Jaguar XJ-S. Manual - part 91

 
 

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Modern kits often feature hollow anti-roll bars.  Compared to solid bars, a hollow bar of the same diameter would be 
weaker -- but that’s not the comparison to look at.  Here’s what’s important:  Compared to a solid bar of the same 
stiffness, a hollow bar will be larger in diameter yet lighter in weight. 

 

ANTI-ROLL BARS -- WHAT YOU’VE GOT:  Really good question, actually, since apparently there are a lot of 
different configurations.  Most of the info in the chart below was provided by Chad Bolles. 

 

 

Front Anti-roll Bar 

Rear Anti-roll Bar 

 

P/N 

dia. 

Bushing P/N 

P/N 

dia. 

Bushing P/N 

1975-82 5.3 

C36887/1 

7/8” 

C32925 

C42178/2 

9/16” 

C44931/2 

1982-87 5.3 

C36887/1 

7/8” 

C32925 

None 

n/a 

n/a 

87-on 5.3, 6.0 

C36887/1 

7/8” 

CAC4651/7 

None 

n/a 

n/a 

5.3 SportPack 

CBC5579 

1” 

CBC5580 C42178/3 

5/8” CBC4901 

6.0 SportPack 

CCC7198 

 

 

 

 

 

4.0 Coupe 

C36887/1 

7/8” 

CAC4651/7 

 

 

 

4.0 Convertible 

C36887/2 

 

CAC4651/6 

 

 

 

4.0 Cpe SportPack 

CCC7197 

 

CBC5580 

 

 

 

XJ6 C36887 

3/4” 

C30502 None 

n/a n/a 

 

Typically, the brackets holding the anti-roll bar bushings will not change with bar size; the outside of the bushing 
remains the same, only the size hole through the middle varies, so the same bracket can be used throughout.  Note that 
the brackets for the front anti-roll bar on the XJ-S were originally C30500 (r) and C30501 (l), but after VIN 179737 
changed to CBC5336 (r) and CBC5337 (l).  Some of the same bushings were used before and after this change, so 
either set of brackets is apparently compatible with any bushing. 

 

ANTI-ROLL BARS -- SUGGESTED CHANGES:  As noted above, the 1982-on baseline XJ-S has a 7/8” front anti-
roll bar only, and understeers accordingly.  However, cars prior to VIN 106452 came with a 9/16” rear anti-roll bar as 
well.  These parts can be added to the later XJ-S, and were designed by Jaguar to provide balanced handling when used 
with the stock front bar.  The radius arm assemblies must be replaced to provide attachment points for the anti-roll bar, 
or attachment points can be welded onto the existing radius arms.  The mounts on the underside of the car were still 
being provided as late as 1988 and possibly later: a reinforced area with two studs on each side of the car, just above the 
radius arms. 

For the pre-1982 anti-roll bar assembly, the part numbers and quantities are as follows: 

   ITEM P/N QTY 

 

 

Radius arm assy 

C41831 

2 

 

 

Rear Anti-roll bar (9/16”) 

C42178/2 

1 

   Bushing 

C44931/2 

2 

 

 

Bracket 

C42114 or C3054 

2 

   Link 

C42907 

2 

 
 

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This is a really light bar, and the change in ride from adding it is minimal.  It does help the handling considerably, 
however. 

While adding a light rear anti-roll bar can do wonders for the balance and handling of a street car, it by no means 
eliminates body roll entirely, and certainly will not make an autocross champion out of the XJ-S.  For those who wish 
to get serious about cornering, an excellent plan is to replace the 7/8” front bar with a stiffer one, and to install a 
suitably heavy-duty item in the rear to match. 

“Sportspack” models come with a stiffer front anti-roll bar, and a rear anti-roll bar that is stiffer than the pre-1982 
model described above.  The part numbers are as follows: 

   ITEM P/N QTY 

 

 

Front Anti-roll bar (1”) 

CBC5579 

1 

   Front 

bushing 

CBC5580 

2 

 

 

Radius arm assy 

C41831 

2 

 

 

Rear Anti-roll bar (5/8”) 

C42178/3 

1 

   Bushing 

CBC4901 

2 

   Bracket 

C3054 

2 

   Link 

C42907 

2 

Addco (see page 710) offers a 7/8” rear bar, along with a 1” front bar.  Note that a 7/8” rear bar would be almost four 
times as stiff as the 5/8” bar that comes on the Sportspack!  It is clear that the two Addco units are intended to be used 
together; Addco does not offer a rear bar suitable for use with the stock front bar under the mistaken assumption that all 
XJ-S cars come with a stock rear bar as the pre-1982 models did. 

