Anyone ever try them? My car is bouncing all over despite a new complete set of poly bushings, and uprated shocks you can pull the car up and down with two hands fairly easily is this normal?

I wanted to try coil stiffeners before splurging on the uprated springs and associated replacement cost.


something like this:
https://superpro.com.au/blog/111-coil-spring-spacers

 

I'm not a fan of items like this. Your XJS shouldnt be bouncing at all IF the shocks are quality replacement likes Boge, KYB or Bilstein. Even with worn springs it shouldn't bounce. I just replaced a set of worn V12 spring with fresh ones. There was a noticeable difference. The car no longer felt like it's legs were coming out from under it over rough surfaces. I reused the same Bilstein Shocks too.

What shocks do you have?

 

KYB grey shocks front and rear.

I'm wondering if my coils are just shot. Id like to see how much lift other people can get from physically bouncing their cars...mine just feels sloppy now. I have put about 600000 miles on since buying so who knows but the shocks are faiiiirrrllly recent.

 

KYB fronts are OK but kind'a too soft for a V12. They are fine for a I6 sedan or AJ6 but I can tell you they're not ideal for a v12. Bilstein Yellows with rubber upper shock mounts are a good combo for the front of a V12. KYB rear shock are fine and they happen to be stiffer than the Bilsteins out back.

Get a Bilstein and compare it to a KYB, the KYB collapses like a footballer looking for a call.

 

The thing is it never used to be this bad, it *was* quite planted before but has progressively worsened to the point of being noticable. I (in the past week) now have mismatched tires to as Im waiting for another two replacements for the discontinued type im on now. Rear tire is goodrich all terrain something or other very meaty tread front is worn yokohama touring tires which may not be helping as I can testify the rear has quite an effect on steering/handling if things are not right.

 

Vancouver
The springs are shot, I would say. Even with shocks disconnected you should not be able to easily bounce the rear of the car through a wide amplitude. having said that, the shocks are shot too, if they were OK, the car would also be stiffer.

 

I can't say mine moves much by hand and i have the same shocks...put on last year. Hope they are not prone to early failure. Sounds like something's let go on yours though.

 

The shocks when new did make quite a difference though if they are carrying more of the car's weight for the past 20000+ km maybe they're spent due to excess wear. I'll upload a video shortly showing the bounce.

 

Part 2:

Did a 1000km road trip - The car's rear end is wigglying at 20-60kph and tram lining on flat fresh ashphalt (literally day old pavement) on the highway at speed, lane changes and turns feel like the car is leaning over itself despite fully pressurized new tires.

Does this bs ever end? I did every sub frame rack shock suspension mount bushing and rubber pancake in the list in the past two years how does one thing throw it all off so badly. Before this I could dart between pylons at crazy speed with 1 finger (poly Superflex bushings help) now I hug the inside lane incase it bounces or the steering is delayed by 2-3 seconds.

On top of that driver side wheel now sounds like a stuck brake...or dry bearing...that dry metal scrapey noise.

5 years I've had the car as daily driver and I'm about done. My ford truck you could drive through a house without so much as a second thought much less this. Can't keep a tow truck on speed dial for ever.

 

I wonder if the tramlining is wheel alignment and incorrect castor. Have you had one done since the bushing work?

 

KalTire did one less than 3000km ago though something tells me their system isn't "Jaguar" specific enough. Maybe I'm just not trusting non-Jag shops but Thing is I had no issues after their alingment and tires. It was quite solid.

Almost feels like a subframe failure the way the butt wiggles like a cat...****. Well if nothing else I'll take Grant's advice to heart and keep drinking till the problem and or pain goes away.

 

Rear end moving is one of the following:

• radius arm bushes/attachment
• outer lower fulcrum bearings
• springs and shocks gone home/shock top mounts broken somehow
• lower inner fulcrums moving (eg shims fallen out)
• hubs bearings gone home (very unlikely)
• subframe mounts gone home.

One of the problems with stiffening up everything with poly is that the remaining rubber components have to take all the designed in flex, and then go home as a result. Once you start looking, it will be obvious what is doing it. Courage as they say over here, remember that a Jaguar is a Mistress, a Ford is a wife.