[xj] Changing the Castor(er) angle

My camber gauge arrived today!
( http://www.motorsport-tools.com/pdf/instructions/GA45.pdf )

I had great fun devising a way to get the front hubs at normal
height with the wheels off but eventually employed a system with
two trolley jacks, one under each spring pan, that got the air hole
in the hub grease covers at the same height as with the wheels on.

Then came drawing out a 40� angle on cardboard and working out
(with a plumb line) where to turn the wheel to.

Flushed with this minor success, I was a bit disappointed to find
the castor(er) angle was less than 2� on both sides. One wheel had
four shims in total, the other had five. I added my sole spare to
the four and transposed one from back to front. This bought the
angle up to a little over two, but nowhere near the required 3.5�.

In fact it appears it needs another 4 or 5 shims a side to get
things to spec (assuming that inserting a shim has a similar effect
to transposing one - unlikely, I know.)

This would make 9 or 10 shims. This seems a bit excessive, when
the parts catalogue calls for just 6. Anyone got a figure for the
maximum number that it is sensible to put in? And, before you ask,
no, I can’t see any obvious wear or damage. Ball joints, upper
shaft bushes and so forth are recent and good.–
al mclean - '05 X type 2.0D Est - '93 XJS 4.0 - '84 DD6
Telford, United Kingdom
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In reply to a message from almcl sent Mon 26 Sep 2011:

Al,

Thanks for sharing. I’m wondering something. When you
supported the car under the spring pans, I understand that
you adjusted the heights so that the hubs were located as if
the car was resting on its tyres. I suppose that means that
the spring pans were also in their natural position.

But what about the car itself? The instructions state that
the car should be supported so that the sills are at normal
height. Then, raise the spring pans so that they are also
at normal height. You did only the latter. I’m thinking of
the lever arm that’s in effect when the car is supported on
the wheels rather than on the spring pans. The lever that
means 1/8 inch of spring extension equals 5/16 inch of car
elevation.

It would sure be nice if supporting on the spring pans were
sufficient, but I’m not sure if you would have the proper
geometry. Any thoughts?–
The original message included these comments:

I had great fun devising a way to get the front hubs at normal
height with the wheels off but eventually employed a system with
two trolley jacks, one under each spring pan, that got the air hole
in the hub grease covers at the same height as with the wheels on.


Bob Wilkinson, 73 XJ6
Saint Louis, MO, United States
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In reply to a message from Robert Wilkinson sent Mon 26 Sep 2011:

It’s a good point, Bob and I’m not sure of the answer.

My garage is a little restricted and I should probably repeat the
measurements on the ‘flat floor’ at work. When I do, I’ll measure
the sill height, which, I must confess, I didn’t do this time.

Some suggest jacking under the ball joint, which I could do using
bottle jacks rather than trolleys, although mine may be too tall.–
The original message included these comments:

the spring pans were also in their natural position.
But what about the car itself? The instructions state that
the car should be supported so that the sills are at normal
height. Then, raise the spring pans so that they are also
at normal height. You did only the latter. I’m thinking of
the lever arm that’s in effect when the car is supported on
geometry. Any thoughts?


al mclean - '05 X type 2.0D Est - '93 XJS 4.0 - '84 DD6
Telford, United Kingdom
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In reply to a message from almcl sent Mon 26 Sep 2011:

Thanks, Al. I honestly can’t quite figure it out.
Supporting on the ball joints would get closer if there’s a
problem at all, but maybe still not quite right.

Here’s the ‘‘gedanken’’ experiment I have in my head. If you
extended the spindles so that the road wheels were, say, 10
feet outboard of the car, would the weight of the car bottom
out the suspension? If so, then the point of support
(spring pan, ball joint or spindle) matters.

OTOH, say you decided that camber should be set taking the
above into account–resting the car on its sills or just
letting it sit on the tyres. Caster is the problem, because
turning the wheels precisely is hard when the car’s on the
ground. But say the car was raised on the spring pans, and
that this caused the body to be higher than it should be.
It would be the same on both sides, and both sides might
change camber due to camber gain built in to the suspension.
But I’ll bet that the caster measurement would still
work–since it’s relative to whatever camber you start with.

