Jaguar XJ6 (X300) Vibration at Speed, Steering Wheel Shake
On the X300 a shake that comes in at a certain speed is most often a wheel out of balance or a tyre out of round; shake only when braking is the discs. A tingle through the floor and console rather than the wheel points at the propshaft. I'd rebalance the wheels and look for a missing weight before anything else.
How bad is it · Garage, carefully
Drivable with care — find it before a long motorway run
Most causes are wheels and tyres. A tyre with a broken belt, a loose wheel bearing or a sticking brake can get worse quickly, so check them soon.
Which one applies to yours depends on your symptoms, your model year and what has already been done to it.
Likely causes, most common first
Read the check cost before the odds: a free check that rules a cause out beats a likely guess that costs money.
A wheel out of balance — often a weight that fell off
Stick-on balance weights come away from the rims. One missing weight is enough to shake the whole car above about 50 mph.
Vibration through the steering wheel that builds from around 50 mph; it appeared after a tyre change or with no warning.
Look on the inside of each rim for a clean patch where a weight used to be.
Rebalance all four wheels and replace any missing weights; a road-force balance finds what a plain machine misses.
Shake only when braking: pad deposits or uneven discs
Pad material can build up unevenly on a hot disc, or a disc can run out of true. Either way the brakes grab and release every turn, and the wheel shakes in your hands.
Steering wheel shimmy and pedal judder when braking from speed, nothing when cruising; often worse the harder you brake.
Look at the disc faces for patchy deposits, and measure the run-out with a dial gauge.
Fit a matched set of good discs and pads — skimming is fine if the discs are above minimum thickness. Avoid holding the brakes hard on hot discs at a standstill.
The propshaft: out of balance, a stiff joint or a tired centre bearing
The two-piece propshaft runs through a rubber-mounted centre bearing, with universal joints and a flexible coupling at the rear. A stiff joint, a sloppy centre bearing or a shaft out of balance gives a drumming tingle that you feel more in the seat and console than in the wheel.
A vibration through floor, seat and gear lever at road speed, hardly in the steering; sometimes a rumble or clunk on a full-throttle start.
Under the car, look at the centre bearing rubber and work each joint by hand for stiffness or play.
Replace the stiff joint and the centre bearing, or have the shaft balanced — a used balanced shaft is an option. Hose clips on the shaft can trim a small imbalance.
A tyre out of round, flat-spotted or with a broken belt
A tyre can be out of round and still balance on the machine. Flat spots after the car has stood, or a belt breaking inside, give a bounce in a narrow speed band.
A shake around 55–70 mph that fades above it; a wobble for the first miles on a cold morning; or a wobble at creeping speed.
Swap the wheels front to rear, one at a time with the spare, and see whether the shake moves. Spin each wheel and look for a bump or a kink in the tread. Load rating should be 98 or higher.
Worth trying: a long, brisk run to warm flat-spotted tyres; replace any tyre with a lump or separated tread.
Loose front wheel bearings
The front hubs use adjustable taper bearings packed with grease. Even a little play lets the wheel wobble at speed and under braking.
Shake in the steering with perfectly balanced wheels, or a shudder that new discs didn't cure.
Lift the front and rock each wheel top and bottom: no more than about 1 mm of movement, none side to side, and no gritty whirr when spun.
Worth trying: readjust the bearings to the right preload, regreasing them generously; replace a rough bearing.
A sticking brake caliper
A corroded caliper piston doesn't let go. The disc on that side overheats as speed rises and begins to shake.
Vibration that grows with speed and on long runs; one front wheel much hotter than the other afterwards.
After a drive, carefully feel near both front wheels: a hot disc on one side is the sticking caliper.
Worth trying: recondition or replace the calipers, then fit good pads and resurface the discs.
The gearbox mount or its cross-member
The rear gearbox mount is a rubber donut on a cross-member. The rubber perishes, and the cross-member itself can crack through.
A shake in a narrow band on light throttle, or with gear changes, that goes when you lift off.
Look at the mount and the cross-member under the car; select neutral at the speed it shakes — if it stops, it's driveline or mounts, not wheels.
Worth trying: replace a perished mount or a broken cross-member.
The torque converter lock-up
At around 52 mph the converter locks up, and it can engage slightly out of balance. A mild, harmless vibration then comes in at the lock-up speed; after a kickdown it can return at a higher speed.
A slight vibration that starts as the revs drop at lock-up, and goes when you accelerate.
Note the revs: if the shake arrives with the small rev drop of lock-up, this is it.
Worth trying: a new gearbox mount can damp it.
The order to check them in
The point of the order is money: each step either rules a cause out or makes the next one worth doing. Green is free, amber costs a little, red is the one to arrive at last.
Note the speed and where you feel it
Steering wheel points at wheels, tyres and brakes; seat, floor and console point at the propshaft. Only when braking is the discs.
freeSelect neutral at that speed
If the shake carries on, it follows road speed; if it stops, look at the converter and mounts.
freeRebalance the wheels
Look for a missing weight first.
a rebalanceSwap the wheels around
Front to rear, or one at a time with the spare, to see whether the shake follows a wheel.
freeCheck the front wheel bearings
Front lifted, rock each wheel top and bottom.
freeFeel the brakes after a drive
One hot side means a sticking caliper; judder on braking means the discs.
freeLook at the propshaft
Centre bearing rubber, universal joints and the rear coupling.
freeWhat it usually isn't
Don't spend money here first:
If none of this finds it:
On jagaux.com
- Jaguar XJ6 (X300) Suspension Knock, Rear ShocksIf it knocks over bumps rather than shaking at speed.
- Jaguar XJ6 (X300) Gearbox ProblemsIf the shudder comes with gear changes.
- Jaguar XJ6 (X300) Wheel Bearing NoiseIf it's a hum or a rumble from one corner rather than a shake.
- Jaguar VIN decoderConfirm your exact model year, engine and factory options before ordering parts — free.
Ratings, fuse numbers and torque figures vary by model year and market. Read the legend on your own car before pulling anything, and use the figures in the manual for your car, not the ones in a video.
Check your VIN: exactly which car you have and which bulletins apply to it.