My 08 XJ8 has developed an oddly intermittent shudder/shake. I just got new tires, balance an alignment to rule those out.. and I noticed this issue even before.

Steering and brake pedal are rock solid while driving and breaking so I doubt suspension, rotors etc.

At times it is quite pronounced, other times can't notice. But it is definately coming from under my feet or seat.

I suspect center bearing or either driveshaft flex disc.. or maybe tranny?

But the intermittency and variation in intensity perplexes me. Seems bad center bearing or flex discs would always exhibit shudder if bad.

Any wild guesses? Is it worth taking to Jag dealer. I have read about their super vibration detection machine😁

Thanks

 

You might also want to consider the rear transmission mount.
Not easy to see by all accounts, but perhaps find some threads about other members noted effects of a failing mount, viewing and replacing.

 

Just wondering if my issue is related. Whenever I stop at the red light, my 2009 VDP seems to do a slight 'rocking' motion. Just rocks once every stop, something like an old baby carriage rocks on its spring suspension.

 

What? no suggestions folks?

 

@Vinnyboy first suspects: motor and transmission mounts;
Second: still have CATS? Does car sways more than usial going over bumps?

 

Hi bk, no, only when stopping at a red light, it rocks as mentioned.

 

I assume the rocking is front to back not side to side?
Try approaching your stop at the normal speed but with the transmission bumped into neutral, so you are just rolling up and under brakes.
If yo don't get the rocking, then you can conclude it is engine/transmission torque that is contributing to the effect.
Big Koshka could be right.....engine mount or transmission mount could have failed, or it could be the not so subtle final downshift of the transmission into first as the vehicle comes to a stop.

 

+1 I did not think about stopping with gear in neutral.
If it is rocking front to back, I may suggest changing to aluminum from lead in right foot prosthesis.
Left foot, for other side of the world!

 

Yes, I do have CATS and the motion is from front to back with a rock motion once, front to back. Only reason I ask is because when I drive any other car, the car slows down obviously to stop for the red light with no rocking motion, just the Jag. Was concerned about a suspension problem, otherwise the car rides like a real beaut.

 

I would think that's normal unless you drive slowly enough not to "spill the Queen's tea."

 

Car at shop this morn for diagnosis... Will update when solution is found... How excitung (and expensive!)

😁😁

 

Well techs could not find anything obvious so invited me for a ride along. Driving down long stretch of road there was no shudder.. smooth as can be. Did a U turn and headed back and sure enough started to shudder and braking felt very shaky.

Tech's gut feel was a caliper/piston hanging up. So going to bite the bullett and do a four corner disk, pad, flex line job and he will advise on the calipers

Big chunk of change but better than ZF work or driveline. It better fix the issue!!!

 

Curious to know if you got any sense if the shudder was coming from the front or rear of the car?
Any feedback through the steering wheel, or were you feeling it in the seat of your pants and/or across your back through the seat?

If you are sensing if from the back of the car, perhaps try turning of the DSC to see if the rear brakes are perhaps being falsely triggered for traction control.
I would expect this is highly unlikely, but it is an easy elimination test to do to rule it out.

 

Hi -

The feeling was definitely more central/forward and under the driver floorboard and seat was where I felt it most. I thought that might have meant driveline, but after re-creating for the tech and the last few occurrences, my bet is on the brakes somehow. Applying brakes at these times the shudder was intensified and felt in the pedal, but tech said rotors are not warped. I should have car back tomorrow so cross your fingers. Hate throwing money at things like this, but brakes seem like obvious place to start.

One odd thing is that they said my fronts had about 75% wear left on the pads.... but they have not been changed in 55,000 miles!! It is almost like they are not even contributing much to the stopping power..... mysteries, mysteries... But admittedly I try to apply brakes as little as possible and when everyone else is jamming on brakes on the interstate.. I just lift my foot from the gas

Randy

 

I have what may be an obscure thought. The XJ has a sizable underbody shield… big enough that if it is still in place and not secured adequately, it could come partially loose and make a considerable racket under there. I doubt it would be enough to feel but surely enough to hear!

chemosabe
72 EType
09 XJ Super V8 Portfolio

 

Shop did 4x rotor/pads but called and said 2 calupers toast.. quoted $4000 for 4x caliper replacement with Jag parts

Politely declined and bought rebuilt on Rock with new flex lines. Do it myself. Mechanical work ok with me but bleed on 4 new caliper system gives me anxiety. Reading X350/8 service man but any pointers to posts would be appreciated
Randy

 

Pressure bleeder attached to the master cylinder is easiest way.
Opening the bleeder will then expell any unwanted air.
Mine only fits European cars master cylinders.
Addapters for other cars available, but for extra cash.
Vacuum pump works on the other vehicles, but not the Jaguar.
But the old fashoned way, of pumping the brake pedal still works.

 

What is actually wrong with the calipers?

15years old

130k/15=8.7k miles per annum

It's not even average miles per year

and you are a careful driver

Not Brembo's are they?

 

Unknown but I am replacing all four soon and will perform "auto"-topsy on them.

Get it! I made a funny 😂😂

 

OK all. Sorry for late reply.

I ended up replacing all four calipers and flex lines after shop just did pafs and rotors.

Everything went well and bleed was successful. Pedal was pretty good. So drove out drive to road for maiden voyage... and my heart sank. I could tell somthing totally wrong. Car was not moving... and after a couple 100 yards looked out rear view and saw SMOKE coming from rear wheel.

WTF!!!!!

Drove back slowly, parked and went home for some bourbon! Slept on it and my hunch in the morning was that ***** f'ing electric parking brake!

Took a look at rear caliper that was smoking and pads were cranked tight on disk WHEN the park brake was off!

I ran the e-brake several times and half the time it responded properly to being on or off. So I disconnected the cable on smoking caliper... and voila'!!!

Everything fine.. car brakes wonderfully, no more shudder or vibration! Just have to deal with msg when I pull key out and slowly release brake so not to tough on parking pin

Which leads me to bitch session. This (and many other) car has a bloody computer in the boot JUST to set a parking brake. Read the f'in service manual and there are 30 pages of debug for parking brake issues. It is so wrong... when did we lose the ability to lift a lever to pull a cable to set a parking brake?

OK.. I hate new car tech so will just live with no parking brake