My 09XF has 25K miles, and since new has had an infrequent noise when braking. The noise occurs once every 500 to 1000 miles (1-2x/mo). That must be about once in every 1000-10000 brake applications? The characteristics:
- it is a snap/thunk in front of the driver (behind dash or under hood), similar to the noise of the doors or trunk locking.
- I've noticed it only when braking at slow speeds; under 30mph.
- it occurs at the top of pedal travel, first quarter inch or so, before braking starts.
- I can't feel it in the pedal, and it has no noticeable effect on braking.
- the dealer tech has looked at it 3 or 4 times, and can't find anything wrong with the braking system.
Any ideas?

 

Does it sound like a spring noise, like a "spring, ding noise" but suddle, if I spelled suddle right, lol?

 

Yes, it does. Similar to when cars used to have pull handles to release the emergency brake, but much quieter, and sound coming from the front, rather than underneath.

 

Dick,

You might want to try spraying some white lithium grease on the spring mechanism on the brake pedal. This will involve some getting under the dashboard though. While you are bent like a pretzel doing this you might as well spray some on the u-joints on the steering column.

Mike

 

Thanks for the suggestion - at my age I don't bend like a pretzel, but I may try just to see what that spring looks like. At any rate, I will carry both ideas in to the next service appt. I'm glad so far nobody has said "my gosh, man, your framitz is about to speil!"

 

The noise is coming from the brake booster assembly itself. I would have them replace the brake booster. The spring in the booster is what is making the noise. I'm supprised it doesn't do it more often, then what you have described. Sounds like it's in the dash correct? Then it's the booster. I work for Jaguar and have seen quite a few of these come through. Took us a while to figure it out. We intially thought that noise was in the suspension, but it's the booster. They all do it. Now I wouldn't go into the dealer and say "Hey replace my brake booster, because some guy on a forum told me to tell you to," But suggest to the advisor and make sure she/he writes that down on the repair order, that you suspect it's the booster, but don't mention the forum. It causes too much BS.

 

I have this also, very intermittently. Hasn't done this for a while but guess what will be on my next service complaint list.

 

By Jove, thanks jaglover922! Brake booster sounds very likely. I don't plan to go in for service for a couple of months, but I will definitely push this recommendation. I'll post the results then.

 

Thanks again to jaglover922. I printed out the forum comments and reviewed with the service advisor; last week they replaced the booster. Since it was happening onlty once or twice a month, it will be awhile before we"re confident that was the cause.