So my last year I had the shocks replaced all the way around on my Jag by my Jag guy (who are professionals.....), but the front end STILL sounds like crap! You hit a bump and it's like there's no shocks at all, making a bunch of racket and feeling like your teeth are going to break. Is there something I'm missing?! Ideas and suggestions welcome!

 

Could it be that the isolators (located either side of the mount, where the shocks bolt into the engine compartment) need replacement or weren't tightened properly? The shaft of the shock needs to be held from rotating when the nut is tightened down.

 

Good to know. I'll have to check that out. Thanks!

 

This is a VERY common issue and the car does indeed sound like crap when this happens.
I just had to do this on a 1994 XJ12 (XJ81) car where a previous mechanic had not properly tightened down the right front upper shock nut.
There should be a spacer in there that prevents over tightening the nut and you will definitely feel the nut stop when it reaches the space.
You might have to grab the flat spots on the top of the shock shaft to accomplish this procedure.
This means you will have to use a wrench rather than a socket to actually tighten the nut.
Depending on what side you are working on, you might have to temporarily move the either the radiator coolant tank or the power steering reservoir out of the way while you do this since the shaft and nut are under these items.

BTW, I usually completely disassemble this upper shock attachment so I can make sure all the parts are indeed present and in good condition.
The OEM upper shock bushings are crap. They are made out of a soft foam instead of rubber. I usually replace them with actual rubber bushings.

 

But those rubber uppers can feel very harsh. That's what I've heard anyway. The Uros I bought are very hard and I didn't even try them.

Yes the OEMs are soft, but they are better than the aftermarket foam copies.

You must also consider the lower shock bushing. If it is gone by now (not replaced already) it would make a lot of racket over bumps. The lower bushing doesn't come with the shocks and can be difficult to replace; hence easily overlooked.

 

Good things to know. I'll probably jack the car up and take a look myself. I had the Jag garage do them, and you'd think they knew how to do it considering they work almost exclusively on antique Jaguars, but when I throw questions out about the 40, they seem lost. Thanks for the advice!