I am currently going through the brake system so will report when I have done it. thanks for all responses.

 

Hi all, I got my new parts yesterday and today fitted new front brake hoses and caliper piston seals, only because I did not want to replace old seals.. I found the pads had a very hard glaze on them which I filed off and the rotors had dark streaks on them which I very lightly ground with a 90 degree grinder. Both pads and disc have less then 2000 miles on them. As for the brake hoses I made the mistake when I first changed the rotors and pads of squeezing them with grips to stop the fluid leaking as we did many years ago when brake hoses were constructed differently, Anyway after a few miles driven they feel much better so I must have done something right. Suspect it was something on the surface of the rotors that caused them to clog the pads and grab and judder.
I hope this will help others. Thank you for all the positive suggestions and help.

 

I stand corrected, as I got the Jag brakes confused with my G35 brakes.



The G's rear piston have a slot that the nubs on the pads must be set in or they will judder like crazy...

 

An update on my juddering brakes - Although a little better brakes still judder and transmits through steering wheel, brakes are very noisy too when operated. I changed the brake fluid because it needed doing and it may have helped a little, so, with new EBC rotors and pads, no sticking pistons and or calipers, no warped rotors, and brake surfaces cleaned, still have problem.

Oscillating the steering wheel to check steering joints for wear there is nothing except a definite metallic knock throughout the steering rack, cannot tie it down to one end of the rack or the other.


Are XF front brakes noisy( have quite loud pad to rotor noise) when applied?

 

I finally got to the bottom of the steering judder when braking. Took all the normal brake related actions but no resolve.
I could not feel any suspension or steering wear using levers and bars but a couple of weeks ago I drove over a very large rain gulley at the end of our street and "BANG" something happened on the right front wheel. Turns out it was one of the bushings pulled out of the lower suspension link, the one that houses the lower ball joint, coil spring/shock and front stabilizer. The bush that popped holds the link that goes to the top suspension wishbone. Have included pics and it shows the bush has been loose for some while as the surfaces were polished.
Fitted two new links ( expensive) and judder has gone away.
NOTE - If you do this job make sure you mark the position of the bolts that go thru the very large bushing in the link and connect with the frame, if you do not put back in same position it will affect the wheel camber. Also best have an alignment done anyway.

 

Interesting but makes no sense.

this is the sway bar bush and does not effect alignment if replaced, it connects the sway bar drop linksbto the lower arm.

it also cannot cure vibrations, the vibration is caused by rotating parts not by a rubber bush.

I believe that this is not the real cause of the problem you have

 

You are partially technically correct and it does make some sense if the lower links are replaced which mine were alignment is necessary. The positions of the eccentric bolt system that connects the lower link to the frame as incorrect position on re installation changes the camber, hence the need for alignment or at least checking the camber.
Yes everything pointed to a rotating component problem and to solve the problem I am on my second set of new rotors and pads in 5000 miles, I had no rotor or hub run out problems, all less than 0.001" I also had one wheel straightened that had 0.050" run out and rebalanced, hub bearings appear to have no play. Brake calipers rebuilt and a fluid flush too. The problem has now changed brakes are smooth at lower speeds but now get more noise with high speed braking but with no steering wheel judder or brake pedal pulsing.

 

The bush is the anti roll bar bush........the arm you refer to is the lower laterral arm.......did not realise you replaced the arm......why did you not replace just the bush? Would have been much cheaper

 

Good point indeed. There are three bushes in the lateral link, one for the pivot to the frame, another for the strut and this bushing. There is no steel outer for this bush so it is not an interference fit. I believe and I may be wrong, this bush is bonded in place as the arm that is fastened to it that goes to the anti roll/sway bar only has a bolt going though it so has to be bonded or something to keep it in place and not pull out which is exactly what mine did.
Another reason I replaced both lateral links was again with the problems I have been having just thought it wise to replace

 

That's fair comment on the replacement arm - its was the referral to the anti roll bar bush that confused me - the small rubber bush that goes onto the anti roll bar drop links is way to soft in my opinion - I'm looking at replacing mine with some POLY versions - there are none on the market that I can find so looking at getting a cotton reel off the shelf one that works with a steel insert sleeve - I'm not actually convinced they are bonded in as well - I believe they are just a tight interference fit............

 

My saga continues, in short, all new rotors and pads, second set, no disc run out problems and new lower control arms but the brake problem mainly manifests itself now when at higher and freeway speeds and braking fairly heavy, very noisy, not grinding, just a noisy pulsating type of sound that fills the interior. I took the car to Jaguar recently for the airbag recall and had them check the brakes, they said working perfect but they did not do the high speed check.






Anyone experienced this?

 

[QUOTE=sdred;149598 When I changed the brakes I did push the pistons back into the calipers and now heard not advisable to do that with ABS. Any comments please?

You have to push the pistons in, but with ABS it is advisable to open the bleeder so the fluid (and any contaminants) aren't pushed into the ABS components.

 

Yes you do have to push the rear caliper pistons in but not in the conventional sense they actually screw in and a special tool is needed, slacking a bleed nipple is good thing to do.

 

I still say this is uneven pad deposits on the disks. Are you replacing EBC parts with more EBC parts? If so try another brand. I had terrible high speed shudder with pagid disks that was completely cured by fittng mintex disks and GENTLE bed in for first few hundred miles.

 

Could be, on the pad deposit on the rotors although they look clean enough and equally worn with fairly smooth rotor surfaces. Run out on the rear rotors was less than 0.002" I am fitting new Brembo discs and pads. If this fails I am going back to Jaguar as I have chased this long enough. I was thinking it could be the ABS system but I have researched and found nothing that faulty ABS controller or ? cause noisy brakes plus I have no ABS warning lights on. Must say though that the noise is akin to the ABS operating.

 

Removed old pads and retracting caliper pistons fully. Everything I have read is that the passenger side piston screws clockwise and driver counterclockwise - WELL mine are both clockwise!! Is this correct for the XF or am I missing something? I removed the drivers side piston seal and manually screwed the piston onto the coarse thread in the center of the bore and definitely clockwise to fully get the piston into the retracted position. Any experienced suggestions please? I definitely know my threads after 50 years of engineering. Thank you.

 

Why are you playing with the rear brakes? AFAIK both rear pistons screw in CW. The fronts push straight in.

 

Thanks Mikey, not playing with them, am replacing rotors and pads so have to retract pistons. Thanks for telling me they both screw CW. I searched this forum and all I found was the CW Passenger and ACW driver side but that was perhaps another Jag model. that is what has been throwing me. Maybe I did not look enough but your info is the first I have seen that they both retract CW.

 

Just following up to close this thread on the brake noise and judder issue. The problem was the rear brake pads, looked Ok but clearly was causing the problem all along. New Brembos working great.

 

It also could be from brake hoses that are getting soft. I have seen some which tend to balloon to a certain extent causing the brakes to surge when you apply them. Sticking pistons in the calipers will also do that. As for the pushing them in without opening the bleeders, I have seen master cylinder reservoir caps explode because they weren't open when the pistons were pushed back in quickly. And I can believe that this could also affect brake hoses in the same manner.