes any difference though.
Its controlled by the top and bottom bearings of the hub and the
direction the wheel is facing, not how much rack is hanging out of
each side.

That's not quite true! If the links from the ends of the rack to the
steering arms on the hubs are of unequal length, there is a strong
likelihood of bump steer. When correcty adusted, those links should shadow
the wishbones - allowing the wheel the move up and down without steering.
But if you make one too long and the other too short, that no longer
applies.

If the suspension moves up on one side and not the other it changes the
track slightly.
It does this under normal conditions.
I doubt if it will be out of spec even if you do move the rack ends over by
an inch or so.
You get a similar movement when you load the car but on both sides.

"Dave Plowman (News)" wrote in message
...
In article ,
Roger Mills wrote:
That's not quite true! If the links from the ends of the rack to the
steering arms on the hubs are of unequal length, there is a strong
likelihood of bump steer. When correcty adusted, those links should
shadow the wishbones - allowing the wheel the move up and down without
steering. But if you make one too long and the other too short, that no
longer applies.

Yup. I'd also expect heavier tyre wear if things are miles out.

It is actually quite critical on my SD1. The rack on that has a centre
finder - an indent in the rack that a bolt fits into to lock it in the
central position. No need for that if it weren't important.

Its very important..
it makes it easier to assemble the car.
It doesn't mean its needed once the car is assembled.

Dave wrote:
Dave Plowman (News) wrote:
In article ,
Dave wrote:
Took one of my Rover 45's down to the garage that the ex Rover
foreman had set up after they went bust, He put a scale on the floor
and pushed the car over it and declared that it was OK.
I have not seen one of these scales in more than 40 years, but he was
right, the tracking was perfet, except for a slight steering wheel
mis- alignment that is not big enough to worry about yet.

With R&P steering if the wheel ends up off centre the tracking isn't
correctly done - the geometry will vary as the wheels turn.

Can you expand on that, please? I assume that is because the steering
geometry varies from neutral to off set when the steering wheel turns
fron neutral, but that the RAP will be in neutral if the steering wheel
does not match it, or have I got that horribly wrong?


You need equal length tie rods from the rack ends to the hub links.
Otherwise wheels will slightly turn more one way than the other when the
suspension rides a bump.

HOWEVER a good thump can actually move the WHOLE RACK sideways. That
makes a nonsense of the statement heIf you are doing the job
properly, the first thing to do is line up the rack again.

Roger Mills wrote:
In an earlier contribution to this discussion,
dennis@home wrote:

On modern cars the steering geometry changes by design.
I can't see how the steering rack makes any difference though.
Its controlled by the top and bottom bearings of the hub and the
direction the wheel is facing, not how much rack is hanging out of
each side.

That's not quite true! If the links from the ends of the rack to the
steering arms on the hubs are of unequal length, there is a strong
likelihood of bump steer. When correcty adusted, those links should shadow
the wishbones - allowing the wheel the move up and down without steering.
But if you make one too long and the other too short, that no longer
applies.
Yuyp. I bought a second hand XJS that had been in a smash..and fixed.
Well I drove it for two years through to its SECOND MOT after I bought
it before they discovered that the actual kingpin was bent, and this had
been taken out with extremely offset track rods and a few other
adjustments. A fast corner on an undulating surface had it squirreling
like mad! You get the same with a lot of McPherson strut type suspension
layouts as standard.

When I used to drive Spridgets madly, and Spitfires, I could always tell
when there was any unevenness or play - well below MOT failure levels -
anywhere in the front suspension. You can feel it in a double wishbone
system. McPerson's you cant, because they are basically crap
anyway..there is more wheel lateral movement from bump steer and it
totally swamps the variable tie rod issues.

In an earlier contribution to this discussion,
dennis@home wrote:


If the suspension moves up on one side and not the other it changes
the track slightly.
It does this under normal conditions.

Indeed. With an unequal length wishbone suspension it also - by design -
changes the camber angle - to try to keep the outer wheel more upright when
the car rolls when cornering. But what it *shouldn't* do - but will do if
the tie rods are the wrong length - is *steer* as the suspension moves up
and down.
--
Cheers,
Roger
______
Email address maintained for newsgroup use only, and not regularly
monitored.. Messages sent to it may not be read for several weeks.
PLEASE REPLY TO NEWSGROUP!

"Dave Plowman (News)" wrote in message
...
In article ,
Dave Baker wrote:
With R&P steering if the wheel ends up off centre the tracking isn't
correctly done - the geometry will vary as the wheels turn.

Ummm no it won't. The straight-ahead position of the steering wheel has
no effect on Ackermann steering geometry which is created by the angles
of the steering pivots and tie rod.

I did also say the rack had to be central too. Which it will usually be
from the factory with the wheel in the straight ahead postion.

