I have a 1996 XJS Convertible.

My drivers side tire wears unevenly. The tread pattern on the outer edge is completely gone. When I bought the car several years ago, it had a similar issue with the tire, but I wrote it off to poor alignment.

Several years later, I need new tires and I want to correct the problem instead of assuming it was indeed a poor alignment. (I had it aligned twice over the past two years, to no avail)

I took it to a shop today and was told that the front control arm bushing needs replacing. (The rear suspension mounts are also going bad)

Does that sound consistent with my tire problem?

I didn't take it to my normal shop, but a "Jaguar Specialist" and the guy who performed the inspection didn't seem to want to speak to me directly. The shop told me about the recommended bushing replacement.

Thanks for any help on the subject. (I will probably follow up and ask if its something that can be done without a lift, torch, etc)

 

Here's a picture of the tire's tread pattern.

 

Holy crap, tha's smooth.
Are you getting any front wheel wobble or vibration?
Is the other tyre at the front worn the same?
Steve

 

The tire on the other side is wearing evenly. I could take a picture, but it would look like a normal every day tire.

As for vibration, yeah, I suppose there is some at some speed.

 

It is too much positive camber. Could be a **** alignment or worn bushings. Maybe even both. Moth so called alignment techs have no clue as to suspensions. They only know if it is in the red or the green when setting it up. Also I find most alignment racks are not calibrated.

 

I'm suspecting it's "both", but I think I'm up to the task of replacing the bushings. Looks like a rewarding job.

I'm sticking with the OEM Jaguar rubber.

Then I'll get a new set of tires from a place that performs "Road Force" alignments.

Not much more I can do.

The shop also mentioned that my rear suspension mounts need to be replaced, but I've had no issues with the rear tires...

 

I suggest you replace all the ball joints (2 each sdie) and track rod ends (1 each side) as well. If one of these is shot it can also have bad effects, and they are not too expensive.

It might be a good idea to get hold of a camber gauge and measure the camber on that side compared with the other side, and to spec. Camber should be 1/4° to 3/4° positive (ie top of wheel slightly tipping outwards). It is worth measuring this before stripping down the suspension to replace the bushes and ball joints, as camber can only be adjusted by shimming the top subframe pivot which the top wishbones use as their inner fulcrum. Effectively the fulcrum is moved either in or out, thereby adjusting the wheel camber.

Similarly measure the castor. Castor is affected by oblong spacers placed each side of the top wishbone outer end between the wishbone and the ball joint itself. The two bolts that secure the top balljoint to the wishbones 'sandwich' the top wishbones and the spacers to the top ball joint. Altering the side of the balljoint that the spacers are placed on alters the castor. If, previously, someone has put these back wrongly, the castor could be out as well, which might also cause the trouble. Castor should be 3 1/4° to 3 3/4° positive.

Greg

 

Thanks Greg. I think I'm going to do just that.

I've learned not to use poly bushings, and to stick to OEM rubber, so it looks like I'll be spending about $120 on four bushings. Ouch.

Jagbits is selling an aftermarket type, and I always thought Jagbits sticks to OEM only unless they have found a top notch alternate.

Also looks like I'll be spending about $200 for Lemsdorfer ball joints.

Lastly, Moog tie rod ends at about $45 for both.

The bushings are the items that chaps my...

 

"Road Force" is not part of an alignment. It is a measurement of the tires. Radial force variation is the technical term. I will try to explain it. Imagine the sidewall of a tire as a bunch of springs. What you are measuring is the difference in the "rate" of the springs. This variation is known as "road force". It is usually measured in lbs. Not a bad idea to measure it but it is of no use for tire wear. It affects the ride quality because if road force is too high you may feel a vibration or even a slight drone at speed. This is a different vibration than the usual shimmy that balancing corrects. Unfortunately most tire manufacturers won't do anything as far as warranty goes regarding road force that is too high. In my day job I am a field engineer for a vehicle manufacturer and I get involved with this all the time.

As for alignments you want a 4 wheel alignment. Ask for printouts before and after. Make sure they give you the actual values not just the red/green printouts.

You do realize that you need special tools to set the suspension height on an XJS. If your shop is not Jaguar specific they will not have the tools or even know they exist. Doing an alignment without these tools is a waste of time. In addition there is a centering pin for the rack. You use this to center the rack and pinion and then the toe is adjusted and after the steering wheel is centered by removing it and installing it straight. If the shop centers the steering with the wheel then again you found the wrong shop.

One last thing if the alignment takes less than 1.5hrs you did not get an alignment. If the rear camber is out your car will be in the shop for 2-3 hrs.

My suggestion is to find a Jaguar dealer and pay them the money. I can tell you a dozen donuts or bagels on the day of your appointment will help make sure you car is done correctly. A good alignment will not be cheap. You get what you pay for.

In my area most shops are $100-$125/hr and more in NY and Boston. So at these rates a $75 alignment is not getting you much time or a quality technician.

Good luck.

 

I cannot exactly disagree with Greg Edge's points, but I think you could address the matter in two stages, thereby hopefully not having to spend a fortune with a main dealer, who may not be any good anyway. Certainly it is a good idea to first check the ride height under the centre of the front subframe; it should be 6 to 6.5 inches of clearance.

