Does anyone have a feeling for how much change is
caused by rotating the various adjustment bolts
one flat?

For the front end:

- tie rod ends (toe)
- front bolt (caster)
- rear bolt (camber)

 

I'd imagine it'd be different, on tire wear for starters, why would you ask or need this setting, are you entering rally cross?! I'd recommend sticking to factory settings a good bodyshop has the tools for laser alignment.

 

Just to be clear, what I mean by flat, is the flat of the bolt head controlling
the movement of the relevant pieces. That is, per 60 degrees of rotation of
the bolt.

So, its not a "setting" but rather action and reaction.

I know the factory spec. I also know what changes I want to make,
and their likely effect.

Alignments have a greater dependency on the operator than the
equipment, given at least adequate equipment. A laser alignment
machine simply affords ease and speed.

So, I choose to do my own as I am free to take as much time as
required and know the exact final result. With my equipment and
methods, it is possible to achieve accuracy of +/- 0.05 degrees.
That is well below the range of anything that could be considered
meaningful error and what tire flex would cancel out in any case.

The only purpose in asking "how much effect does rotating the adjuster
by one flat" is to have an expectation of how much to bump the adjuster
as it is always best to not grossly overrun the required movement.

Factory settings are a compromise targetted at the largest segment of
new vehicle purchasers. An individual owner may benefit from tweaking
those settings to his personal preference. For example, see my post
from a couple of years ago on rear toe and how to gain stability in
inclement weather. It is not the factory setting, but it does achieve
the end goal. Of course, in order to tweak, one has to research and
understand the effects of each possible adjustment.

 

The manual has this to say:

Reading between the lines, the marks on the later version
would be from +/- 3mm.

The part I forgot was that aside from the toe adjustment, the
adjustment is on an eccentric.

Therefore, the min-max is across 180 degrees of rotation, or
three flats.

If we then say that the range of adjustment is perhaps 3 degrees,
then it would be 1 degree per flat. If 6 degrees, then it would be
2 degrees per flat.

That's good enough to work with.

It means a little goes a long way and a little finesse on the wrench
is required.

Shim stacks would have been nice. They don't go out of adjustment
without taking a major hit that bends something else.

 

If bolt head through the adjustment eccentrics on the front control arm are
already cranked all the way towards the center of the car, is that max caster?

.. and

If bolt head through the adjustment eccentrics on the rear control arm are
already cranked all the way towards the center of the car, is that max positive
camber?

If so, I'm hosed.

 

Plums, how are all the suspension bushes looking?

 

They look decent. But I should have a closer look.

There wasn't any play the last time I was in there
inspecting the pads about two months ago.

 

are you talking rear control arms in REAR of car or the rear front arms?

 

All front LCA, so caster adjustment eccentric at front of front LCA and camber
adjustment eccentric at rear of front LCA. Confusing as all get out, but
that's the way Jaguar wants to name them

Both sets on both sides have the bolt heads rotated all the way towards
the center of the vehicle.

That says to me that I can't get any more positive caster, and I can't
get any more positive(less negative) camber out of them because
they are maxed out.

Am I right?

ps. The current numbers are:

... sorry no spreader bar

The car pulls right in the slow lane, and the right front tire has
some serious inside tread wear in the first two inches.

 

with negative 2deg I bet it has tire wear inside. I always say I never notice wear until about 2*. Both eccentrics in the front lower arms set both caster and camber. the max negative camber you can achieve is with both front and rear pointing straight out which has the bolts and bushings and therfore the lower ball joint closer to the oil pan effectively reducing camber to more positive setting. How ever I have never seen that much neg camber without damage or wornout components. bushings, bent arms, subframe, coppapsed upper frame mounts etc. anything that can drop ride height or allow ball joint to move out

 

Still at work?

Yep, all four bolt heads are already "closest to the oil pan" as you say, and the
center hash mark sticking straight out to the outside.

As far as I can tell, the car sits a bit lower than the Euro spec XJR, say 10mm lower.

But, I just noticed:

Did you really mean negative?

Thanks for looking!

 

more positive can still mean LESS negative
-.2 is MORE positive than -.7, aka less negative, aka closer to "0", aka are you confused yet

 

yes ... completely

If you wouldn't mind, let me resort to asking about one specific measurement
for learning purposes.

RF camber = -1.5 degrees
both bolts are closest to the oil pan
both hash marks are pointed towards the tire

In that case, can I get the RF camber closer to 0 degrees?

Reading your two most recents posts carefully, my guess is no.

 

look at your upper a arm bushings. on your car these are the first most likely cause of too much negative camber. If a XK I would say upper strut mounts collapsed, but your shocks are just along for the ride and no affect on alignment unlike the XK suspension. If you see any rust color around them theyre definitly bad. At this point in the cars life I would almost just recommend a suspension rebuild. I dont know the extend of previous work or repairs. Either that or lower the car more, put on some sticky wide tires and wheels and just autocross the car. after all with that much camber it will stick well in hard cornering

 

At first I missed the answer until I peered at the sign.
Eyes aren't getting any better

What you said about the upper control arm bushings
is very helpful since it is so specific. At least it's the
easiest of all possible bushing replacements on the
vehicle.

I wouldn't do the lowers in poly, but I've heard the
uppers do well with poly.

I wont' be seeing any rust since the car has been
oil sprayed. The right lower ball joint was done
twice about 5 years ago. The second time being
a comeback. No idea of why the previous owner
had it done.

Thanks for taking the time to answer all the "but
what about" followups!

 

the OEM bushings are impregnated(can I say that online here lol) with grease on the inner sleeve that rides on the shaft. When these get old and dry like your hip and knees they start grinding and rusting as water finds its way in. Then youll start seeign rust around the bushings. Wether theres play or not at that point theyre bad. I did poly on my Suburban with a nitrous 700hp 383 SBC on the shocks, suspension and body mounts. All have cracked and deteriorated and needs to be redone lasting less time than the OEM rubber stuff. At this point Im on the fence for replacement and may look at deraline(sp) bushings

 

guess you got away with it

did ya'all have to bring that up? again?

used to be able to move a BBC short block on my own.
not easy, but it could be done.
not anymore.

Japthug has pointed out that some poly actually soaks up water.
There is a thread somewhere around here on it.

I have no doubt that OEM rubber can match or exceed poly in
longevity. I also hear that care has to be taken to not put suspensions
into bind when using poly. For example, once both wishbones are taken
into consideration, there may be some twist designed in at the factory.
Rubber allows that. Poly not so much. Definitely not Delrin or bronze.
The last two aren't cheap unless someone already catalogs them
for your application.

That even applies to apparently single plane of motion arms like the
GM upper control arm on a dogbone.

One approach is to mix and match. For example, on the X308 LCA
where we can deduce that the factory intended the front to have
compliance, and the rear less so, due to the TSB updating the front
to the stiffer rear bush, you could retain the front as the weak sister
still using the updated BB part number and put a poly in the back.
Or, put poly only on the upper. Or put poly in one bush of
each arm. By mixing and matching, you keep some compliance
to allow for differing arcs of motion in different planes of motion.

It would require some careful thinking. Maybe even springs out,
and moving the arms around by hand.

I found a couple of clever people who ground the eccentrics on
one side and built up the eccentric on the other to get a bit more
motion. Also found eccentric bushes, not Jaguar though, that add
some desirable offset. On a X308 those could be installed in a static
position and use the existing eccentrics for tuning.