Jaguar XJ-S. Manual - part 110

 
 

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for a bracket attached to the caliper being omitted here.  Measure between steering arm and upright at the long bolt, and 
subtract the thickness of the caliper mount lug to determine the shims needed. 

New shims are available from Jaguar in two thicknesses:  C44146/1 is 0.004” thick and C44146/2 is 0.010” thick.  It’s 
really nothing more than a thin flat washer, so you could just buy arbor shims locally or cut washers out of shim stock. 

Whenever changing shims or anything else involved in this steering arm attachment, the car will need a new alignment 
afterwards. 

It is apparent that the shimming between the caliper and steering lever was originally the only place shims were 
intended to be used here.  Step 4 of Section 70.10.10 and step 3 of Section 70.55.02 in the ROM clearly indicate this is 
the only place to be looking for shims upon disassembly.  However, apparently Jaguar decided that shims might also be 
needed between the caliper and the upright, either to center the caliper or to align it properly.  There’s no excuse for the 
machining incompetence that would require shims here for either reason, but Craig Sawyers and others report that their 
cars came with shims in these locations.  Steps 10-14 of Section 70.10.10 and step 5 of section 70.55.02 discuss shims 
between caliper and upright for centering and aligning the caliper. 

The Parts Catalogue doesn’t list any shims for between caliper and upright, but obviously the shims intended for 
between caliper and steering lever will serve. 

It’s pretty easy to get shims in between the caliper and steering lever.   Getting shims between caliper and upright is 
nowhere near as easy. 

If you add shims between the caliper and the upright, you need to be removing the same thickness of shims between the 
caliper and the steering lever! 

 

FRONT BRAKE ROTOR REPLACEMENT:  Jaguar chose to bolt the rotor to the inside of the hub flange, rather than 
the outside like some cars.  As a result, the hub must be removed to get the rotor off. 

The various manuals suggest unbolting the rotor from the hub during this process by inserting a tool through the 
opening in the dust shield.  However, Nance O’Neil points out that there is no need to unbolt the rotor before removal, 
and instead the hub/rotor assembly can be removed as a unit and then disassembled on the bench.  Either way, the brake 
caliper must be unbolted from the upright. 

John Himes adds a tip: “The 5 bolts that hold the rotor to the hub assembly can be very stubborn, especially when 
working alone.  If you place the wheel face down, then place the lug nuts through the holes, now you’ve got a nice big 
vice to hold it in place without buggering up anything.” 

Matthias Fouquet-Lapar has an alternative suggestion:  “I actually took the hub out and put the disk in a large bench 
vice.  When I mounted the new disk, I simply used the old brake pads to protect the disk from the vice.” 

If you intend to have the rotor turned, don’t separate the rotor from the hub.  Leave them together; you get a more 
accurate turning job by allowing the machine shop to mount the assembly by the hub. 

 

FRONT BRAKE CALIPER SEPARATION:  On the front calipers, fluid communicates between the two sides via 
drilled passages through the caliper halves themselves.  Hence, there are seals between the two halves to prevent 
leakage.  If you separate the caliper halves, you’ll want to put it back together with new seals.  Note, however, that the 
square-section O-ring seals used between the halves may be difficult to find, and the Lucas caliper overhaul kit SP2887 
does not include them.  A normal nitrile O-ring -- square-section or not --- won’t work; if you don’t believe me, put one 
in a jar with some brake fluid and watch it for a few weeks. 

Chuck Sparks says the seals are Lucas part number 67320782.  The package these seals come in says they are .325ID, 
.495OD x .070, but measuring one found it to be .079” thick.  Basically, they are 1/2” OD, 1/16” thick (the ID doesn’t 
really matter as long as there’s a hole).  Each front caliper needs two, so you need four per car.  The burgerflippers in 
the local auto parts store are likely to give you a blank stare when you ask about such seals, but according to Rob Reilly 
you can get them from John Farrell (page 708).  John Robison says, “XK's unlimited sells the caliper seals separately.” 

