The initial symptomwas a front endshimmy between 30 and 50 mph. The fix was a combination of new balanced tires and lower ball joints.

I firstbalanced the tires, which cured some, but not all of the shake. However, we found theDunlopswere out-of-round andreplaced themwith Michelin Pilot Sports A/S. New [balanced]tires cured about 80% of theproblem; however, there remained a bothersome vibration on washboard roads or after a pot hole.

Theculprit turned out to be worn lower ball joints. We had checked for ball jointsin the traditional way ofpulling the tireat 9/3 and 12/6when unloaded. This diagnostic proved insufficient to uncover the loose ball joint. The technique which proved successful in uncovering the worn ball jointswas this:

While the car sat on a 4 point lift about six inches off the ground, thetech put a floorjack under the A-arm to load the suspension. Then a 5 foot long breaker bar was leveraged under thefront wheel. You could feel and hear the freeplay; and looking underneath, you could see the movement.

I did the replacement work myself. This job is not toodifficult if you have a good workspace and a big hammer. Just follow the JTIS. Of course it helped to have a rust-free AZ car. All the bolts came right off with no problems. Only the tapered lower ball joint fittings were stubborn... but that's what the big hammer is for.

Gordo

 

Checking ball jointsin the courseof a routine scheduledservice or wheel alignment: N/C

Performing a "Prybar Diagnostic" to inspect suspension components for axial and radial freeplay: $89.95

Having to pull the vertical links off again to replace the wheel studs at the advice of an SCCA backmarker/ tire buster : ya got me, I wouldn't charge for that job either.

 

lol

I love my prybar!! Everything from 3 inch to 6 foot in my collection. 6 footer is great when doing front lower control arms on X-Types!!

 

good old prybars lol

 

Hey Gordo,

You got bad info on the wheel stud threads, too. I just ran a rethreader die on the studs fitted to a '97 XK8 rear hub, and they're 1/2" x 20. And the hub is the same part number, at least through 2000 MY. Ifmetric studs are in use, it's not until '01 at least.Better watch your nuts.

 

Thanks Andrew. The two sizes are so close it probably makes little difference in other applications; however on a wheel lug, I want to be absolutely certain I am using the correct fastener thread combinations. gordo

 

Since when does wrong=close? Maybe the phrase "cross threads are better than no threads" works for 30 year old Japanese shock mount bolts. Not my cup of sake.

 

I wasn't suggesting using an SAE bolt w/ a ISO nut. I meant that 1/2x20 and 12mm-1.25are so close insize, that 0.7 mm is not alot. It isalso difficult to measure the differences in thread countusing the shopguagesI have, which iswhy I askedthe question. gordo

 

FJT... a 6 footer?
You da man.

 

Well the saga continues with front shock absorber bushings. New, balanced, tires coupled with new lower ball joints did their job andtightened up the suspension dramatically. However, there remaineda slight vibrationalpulse in the suspension whilegoing over bumps and on washboard roads.

I again raised the front end, and using a pry bar under the tiresuncovered two bad shock bushings. Not ripped or torn, but loose enough to feel movement when upward force to the bar was applied.

Since the upper control arm must be removed to fix the shocks, I thought I may as well replace both sets of upper bushings. I ordered the parts from Britishparts.co.uk.

The progress made so far has inspired me to continue to. There are some roads in Florida which are smooth as silk, and I can already see that this car will be able to take full advantage. gordo

 

You need to compress the spring to change the shock bushings if you are talking about uppers. They crumble away. get the pancakes and bushings. You will notice a huge difference.

 

The movement is in the lower shock bushings; but I will conduct a careful examination of the uppers while they are on the bench. At this point in the project, I vow to leave no stone unturned. gordo

 

Maybe you could post pics of the damage.

 

Here's the lower shock bushing. It looked OK in situ. However,when a pry bar diagnostic was applied, it was obviousthe bushing had collapsed andwas no good. gordo

 

Well I think I have gotten as much shimmy out of the front end as is possible. All new upper control arm bushings. New lower ball joint (w/main control arm bushing), and new lower shock absorber bushings.

The shock absorber bushing replacements where oversized and we had to use a die grinder to open up the sleeve. This is not a DIY replacement in the apartment parking lot. I had a full shop, with press, at my beckon and call, and it was still a major task.

I can see why Jaguar does not sell the replacement bushing as OEM.

There is still some vibration, more in the body than the steering wheel, so I think that much is cowl shake. I can't think of anything else to check, so I am getting it aligned and just drive it for awhile. gordo
gordo

 

I forget what year your car is. 97-99 had weaker body structure and they all kind of shake a little.

 

Good work, Gordo! What sort of upperwishbone bushings did you use, were they factory?

 

All replacement parts are OEM Jaguar.

I still have a little wobble. Something is not right. This is NOT cowl shake, there is a wobble or a bounce somewhere. Comes in around 20mph, worse at 30; fades out by 50. Not brake dependent.

My next step will be to get the wheels balanced with a Roadforce balance on Hunter GSP9700 machine.

Is there a definitive diagnostic for the upperball joints? They seemed fine when I examined them while the upper A-arm was disconnected for new bushing installation. There was no freeplay, but they were not stiff either. They wereloose but I could find zeroslop. I am wondering if they are loose under load?

If those don't check out, then the last peice would be to replace the lower front control arm bushings. I looked at these pretty good out of the car, and a Jag Tech also pronounced them OK. ???

What am I missing here? I have done all the the suspensionwork. I am satisfied everythingwas done correctly.

So farfor front end vibration the workincludes: __________________________________________________ __

Four (4) new Michelin Pilot Sport A/S 245x50 x17” ;Balanced on dynamic balancer

Alignment (going back for a recheck)

Dial indicator hub runout: less than .010 inch
Rotor runout: less than .010 inch
Wheel runout at the rim: .040 inch

Upper control arm bushings, OEM four (4) each, both sides

Ball joint lower w/ wishbone OEM (which includesrear lower control arm bushing), both sides

Shock absorber lower bushing, both sides; upper pads checked out OK, shock tower bolts tight

Front sway bar bushing OK and links are solid and tight.

Tie rod ends are tight.

Double checked all bolts and fasteners for tightness
_________________

I read about a TSB for steering shaft universal joint. Any possiblity this could be the culprit?

 

Hey Gordo,

Basics first.

Is the wobble in the steering wheel or your seat?

Did you try rotating the tires fr to rr one at a time?

Does this aftermaket wheel/ lugnut combination fit the hubs properly, i.e. are the wheels hubcentric?

The stock wheel is a close tolerance fit on the hub boss, front and rear. And the lugnuts are not a taper seat against the wheel, the stock ones have a shoulder which is a close tolerance fit inside the mounting holeof the wheel.

You have measured little radial runout, but if the wheel is not hubcentric you may have axial runout.

 

I read that and it looks backwards. You get my point.