You can try a little exercise if you have a convenient car to play with.
It's been a long time since I last messed about with tracking but from
memory let's say the dangly bits either side of the rack that move up and
down with the suspension are about 1 foot in length. What we're talking
about here is differences in the length either side created by a steering
wheel slightly off-centre amounting to the odd mm or two in maybe 300 plus
mm. It simply isn't material in how those dangly bits follow the hub as the
tyre moves up and down or indeed how the rack moves each wheel in a turn to
create Ackermann steering. I bet if you measure any undamaged car that's got
its tracking set as spot on as you can get it you'll still find the distance
from the track rod end ball joint to the rack end pivot point is nothing
like the same on both sides. Production tolerances in chassis dimensions,
rack dimensions, mounting points, camber on each side, caster on each side,
wheelbase on each side etc etc add up to affect that dimension and track rod
ends are made with enough thread length in them to take up those
differences.

Like I said with my Fiesta, even the most extreme steering wheel positional
error you could imagine, which in fact had used up nearly all the track rod
end adjustment on each side, so about 3/4 of an inch or so, still made no
apparent or effective difference to how the car drove or how the tyres wore.
One sixth of a turn, which was the error in the steering wheel position, is
60 degrees or effectively a steering wheel that instead of pointing to 12
o'clock would actually have pointed to 2 o'clock if it hadn't been moved on
its mounting. That's way bigger than any error you'd get from tracking
places that don't hold the steering wheel perfectly level when they set
things up. At worst they might be an inch or two out at the rim.

Talking on a theoretical level and what actually matters in practice are not
even closely related. The average mass production suspension system doesn't
have geometry that generates either perfect Ackermann steering or absence of
bump steer or scrub anyway. None of that really matters as long as the
wheels are correctly tracked in the straight ahead position regardless of
where the steering wheel sits. Tyre wear, or at least the vast majority of
it, is caused by errors in that straight ahead alignment not errors in
Ackermann geometry, bump steer, scrub or any other fault of production
tolerances or design. The next biggest culprit is errors in camber and if
you go to one of those fancy tracking places you'll get a print out of what
the camber is on each side. Not even remotely the same on both wheels I can
guarantee you. Cars just aren't built that accurately and they have too much
play in rubber suspension bushes to make close tolerances achievable anyway.

On race cars you might strive for higher standards after you've eliminated
the play in bushes and linkages but on road cars you're just ****ing in the
wind to worry about steering wheel position as long as the actual tracking
is correctly set.
--
Dave Baker

The Natural Philosopher wrote:

Yuyp. I bought a second hand XJS that had been in a smash..and fixed.
Well I drove it for two years through to its SECOND MOT after I bought
it before they discovered that the actual kingpin was bent, and this had
been taken out with extremely offset track rods and a few other
adjustments. A fast corner on an undulating surface had it squirreling
like mad! You get the same with a lot of McPherson strut type suspension
layouts as standard.

A tale that is remarkably interesting.

Not least because an XJS does not have either kingpins or MacPherson
strut suspension.

Steve Firth wrote:
The Natural Philosopher wrote:

Yuyp. I bought a second hand XJS that had been in a smash..and fixed.
Well I drove it for two years through to its SECOND MOT after I bought
it before they discovered that the actual kingpin was bent, and this had
been taken out with extremely offset track rods and a few other
adjustments. A fast corner on an undulating surface had it squirreling
like mad! You get the same with a lot of McPherson strut type suspension
layouts as standard.

A tale that is remarkably interesting.

Not least because an XJS does not have either kingpins or MacPherson
strut suspension.
I never said it did have McPherson. I said, you get the SAME with McPherson.

It sure has kingpins tho. Or at least that's what I call them. The bit
between upper and lower wishbones that swivels and carries a stub axle.
And to which the steering links attach..

Roger Mills wrote:
In an earlier contribution to this discussion,
dennis@home wrote:

If the suspension moves up on one side and not the other it changes
the track slightly.
It does this under normal conditions.

Indeed. With an unequal length wishbone suspension it also - by design -
changes the camber angle - to try to keep the outer wheel more upright when
the car rolls when cornering. But what it *shouldn't* do - but will do if
the tie rods are the wrong length - is *steer* as the suspension moves up
and down.

Oh, it does, and will, by design.

That's why normally you have a drooping front leading steering link..it
reduces the wheel angle as you lean into a tight corner, tending to
understeer on the way in as the thing loads up, and on any bumps..

It can help fine time a cars handling. Not that most cars today would
bother. Most small hatchbacks are perry appalling.

