Alignment help and ride height

Hello, I searched the forum as to not create a duplicate post/responses, but I didn’t quite find what I was hunting for. If these questions have already been addressed, I apologize.

I swapped my XJ6 and now need to get it aligned. I found a shop that will do the alignment but they only have specs for a XJS. My question is, what specs should I use the alignment and do I need to worry about ride height with more modern tires and an engine with a different weight. Any help is greatly appreciated.



There are 3 iterations of XJ6 in this forum section. Please state MY.
When I did alignments for these cars I remember that the XJS had much more CASTOR than the Sedan.
I am remembering something like 3.5 to 4.0 for XJS and 2.5ish for the XJ6.

That sounds about right although circa 1983-84 the XJ6 got the revised geometry control arms and the specs were changed. I think the newer spec was the same as XJ12/XJS

It’s all in the archives. But no point in going into those weeds until we know the model year.


Give the shop the relevant data from the xj workshop manual, Adam - it is as good as it gets, and the shop can then decide whether the differences are material…

You have an xj and should adhere to the specs for that. The tyres will make no difference to the suspension geometry - and it has the heavier engine.

That doesn’t mean that some tweaking from original will have adverse effects, but who knows - and the PO may already have ‘done things’…;0

xj6 85 Sov Europe (UK/NZ)

Yes you do Adam.
For the rear the ride height tools are imperative, they are necessary for determining camber at the center travel position of the suspension.
At the front, at least at my V12 XJ, the required height is very close to the actual height.
The tools are very easy to fabricate and I strongly suggest that you do so.
Kirbert’s book has all the info.

I wouldn’t worry much about Castor, as long as both sides are equal. You can very easily adjust it yourself later if you want more or less wheel self-centering without affecting any other angle.

Also make sure that when they put the car down at the shop the roll the car so the REAR settles.
A very common mistake that will skew (by much) any measurements taken.

Your CV says you have a 1986 VP Adam. I’m surprised they don’t have the data for the later XJ6. I had my 1971 aligned last year and they were short of some of the figures but used the SII data instead and it was fine. Perhaps you should try another shop?


Thank you for your responses. I do have an 86 XJ6 VP.

The entire topic leaves me a bit confused as I know almost nothing about alignments.

Also make sure that when they put the car down at the shop they roll the car so the REAR settles.
A very common mistake that will skew (by much) any measurements taken.

@Aristides - I’m not sure what this statement means. Can you provide a few more details on this statement?

Kirbert’s book has all the info.

Does anyone know where I can find Kerbert’s book to read more about height requirements?

Ride height is important, as the factory specs are developed with a specified ride height in mind. So, if the ride height isn’t at or close to specs the factory alignment specs might not be the best choice. To some degree an experienced alignment guy can compensate for all of this and you can still end up with a satisfactory result…with an understanding that ‘satisfactory’ and ‘optimal’ are different things.

Jaguar alignment, by the book, requires the suspension to be locked into xxx-position using special links. The absolute necessity of this procedure has long been debated. I’ve owned several Jags and never had an alignment done with the special tools and I’ve always been happy with the results. That is, the cars steers and behaves well, drives straight down the road, and I’ve never had tire wear problems. I might well be even happier if the special tools were used. Or not. I dunno.

I’ll add that I always request that the caster (positive) and camber (negative) be adjusted to the max allowable setting with the specified range.


How far off is your ride height? IMO, that the first question to address.


What makes you want to have the alignment checked? Have you had work done, experienced poor handling or are you just curious?


@Frankie - I dropped the entire sub frame to replace all of the bushings. The car pulls to the right when driving it down the road.


pulling right while driving sounds more like front axle to me.

Why do you think that

Unless you change dimensions modern tires won’t affect ride height.

My SII OM indicates for a 4.2 LWB car - like yours

Front castor + 2 1/4° ± 1/4°
Front camber + 1/2 ± 1/4
toe in 1/16" - 1/8" (1.6 - 3.18 mm)

Rear camber - 3/4° ± 1/4°
Rear wheel alignment parallel ± 1/32" (± .8 mm)

Without any serious engine or wheel (205/70 x 15) modification you should be fine with these figures.

