Hi,

I am going to have a wheel alignment done tomorrow and I remember the last time, the rear toe was asymmetric (one side slightly out of spec) but the workshop wasn't able (or willing) to fix it. I have always thought that all XJ40/81 had adjustable rear toe but indeed it looks like it is only possible from VIN 687219 on. My car has VIN 675xxx so it should have the non-adjustable rear hub. But when looking at the parts catalogue, the only difference seems to be the pivot pin (#14 in the drawing). So could every XJ40/81 have adjustable rear toe by just exchanging the pivot pin?

EDIT: Just searched a little bit and found a picture of the newer pivot bolt, it looks pretty much the same as the one I have, except it has a fixed head with an integrated washer. Is that the whole deal? If the rear toe depends on the position of the pivot bolt within the hub, it should be adjustable anyway in my opinion, just need to locate it at an adequate position with the given lock nuts and washers.

Thanks,
Oliver

 

These TSBs were issued a few decades ago when I worked at the dealer.
These may help explain.

 

Thank you, but actually these bulletins don't precisely answer my question. Do you believe the rear toe adjustment capability is implemented through the new rear wishbones?

EDIT: I think I finally got it, when looking it once again (and some more sources), it's not the hub or fulcrum bolt that adjusts toe, it's indeed the whishbone, which has a slot instead of a concentric hole to take the hub. So if you want to adjust toe on pre 687219 cars, you'd need to cut a slot in your wishbone's hub seat ... which is probably not recommendable.

So finally: what else can you do, when your rear toe is out of spec?

 

I remember some later Jaguar models (X308 or X100?) had slots for adjustment on lower control arms or frame mounts but used STRAIGHT BOLTS from the factory.
We were supposed to get new ECCENTRIC BOLTS from the part dept to replace the straight bolt when an alignment was performed.
Cutting a slot will work on the rear lower control arm if it is done CORRECTLY.

You don't need an eccentric bolt if it is 'nudged' back and forth until the correct reading is obtained and 'locked-down' TIGHT!

The eccentric bolt will only work with welded raised bosses for the eccentric 'washer' to force the bolt to move 'side-to-side' as it is rotated.

 

Do you have some source for these eccentric bolts? Reading this, I believe alignment issue where quite common on these cars, weren't they?

So you say even the bolt-hole for pre-687219 cars provides some play to tackle rear toe issues? Should be worth a try.

I already thought about retrofitting the late XJ40 rear wishbone, but most parts aren't available any more and even getting them in used condition will require quite some money. I've already thrown a lot of effort and money at my suspension issues and I gotta stop somewhere.

 

I have BINS AND BINS of 3 ring binders and some of that info was transcribed to .pdf documents.(Jaguar started that in the early 2000s)
The info is somewhere in my 'piles-of-documents'.

I remember 'doing alignments' on some cars and having to go to the parts dept for the eccentric bolts to get the suspension into alignment.(been way too many years to remember exact details)

Sometimes a skilled mechanic just has to 'deviate-from-the-norm' and modify factory parts.
We did that upon occasion and sometimes we were 'sanctioned' with the 'mod' and sometimes admonished and sanctioned with a 'back-flag' of payment as punishment for deviation of procedure.

Mechanics always try to come up with 'easier' or more efficient ways of repairing faulty/broken machinery.

 

Late XJ40's with cast wishbones have the eccentric setup. My DD and my parts car are set up like this.

 

What I notice when standing behind the car is that on the right side it looks like the wheel stands further out than on the left side. I think that could be caused by the deviating toe, but it could also mean the rear axle as a whole is not well centered. Gotta try to measure from wheel hub cap to the wheel arch.

Update: tried to measure it and it looks like the hub cap is about 1/4-1/2 inch further out on the right side. My measurement might be affected by camber ... well, let's see what the guys in the car shop say after the alignment, might be tomorrow until they can do it.

 

Got the car back from the alignment and the camber on the front right is out of spec, it's too negative (-1°18'). Bushes, ball joints etc. are all new. What's going on here? I already installed camber shims to the v-mounts (which helped to bring the left side camber into spec), but the right camber is even worse than before.

On the rear the toe on the right hand is in spec, but on the left hand is out of spec, too (-1°01'). Right side toe is even better than last time, even though I did not change anything. The only thing I did on the rear is to lower the diff because I needed to access the diff filler. Therefore I loosened the right control arm.