Dave Baker wrote:
"Dave Plowman (News)" wrote in message
...
In article ,
Dave Baker wrote:
With R&P steering if the wheel ends up off centre the tracking isn't
correctly done - the geometry will vary as the wheels turn.
Ummm no it won't. The straight-ahead position of the steering wheel has
no effect on Ackermann steering geometry which is created by the angles
of the steering pivots and tie rod.
I did also say the rack had to be central too. Which it will usually be
from the factory with the wheel in the straight ahead postion.

You can try a little exercise if you have a convenient car to play with.
It's been a long time since I last messed about with tracking but from
memory let's say the dangly bits either side of the rack that move up and
down with the suspension are about 1 foot in length. What we're talking
about here is differences in the length either side created by a steering
wheel slightly off-centre amounting to the odd mm or two in maybe 300 plus
mm. It simply isn't material in how those dangly bits follow the hub as the
tyre moves up and down or indeed how the rack moves each wheel in a turn to
create Ackermann steering. I bet if you measure any undamaged car that's got
its tracking set as spot on as you can get it you'll still find the distance
from the track rod end ball joint to the rack end pivot point is nothing
like the same on both sides. Production tolerances in chassis dimensions,
rack dimensions, mounting points, camber on each side, caster on each side,
wheelbase on each side etc etc add up to affect that dimension and track rod
ends are made with enough thread length in them to take up those
differences.


Not on a proper set up sports car..
Like I said with my Fiesta,

Well stop right there. That is not a car. Its a McPherson strutted
shopping trolley, built down to a price, and detailed to attract the
unsophistcated Gucci handbag market.
..

In article ,
dennis@home wrote:
It is actually quite critical on my SD1. The rack on that has a centre
finder - an indent in the rack that a bolt fits into to lock it in the
central position. No need for that if it weren't important.

Its very important..
it makes it easier to assemble the car.
It doesn't mean its needed once the car is assembled.

You've obviously not seen the way they were 'assembled' ;-)

--
*Everyone has a photographic memory. Some don't have film *

Dave Plowman London SW
To e-mail, change noise into sound.

In article ,
The Natural Philosopher wrote:
You need equal length tie rods from the rack ends to the hub links.
Otherwise wheels will slightly turn more one way than the other when the
suspension rides a bump.

HOWEVER a good thump can actually move the WHOLE RACK sideways. That
makes a nonsense of the statement heIf you are doing the job
properly, the first thing to do is line up the rack again.

Dunno what car you mean, but the one on mine has thick aluminium brackets
on the rack mounted to thick steel ones on the subframe. You'd need a lot
more than a good thump to shift it.

--
*Ambition is a poor excuse for not having enough sense to be lazy *

Dave Plowman London SW
To e-mail, change noise into sound.

The Natural Philosopher wrote:

It sure has kingpins tho. Or at least that's what I call them. The bit
between upper and lower wishbones that swivels and carries a stub axle.
And to which the steering links attach..

Referred to as the upright on the Jaguar, IIRC.

Dave Plowman (News) wrote:
In article ,
The Natural Philosopher wrote:
You need equal length tie rods from the rack ends to the hub links.
Otherwise wheels will slightly turn more one way than the other when the
suspension rides a bump.

HOWEVER a good thump can actually move the WHOLE RACK sideways. That
makes a nonsense of the statement heIf you are doing the job
properly, the first thing to do is line up the rack again.

Dunno what car you mean, but the one on mine has thick aluminium brackets
on the rack mounted to thick steel ones on the subframe. You'd need a lot
more than a good thump to shift it.

1/. 1.5 tons of hatchback hitting a kerb at 30mpoh is more than a 'good
thump'. I've seen alloy and steel wheels buckled just hitting a 6"
pothole..I've seen a tyre blow on simply doing 5mph into a kerb head on!

2/. Most racks are rubber mounted for shock and vibration reasons.

3/. Bending a chassis or subframe is common in minor accidents.

The fact of a steering wheel being offset in a second hand car is almost
a guarantee its been whacked hard or badly repaired at some time.

The Natural Philosopher wrote:

I've seen alloy and steel wheels buckled just hitting a 6" pothole..I've
seen a tyre blow on simply doing 5mph into a kerb head on!

I've seen things you people wouldn't believe. Attack ships on fire off
the shoulder of Orion. I watched C-beams glitter in the dark near the
Tannhauser gate. All those moments will be lost in time, like tears in
rain. Time to die.

"Roger Mills" wrote in message
...
In an earlier contribution to this discussion,
dennis@home wrote:


If the suspension moves up on one side and not the other it changes
the track slightly.
It does this under normal conditions.

Indeed. With an unequal length wishbone suspension it also - by design -
changes the camber angle - to try to keep the outer wheel more upright
when the car rolls when cornering. But what it *shouldn't* do - but will
do if the tie rods are the wrong length - is *steer* as the suspension
moves up and down.

