I bought new tires and got an alignment. The report is showing that the toe reading for the rear wheels are as follows:
Left Tire: +0.10
Right Tire: +0.12

The acceptable range is -0.03 to +0.03

I don't think that the toe is adjustable in the rear. Do I have a problem?

I did recently change the radius arms. I've also changed the rear mounts, quite some time ago.

Do I have any options here?

They also included readings for the following:
Setback:
Front: 0.24
Rear: 0.07
Track Width Diff: -0.26
Wheel Base Diff: 0.17

Not sure what those numbers mean.

 

You do not have a problem. As far as I can understand the numbers you posted, the only rear one you can adjust, OEM, you have not mentioned: that is rear wheel camber. This is adjusted by adding or subtracting the large slightly oblong shims between the inner driveshaft flanges and the discs each side. If you subtract enough shims to get the camber to 0.5 or 0.7 degrees negative (Wheel sloping inwards at the top) it will make a big difference to the cornering grip at the back.
Greg

 

I think I remebered seeing some offset screws/shafts at rear. I might be confusing this though with the XJ40/X300/X308 rear axle...

 

Rear camber is -0.49 and -0.34.

The range is -1.00 to -0.50, so I guess I do need some work there too. Thanks for asking. I overlooked that thinking that the range was 0 to -0.50

 

The outboard brake rear end has adjustable toe.

 

I will check the rear brake end for an adjustment bolt? How do I adjust?

I made some changes to the front camber and caster.

My right camber was at -1.37; so I removed 7/32" worth of shims, and that should land me at -0.495

My left camber was at -0.12; so I added 3/32" worth of shims, and that should match me up at -0.495

My right caster was at 4.5, so I moved 1/8" worth of shims from the front to the back; and that should get me to 4.0. I wouldn't have bothered normally, but I was already in there.

My left caster is at 4.01; so there it shall stay.

Did I get that right?

 

The large radius arm bushing needs to be oriented correctly. Was this done when you changed them? The 2 gaps in the bush need to be installed forward and rearward facing. If the bush was oriented incorrectly it can increase positive toe.

I dont recall any way to adjust rear toe and the XJS IRS.

 

Yes, I was careful to align the holes along the axis of the radius arm itself.

Getting back to the front camber...adding shims results in a positive change in the angle, where as reducing shims will result in a negative change to the angle.

The camber at -1.37 requires removing shims to get closer to -0.5 degrees.

The camber at -0.12 requires adding shims to get closer to -0.5 degrees.

 

Vee is your rear IB or OB brakes. The outboard brake rear has toe adjustment in the fulcrum shaft just like the XJ40

Inboard brake rears have no toe adjustment.

 

The XJRS had the gaps facing side to side; this apparently tightened up the rear end response.

 

Hi Vee,

I recently had my car checked and re-aligned following my front and rear suspension rebuild. I found there were some slight discrepancies between the recommended XJS figures that the operator had in his database for the Hunter alignment bed and the figures that I had found in the Jaguar service manual.

The figures that I found in the manual were:

Front
Caster: 3 to 5 degrees, balanced to 0.5 degrees positive
Camber: 0 to 0.5 degrees
Alignment: Parallel +/- 15 minutes

Rear
Camber: -0.5 degrees to -1.0 degrees
Alignment: Parallel

The Hunter database suggested that the rear toe recommended figure was -11 minutes to +11 minutes. As my rear toe came in at +2 minutes on left and +4 minutes on the right, I was quite happy with that. (I have my radius bushes aligned as per XJR-S as we usually recommend to club members.)

I was interested that they quoted the figures to you as decimal points of a degree. All the printouts that I have from álignment beds show them as degrees and minutes, which is naturally quite different. So I wonder if there is any confusion in the figures that you've been given.

Also, where did you get your figure of -0.03 to +0.03 for the rear toe and is that really decimal or is it minutes?

Cheers

Paul

 

PTJS1,


My service manual has all of the alignment data. It lines up with what the shop has.

Front camber is definitely a negative value, at least for the XJS. If you are using XJR-S values, then it does differ. I've added a link that shows the values based on a later TSB. My manual shows 1/2 degree, +/- 1/4 degree, negative (both wheels to be within 1/4 degree of each other).


Front caster reads 3-1/2 degrees, +/- 1/4 degree positive.

Toe Alignment, 0-3.18mm (0-1/8 degree) toe in.


Hope this helps.




http://www.jagrepair.com/images/TSB/...ifications.pdf

 

Vee,

Tks very much for providing the link to that US TSB. It perhaps means that there are different figures for US than UK, so I'll try not to add to any confusion with any more UK figures!

As a matter of interest, that TSB you linked stated Total Rear Toe was 0 +/- 0.33 degrees (-0.093in to +0.093in with 16" wheels) which does seem at odds with your figures above of -.03 to +.03 or maybe I've misunderstood. I'm still not sure if your figures were inches or degrees?

Cheers

Paul

 

It's all degrees and my manual was written before the TSB. I would let the TSB supersede my manual. The shop which did the alignment seemed to carry the TSB datapoints.

 

Brakes on my car are outboard.

 

Tks Vee,

So as the TSB states that Total Rear Toe is 0 +/- 0.33 degrees, then the figures for your car are ok, aren't they?

Cheers

PAul

 

Oh crap, so I adjusted the shims this week and took the car back for a "warranty" realignment.

I nailed the front castor, however the previous readings of 4.01 and 4.50 turned into 3.89 and 3.87. Nevertheless, I consider this case closed.

My front camber numbers flew out the window though. Originally read at -0.12 and -1.37, I moved some shims around and now they read -0.21 and -0.03. I added 3/32" of shims to the -0.12 number and only got to -0.21? I pulled 7/32" from the -1.37 number and got all the way to -0.03? Something is not adding up.

The rear, which I made no adjustment to is where things get dicey.
Rear camber went from -0.49 to -0.34 and the right rear wheel went from -0.34 to 0.
Rear toe went from 0.1 to 0.02 and the right rear wheel went from 0.12 to 0.21.

Regardless of what happened to the readings, there's something off with my right rear wheel. Both toe and camber are really off.

 

Are you certain the problem is the car and not a repeatability issue with the equipment the shop used to do the alignment.........

If I were you I would setup a string box around the car and check the alignment yourself. I use this method to do the alignment on my car and it's very accurate if you get the centered in string box.

BTW I run almost ZERO toe on the front, always have. Makes the car turn in quicker.

 

Warrjon,


I think so. The two alignments, even though they carry differing numbers, still consistently claim a big difference between the right and left rear wheels, for both camber and toe.


I'm not sure it can be corrected, easily. There does not seem to be any way to adjust the toe on the rear wheels without doing some major bending, and then it'll be a total crap shoot as to how much I need!


I think I'll attempt to adjust the rear camber and see what happens.

 

Vee,

A random thought but have you considered if your right rear wheel is fractionally out of true? That could cause a simultaneous change of both camber and toe if the wheel is out of true and then slightly rotated from its previous position from when the readings were last taken.

Good luck

Paul