Also, you can get both sides the same even if they’re not
precisely what you set them too once you put it down. In
fact, if someone simply told us what to aim for with the car
on the spring pans, that would solve the problem. A kind
and generous lister with an aligned car could measure caster
and camber when supported on spring pans–that would be what
we want.

I’ll have to find out where I can get your device in the
colonies. My caster is really messed up according to a
professional measurement.–
The original message included these comments:

Some suggest jacking under the ball joint, which I could do using
bottle jacks rather than trolleys, although mine may be too tall.


Bob Wilkinson, 73 XJ6
Saint Louis, MO, United States
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In reply to a message from Robert Wilkinson sent Mon 26 Sep 2011:

Good thoughts, thanks, Bob.

I’ll try that experiment with measuring the sills; I wonder if the
front subframe would do as well? Get that down to where the large
trolley jack scarcely slides in and we are pretty much ‘as normal.’

Like you, I got a print out from the first alignment shop I have
had confidence in for a while, that suggested camber was way off
and hinted that other things were out of whack as well.

I don’t mind paying them to measure, but as they had no idea how to
alter things (no old Jaguar experience) I’d rather do the adjusting
myself. When I think I’ve got them right, I’ll go back and see how
close we got.

Here are some other ideas for gauges:
http://www.motorsport-tools.com/camber-castor-c-17780.html

I am sure you’ll be able to get them for half the price on your
side of the pond!–
The original message included these comments:

Here’s the ‘‘gedanken’’ experiment I have in my head. If you
extended the spindles so that the road wheels were, say, 10
feet outboard of the car, would the weight of the car bottom
out the suspension? If so, then the point of support
(spring pan, ball joint or spindle) matters.
I’ll have to find out where I can get your device in the
colonies. My caster is really messed up according to a


al mclean - '05 X type 2.0D Est - '93 XJS 4.0 - '84 DD6
Telford, United Kingdom
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In reply to a message from almcl sent Mon 26 Sep 2011:

Al:

I was in the midst of a post with more detail. then, this machine
froze. Oh boy, it is next to the other freeze happy HP.

There are or were tat the wheels can rst on that have turntables so
that the wheeels may be turned rght and left to read the caster
throughout the turn radius at near ride height.

I remember thse from my very early days, seeing my former employer
getting into Wheel alignment complete with a big rack and bending
tools.

Carl–
Carl Hutchins 1983 Jaguar XJ6 with LT1 and 1994 Jeep Grand
Walnut Creek, California, United States
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almcl wrote:

My camber gauge arrived today!
( http://www.motorsport-tools.com/pdf/instructions/GA45.pdf )

I had great fun devising a way to get the front hubs at normal
height with the wheels off but eventually employed a system with
two trolley jacks, one under each spring pan, that got the air hole
in the hub grease covers at the same height as with the wheels on.

Then came drawing out a 40� angle on cardboard and working out
(with a plumb line) where to turn the wheel to.

Flushed with this minor success, I was a bit disappointed to find
the castor(er) angle was less than 2� on both sides. One wheel had
four shims in total, the other had five. I added my sole spare to
the four and transposed one from back to front. This bought the
angle up to a little over two, but nowhere near the required 3.5�.

In fact it appears it needs another 4 or 5 shims a side to get
things to spec (assuming that inserting a shim has a similar effect
to transposing one - unlikely, I know.)

The shims adjustment is principally made by moving the shims from front
to rear, Al, not just adding shims - nominally there is only space for a
specific number of shimd in total, likely the 6 spec’ed - to maintain
the correct angles between the upper whishbone arms and the pivot
shaft…so…?

In extreme cases you may have all shims on one side, but this relates to
another list topic; the different whishbone arms used by Jaguar. This
change was done to allow for increasing castor angles anyway - and
setting increased castor on the ‘other’ type of wishbone may call for
extreme shim moving. Naturally; ex factory they wanted equal shimming
front and back to afford maximum adjustment leeway…:slight_smile:

What an ingenious and simple device, I knew of its existence of course,
but prices have come down - couldn’t afford it when I needed it…:slight_smile:

Some other remarks; in setting up the tool the wheels should be ensured
fore and aft - any turn of the wheels affects the plumb setting, against
which the castor angle is actually measured, of course.

