While driving, whenever driving over a bump or dip, there's a noticeable THUNK on the passenger side front end. It's as if the shock is OK, but whatever connects the car to the shock is loose, something like that. When the car is in the garage and I give it the shock bounce test, all is well there. Car is not lopsided, sagging or the like.

I know that's vague, but I am not mechanically inclined. What are all the possibilities? I see talk of bushings, but I haven't a clue what those even are.

 

Bushings are bits of rubber that connect suspension components to the car (or to each other). The idea is to allow some compliance so that too much noise and vibration isn't transmitted to the cabin.

They have a limited life before splitting, cracking, or otherwise falling apart. Then metal hits metal, and THUNK.

The shock absorbers have bushings at the top mounting to the body, and at the bottom where they are mounted to the control arm, both of which are prone to failure.

 

Is that an easy repair? As in, something I could accomplish as an amateur? If not, what do bushings run? I have a trustworthy mechanic.

 

The upper ball joints are normally the first major item to go. You can test with the wheel lifted -- grab top and bottom of wheel and see if it moved.

The sway bar bushing and links will also make noise -- not the same thunk as the ball joints

 

You don't mention what year and how many miles, and I assume you have a XJ8.
If you are replacing bushings I would suggest you include the sway bar mounts and end links, as yeldogt mentioned. They are inexpensive and easy to replace.

 

I have a 2001 XJR with 78,000 miles on it.

 

And as cute as Earth is, where do you live? temperature and weather matter: Earth is big ^^^^ing place. If you are already freezing, your problem is hard rubber . . .

 

Since you mention a mechanic -- it's best to take the car to him for a look .. and a drive.

There are numerous bushing and joints that could be causing what you describe -- some very easy and others more involved.

Age becomes a factor with tie rod ends and ball joints -- the boots crack and the joint grease becomes compromised. They fail in short order. Normally -- the ball joints would be fine at 78 k -- I just had to replace them on one of my 02's with 68k.

In most cars the sway bushing and links are the first place to look when searching for a front suspension noise ... I have owned 5 x308's, none has needed them.

 

I get an equivalent thunk on the left side at or just forward of the A-pillar when the body flexes over drainage runs and speed bumps. Significantly worse in cold weather (below 40*F). Replaced the sway bar bushings (an easy job) and the links with little change; problem started when I changed the upper shock mount bushings (harder neoprene). I can quiet it down with silicon spray (unless it is real cold outside then the thunking sound is much more frequent). My local guy thinks the more frequent cold weather thunking was caused by the shock rod bouncing against the metal mount bushing; he shimmed it, which helped a little.

But I think some of the noise is from the ancient body flexing (the car, not me, although I also have flexing groans, but not thunks, yet) or dried and stiff body mounts.

 

So far on my 2002 I have replaced :

Front :

One upper balljoint
All 4 bushes in the upper control arms
The sway bar mounts and links
The shock upper mounts
The shocks themselves, which come with the lower bushes

Plus at the rear : the sway bar mounts, links, and the bushings in the links.

 

A thunking noise is almost always the sway bar bushings/links.

I replaced my front upper shock bushings, front and rear sway bar bushings and links on my 76K mile 2001 XJR, cost about $250 in parts IIRC and took about 3 hours to install myself.

The front shock bushings are $70 a pair, complete assemblies from the dealer are $300+ per side. I bought all the parts off Ebay.

Fairly easy and cheap DIY project and made a huge difference.

The front shock bushings require that you take them to a shop to have the old bushings pressed out and new ones pressed in. You can also do it with an appropriate sized socket and a BFH but the danger is if you break it you are back to $300 for the part from the dealer. The rear sway bar is small and light compared to the front, which is quite heavy.

Made a tremendous difference in how the car drove, handled and it felt "tight" and new again. It also cured a slight vibration issue I couldn't solve via other means.

I posted a thread with pics about replacing the front upper shock bushings. If you search, you will find it.

There are also threads on replacing the sway bar bushings and links on the forum.

Do it!
Vector

 

I would be surprised if it is the body ....

The design of the suspension is such that it has many bushing --- and aftermarket suppliers have been touting the benefits of harder longer wearing bushing for as long as I can remember . Sadly, most cause noise or roughness in pursuit of longer life. Same goes for the engine and subframe mounts.

 

I was doing some general maintenance under the hood, and, keeping in mind the clunking sound from the right side and just reading about bushings etc, I decided to play around the shock absorber area. I found it rather loose! The foamy "NAPD" yellow piece moves around (side/side, up/down) without applying much force, and I can spin the nut quite easily as well, although I noted the bolt moved along with it so I believe I wasn't gaining anything.

Should I do anything? Secure the bolt in place while tightening the nut?

 

Since no one has replied, do nothing? Either that or I didn't describe my findings very well.

 

Yes, tighten. The nut may be loose because the upper and lower foam bushings are failing and should be replaced. I recently did that on my XJ6 and if the XJ8 is the same design it's quite easy.

 

You need to renew the upper shock mounts. Plenty of threads in this forum describing how, where to buy the parts, and issues around various ways of doing the job.quite likely you also need to replace the lower shock mounts, which are integral to the shock absorber. Next up, the bushings for the swaybar, and then the links. Search on shock absorbers; Shock absorber mounts; Swaybar bushings; drag links. Search both this forum and Google. Tons of information.

Specific to tightening the shock: use a box wrench on the large nut, while holding the shock Rod still with vice grips (or shock absorber wrench if you have one). I would guess that if the nut Titans in a bit (Siri you're dumb ***!) Tightens any bit, you have found your problem.

 

As has been said, replace the upper shock bushings, not the entire mount, cost is about $70 including paying a shop to R&R the bushings with a proper press.

Your bushings are going to turn to orange dust soon otherwise!

Complete mounts with new bushings from Jag are about $300+ per side, so this is an economical way to tighten things up.

My DIY thread with pics:https://www.jaguarforums.com/forum/x...cs-how-128562/
Vector

 

I had the same clunk and also had a nice vibration at 50mph to go along with it, replacing the steering rack and tie rods solved all of it.

Cheap and easy, drives like new.

I also replaced the shock bushings a year ago with no change.

 

Well... I tried tightening the nut by using two adjustable wrenches, one for traction and other for counter-traction. The nut wouldn't budge very well so I gave it some juice, and the top of the bolt (where you can apply the wrench) sheared right off. Now there's nothing to grab on to. Problem?

 

Pic.