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Discussion Starter #201
I'm still of the opinion that the problem lies with the calliper(s) rather than the disc(s).
 

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I'm still of the opinion that the problem lies with the calliper(s) rather than the disc(s).
I think it is indeed. But it’s the design, not maintenance. The calliper is literally float. On my toyota it is only free to move perpendicular to the disc surface. But on XF in can move on any direction. One side sits on a spring and the other sits on rubber. It’s not mechanically tied that much. As a result with all judder I had pads were worn very uniformly. I am thinking that having a dial indicator is necessary to fit new disc.
 

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Just run a standard cycle to burn pad deposits off the disks and all will be good again.
Find deserted piece of road- 60 to near stop braking firmly, repeat 3 times, never stop, drive a mile to cool them.

Don't sit on brakes at junction to avoid same happening again.
Doesn’t always work. The only thing that fixed mine was to replace the EBC red stuff that were causing it with EBC yellow stuff.
 

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Discussion Starter #204
Doesn’t always work. The only thing that fixed mine was to replace the EBC red stuff that were causing it with EBC yellow stuff.
I agree insofar as having a pad with friction material that is less likely to react to heat by leaving remnants of itself on the disc will probably (and it seems, does) cure the symptoms, I still believe the root cause is a sticky caliper that leaves one or both pads in contact with the hot disc.
My XF repeatedly had this issue during the 5 years I owned it. New discs would make it go away for a while. I've now had the XJ (with the same brakes) for over 2 years and 40,000 miles with no hint of judder.
 
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I agree insofar as having a pad with friction material that is less likely to react to heat by leaving remnants of itself on the disc will probably (and it seems, does) cure the symptoms, I still believe the root cause is a sticky caliper that leaves one or both pads in contact with the hot disc.
My XF repeatedly had this issue during the 5 years I owned it. New discs would make it go away for a while. I've now had the XJ (with the same brakes) for over 2 years and 40,000 miles with no hint of judder.
Same callipers.

All three of my XFs have done this, even from brand new. I had replacement discs and pads under warranty on the white one.


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Discussion Starter #206
Same callipers.

All three of my XFs have done this, even from brand new. I had replacement discs and pads under warranty on the white one.
I know. All I can think is that either the caliper design is 'prone' to this issue but not all develop the problem. Or . . . as there is 5 years between the manufacturing years of my XF and XJ, there has been a design tweak, perhaps with the slide pins and their seals. A design tweak so subtle and cunning that no-one has noticed it. :sneaky:
 

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I know. All I can think is that either the caliper design is 'prone' to this issue but not all develop the problem. Or . . . as there is 5 years between the manufacturing years of my XF and XJ, there has been a design tweak, perhaps with the slide pins and their seals. A design tweak so subtle and cunning that no-one has noticed it. :sneaky:
If someone was so inclined, they could check the part numbers to see if they match.

XF Front. 16mm guide pin. C2C29162. Bushing kit. C2C27296.
182336


XJ Front. 16mm guide pin. C2C29162. Bushing kit. C2C27296.
182335


One thing I forgot to note was that my first 2 XF came with the 326mm front brakes, I upgraded the second one to 355mm. The XFR-S has 380mm front brakes. The examples above are for the 355mm brakes I believe.
 

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Think I have mentioned this before.

After washing the car, take it around the block and do whatever you have to to dry off the discs/pads before leaving it.
If you don't, the pads get "stuck" to the discs and material transfers when you first drive off next (if you hear a "bang" as you do so, that's what it is).

I do this routinely on all our cars, never have a judder problem now.
 

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Discussion Starter #209 (Edited by Moderator)
Think I have mentioned this before.

After washing the car, take it around the block and do whatever you have to to dry off the discs/pads before leaving it.
If you don't, the pads get "stuck" to the discs and material transfers when you first drive off next (if you hear a "bang" as you do so, that's what it is).

I do this routinely on all our cars, never have a judder problem now.
But why would the front pads be in contact with the discs?
Unless you're suggesting that the judder actually originates from the rear brakes.
 