 
 

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It’s also been suggested that you can find suitable seals at a Chevy dealer. 

Coventry West (page 690) sells an O-ring, 1/2” OD and 1/16” thick and made of EPR.  Apparently this works OK; 
according to their rep, “The o-ring will seal better on uneven surfaces than the square seal.  We've never had a problem 
with the o-rings sealing. Not a single warranty or return.”  Nevertheless, most mechanics would probably agree that the 
original Lucas square-section seal is preferred.  It does provide an idea for buying seals locally, since any industrial O-
ring supplier can presumably provide EPR O-rings. 

Brian Schreurs found that Motorcars Ltd. (page 692) lists a “caliper half O-ring” part number IN101648. 

Joe Bialy says, “If you want to cut your own gaskets, McMaster Carr sells EPDM rubber sheeting, a 12" X 12" piece 
1/16" thick is $3.78. Part #8609k31.  I'm sure they'd have the cutters too.  I don't know if it's applicable for this, but they 
also sell 1/2" OD X 1/16" width EPDM O-rings.”  See page 708 for McMaster-Carr. 

On the rear calipers, the fluid communicates between the two halves via an external hard tube so there are no issues 
with seals. 

 

FRONT BRAKE HOSES:  The front brake hoses have coils around them to prevent kinking and to protect the hose in 
case of a tire rubbing against it or debris flying around in the wheel well.  On the ’83, the coil around the original hose 
is plastic about 1/8” thick.  Replacement hoses, however, as well as the originals on some other year cars, come with a 
steel coil around the hose.  Obviously, the plastic coil won’t rust -- but if your steel coil is rusty enough to be a concern, 
it’s probably time to replace your brake hoses anyway. 

Ed Sowell says, “The new hoses I got came w/o coils.  I reused my original plastic ones.”  This is a workable plan, 
since it is a simple matter to wind the plastic coil off the old hose.  If your old hoses have steel coils, though, they 
apparently cannot be removed without destroying them or the hose itself.  Since it probably would not be a good idea to 
operate the vehicle without coils at all, if you don’t have the plastic coils you should either make sure your new hoses 
come with coils or try to get some plastic coils from a junkyard.  And if you’re replacing hoses with plastic coils with 
new hoses with steel coils, you may want to wind the plastic coils off the old hoses and store them away in case you 
need them next time you replace hoses. 

 

FRONT BRAKE COOLING -- ’92-ON:  The 1992-on XJS comes from the factory with air scoops for the front brakes 
built into the front spoiler.  According to David Buchner, it also comes with an inlet built into the dust shields on the 
front brakes themselves.  To obtain the same sort of ducted cooling that race cars have, all you need to do is connect 
flex ducts from the back side of the spoiler to the dust shields on the brakes, and tie them up so the front tires won’t rub 
them when turned full lock.  Simple.  The opening at the back side of the spoiler is a rectangle, but you might actually 
be able to find a section of flex duct sold in auto parts stores for engine intake ducts that has a rectangular end on it.  
Otherwise, any place that sells air conditioning supplies can provide a small sheet metal transition piece for connecting 
a round duct to a rectangular opening. 

 

TWR FRONT BRAKES:  Alan Heartfield owns an ’85 TWR, and relates the following info from a TWR brochure:  
“This document states that the front rotors are 295mm X 35mm.  The calipers are AP Racing 4 pot solid calipers.”  
Obviously, this may provide some guidance to anyone looking to upgrade the front brakes on a non-TWR XJ-S. 

 

 

Inboard Rear Brakes 

 

REAR BRAKE HOSE:  There is a single hose on the driver’s side connecting the line from the car to the line on the 
subframe.  This hose,  CBC1393 or CAC6143 or GHP65, is unique to the XJ-S; the saloons use a different hose. 