Good luck and start with changing the tire shop;-)


75 XJ6L 4.2 auto (UK spec)

I’ll point out the Adam has dropped a V8 into this car hence the questions on ride height.

So if he gets the height down as he should, for which he needs the measurements to a fixed point of the car to the ground as given in the workshop manual, he will want the same measurements as Jochen. Correct?

And if you ever had a car in the air partially or fully it will sit funny, wheels further inwards and car higher up than usual, hence it needs to roll before the measurements that have to happen at about the correct height so the values are useable.

Those specs are the virtually the same, as I recall, as early early Series III and, as you say, should be fine.

However, even better would the specs used on the later cars (after VIN 360146), which would include the 1986 car in question:

Castor 3½º positive +/- ¼º
Camber ½º negative +/- ¼º
Toe 0" to 1/8" toe in

This change in specs is due to different control arms being used


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That doesn’t matter, Adam; the alignment shop knows it all - what they need are the numbers…:slight_smile:

Ride height has some bearing on alignment, but as Doug remarks - within reason; the influence of slight variations in ride height on steering geometry is negligible. Also, while the alignment shop can measure to small fractions of degrees - the adjustment shims give far cruder settings…

Fitting a lighter engine may lift the front a bit, but a PO may have adjusted it? You can measure the front ride height; measured to the center of the outer head lamps it should be 611 mm (24 5/6") minimum - equal on both sides. To check; roll out, firmly depress on front bumper, then lift ans slowly release. Rear; 189 +/- 6,4 mm (7,45 +/- 0,25") - tanks full. If reasonably so; follow Doug’s sage advise…

Most likely; the pulling is likely due to wrong toe-in…

xj6 85 Sov Europe (UK/NZ)

In order to mount and set the laser projectors at the wheels they raise the car and turn the wheels to zero the machine. This is necessary because the wheels are not always true and straight.
When they put the car down the front will settle ok as the alignment lift has the special free rolling plates under the front wheels.
At the rear though there are not such plates. With a live axle this is no problem, everything is fixed, but with an independent rear suspension (like the Jaguar or my Mercedes) the rear wheels will be far from their normal position if the car does not roll back and forth for the suspension to settle.
And as the reference for the alignment is the rear wheels all the measurements will be off, and even worse, different every time.
Before I gave up and did it myself, I went three times to an alignment shop (the only one available in our rural area) and every time the rear values were different and by as much as 1°…

The Jaguar IRS is a very sophisticated piece of engineering. Camber and Toe are variable according to suspension height, same as in the front, all calculated for better stability and minimum tyre wear. It’s also designed to provide some passive steering.

The book:

Wrong Toe-in will not cause a pull.
It will wear tyres very quickly and the steering wheel might not be straight.

A car will pull because:
Front Castor or Camber are not equal on both sides.
Rear Toe or Camber are not equal on both sides.
Camber and Toe are tyre wearing angles, Castor is not.

Hi Jochen - thanks for the specs. I/m running 225/55R16 on it.

@Aristides - thanks for the explanation. That will help a ton when I talk to the alignment shop.

Oddly enough, I’ve tried four garages and no one will do the alignment for me. One of the shops is Jaguar dealership. They all refer to a special tool that they don’t have.

Pretty common.

They’re referring to the ride height links mentioned earlier.

Sometimes you can convince the to do the job without the links, sometimes not. And, if your ride height is too far off, it might not be a bad thing that they’ve refused.

I’ve had good luck using specialty brake/alignment shops that cater to the hot rod/specialty car crowd. They are accustomed to unusual situations and can help you get things right. You probably won’t find any of the high volume, franchised type retail outlets willing to work on a Jag. It’s contrary to their business model.


Wrong toe-in will cause the car pulling, Aristides, and indeed wear the tyres very quickly. But it’s not
the only reason for pulling…:slight_smile:

xj6 85 Sov Europe (UK/NZ)