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Doesn’t always work. The only thing that fixed mine was to replace the EBC red stuff that were causing it with EBC yellow stuff.
This is because some pads eat through discs more easily and make corrections also leave less dust.
 

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Think I have mentioned this before.

After washing the car, take it around the block and do whatever you have to to dry off the discs/pads before leaving it.
If you don't, the pads get "stuck" to the discs and material transfers when you first drive off next (if you hear a "bang" as you do so, that's what it is).

I do this routinely on all our cars, never have a judder problem now.
This shouldn’t cause the problem when disc has fairly low runout because pad transfer would be uniform and removed when disc gets hot. However excessive runout will cause some higher spots due to brake pad transfer at high points, protecting disc at those spots and wearing low spots. over time this uneven brake disc wear gets worse and this loop continues until brake judder starts. I just ordered a dial indicator because I think it’s an essential tool for installing new rotors correctly otherwise judder will start again down the line. I will shim it if they weren’t.
I have read that it’s a routine brake service to resurface the brake discs (Even if there is no judder) on higher performance cars specially those with ceramic discs. Maybe they use a similar calliper design.
 

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Funny how I have installed new rotors and pads myself on all three of my Jags and I have never checked runout etc and I have never ever ever had any brake judder. The one and only "extra" thing I have ever done when fitting new rotors is to clean up the hub faces (with steel wool and turps!).
 

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Funny how I have installed new rotors and pads myself on all three of my Jags and I have never checked runout etc and I have never ever ever had any brake judder. The one and only "extra" thing I have ever done when fitting new rotors is to clean up the hub faces (with steel wool and turps!).
Because you are doing it properly and used new discs. Mine was loaded with copper grease between hub and disc causing run out in first place. And after a lot of brushing, I am worried if I caused run out at hub. Judder is many times better but not completely gone. On my Toyota I don’t even clean hub surface and never had this issue. It’s a combination of heavy weight and bad brake calliper design IMHO making them too sensitive to runout.
 

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Funny how I have installed new rotors and pads myself on all three of my Jags and I have never checked runout etc and I have never ever ever had any brake judder. The one and only "extra" thing I have ever done when fitting new rotors is to clean up the hub faces (with steel wool and turps!).
I’ve done that too.

I think they are several causes for it on the XF, it just seems more susceptible to it.


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Never had any brake judder on the 2x XF's I had.
 

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Discussion Starter #216

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Two XFRs and an Ftype over about 8 years and maybe 100,000 miles, no brake judder. I don't dry the brakes after a wash unless I drive somewhere straight away, which would be unusual. OEM discs and pads. If i leave the car for a day or two after a wash, rear brakes bang on take off. Lately I dont use the handbrake to park in my garage, just rely on P. In my case I do things wrong from a judder point of view, but don't have it. There are times when my brakes have very heavy use, but normal most of the time. I do let the car creep with slight braking at the lights after any heavy braking. I hope this aids ideas about judder.
 

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Never use the handbrake, always transmission brake "P".
 

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Two XFRs and an Ftype over about 8 years and maybe 100,000 miles, no brake judder. I don't dry the brakes after a wash unless I drive somewhere straight away, which would be unusual. OEM discs and pads. If i leave the car for a day or two after a wash, rear brakes bang on take off. Lately I dont use the handbrake to park in my garage, just rely on P. In my case I do things wrong from a judder point of view, but don't have it. There are times when my brakes have very heavy use, but normal most of the time. I do let the car creep with slight braking at the lights after any heavy braking. I hope this aids ideas about judder.
Almost identical history here.
XFS in 2013, XFR in 2014 then F-Type in 2016.
And I also never use the EPB in my (level) garage, I just turn 'er off and let it go into P all on it's lonesome.
But I do use the EPB a lot when tootling about the 'burbs, if I know or judge I will be stopped for anything more than about 30 seconds I shove it into N, apply the EPB and relax.
Pretty much never any heavy braking these days in my dotage!
 

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Good point......I do not apply the EPB as my drive is as pat as a flancake, but I do tend to “exercise” it (EPB) every so often in order to keep the motor and/or any relevant moving parts and linkages mobile.
Does that sound senseful......?
 
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