 
 

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INBOARD REAR BRAKE ROTORS:  The OEM rear brake rotors are described as “externally damped”.  This means 
they have an iron ring around the circumference that actually fits rather loosely.  If the disk tries to “ring”, this ring will 
rattle, and the rattling will absorb the energy trying to cause the disk to ring.  IOW, the iron ring is to help keep the 
brakes quiet. 

Michael Neal pointed out that the OEM rear brake rotors are a “sandwich” construction.  This probably has something 
to do with fabricating a disk with the external iron ring.  “The stock rear rotors have the actual thin outer rotor surface 
attached to a solid core.  These thin outer surfaces are very brittle and break easily.” 

There are also reports of the ring breaking and coming out and jamming things up. 

When rebuilding, Neal recommends the use of aftermarket rotors made from a single chunk of iron.  Often, when you 
order new disks, suppliers will send you these aftermarket rotors without even asking; the aftermarket parts are what 
they stock.  The aftermarket rotors don’t have the iron ring, but nobody seems to have noise problems with them.  The 
aftermarket rotors are arguably quieter, since the loose rings on the OEM rotors sometimes jingle when you close the 
car door or the like. 

“Never turn the rear rotors, the oem style rotors are sandwiched construction and would probably self destruct when 
you put a bit to them.  The aftermarket style could probably take one light surfacing but it just isn’t worth it, price them 
sometime, they aren’t that much.” 

Randy K. Wilson concurs: “Don’t bother turning the rear rotors.  It’s around eight hours of labor to get the things out.  
If they are bad enough to require turning, the labor involved warrants replacing them with new ones.  Besides, it’s rare 
for those rotors to be torn up and still be turned down and remain in spec.” 

 

INBOARD REAR BRAKE ROTOR REMOVAL:  The instructions in the manuals are for removing and replacing the 
rotors with the rear suspension subframe in place.  However, many suggest dropping the entire subframe to make the 
job easier -- and dropping the subframe is really easy, much easier than most people expect; see page 383.  Note that, 
regardless of whether the subframe is in the car or not, the lower swingarms will either have to swing down a long ways 
or be removed altogether to get the rotors out.  This means that the shock absorbers will have to be disconnected from 
the lower swingarms, so you might as well get to it.  It also means that the tie plate on the bottom center of the subframe 
will have to come off, because the swingarms hit it before they swing down far enough.  All in all, a case could be 
made for leaving the subframe in place if you’re not doing other work that requires dropping it; at least, with it attached 
to the car, you don’t have to worry about how to support it while working on it! 

If you have the cage out, swinging the swingarms down far enough to get the rotors out means you have to get the cage 
a couple of feet off the ground -- and supported in such a way as to allow the swingarms to swing down.  Peter Cohen 
suggests, “since the cage is out, just tilt the cage backward so that the input shaft is facing up, and then swing the 
swingarms to your heart's content.”  Note, however, that before doing this you will need to either cap the differential 
vent or drain the differential, or it’s gonna drain itself! 

The ROM, Section 70.10.11, Step 8, says that after you remove the nuts holding the axle inner U-joints to the brake 
disc and output shafts, you are supposed to “Tap disc mounting bolts towards final drive unit.”  Those bolts are welded 
to the output shafts; if you manage to tap them towards the final drive unit, you have screwed up big time!  The Haynes 
manual, Chapter 9, Section 12, Step 8, contains similarly erroneous instructions. 

The rotors will not come out without removing the calipers.  Hence, before tackling the job of rotor replacement, read 
on about two different methods for disassembly of brakes mounted on a Salisbury final drive unit as well as the 
disassembly of brakes mounted on a Dana final drive unit. 

 

DANA VS. SALISBURY:  Much of the work on the inboard rear brakes is dependent on which type differential you 
have; see page 349.  If your car is in the 1985-88 range, check your differential before ordering parts or planning your 
work.  It’s fairly easy to check: if the differential has a drain plug, it’s a Salisbury; if not, it’s a Dana.  If it’s ’84 or 

 
 

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earlier or ’89 or later, you can safely presume it’s a Salisbury.  You have to check in the ’85-88 vintage because the 
official Jaguar repair for a Dana is to replace it with a Salisbury. 