It will always try to steer whatever length the tie rods are.
The tie rod just pivots about a point so it moves the wheel in the steering
plane every time the suspension compresses.
You would have to invent some sort of parallelogram link to stop it steering
as the suspension compresses.

"Dave Plowman (News)" wrote in message
...
In article ,
dennis@home wrote:
It is actually quite critical on my SD1. The rack on that has a centre
finder - an indent in the rack that a bolt fits into to lock it in the
central position. No need for that if it weren't important.

Its very important..
it makes it easier to assemble the car.
It doesn't mean its needed once the car is assembled.

You've obviously not seen the way they were 'assembled' ;-)

I have seen some.
I saw a dented Jenson interceptor on the assembly rigs once.
They used plastic filler to get rid of the dent.

On Tue, 19 May 2009 17:25:39 +0100, Steve Firth wrote:

The Natural Philosopher wrote:

I've seen alloy and steel wheels buckled just hitting a 6" pothole..I've
seen a tyre blow on simply doing 5mph into a kerb head on!

I've seen things you people wouldn't believe. Attack ships on fire off
the shoulder of Orion.

To my shame, I had an Orion once. Bloody horrible car. I've tried so hard
to blot out all memory of it that I honestly can't remember what I did
with it :-)

Jules wrote:

I had an Orion once. Bloody horrible car.

It was part of Ford's attempt to establish an Irish range of cars. The
Ford O'Ryan, Irish 2000 etc.

On Tue, 19 May 2009 10:36:29 +0100, "Dave Baker"
wrote:

The effect of a slightly off centre steering wheel on the relative lengths
of the tie rod ends at each side of the car is not large enough to make any
significant difference to bump steer or any other steering input. Cars
simply aren't made to that level of accuracy.

It makes a hell of a difference on a Lotus Elise/Exige/Europa, a
linear bump steer response is critical, adjusted by rack height, track
rod end height, and track rod length.

I bet if you take a tape
measure to each side of your car and measure the wheelbase from front to
rear wheel centres you'll find it's nowhere near the same. 1/4" inch out is
not unusual and if the wheels aren't located to within a fraction of a mm

On the above vehicles there is a maximum of 2mm *total* tolerance on
chassis hard point location.

anyway then a similar sized error in the lengths of bits of steering rack
isn't going to affect them either. Similarly camber and caster can vary each
side, both of which affect track rod end settings.

Only if your suspension is mass produced and un-adjustable.


--

We were somewhere around Barstow, on the edge of the desert, when the
drugs began to take hold. I remember Alan
saying something like:

When did car tyres last have inner tubes?

Last year, last week, this week, next week. Whenever I need one.
I don't like putting a tube in, but if circumstances dictate, I will.

We were somewhere around Barstow, on the edge of the desert, when the
drugs began to take hold. I remember The Natural Philosopher
saying something like:

I've seen alloy and steel wheels buckled just hitting a 6"
pothole..I've seen a tyre blow on simply doing 5mph into a kerb head on!

I've seen the yellow lights go down the Mississippi.

On Tue, 19 May 2009 16:52:41 +0100, Dave Plowman (News) wrote:

In article ,
dennis@home wrote:
It is actually quite critical on my SD1. The rack on that has a
centre finder - an indent in the rack that a bolt fits into to lock
it in the central position. No need for that if it weren't important.

Its very important..
it makes it easier to assemble the car. It doesn't mean its needed once
the car is assembled.

You've obviously not seen the way they were 'assembled' ;-)

I knew a bloke who worked at rover in the late seventies. His job was to
get them as they came off the production line and make the doors 'seal
better' by putting a knee in the middle and yanking the window frame into
place with a practised eye.

On Sat, 23 May 2009 18:55:16 +0000, PCPaul wrote:

On Tue, 19 May 2009 16:52:41 +0100, Dave Plowman (News) wrote:

In article ,
dennis@home wrote:
It is actually quite critical on my SD1. The rack on that has a
centre finder - an indent in the rack that a bolt fits into to lock
it in the central position. No need for that if it weren't important.

Its very important..
it makes it easier to assemble the car. It doesn't mean its needed once
the car is assembled.

You've obviously not seen the way they were 'assembled' ;-)

I knew a bloke who worked at rover in the late seventies. His job was to
get them as they came off the production line and make the doors 'seal
better' by putting a knee in the middle and yanking the window frame into
place with a practised eye.

Heh - I remember doing much the same thing in recent years, both on Rover
P6 and Triumph Stag window frames; funny to know it was also a
factory-approved technique! ;-)

Seems to be a feature of British cars of that era I think - I suppose
later on cars started getting doors where the frame was an integral part
of the door skin, so no such 'careful adjustment' was necessary.

cheers

Jules