[modern] RE: [Modern] Suspension

Hello listers, from New Zealand, I have had a 1987 3.6 Daimler XJ40 for
over 2 years and have done some suspension work, but still think not
entirely sorted out yet.

So far have replaced all shocks with new Konis (but not top spongey
rubber washers) - in the process converting from SLS, using 2nd hand
genuine Jaguar springs (4) from a 92 4.0 litre XJ6 (not Sov). I tried
re-using original SLS rear springs at first, but as you know they are
too soft. Have renewed top & bot A-frame bushes at the front.New front
sub-frame rubber supports (front & rear of frame). Also, as far as
possible, have got rid of bump steer which was present on front left
(detected using a laser beam). There has been an improvement in
drivability, but on moderate to large bumps there is still a thump which
resonates through the body of the car. The tops of the front shocks are
not binding on the metal of the car body. I refitted the old front
shocks (Bilstein) recently, which still work OK (they were really
changed in sympathy with SLS conversion), but apart from a slightly
softer ride there is no change. If windows and sunroof are open, the
thumping is hardly noticable. I don’t know if the thump is so much felt
as heard. Is this normal, or not?

A thump is also present at the rear, and some rear wheel steer, but I
haven’t started there yet. Using a large lever ( 6’ piece of wood) on
the rear wheels I can only detect slight fore & aft movement on the
inner A-frame bushes, not lateral. What wears first at the back?

Also am confused about the gearbox mount - namely the foam ring. Is it
supposed to stop up & down movement, or just sideways? I’ve read the
listings and Haynes and just don’t know what to think. The box could
move up and down on its springs, with no damping effect, and this could
be felt through the seat of the pants on bumps. I have made a make-shift
rubber modification to damp this vertical movement. I’m reasonably sure
the gearbox mount is not the cause of the thumping described above.

Overall not a bad car, my wife likes it - can get 28 or 29 mpg
(imperial) on a trip, if careful.

If somone can give me the benefit of their experiences re the above I
would be grateful.

Glenn
1987 XJ40 Daimler

Glenn,

There has been an improvement in
drivability, but on moderate to large bumps there is still a thump which
resonates through the body of the car. The tops of the front shocks are
not binding on the metal of the car body.
I refitted the old front
shocks (Bilstein) recently, which still work OK (they were really
changed in sympathy with SLS conversion), but apart from a slightly
softer ride there is no change. If windows and sunroof are open, the
thumping is hardly noticable. I don’t know if the thump is so much felt
as heard. Is this normal, or not?

Not at all.
You could have problems with the shock bushings.
With the car jacked up with the wheels off the ground, there
should be NO space between the bushing and the body…if
there is, they are shot.

A thump is also present at the rear, and some rear wheel steer, but I
haven’t started there yet. Using a large lever ( 6’ piece of wood) on
the rear wheels I can only detect slight fore & aft movement on the
inner A-frame bushes, not lateral. What wears first at the back?

Nothing much except the shocks.
With a lot of age, maybe the rear sub frame mounts.

Also am confused about the gearbox mount - namely the foam ring. Is it
supposed to stop up & down movement, or just sideways? I’ve read the
listings and Haynes and just don’t know what to think. The box could
move up and down on its springs, with no damping effect, and this could
be felt through the seat of the pants on bumps. I have made a make-shift
rubber modification to damp this vertical movement. I’m reasonably sure
the gearbox mount is not the cause of the thumping described above.

You can buy the foam ring separately from Jaguar or
mail order suppliers.
The transmission is supposed to be able to move easy.
You should be able to move it about 4 inches by hand.
Its sort of balanced.
The foam ring stops a lot of side to side movement,
and also compresses the springs.
There is also supposed to be a travel limiter strap around
the mount.
Failure of the foam ring will cause clunks with bumps.

Overall not a bad car, my wife likes it - can get 28 or 29 mpg
(imperial) on a trip, if careful.

If somone can give me the benefit of their experiences re the above I
would be grateful.

Glenn
1987 XJ40 Daimler

Both the shock bushings and the foam ring are made of the
same stuff…the shock bushings on the left side of the car
seem to fail first…maybe because the coolant tank sits above
it on that side…

Brett
1990 XJ6