There is a loud clicking sound when I accelerate aggressively (in either forward or reverse, although I am rarely accelerating aggressively in reverse!) or am doing an aggressive downshift with the paddles. It appears that sometimes, simply changing from D to R can cause the noise to happen.

Any idea what it could be?


I'm taking the car back to the dealer. Last time they said they couldn't replicate the sound.

 

I heard it loud and clear. Suspension bushing? What if you bounce the car up and down while in park?

 

Bouncing the car up and down seems not to do anything in park. However, I am also leaning towards suspension bushing of some sort. Any ideas which one? I'm guessing it could be a sway bar bushing that needs some lube. I'll shoot it with some silicone spray and see what happens.

 

Might be a loose brake caliper. You could start by asking another person to hear which wheel generates the click.

 

My first thought initially was that the brake pads were somewhat loose because there was a TSB for loose brake pads that was fixed by putting special grease on them. However, I think that this sound is so loud that it couldn't be that.

 

No, not the pads, but the caliper might not be tightened well after replacing the pads.

 

My guess is that the noise is coming from the Brake Caliper moving.
That's not as bad as it seems - its meant to move !

Our cars (both XK and XK-R EXCEPT the models with the optional Alcon brakes) have sliding calipers. There's a single big piston in each caliper. Its on the inside of the caliper, and pushes the inside pad onto the disc. That then causes the entire caliper to slide inwards on slide mounts, pulling the outside pad into contact.

(Weird huh ?? In the Ducati motorcycle world, a popular upgrade to this kind of Brembo brakes is to replace this kind of caliper with a 2 piston caliper. Works much better, as it gives more progressive linear feel.)

Anyway, this movement of the caliper can generate a 'creak' when braking and turning (eg parking). My 2008 XK does this, and its on my list to fix. Its a creak, however (and I think I heard it at one point in your video), but your sound is different, and pronounced when going forwards/backwards. But, I think, related.
I'd pull a wheel off and check for movement of the caliper,especially forwards and backwards. It should move in-and-out.

I've attached the TSB (courtesy of Jag Docs!) for this noise. Doesn't specifically mention the XK-R, but my workshop manual says you have similar, but larger, brakes.

Good luck - and good idea to make the diagnostic video !

 

JeremyB is correct...that's your brake caliper/pads engaging/relaxing.

 

I am doubtful that it is the pads relaxing since I can create this noise repeatedly without having ever touched the brakes.

I have a different creaking sound while turning/braking, but that is much much quieter. I plan on performing that TSB myself, as the dealer has stated it won't be covered under warranty.

 

Not that this probably has anything to do with your noise issue but are those tires completely bald?

 

Haha, nope, they're not bald. Although they could probably be changed in another 5k miles or so. I just have a crappy camera phone (Droid 4).

 

Your brake pads move more than you realize, even when you are not pressing the brake pedal.

Not that this is any issue for you, but do you have Dynamic Stability Control? The DSC uses your rear brakes to control the rear wheels...just FYI.

This is (one of the reasons) why the rear brakes wear out quicker on these cars than one might expect.

 

I yanked on the calipers with a rubber coated wrench and they did not move much or produce any sort of noise. And yes, I do have creaking pads, which are also somewhat audible in my video. However, the noise in question is (in my opinion) distinct from this sound. I'm thinking it could be a loose bolt in the suspension somewhere, or a control arm bushing.

Interesting theory about the DSC--I should try turning off the DSC completely and see if the noise still occurs. I doubt it will make a difference, since the noise doesn't always have to happen when I am losing traction.

The car is at the dealer now, hopefully they can figure it out.

 

I wasn't saying that the DSC was causing your issue...was just pointing out that the DSC uses the rear brakes...just an FYI.

 

I have heard this noise before but in a different models and usually more severe, I hear the brakes creek,the linkage clicking, but as you take the pressure off the drive line I hear what COULD be the sounds of a bearing in the universal joint popping, if you are traveling forward the torque is steady in that rotation direction so you won't hear it on the highway, same in reverse as long as you don't change directions, but changing rotation directions if the needle bearing are wore they sound like the one I'm hearing. probably the rear drive shaft.Not enough to cause vibration YET but soon you'll get a harmonic hum at road speed.It happened to my 03 @ 43000.I told them what it was and they replaced the drive shaft, noise gone.

 

I did think of the u-joints in the drivetrain as I have had them go bad before in the past (different car). Interesting what you said about a harmonic hum. I do seem to have a harmonic hum, but I thought it was just in my head. It always seems to be approximately the same pitch and is most noticeable whe at highway speed or just cruising around town at a constant speed. I always assumed this was the "exhaust drone" that people were complaining about but now I'm not so sure...

 

When you say they replaced the driveshaft, do you mean the driveshaft or the halfshafts?

 

CHeck out my Gremlin thread on my 2013 XKRS...im hearing chirps and creeks as well!!!! I was at my jag dealer and they are replacing struts and springs (on order from UK). CHECK IT OUT!

Loth

 

Did you ever get this problem resolved? What did the dealer do for you?

 

No, the dealer did nothing and kept telling me it's normal. Twice.