Unfortunately, since their kit assumes the existence of a rear bar, it doesn’t include the links and other parts needed to 
connect the rear bar to the rear suspension of later cars.  To use their kit it will be necessary to purchase the links from 
Jaguar, and the radius arm assemblies will need to be either modified or replaced.  When ordering, check that the 
Addco kit comes with a bracket (a bushing will be included, since it is larger than stock); if not, the Addco “D” series 
or “W “ series are suitable brackets. 

Gran Turismo Jaguar (now defunct) offered anti-roll bar kits for the XJ-S with two features of note:  First, the rear bar 
appeared to have an end link assembly that mechanically attached to the radius arm without needing to weld on an 
attachment.  Second, while their bars could be installed the same way the OEM bars were installed, they could also be 
set up with slider links that provide an adjustment to the anti-roll stiffness.  

 

POLYURETHANE SUSPENSION GOODIES:  Polyurethane (or urethane) is much stiffer than the rubber used in the 
OEM mounts and bushings.  It is also more durable.  And, due to the nature of aftermarket supply vs. original Jaguar 
parts, considerably cheaper. 

Craig Sawyers says that Classic Spares (page 690) offers several parts. “They are called Superflex, polyurethane, and 
come from Australia originally.  They are sort of a translucent purple colour.  Bottom wishbone (i.e. swingarm) bushes, 
top bushes, rack bushes and anti-roll bar bushes too.” 

It would probably be a good idea to update all comparable parts on both ends of the car at the same time.  Stability at 
speed in a softly-sprung car requires a careful balance of compliance in suspension parts and tires, and making one end 
stiffer while the other is still soft may result in dangerous instabilities. 

 

 

 
 

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Front Suspension 

 

CLUNKS - FRONT:  If something in the front goes “clunk” when you drive over a bump, check the rubber bushings 
on the top of the front shock absorbers.  British non-metallics again.  Any generic rubber shock bushing will do, and 
will do better than the original. 

David Littlefield says, “Generic replacement bushings are available in the "Help!" 

section of your local auto parts store.  Look for the area with a variety of parts on red cards.  The part number is 31018 
and they come two to a pack.  The pack also says "Ford/Mercury" on it, so if you can't find the "Help!" products, 
perhaps you can ask for a Ford/Mercury replacement.  You will need two cards (or four bushings altogether).  I paid 
$2.58 per card at Pep Boys.  I would describe them as being about the size and shape of a medium sized mushroom cap; 
only, of course, with a hole through the center. 

“Replacement is a breeze.  I did both sides in a little over an hour.  The biggest operations are jacking up the car, 
removing the tire, and removing the hinged side of the air filter on each side.  Removing the old bushings and installing 
the new ones is a straightforward and simple procedure.”  Note: you can easily compress and release the shock while 
you’re there, thereby checking that it’s in good shape -- see page 354. 

“The old bushings were the consistency of foam rubber after five years and about 25,000 miles.  These were Jaguar 
replacements done after the car had traveled 32,000 miles over four years on the factory installed bushings. 

“Bottom line:  About $5.00 and an hour and a half of my time for a fix that should hopefully last a long, long time.  
This versus about $25 in parts and $75+ in labor to the dealer for a fix that would last, at most, about 30,000 miles.” 

  Note that the XJ-S has steel washers that fit between the bushings and the chassis; purpose unknown, but it won’t hurt 
to put them back in with the new bushings.  Littlefield says, “The real purpose of the washers seems to be to let you 
know your bushings are bad by clanking around and driving you nuts until you replace them!” 

Some people want to know just how much to tighten the nuts when putting in new bushings or new shocks.  The 
answer: all the way.  The posts on top of the shocks have a shoulder, and the nuts should be tightened until they sit 
down on this shoulder. 

Another common cause of clunks is loose diagonal supports across the top of the engine compartment.  Make sure the 
bolts at both ends are tight. 

Also check for a failed subframe mount.  When the rubber within the mount is torn but still in place it would seem that 
it shouldn’t make any sound, but it does.  There are two doughnut-shaped mounts at the front, and two V-shaped 
mounts near the steering rack.  If the rubber is torn or otherwise damaged, they should be replaced. 

 

FRONT SUSPENSION CHECK:  You may be confident that your front suspension is just fine, but this test is so quick 
and easy you might as well try it.  Stand beside the car and grab the top of a front tire and shake it vigorously in and 
out.  If everything is OK, the only thing you will feel is the flexing of the tires, and you will hear nothing. 

If you feel any slop, or you hear a “clunk” back and forth, your front suspension is not up to snuff.  You should check 
the following items, which are discussed in more detail below: 

 

1) 

Adjustment of the wheel bearings. 