Now; the plumb line and angles measured with the tool hereafter refers
to ‘horizontal’ ground - and the point of the ride height setting tools
is to bring the car also 'horizontal; ie parallel to the ground. This is
because the castor angle is measured with reference to the car itself,
not to ground - and jacking up the front of the car increases the
‘backward’ angle of the ‘kingbolt’ to the horizontal ground, distorting
the castor angle readings…

An alternative to counter this; with the car on the ground; set the tool
and adjust to ‘horizontal’ - then jack the car up (no wheel rotation)
and record the angle difference. This can then be subtracted from the
castor measurement angles. But both this and during the actual measuring
porces; it’s absolutely essential that the wheels/hubs are not rotated.
Removing the wheels as you did and using jacks for the ‘horizontal’
setting is likely equally good - and in some respects better; setting
hub height with and without road wheel can be done wth some precision…:slight_smile:

All this presumes of course that the car’s ride height is otherwise
correct, and you want ultimate precision. But in all this, except for
wheel rotation which directly affects horizontal settings and angle
readings; the deviations are likely fairly small. And as long as one is
reasonable consistent side to side, the errors likely insignificant in
practice…

Frank
xj6 85 Sov Europe (UK/NZ)>This would make 9 or 10 shims. This seems a bit excessive, when

the parts catalogue calls for just 6. Anyone got a figure for the
maximum number that it is sensible to put in? And, before you ask,
no, I can’t see any obvious wear or damage. Ball joints, upper
shaft bushes and so forth are recent and good.

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A bit shocking, as changing the settings on the older Jags is about as easy
and straightforward as it gets!

Cheers
Doug Dwyer
Longview Washington USA
1995 XJRFrom: “almcl” al.mclean@blueyonder.co.uk

I don’t mind paying them to measure, but as they had no idea how to
alter things (no old Jaguar experience) I’d rather do the adjusting
myself.

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Doug Dwyer wrote:

A bit shocking, as changing the settings on the older Jags is about as
easy and straightforward as it gets!

Indeed, and he even has the proper tool and technique for the castor
adjustment, Doug…:slight_smile:

Referring to the list discussion on the changes to castor and variants
of the whishbone arms. As I see it, the arms are immovable for and aft
as they are fixed to the pivot shaft for only up and down movement.
There will then be a distance between the upper arms at the balljoint,
greater than the upper ball-joint base. This gap is then ‘filled’
completely by shims, to avoid sideways tension of the arms - and the
shims are just moved around fore and aft to adjust castor angle…?

As the castor angle specs were changed/increased there were not
sufficient space to increase the castor to new spec angle, and the arms,
or pivot, were then altered, upper and/or lower, to allow increased
castor. And, as he wants to increase the castor from 2,5 to 3.5 or more;
with the ‘wrong’ combination of arms this may not be possible with his
present set-up…?

Franl
xj6 85 Sov Europe (UK/NZ)> From: “almcl” al.mclean@blueyonder.co.uk

I don’t mind paying them to measure, but as they had no idea how to
alter things (no old Jaguar experience) I’d rather do the adjusting
myself.

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In reply to a message from Frank Andersen sent Wed 28 Sep 2011:

Bob, Frank, Carl, Doug

Many thanks for your thoughts, much appreciated.

I am not sure that the DD6’s suspension is in its original state.
I have seen otherwise competent body repair specialists remove and
discard castor shims, apparently because they couldn’t see a need
for three either side of the ball joint. This could easily have
happened here.

On the other hand my XJS, which I acquired with 25,000 miles and
for which I have all the previous owner’s bills, had, apparently
from the factory, 7 shims, all in front of the top ball joint. So
there’s clearly some margin for error in the original construction.