Then gauge up the camber/castor. If something is miles out, there is the problem. If it IS miles out, it can always be the subframe itself has bent somehow - but this is unlikely though possible. If all measurements are in the realms of adjustment, or even NOT out at all, then go the "replace everything" route and then, ensuring the rack is centred, get the toe accurately set at, say 0.5° toe in, using a good laser four wheel place.

You will be very unlikely to continue to have problems and need to do anything else at all if all this results in everything to spec. The front suspension subassembly was designed to be built up at the factory with correct camber/castor and toe and then bolted up to the monocoque and never looked at again once on the car. If all measurements check out as correct, after worn parts rerplacement and adjustment, you will almost certainly be fine.

My car certainly was; even recently after a full strip and rebuild with all new bits, in which all I did was to set the toe (as I knew the camber/castor was OK before the strip down, so had to be after the rebuild as nothing was done to change it) the car is perfect.

One other thought: while you are at the front suspension, check for wheel bearing play, and if you find any renew the wheelbearings and even stub axle if they show wear grooves. Play in this area can also cause tyre wear.

 

Greg, absolutely correct. A factory builds the suspension and installs it. The factory does not measure the alignment on every vehicle produced. The factory does pull a vehicle and check measurements every so many units.

Anyway a dealer is not always the best choice for older vehicles. I have stated this before. They are far from interested in your car. However if there is a technician old enough to have actually work on an XJS you have hope of getting a really good alignment. To Greg's point if your suspension was aligned properly before the bushing became worn then with new bushings and ball joints fitted you should be real close on camber and caster. Toe is all you need set. However if some monkey attempted a camber or caster adjustment you will likely have to do a real good alignment. Also there are tools to set the suspension to a certain height when aligning. Many so-called alignment techs will add or remove shims on the upper wishbone in an attempt to adjust caster. On these cars you adjust camber with equal shims addition or removal on the upper wishbone. Caster is done at the ball joint with shims.If the caster is adjusted at the wishbone rather than at the ball joint you may experience odd tire wear. This is due to the camber change when the wheel is turned.

 

I've ordered parts to replace a suspect pair of Upper Control Arm Bushings.

While in there, I decided to replace the upper and lower ball joints as well as the tie rod end.

Assuming the worst, let's say it wasn't the Upper, but the Lower Control Arm Bushings that are bad. (or maybe both) Am I saving any real time by not replacing the Lower Control Arm Bushings while working on the other 4 pieces?

It almost seems that the Lower Control Arm Bushing replacement is a beast of a job by itself, and that there is no real labor savings by doing the lower at the same time as everything else I mentioned above.

Save for the additional alignment that would have to be done. (I purchased a "Lifetime Alignment" so I am not concerned about going back to the shop to have that done)

Thanks.

 

The lower bushings are indeed a big chore in and of themselves. The lower control arms must come off. The only overlap I can think of off hand is the lower ball joints and tie rod ends, both of which will need to be disconnected (not removed) if you do the lower bushings at a later time.

The control arm bushings can be visually inspected. What you're looking for is concentricity of the bushing within the arm and concentricity of the shaft/bolt that goes thru the center of the bushings. Lack of concentricty means the control arm is not being held in the correct position.

Sometimes they are so worn the actual free play develops and allows the control arm to flop around. A long pry bar to lever against the control arms can be used to check.

Cheers
DD

 

%^&(%^&(!!!!

Its the lower then. The front one does not look concentric...but I have to admit, the one on the passenger's side, where I don't have a problem doesn't look much different.

I suppose the lowers will have to be done.

I'm in for a lot of work...

I believe I may have to drop the steering rack to get to those, won't I?

 

Here's a pic. See how the lower side is thicker than the upper?

 

Yes, you are :-)

As suspension work goes the ball joints and upper bushings are not biall that bad. Easier than many other cars, actually. But the lower bushings are labor intensive no matter how you slice it.




Yeah, to allow the big bolts/shafts to to pushed out, rearward.

Have you ever removed springs before? If not, there's are safety issues you need to made aware of.

Cheers
DD

 

That one looks about perfect. If they are all like that, and no broken bits of rubber poking out of the ends, then they look fine to me.

If you do decide to do the lowers, the entire front subframe has to be lowered at the rear (and the engine supported across the top of the wings by a bar, and the steering and engine mounts disconected, before the lower fulcrum pins can be driven out rearwards (if they will come out), as otherwise they foul the sump on coming out. A very great deal more work and hard to do without proper tools and a good ramp or lift.

If there is no undue play in th wheelbearings and stub axles, then just check the camber and castor and do the top bushes and ball joints and track rods, is what I would do at this stage.

 

You are right. I don't believe I can change the lowers out myself.

I will likely stick to the original plan and change everything i CAN change out...if it doesn't do the trick, I'll likely pay someone to do the lowers.

I've already asked the dealer what he will charge me. There's also a local Jag Specialist. I'll talk to them on Monday.

Thank you for talking me through this. I'm glad I didn't get started....

 

Don't forget the subframe bushings.

Lifetime alignment? A bargain offered by a tire shop?

 

In case anyone was interested, the dealer quoted me a price of $1,629 to have the lower bushings (on both sides) replaced. This price includes parts and an alignment as well.

I will check with my mechanic as well.