And how much do they cost to replace? My XJR has 117K miles and I'm not sure if they have ever been replaced.

 

Mine were still good at 130k, but the bushings on lower front had worn out. I replaced the bushings, and were still good. It wasn't until I did a complete overhaul around the 140k mark to fix the rear end, that I swapped them all out. And they were still good then. People get plenty of mileage, but it's usually the mounts and bushings that will go out before the shocks themselves do.

As for replacement, the direct CATS replacements were something around 300 dollars apiece? something like that, I haven't looked recently, so I could be off a bit either way. Or, you can replace them with standard shocks and mounts all around to save some money. I haven't noticed much difference between the CATS and the standards I replaced them with. There are also places that will rebuild your CATS shocks for a little less than new (200ish?) but that obviously requires time so if it's a daily driver, that might not work.

 

Replaced mine at 15 years old, but the car drove better afterward than I've ever felt it, implying they were already bad when I bought the car at 9 years old.

​​​

 

I just recently replaced my rear struts(aka dampeners). One of them went bad and started leaking oil, due to a pretty bad differential output bearing. Keep an eye out for this, will kill your suspension. Look for play when you push in and out on the tire at 12 o clock.

 

I think most people just keep driving till they wear out bushings, make noise or start leaking. Best to replace in pairs IMO if your going to replace one.













To add to what Robert said, slight up and down movement in the rear wheels when checking bearings is normal on the 308's, roughly 2-3 mm of movement, anything over that I would question. However if you get ANY side to side movement, most likely bearing failed.

 

Then life of shocks vary greatly depending on the driver(s) and the road conditions (loads notwithstanding).
The way to check shocks is:
First, a visual for leaks (dampness on the outside of the shock) and the condition of the bushings (look for severe cracking and rubber deterioration.
Second: Rock one corner of the car by hand, violently and let go at the bottom of the "down stroke". The car should rise up and then settle at mid-point. If this is so, the shocks are good, if not, time for replacement.
Caution though. So not be tempted to install "heavy duty shocks" unless you typically carry a heavy load.....the shocks ride much harder...you will most likely not like the ride. Original standard duty will do the best job.
As for price; Just go online and check the prices...they will vary.....;all in all, Midas is probably a good medium

 

whoooops: Obviously, when you rock the corner of the car, the process should be repeated at all four corners.

 

If you have the CATS suspension, which you probably do with the XJR (you can check by taking off the plastic cap on your front shock mount under the hood, if you see a cable connected you have the CATS). The CATS shocks are very pricey, when i was looking a few months back they were about 1000$ Canadian a piece, compared to about $100-300 a piece for non-CATS. If you do not install the CATS shocks, you will have a warning light on the dash(suspension fault).

 

To add: There's a module in the passenger side (US cars) front kick panel that controls the CATS suspension, and removing it will disable the suspension fault indicator. It's how mine has been going for the last 15k miles.

 

I did a carfax last week and saw the struts on my XJR were replaced at 37K miles. That seems early.

 

37k is early for any car. I would say if it wasn't a typo'd 137k, they were probably trying to hunt down another issue and ended up changing them in the process. Especially if they're CATS shocks, those things are expected to last for darn near ever. But even regulars should last well beyond that.

 

According PO records, my car had the original rears replaced at 40k miles / 13 years old.
Don't know why though, maybe bad Bilstein badge?

And my original fronts collapsed (totally empty but no leak) at 70k miles / 19 years several months ago.
Maybe time is an other factor ...

 

That could be very possible. I'm not an expert in shock construction or dymanics, but with low miles over a long number of years, perhaps there are some seals that would wear out, maybe moreso if they aren't subjected to use as often to keep them loosened up? Not really sure. I've always had good lucks on almost all my cars though. Granted, they're probably well on their ways out when I replace them after 100k miles, but you never realize how they've gone until you replace them and go "wow, so THAT'S what it feels like again"