 

INBOARD REAR BRAKE CALIPER REMOVAL (SALISBURY):  Removal of the left inboard rear brake caliper is 
straightforward using the steps described in the manuals.  However, removal of the right inboard rear brake caliper 
might be considerably more tricky due to the proximity of the pinion shaft of the differential.  The pinion is located to 
the right of center so there’s lots of room on the left side, but the right side is tight.  Specifically, the lower bolt holding 
the caliper to the output bearing flange is trapped and won’t come out other than with the caliper itself, and it just barely 
comes out with the caliper!  If the bolt was a quarter inch shorter this job would be a snap -- but you don’t wanna 
shorten the bolt! 

The particulars here vary from car to car, so some people won’t even understand what the problem is while others will 
have trouble.  This author couldn’t get that caliper out for two days -- and then it finally came right out without doing 
anything noticeably different!  Peter Cohen says, “Correct!  I have had experience with that bolt.  There is a single 
caliper position and bolt angle at which it will come out, and when it does, it happens so unexpectedly that you will not 
remember what you did.” 

Here are some tips that might help.  When trying to get the caliper out, hold the upper end of the caliper rearward -- 
toward the disc.  Once you’ve moved the bottom of the caliper forward and upward and reached the point where it 
doesn’t want to move any more, twist the forward edge of the caliper (the edge where the pad retention pins go) in the 
outboard direction, away from the differential pinion.  If you can’t twist it far enough to get it to come loose, you may 
need to remove the nuts holding the axle and rotor to the output shaft to allow the rotor to wobble a little. 

 

INBOARD REAR BRAKE CALIPER REMOVAL (SALISBURY W/ BREMBO ROTORS):  If you obtain Brembo 
replacement brake rotors for a Salisbury, they come with a pair of large access holes drilled in the mounting flange -- 
and no explanation.  Tim Dapper figured out what they were for:  Using the access holes, you can remove the five bolts 
holding the output shaft bearing assembly onto the differential.  Remove the exhaust pipe hanger attached to the top of 
the cage with two bolts.  Then slide the output shaft bearing assembly out of the car with the rotor and caliper still 
attached!  The caliper mounting bolts can then be dealt with on the workbench. 

The shims between the rotor and the output shaft obstruct the access holes a bit.  Before installing the shims, cut 
suitable notches in them.  Dapper suggests that if you find your car already has rotors with access holes but they are 
obstructed with the shims, it’s easier to break out the Dremel and trim those shims in situ than it is to remove the brakes 
using the method described in the ROM. 

When working on the handbrake caliper, you’ll want to have the new rotor securely bolted to the output shaft.  Since 
the axle isn’t in place, the nuts won’t thread down far enough to seat on the rotor; you’ll need to provide some washers 
or spacers. 

Obviously you need new O-rings for reinstalling the output shaft bearing assembly.  This should be considered a benefit 
of using this method; any opportunity to seal that thing up better is good. 

“But what good does this do me?  The old rotors on my car don’t have the access holes.”  Dapper nevertheless suggests 
you get Brembo replacement rotors with access holes.  That way, you can sweat and cuss and skin knuckles getting the 
calipers and rotors off, then take the output shaft assemblies out, then assemble them all together with the new rotors on 
the bench and reinstall them as a unit.  “I must admit I was quite surprised when the whole thing just slid into place.  A 
little jiggling is needed to get the splines to align.  This is so much easier than dealing with the caliper bolts and no 
clearance!” 

When installing the five bolts in the output shaft bearing assembly, you must screw each one all the way down before 
turning the rotor to install the next.  There is precious little room between the heads of these bolts and the heads of the 
axle bolts on the back side of the output shaft flange.  If you start turning the rotor around with the bolts only part way 
in, you can get it jammed and have to struggle with an open-end wrench to get moving again.