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I’ve not just got greater wear on the inner pad, the wear pattern is very strange too. The lip on the outer edge tapers so there is more wear towards the centre of the disc. Never seen anything like it.

The left is the inner side, not a great drawing but it hopefully gets the point across.

Yeah, that’s a similar pattern to the last ones on my X250.

Changed the discs and pads together. If you recall, this was the time I had the brake failure due to a rear pipe warring through. I had to bleed the system.

Sold the car about 8 weeks later so I never found out if the brake bleed helped.

Might be worth getting the fluid changed to achieve a full bleed and see how it goes after that.
 

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Yeah, that’s a similar pattern to the last ones on my X250.

Changed the discs and pads together. If you recall, this was the time I had the brake failure due to a rear pipe warring through. I had to bleed the system.

Sold the car about 8 weeks later so I never found out if the brake bleed helped.

Might be worth getting the fluid changed to achieve a full bleed and see how it goes after that.
Fluid was changed at the last service in sept so not sure if that’s the issue. Damage could have been done by the old brake fluid perhaps?

I also think maybe the bed in wasn’t done correctly? It’s like there isn’t proper contact between pad and disc or a chunk of pad missing near the outer edge (Probably the former realistically).
 

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I personally believe that it has nothing to do with what particular brand of pads and/or discs you use.
Over the 5 years of driving my XF-S, the brake judder was present most of the time. Changing the discs and/or pads would "cure" the issue . . . fir a while but it always came back.
The XJ has the same callipers and after I fitted them 15 months ago, the same make of discs and pads (Pagid/Brembo) and I have never had the problem.
So, I have always maintained that the issue is caused by the callipers not fully releasing and holding one of the pads against the disc causing material transfer when the discs are hot.
Conclusion: swap them or regularly strip and service the front callipers.

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Maybe the mystery machine can help?




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Toyah has an idea


 
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Discussion Starter · #29 ·
EBC recommend pro cut disc skimming to remove any irregularities with the hub, and to reduce pad bedding in time.

With new EBC disc and pads and no skimming, it took me about 1,000 miles to fully bed in the pads.

So far, on skimmed EBC discs and new red stuff pads, it’s taken me 500 miles, and still not quite there with a full contact patch on the on the rear discs.

At that point you then do the multiple decelerations that Oz describes.

I did that with the first set, but got the judder about 12,000 miles later, and it was just getting worse. That’s when the run-out was measured, and discs skimmed.

I also do the brake and roll forward described above, to prevent pad residue on the discs, and do a lot of engine braking with the paddles down to 2nd where I can, and creep forward. It must be a joy to drive behind me.

My Porsches have always lived their lives with advisories on “pitted and corroded discs”, but they’ve never been skimmed, as it is more caused by low mileage and just surface rust which can be removed with a bit of heavy braking.

As to why the pro-cut place won’t do your discs - if you don’t have much life on your discs, or if they are cheap, then it may not be that economic to get old ones lathed.

What do you have on at the moment, and how much wear do you have?
They didn’t ask or check the discs. It was over phone. I have currently brembo discs and oem pads. 31.5mm. Roughly 75% left. Run-out is about 0.1 mm but I think it is mostly DTV.
 

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Discussion Starter · #33 ·
Fluid was changed at the last service in sept so not sure if that’s the issue. Damage could have been done by the old brake fluid perhaps?

I also think maybe the bed in wasn’t done correctly? It’s like there isn’t proper contact between pad and disc or a chunk of pad missing near the outer edge (Probably the former realistically).
My discs are worn more on inside as well. I cleaned slider pins that could cause this. But it also could be the calliper I guess. My brake fluid is due to change as well. Something strange was that when I was cleaning the slider pins, I noticed the pads tails (?) that slide on the bracket abraded the bracket and it was shiny. I flatted that out by sanding but there no improvements at all after that cleaning. Run out measurements are slightly better now. Use to be 0.15mm and now it is 0.1mm.
 

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Discussion Starter · #34 ·
I had quotes for Pro-cut of between £60-90 per axle (incl VAT), if that helps with the economics.
Thanks. I read that on their website. Maybe I need to try another garage that comes up on their website. Price is not much cheaper compared to a brand new disc set. However I prefer that because you know there is no run-out.
 

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My discs are worn more on inside as well. I cleaned slider pins that could cause this. But it also could be the calliper I guess. My brake fluid is due to change as well. Something strange was that when I was cleaning the slider pins, I noticed the pads tails (?) that slide on the bracket abraded the bracket and it was shiny. I flatted that out by sanding but there no improvements at all after that cleaning. Run out measurements are slightly better now. Use to be 0.15mm and now it is 0.1mm.
This is the norm for Jag brakes with floating single or double piston calipers and most report double the wear on the insides of the discs compared to the outsides.
I recall a brake "expert" somewhere explaining that this is due to the pistons bearing directly on the inner pads and indirectly on the outer pads.
 

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Discussion Starter · #36 ·
I personally believe that it has nothing to do with what particular brand of pads and/or discs you use.
Over the 5 years of driving my XF-S, the brake judder was present most of the time. Changing the discs and/or pads would "cure" the issue . . . fir a while but it always came back.
The XJ has the same callipers and after I fitted them 15 months ago, the same make of discs and pads (Pagid/Brembo) and I have never had the problem.
So, I have always maintained that the issue is caused by the callipers not fully releasing and holding one of the pads against the disc causing material transfer when the discs are hot.
Conclusion: swap them or regularly strip and service the front callipers.

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I totally agree John. Reading all helpful comments I am confident that it is DTV and not warping and started by one of these:
-brake pad transfer (driving habit could help)
-sticky callipers or slider pins (regular striping could help)
-not driving car for long periods that makes the surface corrosion becomes deep (not sure if there is any brake safe anti corrosion spray when car is not moving.)

However, when DTV happens there is now way to fix it without lathe or replacing them. Now I can confidently change the discs and do regular maintenance. But reading how many times people changed the discs for judder and cost of EPC stuff, buying a brake lathe is becoming economical!
 

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This is the norm for Jag brakes with floating single or double piston calipers and most report double the wear on the insides of the discs compared to the outsides.
I recall a brake "expert" somewhere explaining that this is due to the pistons bearing directly on the inner pads and indirectly on the outer pads.
Weirdly then every single car I’ve ever owned has had this design and none have had this issue unless there was an issue with the sliding pins.


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Discussion Starter · #38 ·
This is the norm for Jag brakes with floating single or double piston calipers and most report double the wear on the insides of the discs compared to the outsides.
I recall a brake "expert" somewhere explaining that this is due to the pistons bearing directly on the inner pads and indirectly on the outer pads.
Yes that makes sense. Having a more free slider pin would help a lot which means outer pads will touch the disc effortlessly and the differential force applied is minimal.
On my Toyota I removed the rubber bushing and replaced that with heat shrink. I think rubber bushing was just for preventing clucking and heat shrink work well. It has dust boot to prevent dirt. Cured the problem but I doubt it’s possible on Jag slider pins.
 

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Discussion Starter · #40 ·
I might put some Archoil on my slider pins.
I used silicon grease which is after damage was done. However even with grease on, slider pins where not moving easily. When was changing the upper control arm, the ball joint was easy to move when cold but even if I held in my hand for few minutes, it got lock due to expansion. Now I am thinking this could happen to sliders. When they warm up they might be not free to move at all.
🤔 that worth a try. Make the rubber hole bigger see what happens. Maybe 0.5mm.
 
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