There is a good amount of information in Kirby’s book
related to improving the handling of the XJS by
installing/ changing the stock ones. I would like to
improve the car’s cornering ability without sacrificing
too much of the ride comfort. Any experince that one may
Have would be appreciated.
Thanks,
Jim McMullen
Tiverton, RI–
jim mcmullen
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In reply to a message from calhoon sent Mon 4 May 2015:
The first thing I would do and have done is upgrade to
polyurethane Swaybar and steering rack bushings. I would
be surprised if you would need much more than that for
street driving.
Jim–
87’ VDP (black), 86’ XJ-SC (grey), 88’ XJS sport convert
Fort Lauderdale, United States
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In reply to a message from Big Squatt sent Mon 4 May 2015:
Jim,
If you’ve got a 4.0 convertible, remember that you’ll have
‘‘Touring’’ suspension as opposed to the Sports suspension
fitted to the Coupes as standard. A change to the dampers
such as Gaz adjustable ones can make a lot of difference even
if you keep the stock springs.
Paul–
Paul 04 x350, 4.2 SE, 94 XJS 4.0 Conv, 97 XJ8 Sov LWB 4.0
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In reply to a message from calhoon sent Mon 4 May 2015:
I have installed an anti sway bar to the rear of my 94 XJS
coupe. The bar came from a 78 XJ-S parts car I have. My 94
XJS radius arms were already fitted with the brackets for
the sway bar links and the studs and nuts were present to
receive the sway bar brackets. The car feels much better.
It is hard to describe but it feels planted. Ride quality
is better and not rougher at all.
Stephen–
The original message included these comments:
There is a good amount of information in Kirby’s book
related to improving the handling of the XJS by
installing/ changing the stock ones. I would like to
improve the car’s cornering ability without sacrificing
too much of the ride comfort. Any experince that one may
Have would be appreciated.
Thanks,
Jim McMullen
–
dizmando
West Jefferson Hills PA, United States
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In reply to a message from dizmando sent Wed 6 May 2015:
Stephen:
You are the first person I have seen post that their radius
arms were equipped with the brackets for the sway bar
links. I have not seen this on the XJS except for the
earliest models (1970’s) for which this was standard.
The OEM bar is pretty thin, but probably does just about
right, especially if you have the OEM bar in front.
To the point of the thread:
I run the Addco front and rear bars, and had to craft
brackets for mounting the rear links. Was easier to do
than I expected.
Adding the heavier front bar made a very noticeable
improvement, and adding the rear addco bar flattened things
out very nicely. Rear gets twitchy in the rain, though,
and I can feel the rear getting ready to break loose when I
push the car hard. But for 99% of the driving I do, it’s a
great change. But I can see why road racers do not use the
rear bar, and instead pay attention to shock valving and
spring rate to get the desire result.
Poly helps, too, on the front end. On the rear, I think it
makes more sense to spend time locating that cage and
locking down the fore and aft movement. The rear wheel
steering due to the radius arms isn’t too bad for street
use, as long as the bushes are in good shape. When those
go bad, and the cage mounts are iffy, this car can be a
handful on high speed sweeping turns.
What to do in terms of all this depends on your model: if a
convertible, be very careful, because these cars are not
nearly as torsionally stiff as the coupes. The later
facelift convertibles are probably better because Jag
finally fitted X braces front and rear. But the earlier
models are pretty flexible, and stiffening the suspension
too much will only make you unhappy.
I have lowered/adjusted the ride height on my car by
removing the packing rings in the front spring towers and
by the use of limited spacers in the rear to bring the
heights in front and rear to where I want them. This has
also had a very positive effect on handling. I was going
for the TWR XJS-R spec when I did this (the lowering and a
tire/wheel change were worked to get here), and I can see
why these cars were set up this way- good results.
Personally, I chose to keep the OEM spring rates and shock
valving (well controlled but far from stiff), and then
increase the roll stiffness with the front and rear bars,
and add some poly to the front suspension. I run 245/50-17
in the rear and 225/45-17 in front. These have added
stiffness to the suspension (especially those 45’s on the
front) and this is about at the limits of what I can
tolerate in terms of ride change. Car is great on the
freeway, rides extremely nice. On rough city roads it’s a
bit jarring at times, though. Not quite the magic carpet
it was when set up OEM. But then, it out handles the OEM
setup by far.
-M–
Mike, '90 5.3 XJS Conv., 5-spd+3.54, SE-ECU+TT F/R bars
Lakewood, OH, United States
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You are the first person I have seen post that their radius
arms were equipped with the brackets for the sway bar
links. I have not seen this on the XJS except for the
earliest models (1970’s) for which this was standard.
Late 70’s/early 80’s Jaguar deleted the rear bar altogether, and
deleted the attachment points. Sometime in the early 90’s Jaguar
added the rear bar back in on SOME models (Sportspak, etc.). Since
the attachment points would be necessary on these cars, perhaps they
added them back on ALL the trailing arms. That’s what I woulda done
if I were Jaguar, as it’s simpler than trying to keep track of which
cars on the assembly line get which trailing arms.
The OEM bar is pretty thin, but probably does just about
right, especially if you have the OEM bar in front.
It is pretty thin as anti-roll bars go, but it works wonders on this
softly-sprung car. Others go with the much, much, MUCH heavier bar
offered by Addco. That’s where things get complicated by the
trailing arm bushings. On most cars, the rear anti-sway bar is
connected directly to the rear swingarms with only a minimal amount
of rubber bushings. But on the XJ-S, the anti-sway bar attaches to
the trailing arm, and the trailing arm attaches to the rear swingarms
with a big, soft, cushy rubber bushing. Hence, you put on that
massive anti-sway bar and it doesn’t seem to do much because the
trailing arm bushings are absorbing its action.
