I finally got around to replacing my rear shocks with green Bilsteins, and the springs with lower/firmer Minas. I also replaced the spring isolator and packer (switching from the stock 6mm packer to 3mm packer).

The stock rear ride height with 1/2 tank of gas is about 15" (measured from center of wheel cap to edge of fender). Before replacing parts the measurement was 13.75', which i attributed to sagging springs. I expected the "after" measurement to be about 13.25-13.5". However, it was 12.63", which is too much. I am looking for suggestions as to why the car is sitting quite so low. I can switch the packer back to the 6mm, but I am wondering if something else (collapsed subframe bushings?) is going on.

Opinions?

 

Seems a big drop from stock to start.

Per Workshop manual, XJR NAS rear suspension showroom height (1/2 tank) 382mm or 15.02" so you are dead on there. Maybe try the Curb weight with full tank and see where you are, the stock the difference was 10mm or .4" but also say build variance of 15mm or .59"

The Mina springs and smaller shim should give a 1.3" drop (1.2"+.1"), pretty close to the drop height between the before and after 13.75 -> 12.63 .

30mm plus 3mm drop almost equals the 349mm->320mm ride height in non-freedom units.

Regardless of the change in height from springs and shim the overall is still about an inch low.

Did you replace the upper spring isolator (foam ring)?
How do the bushings on the differential strut, or K-bar mount look?

Assuming you aren't missing parts like the spring pan and spring seat, and do not have excess weight in the trunk/back seat I would have to assume those bushings above are toast.

Even if the stock springs were sagging an inch from the beginning the switch to the Mina should not have changed the ride height much. There is something else sagging and the two places above are the first two suspects.

 

I did replace the upper spring isolator with new units. I do not know what the condition of the bushings on the K-bar mount look like. I will crawl under and inspect tomorrow.

Dan

 

Where exactly is the K-bar mount?

 

I'd double check the A-frame bushings as well to see if they are stretched (bosybsitting too low in them) while down there.

Outisde of that I'd drive a bit to make sure everything is settled and have another measurement because after that I'm running out of ideas....

 

I take a slightly different view on it.

You mentioned you took measurements before the change, then again afterwards right?
I don't believe too much that something else 'collapsed' just because you had the car on a lift changing shocks.
Yes, it can happen, but imo there is something in the re-assembly.

I have always wondered about the difference in packer thickness.
I still think it allowed Jaguar to modify the ride height between the NAS and the ROW, using the same springs.
If that is true, the 3mm represents ~1/2 inch difference, explainable due to the geometry of the suspension arms).

I think if you change the packers back to 6mm, you will get some 1/2" suspension back, and I guess the rest is from the Mina springs (they are lowered version after all, aren't they?)...




Should be interesting to see some measurements from the packer-change.

 

Just for information, on my one owner, 40,000 miles, 2001 XJR (NAS) with Milan wheels and 255/40/18 new tires, front is 14.5 and rear is 14.25
Obviously tire sizes has a big impact on ride height

 

Luc,
If you measure according the Jaguar spec, any tires size / rim size is ruled out, cause you measure from the middle of the axle to the apex of the fender.
If you should measure from the floor, yes, then rim and tire sizes are an issue.

 

Eric
of course you are 100% right. I must have had a brain fart (or old age)

 

Dan, did you ever sort this?
I am extremely interested on the packer thickness issue.

E.

 

Eric,

The firmer ride with the Mina springs, and the increased negative camber, were not to my liking. So, I replaced the Mina springs and thinner packer with the stock springs and thicker packer. My current set-up is: new rear shocks, new spring isolation donut, and stock 6mm spring packer. With a full tank of gas the rear measures 14.0". The measurement with a 1/2 tank of gas was 13.75" before any of this started. I would conclude that the deteriorated springs isolation donut was responsible for some of the drop, and that there is some spring sag as well. Also, I am going say that the thinner spring packer does have an effect on height in-line with the difference between 6mm and 3mm (and not a multiple of the difference that has been discussed in previous posts).

 

Thanks Dan!

The info I was looking for, although debunking my theory ... now I am really wondering why Jaguar is using the 2 different packer thicknesses ...

 

What are the part numbers of the 3mm packers. Might be a good trick to drop my VDP some.

Does the front have similar packers?

Trying to make a VDP/ sporty sleeper. Keep it all stock looking but corner flatter. So far XJR Sport "red"mono strut, rear sway, regular Bilsteins (may need to go to R) and powerflex K bushings.

Was thinking about going to R springs, but if I can get roll stiffness and balance in place with stock I will keep the long springs in place.

Lowering with packers would be handy!!

 

I have no part numbers, but if you search under suspension on any Jaguar parts supplier, you will see them showing up in 2 different sizes for front and 2 for the rear.
But the difference is only ~3 mm, so if the conclusion is true, it will not do much.

And I read some bad experience combining the green (XJR) struts with the comfort springs, but no personal experience.

 

Yeah I am a little leery of that combo. I would imagine they would pump down pretty fast without the stronger spring.

I think roll stiffness to balance the car is my answer and leave the long travel suspension alone.

Thanks for the info....

 

2 different packer thicknesses are listed on the SNG Barratt website. That is where I purchased from. I am going to use the thinner packer at the front (replacing all of the front end bushings tomorrow), but you are welcome to the thinner rear packers if you would like them.