Brake judder - Jaguar technical bulletin. True or FAKE news ?

[paullbuck210]

Not sure if this has been covered before, but a very strange situation which must have a resolution to.

When I first got my 2004 XKR with Brembo Brakes, the rear discs were very thin so replaced them, and the fronts at the same time. I noticed before replacement that I had brake judder from the rears mainly so thought replacement was the way forward.

All for discs and pads replaced. After 2000 miles, all judder returned. Took the car in to get advice, and was told the discs must be warped, or cheap pads, or both.

Couldn't believe this, so started to do some Google digging. Found that lots of people have had the same issue. That is, brake judder, new pads and discs fitted and then it returns after a few miles. Some have replaced with cheap discs, some with Brembo originals and Brembo pads. Still the judder returned. They cant all be rubbish discs and pads!

Now found that Jaguar released a technical bulletin to say that the judder may/will return. Seems its more down to incorrect fitting or suspension issues.

Jaguar Bulletin here: http://www.jagrepair.com/images/TSB/TSB ... raking.pdf

So my questions are:
1) anyone else had this?
2) anyone have the cure?

It seems even Jaguar are not really sure why this happens. ????

[DaveNeedham]

BMW too... at least on my E60. I always replace discs and pads at the same time. The first couple of times no issue at all. The last time all was good for about a fortnight then the vibration started. I discovered if you got the brakes hot and used them hard it wasn’t an issue! Brembo replaced them all FOC. But they insisted they weren’t warped, (I knew that because I’d had a DTI on them). Again after a week or more they got progressively worse, so I just live with it. I believe it was due to not bedding them in properly and leaving your foot on the brakes after pulling up can result in material transfer onto the rotor.
Here you go.... https://www.zeckhausen.com/catalog/inde ... =6446_6443

[Gander]

Paul, Dave,

I had exactly the same problem. XKR, Brembo brakes, constant judder, drove me crazy for about 2 years. Replaced discs all round with Brembo copies (original Brembos were stupid expensive) and the judder returned after a few months. Checked with micrometer to find there was no run out on new or old discs, and obviously no wear on the new ones. You could however, clearly see the marks of the pads on the discs caused by transfer of brake pad material to the disc when the car is sitting for a while. This was causing a sticky section on the discs, resulting in the vibration. Tried sanding with limited success. Didn't want to go too deep and damage the disc. Next time the car sat for any length of time there would be other pad marks on the disc and the vibration returned. Changed the pads for EBC yellow stuff and the vibration has gone. Took a bit of running (400 - 500 miles) to clear the sticky marks but the vibration is now history.

Hope this helps.

Graeme

[J44EAG]

The Brembo set up is I believe identical on the similar year X350R. Part numbers, XK/XJR/4.2XFR/S-type R were the same when I researched the subject prior to rebuilding me XJR brakes. See my articles in the magazine in the X350 pages relating to Brembo overhaul and assessment. Look at back issues between Jan-March 2018. You will recognize much of what you yourself have found, mirrored in those articles.

Ex-factory, Brembo parts appear confined to just the calipers. Whilst Brembo do supply discs and pads in a genuine Brembo box, it is highly likely that the parts are in fact TRD/Mintex re-badged. The same with genuine Jaguar OE consumable brake parts which are Mintex.

I think you will find that the front discs are 365mm diameter. These have always been prone to warping. Despite my best efforts to get the discs fitted with minimal run out, I`ve found them badly warped within 5k miles of fitting. One might assume that the change (certainly on 06> XJR) to Teves as standard R brakes with a reduction to 355mm diameter, might have been driven by the need to attempt to stop issues with warping. In my opinion, the 365mm "Brembo" discs are rather to large in diameter and in disc nominal OE thickness and as a consequence, warping issues are very common indeed. Knowing what I do about the car of this period, I suspect that most similarly equipped cars on the road almost certainly have warping issues in greater or lesser forms.

So what can one do? Certainly EBC were aware of the issue and recommended their specially heat treated up-grade discs used in conjunction with Red or Yellow Stuff pads. The problem is though that the EBC parts costs are nearly double that of the standard Brembo/Jaguar/Mintex OE parts. ......So you pays your money and take the choices.

These warping problems come as no surprise to me. I`ve had to live with similar issues ever since I`ve owned the XJR. My solution would be to change to the EBC up-grade parts and dig deep into my pocket. Even then, there is no guarantee of a lasting solution. The harder one works the brakes, the quicker they warp.

One tip. If you have pounded the bakes on a motorway slip road and then have to sit at a roundabout awaiting traffic lights to turn to green, do not hold the car stationary on the foot brake which puts pads into contact with the discs. This causes uneven cooling and exacerbates warping. Better to use the park brake and nip the car into neutral whilst you wait for the lights to go in your favour.

Mike K

[Gander]

Mike,

My front discs are 355mm, drilled and vented. Changing them made only short term improvements, but within weeks it was back to the same vibration. To fix the judder I only changed the pads, there was still some judder at first, but it got gradually better once I'd driven a it a few times. I'm sure it had to be "yellow stuff" due to the power output, or speed. Can't remember, it was a while ago now. Don't remember them being super expensive, not like buying original Brembo discs. Braking is now perfect.

[paullbuck210]

So, back again! Really keen to get to the bottom of this issue..... tried to ignore it as I only use the car on sunny days, not as a daily driver.. but the vibration has got worst.

To recap, new pads and discs to stop the vibration on braking, after a short while it returned (as a few owners have experienced)

So I (as we all get) have found lots of answers as to why... Discs warped, discs not placed on the hub correctly, pads leaving a residual on the discs which produce a "bump" on the discs which produce the vibration on braking......all of the above, none of the above...

So having checked my discs I am leaning towards the pad residual route, and that the "harder" yellow pads might "scrape off" the residual and remove (eventually) the vibration. I guess new discs as well would work but reluctant to buy new discs after 1200 miles!

So...... Did you guys get the desired results from just yellow pad replacements? Or new discs as well..... or is this a total red herring and fake news!

Oh the joy of it all !

[J44EAG]

I had front brake judder return recently on my XJR. One lower damper bush was shot. Changed the bush...back to normal. No brake judder.

I ALWAYS remove the paint and just a tad of metal on the ends of the pad backing. This stops the pads from sticking in the caliper. A little copper grease is also applied to the pad/caliper running surfaces and I always ensure all pistons within the caliper move freely. The anti-squeal shims and pad backings also need a spot of grease to stop components seizing.

All parts should be cleaned of road dirt, corrosion etc prior to fitting. When I overhaul my brakes, everything goes back together like a well oiled machine.

Mike K

[rosemary]

Hello Folks
Has anybody looked at the ABS/DSC system causing brake chatter?
Dave