If you just want a more stable drive for the street, go with the
light rear bar. If you want more than that, replace the bushings at
the REAR end of the trailing arms with poly. Only if you want
competition stiffness would I recommend the Addco bar, and I’d
suggest the poly bushings along with it.
Note that some have reported that, for competition, they take the
rear bars OUT. I’ve driven street cars with and without and it’s
difficult to imagine without being competitive, but they put really
stiff bars at the front and are free to adjust tire pressures and
even tire sizes to achieve the balance they need. On cars without
powr-lok in the diff, a rear bar can cause lifting and spinning of
the inside rear tire in a turn, but this car has powr-lok so that
shouldn’t be an issue.
I run the Addco front and rear bars, and had to craft
brackets for mounting the rear links. Was easier to do
than I expected.
Yeah, I did that, too. Really easy. I handed it to a welder and he
managed to weld them on without even removing the nearby rubber
bushings. If the bushings had been damaged I had planned to push
them out and install new, but I ended up not having to.
Poly helps, too, on the front end. On the rear, I think it
makes more sense to spend time locating that cage and
locking down the fore and aft movement.
Of course, the FIRST order of business is to lock down the steering
rack with aftermarket bushings – unless you have the OEM Sportspak
steering rack bushings. But yeah, it helps to remember that Jaguar’s
objective was a world-class ride, not performance. If you’re more
interested in driving enjoyment, judicious use of poly bushings is
warranted.
Personally, I chose to keep the OEM spring rates and shock
valving (well controlled but far from stiff), and then
increase the roll stiffness with the front and rear bars,
and add some poly to the front suspension.
I wholeheartedly agree with that scheme. I’ve even heard of racing
teams that go for soft springs and stiff anti-roll bars as a general
policy. And I’ve watched racing teams lose races because their
springs were too stiff.
In addition to the poly in the front, I would suggest poly at the
rear end of the rear trailing arms.
– Kirbert
// please trim quoted text to context onlyOn 7 May 2015 at 6:07, mike90 wrote:
In reply to a message from dizmando sent Wed 6 May 2015:
good to know. Thanx! I’ve been looking at Addco swaybars
for my XJS and XJ6, my fear was it would destroy the famous
Jaguar ride. Thanx for the update
Mark–
The original message included these comments:
I have installed an anti sway bar to the rear of my 94 XJS
coupe. The bar came from a 78 XJ-S parts car I have. My 94
–
God made women in the likeness of a Jaguar
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In reply to a message from Kirbert sent Thu 7 May 2015:
I have an 88 XJ-S coupe that I have put The Drivenman sway
bars on. This car does have the mounting studs in place
from the factory. The radius arms did not have the brackets
and I had to add those. I will casually check my other XJ-S
to see if they have the mounting studs in place. My 88
isn’t at a point where I can drive it but once it is one
the road I’ll report on how I like the ride. It does have
the full performance suspension upgrades from The Drivenman
installed on it. My 94 XJS does have the 6.0 liter upgrade
wheels and rear spoiler on it. Maybe someone made a mistake
and put the wrong radius arms on it. I was surprised to see
that the radius arms had the sway bar link brackets on them.
Stephen–
The original message included these comments:
links. I have not seen this on the XJS except for the
earliest models (1970’s) for which this was standard.
Late 70’s/early 80’s Jaguar deleted the rear bar altogether, and
deleted the attachment points. Sometime in the early 90’s Jaguar
added the rear bar back in on SOME models (Sportspak, etc.). Since
the attachment points would be necessary on these cars, perhaps they
added them back on ALL the trailing arms. That’s what I woulda done
–
dizmando
West Jefferson Hills PA, United States
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In reply to a message from dizmando sent Sun 10 May 2015:
I purchased a used rear bar to install on 95. The trailing
arms have the two ‘‘ears’’ to attach the down link, but the
body mount is not there. There is a difference at the body
mounting point for cars that have it VS the cars without.
Where the two studs go through the body there is a small
welded plate with the studs attached from under the rear
seats through the floor. There is a welded strip about 6 or
8 inches long on the underside of the body that looks like
a channel iron strip just wide enough for the ‘‘U’’ strap to
fit between the 1/8th to 3/16th inch down faving verticals
of the channel iron strip. The strip is actually heavy
gauge sheetmatel, but you know what channel iron looks like
so I used that visual. I forgot how to include a picture
with this so I will try to post them later.–
The original message included these comments:
I have an 88 XJ-S coupe that I have put The Drivenman sway
bars on. This car does have the mounting studs in place
from the factory. The radius arms did not have the brackets
and I had to add those. I will casually check my other XJ-S
to see if they have the mounting studs in place. My 88
–
Ron - Purr more…Hiss less 95 XJS Coupe 4.0 , 99 XJ8L 4.0
Lawrenceville Georgia, United States
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In reply to a message from rppetrey@bellsouth.net sent Wed 13 May 2015:
see my photos for pictures.
Rob–
Robert Laughton www.leatheriquecanada.com 1999 Super 8
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would you mind either posting pictures on the forum or sending to me in private. I’m interested in where and how you mounted a rear sway bar. My interest lies in a (insurance write off -rear ended) XJSC that I’m considering transforming into a track day car.
Thanx
Mark