 

2) 

Condition of the ball joints, upper and lower. 

 

3) 

Wear groove on bottom of front axle. 

 

4) 

Bushings at inner end of upper and lower swingarms. 

 

5) 

Front subframe mounts. 

Perform this test and correct any problems noted before having your car aligned.  The repair or replacement of ball 
joints, tie rod ends, swingarm bushings or subframe mounts normally requires realignment, and it’s a shame to have to 
do it over. 

 
 

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Peter Havas says passing the shake test doesn’t necessarily mean all is OK: “The suspension is too heavy to give any  
accurate indication by shaking it.  Okay, if we're talking metal to metal, then yeah give it a shake. But a dried out 
bushing, frozen on the inside won't move.  Bad lower wishbone bushes don't display any bad behaviour at all when 
pushed around.  I would suggest: 

“Uppers:  Remove the wheel.  As the bushing is a mushroom shape and protrudes from the yoke of the wishbone, 
check that the lip holding the metal backing plate is not torn or worn to the point that you can peel it back from the 
plate.  The plate at the end should be uniformly held in by the rubber.  Check for obvious cracking, and if the bushing is 
rust coloured, or seems to seep rust from the mating surfaces around the yoke, or the backing plate.  Insert a longish bar 
diagonally through the upper wishbone, and flex the fitting to check for any undue movement, water seepage, or 
cracking. 

“Lowers:  On the steering wheel side (rhd or lhd) check that the rear bushing is dry.  If it is oil soaked, dig around the 
nut to see of the bush has become spongy.  For the other bushes: ensure that the wishbone is centered on the fulcrum, 
and no rubber is protruding around the castellated nut.  Remove the split pin and nut on the front two bushes, and check 
that there is no rust between the fulcrum (carrier) and the bush.  With the car supported on jack stands, put a length of 
2x4 under the lower wishbone and lift while an assistant checks that there is no play in the bushes. If no assistant is 
available, feel for play or obvious shifting when the suspension is moved.  Using the same longish bar from the upper 
test pry the wishbone directly away from the fulcrum to see if there is any play. 

“The lower bushes, especially in the front, tend to freeze to the fulcrum and "squash" for lack of a better term.  The 
constant chaffing heats the rubber so it starts to come out around the nut on the end.  Usually after many miles, the set 
of the wishbone on the fulcrum is evident.  It really starts to show when someone has changed to nice sticky tires, and 
the suspension is doing all the work it can.  Because of their tendency to freeze up, they often don't display any 
movement at all when static, and people tend to pass them up: "If it ain't broke don't fix it."” 

It should also be noted that, contrary to common belief, a car will not periodically require realignment for no good 
reason.  If a car was correctly aligned at one time and no longer is, it is because parts are either worn or damaged, and 
merely realigning without addressing those parts is unwise. 

 

FRONT HUB REMOVAL:  Michael Neal suggests the brake caliper not be removed when pulling the hub, to avoid 
fiddling with steering lever shims (see page 434).  Instead, unbolt the disk from the hub by inserting a socket through an 
opening in the dust shield.  Then, remove the hub leaving the disk in place. 

That works, but really fiddling with the shims isn’t bad. 

If you do separate hub and rotor, it’s probably a good idea to mark it first so you get it back together the same way.  
Couldn’t hurt, and may help avoid brake shudder problems. 

 

FRONT WHEEL BEARINGS:  According to Chad Bolles, the XJ-S uses standard front wheel bearings, available in 
any auto parts store.  The pre-1977½ XJ-S outer is an A-2, the inner is an A-6.  The 1977½-up car uses A-13 for the 
inner, A-12 for the outer. 

 

FRONT WHEEL BEARINGS/SEALS SERVICE INTERVAL -- ABS-EQUIPPED CARS:  Bruce Segal reports from 
Canada:  “Jaguar was recommending that the front wheel bearing seals be replaced every 15,000 mi (24,000k).  At the 
same time the bearings should be looked at and replaced if there is any evidence of water ingress.  I don’t know if this 
applied anywhere besides Canada.  We found that after going to this procedure front wheel bearing failures 
disappeared.” 

Stefan Schulz provides a possible explanation:  “It could well be the likelihood of contaminant ingress that causes 
Jaguar to specify the change interval.  The grease seal at the inside of the front hubs was changed with the advent of 
ABS.  The pre-ABS grease seal looks like it will properly do the job, since it sits firm in the hub casing and its sealing 
lip rotates (and presumably experiences friction and wear) over the relatively smooth surface of the stub axle.  The post-