 

*

 

Little update on this issue: I installed new shocks (all 4) and they brought the camber on the front back into spec. But on the rear end it's now slightly out of spec, camber is not negative enough .. even though the car sits about 0,5cm lower now. Besides that, the car drives much better. Also installed new wheels (with V-shaped profile) and it drives even better, no more tram-lining!

But it still pulls to the right, at least slightly. I tried modifying front toe from toe-in to toe-out, but that didn't cure it completely. Besides that, the more toe (whichever direction) the smoother it rides. I now feel a lot less vibrations in the steering wheel and the car feels so much sublime, like you expect a Jag to drive. But I think I am currently way out of spec with front toe.

According to the protocol, the rear toe is asymmetric and out of spec, too. During the last measurement it was 26' toe-out left and 13' toe-out on the right hand. Factory says 10' toe out is maximum. What do you think, can this deviation cause the pull to the right? And will it cause tyre wear or any other issue on the long run?

Oliver

 

I did some measurements myself and tried to figure out, what is the situation. I measured the distance from wheel to wheel and also from the suspension mounting points to the wheels.

So that's what I basically found out:
1. the wheel base left/right is almost the same (maybe 1 or 2mm difference)
2. the distance between the front jacking points to the wheels differs, the right wheel is about 5mm ahead of the left one (the position of the wheel within the wheel arch tells the same story)
3. on the rear I have a toe-out of about 1cm, but it is not symmetric, the left wheel has about 26' and the right wheel only about half of it
4. the distance of the right and the left wheel to the center of the rear subframe is equal, so the axle as a whole is rather symmetric
5. the distance of the front rear subframe mounting point (spherical bearing) to the respective rear wishbone differs by about 5mm, so the left wheel is further behind than the right wheel.



My believe is that the toe-out on the left rear wheel causes the car to constantly pull to the right (just think of a car with 4-wheel steering and the way this works). So how could I fix this?

I have pressed steel whishbones, so there is no toe adjustment possible by the factory.

But what if I manage to turn the rear axle as a whole by about 6 or 7 '? Than the rear toe would still be out of spec, but at least it would be symmetric and should not cause a pull to any side. I already loosened the complete rear axle and tried to give it a little twist, but I don't think it worked, it still pulls to the right.

Another approach would be to reduce the different distance between the rear axle mounting and the whishbones. If I would remove the spacers on the left rear whishbone assembly it should move forward by maybe 2 or 3mm. I also could add additional spacer to the right wishbone assembly and thereby move it backwards. So then the rear wheels would be at the same 'height', but will it fix the toe? I think this will depend on the turning radius of the half shafts.

But actually removing the spacers from the wishbone assembly is probably not a good idea, because it would mean that the whishbone has direct contact to the pendulum. So next idea: Put spacers between the differential and the pendulum one the left side. This would cause the pendulum to move to the front on the left side, allowing the wishbone to move to the front as well. Could be the better solution, but would require to undo the rear axle more or less completely.

What do you think?

 

I am going to ask this because of my own issues with my 94. Has your car ever been in an accident? Is it possible that there is something bent that you are not aware of?
Mine has a rebuilt title and is never going to steer correctly. On mine the right lower fulcrum bolt had a 15 degree bend in it just ahead of the rear bushing causing the car to ride like a "bucking bronco." I changed that bolt and the lower control arm, then took it to an alignment shop and made my plea. It has gone 10,000 miles since.

 

As far as I can tell, it has not been involved in an accident. The body panels were all original when I bought it and I can't see any proof of accident-caused bodywork, the clearances are all fine.

The front and rear subframes all fit to the respective mounting points so I am gonna say this is all within factory tolerance. If it had been in an accident where one of the frames had been bent the bodywork must have been bent, too.

But I can't tell if it maybe got hit on one of the axles so a wishbone got bent. With my bare eyes, they all look well in shape.

What I do know is that the rear axle has been completely apart at least twice, once when it got a new differential (according to the part. no it's a X300 or X308 differential) long time before my ownerhsip, once when I refurbished the whole axle. Interestingly I have figures from all-wheel alignments prior and after I had the axle out and the rear toe is exactly the same. So either there is only one way of assembling the rear axle correctly or I did the same mistake as the one who assembled it before.

Talking about the differential: I didn't have that on my plate yet, is that maybe the cause? Does a X300 diff have slightly different measures so the half shafts create a different toe and/or camber?

 

I just gave it a try and removed one of the spacers and the toe-out dropped to just 2mm.