I am having the front lower subframe (Crossmember/K frame) replaced in my '99 XK8 due to elongated holes at the Upper control arm pivot point. I have the opportunity to replace most of my front end proactively for the cost of the parts (I provide). Even if not an overt problem would you replace:
1. Upper and lower control arm bushings
2. Upper and lower ball joints
3. Tie Rod and Sway bar end links
4. Shocks, Upper Shock Mounts
5. Antisway bar bushings
6. Eccentric alignment bolts
7. Anything else I'm forgetting?

I am replacing the upper control arm pivot bolts and nuts and washers. Cross your fingers with me because I bought the used subframe off Ebay from a reputable seller showing car with no front end damage and am installing it at very reputable local Indy front end shop but not Jag specialist. Nearest reputable Jag Indy I know is 200 miles...

 

Clearly, if you are replacing the subframe all of the suspension components will be out and easy to get to. So, yes being proactive and replacing all the items you noted makes good sense. You should also check the condition of the engine mounts and the subframe mounts as as they may also need to be replaced. When you receive the subframe unit check it over real carefully for signs of stress/impact fractures.

Good luck on the rebuild.

 

I take the other point of view, Thre is no clear pattern of failure in the front end of this car. You would be taking a crap shoot unless you replace everything. My experience is that many front end components get replaced due to misdiagnosed wheel and tire issues. The weakest part of the system are the sway bar bushes, but they are easy to change at any time.

 

All that was diagnosed as faulty was the upper control arm bushings and the bolt that goes through them (in addition to the subframe...). I agree about the sway bar bushings, but already replaced them with poly. I know one of my ball joint covers is mangled, but no overt ball joint issues. If the contol arms are out the lower bushings and ball joints are fairly inexpensive (Jagbits), although my Indy shop may mangle them trying to replace the ball joints... My initial impulse was replace everything, but it adds up despite the labor savings. I am now holding off on the shocks and upper shock mounts (still centered) as I could replace these myself (with Reverand Sam's awesome video) if necessary. The kicker is that if I still have issues once the thing is back together then I either start replacing ***** nilly or deal with a 3 hour commute for service. The other factor is once torn apart the availability of parts and whether the shop will let me buy my own (and overnight them...). Paying Indy shop retail for last minute Jaguar parts could make me wish I had just supplied everything... Really Appreciate Everyones input!!

 

At 82k, I'd do the rebuild for the parts prices and not worry about them again for 50k more miles, if at all (due to 'improved' rubber bushings). Shocks, definitely. you'd be amazed at what new shocks do to the ride...rebound quicker, stiffer initially too. I know its $100 here and there, but if you have the money to spare now, and serviceability down the road worries you, the decision becomes even more clear. +1 on checking the motor mounts too as goldlion recommended.

 

What symptoms led to this diagnosis? There is currently a thread on another forum about the same problem on a similar year XJR. It seems the members there are more familiar with the problem in the UK.

As far as the rest goes, you have three alternative approaches available:

- buy and replace those parts you know you do not want to do yourself

- buy everything from vendors who will accept returns, inspect and replace as required, return unused parts

- buy everything and keep the remaining parts as spares or resell them

 

The front end was clunky over bumps at 65K. Some I considered the price I paid for 1 inch oversize wheels and slightly lower profile tires. Sway bar bushings were shot and there was a little play in the right front wheel. Popped out the upper control arm bolt and the bushings seemed snug but the slight elongation of the holes through the subframe was noted (less than 1/8" for a half inch bolt hole in the up/down direction). There is another thread where a guy drilled out and sleeved the subframe (once it was off the car) but used subframes are pretty reasonable on EBay. Buttoned it back up and the new sway bar bushings tightened things up significantly and I only drove it casually as a third car. The clunking came back after about 10K. Also felt almost like a bad bearing with two passengers and a tight turn. ALthough I couldnt induce movement with the car on the ground the tire was overtly loose once in the air. There was also a sensation of the front end "loosening" when put into reverse but tracked straight and rode smooth except over bumps.