My exec summary is that the DD6’s suspension appears to be out of
spec (it is a V12 which were always 3.5�) and I want to put it
right. Adding shims seems to be the only option, or have I missed
something?–
al mclean - '05 X type 2.0D Est - '93 XJS 4.0 - '84 DD6
Telford, United Kingdom
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almcl wrote:

In reply to a message from Frank Andersen sent Wed 28 Sep 2011:

Bob, Frank, Carl, Doug

Many thanks for your thoughts, much appreciated.

I am not sure that the DD6’s suspension is in its original state.
I have seen otherwise competent body repair specialists remove and
discard castor shims, apparently because they couldn’t see a need
for three either side of the ball joint. This could easily have
happened here.

On the other hand my XJS, which I acquired with 25,000 miles and
for which I have all the previous owner’s bills, had, apparently
from the factory, 7 shims, all in front of the top ball joint. So
there’s clearly some margin for error in the original construction.

My exec summary is that the DD6’s suspension appears to be out of
spec (it is a V12 which were always 3.5�) and I want to put it
right. Adding shims seems to be the only option, or have I missed
something?

Not really, Al…

…but the maximum angle obtainable is of course with all the shims in
one position, front or rear. However, the ‘gap’ itself between the two
arms must represent the maximum amount of shims and adjustment. Adding
shims beyond that will just ‘spread’ the arms apart, ‘bending’ the arms
so to speak - and there is no way of telling which way the camber angle
will then move…

The number of shims it not necessarily conclusive; one may visualize a
PO or indeed the factory to use shims of different thickness, to afford
more setting precision - though hardly necessary? That your xjs came
with 7 shims in extreme positions may have a variety of explanations.
One being that the suspension parts were carried over from other models
which required less castor - and/or more than 3,5 deg was regarded as
improbable. Another one is of course for some reason this car needed
more adjustment to get the correct angle - for whatever reason. And a
third; we assume that the castor is in fact verified to spec…:slight_smile:

‘Otherwise competent’ body shops also handles cars with damage - which
may require ‘unorthodox’ methods. My view is that if there is ‘free’
room for only 5 shims one would rather discard one or two, or several,
rather than force them in - and indeed add shims if there is room
enough. The shims being adjustment devices; without them, apart from
forcing the arms; without them the castor, in this case, would be the
‘natural’ angle caused by the parts themselves…

As an aside; ideally one would expect the same amount of shims and their
placings to be equal on both sides with the same castor, or any
relevant, angle set - confirming ‘symmetry’; no difference due to
‘sided’ damage, wear or building tolerances. Whether difference should
be considered as ‘acceptable’ or not is anybody’s choice - but I
certainly wouldn’t consider minor differences as ‘significant’…:slight_smile:

So, within this; can you get, or have you got, the castor to the desired
angle…?

Frank
xj6 85 Sov Europe (UK/NZ)===================================================
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In reply to a message from almcl sent Mon 26 Sep 2011:

Al,

Have you had more experience with your castor/camber gauge?
I now have the Yank equivalent (Longacre Racing) and am
wondering about supporting the car to allow measurement with
the wheels off, as discussed a while ago.–
The original message included these comments:

My camber gauge arrived today!
I had great fun devising a way to get the front hubs at normal
height with the wheels off but eventually employed a system with
two trolley jacks, one under each spring pan, that got the air hole
in the hub grease covers at the same height as with the wheels on.


Bob Wilkinson, 73 XJ6
Saint Louis, MO, United States
–Posted using Jag-lovers JagFORUM [forums.jag-lovers.org]–
–Support Jag-lovers - Donate at http://www.jag-lovers.org/donate04.php

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In reply to a message from Robert Wilkinson sent Thu 13 Oct 2011:

Robert

Sorry to say, no, not yet. There’s a high spec level floor at work
that I plan to use for some detailed measurements, but at the
moment it is fully occupied and I haven’t had a chance.

Also needed is a straight edge to engage the Pepperpot (Ogle)
wheels. Their hubs stick out beyond the rims and fabricating
something suitably accurately may prove challenging.–
The original message included these comments:

Have you had more experience with your castor/camber gauge?
I now have the Yank equivalent (Longacre Racing) and am


al mclean - '05 X type 2.0D Est - '93 XJS 4.0 - '84 DD6
Telford, United Kingdom
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