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I watched some videos and I am convinced the rust on hub surface could cause this. Even though I spent 1hr cleaning hub surface with wire brush on a drill, I did start to chip the dirt off by a screw driver following a video on utube. They do come off even do wire brush couldn’t. I ordered hub surface cleaner that sits around studs that should arrive tomorrow morning. I feel I can save the hubs. Also, I am going to drill the sliding pin rubbers with a 13mm drill bit to make it bigger. I am not sure if it works. The idea is to have pins free when calliper gets hot.
The sliding pin alteration will be interesting. Would it be worth only do one thing at a time so that you can be 100% sure what fixes it?

As a side note, the more I read this thread the more insane all this time and effort seems.
 

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Discussion Starter · #222 ·
The sliding pin alteration will be interesting. Would it be worth only do one thing at a time so that you can be 100% sure what fixes it?

As a side note, the more I read this thread the more insane all this time and effort seems.
I only found 14mm wood bit today. I think it would be fine because it’s rubber. Maybe It cannot cut at all.

yes I really cannot spent more time on it. I have taken apart brakes 3-4times in past few months.

I have seen another strange thing on old rear discs. There is a deep lip on the edges. About 1mm each side. The contact surface though measures 19.5mm. There was a lot room left. However, the thickness over the lips is 22mm. The rear discs come in 20mm and min is about 17.5 to 18mm. It seems lips are inflated for about 1mm. This was large enough to grind the pad sensors. However I didn’t have pad warnings. Is the assumption right that discs can inflate due to rust? Or old disc was somehow thicker than standard?
 

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Yes, rust on the lip will certainly increase the diameter. It will have been the correct size when you got it. If they're oversized slightly when new and you've got new pads too, they probably wouldn't wind back far enough to get them in.

Pretty sure from my college days that it can increase the size by up to 7 times its original size in extreme circumstances. That's why rebar in concrete can crack the concrete if it's allowed to rust.

Easy solution to it is to jack the back of the car up, let it coast in first gear with the wheels off and run round the lip with a grinder and flap disc on to get the worst off. It may need the T/C turning off to allow it to run properly.

Front wheels...bit more awkward but doable. That said I've never had an issue with oversized lips causing any binding :oops:
 

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Discussion Starter · #224 ·
Yes, rust on the lip will certainly increase the diameter. It will have been the correct size when you got it. If they're oversized slightly when new and you've got new pads too, they probably wouldn't wind back far enough to get them in.

Pretty sure from my college days that it can increase the size by up to 7 times its original size in extreme circumstances. That's why rebar in concrete can crack the concrete if it's allowed to rust.

Easy solution to it is to jack the back of the car up, let it coast in first gear with the wheels off and run round the lip with a grinder and flap disc on to get the worst off. It may need the T/C turning off to allow it to run properly.

Front wheels...bit more awkward but doable. That said I've never had an issue with oversized lips causing any binding :oops:
Thank You. I am replacing the discs anyway. Winded back the piston all the way and there is 5mm room with the new disc and 3mm with rusted one. I think a similar thing is happening to hub surface that I hope to be able to grind off. Kit hasn’t arrived yet. Amazon prime one day delivery used to be impressive!
 

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and yes, my jag also suffers from brake judder and it’s driving me nuts.
Different symptom, different problem. The article refers to pedal vibration, not steering wheel vibration. And yes, if the rotors aren't mounted true to the hub it would cause them to wobble and give you a vibrating pedal.
 

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Using red stuff and no judder at all. Mind you, I meticulously cleaned all brake parts before reassembly.
 

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Discussion Starter · #229 ·
I replaced the discs and all was fine but for both rear discs I couldn’t get to anything better than 0.20mm. Later when I did rear bearings, it was confirmed to be warped wheel hubs. Hubs were cleaned enough that I could see original machining grooves. I skimmed the hub on a mini lathe and runout dropped from 0.20 to 0.02mm.
for the front ones I bought a kit that sits around stud, that took the runout from 0.05 to 0.01mm.
For those with reoccurring brake judder, If you rule out suspension issues, I would use a dial indicator and take runout down to spec. Quickest way is to use on car brake lathe. Otherwise you might need a new brake disc, brake hub or wheel bearing. In my case worn bearing was giving inconsistent dial reading on top of all of above.
 

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I replaced the discs and all was fine but for both rear discs I couldn’t get to anything better than 0.20mm. Later when I did rear bearings, it was confirmed to be warped wheel hubs. Hubs were cleaned enough that I could see original machining grooves. I skimmed the hub on a mini lathe and runout dropped from 0.20 to 0.02mm.
for the front ones I bought a kit that sits around stud, that took the runout from 0.05 to 0.01mm.
For those with reoccurring brake judder, If you rule out suspension issues, I would use a dial indicator and take runout down to spec. Quickest way is to use on car brake lathe. Otherwise you might need a new brake disc, brake hub or wheel bearing. In my case worn bearing was giving inconsistent dial reading on top of all of above.
Do you know how the wheel hub and discs became warped?
 

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Discussion Starter · #231 ·
Do you know how the wheel hub and discs became warped?
I don’t think the disc was the problem. The hub was. By problem I mean being out of tolerance. It was 0.15mm. The limit is 0.0135mm according to WM and I think generally they say 0.05mm is acceptable. No idea. The machine shop was surprised as well. Because if anything, rim or bearing should go first.
 

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My next move is to fit new front discs and red stuff pads to see how I fare. If the problem persists then two new front hub assemblies will be next.
 

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My next move is to fit new front discs and red stuff pads to see how I fare. If the problem persists then two new front hub assemblies will be next.
Just had a look on eBay and a pair of new hubs can be had for £90. No doubt made from the finest Chinesium but maybe worth a punt…
 

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I don’t think the disc was the problem. The hub was. By problem I mean being out of tolerance. It was 0.15mm. The limit is 0.0135mm according to WM and I think generally they say 0.05mm is acceptable. No idea. The machine shop was surprised as well. Because if anything, rim or bearing should go first.
I wonder if there was some widespread manufacturing defect, seeing as so many seem to have this issue? Although if that were the case, how come putting new discs and pads can solve it for a while for some people?
 

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I don't think the hubs are up to it. Tightening the wheel nuts out of the correct order with just a small amount of rust or grit would twist them. When garages use high torque hammer wrenches on them they are easily pulled out of true. My view is thicker metal and better quality steel.
 

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Discussion Starter · #236 ·
I wonder if there was some widespread manufacturing defect, seeing as so many seem to have this issue? Although if that were the case, how come putting new discs and pads can solve it for a while for some people?
I know the changed the hub and carrier when moved to X260. That could be a hint. The rear hub look more like front wheels hubs now.
 

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I don't think the hubs are up to it. Tightening the wheel nuts out of the correct order with just a small amount of rust or grit would twist them. ...
I doesn't twist them. It puts the rotor and hub faces slightly out of parallel and the 'wobble' worsens over time.
 

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Maybe that's why this is in the workshop manual:
187749
 
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Discussion Starter · #239 ·
I think the wheel is considered to be part of system meaning it adds to the hub strength, should it be torqued properly. Something I don’t like about the hub design is that they use studs+wheel nuts instead of bolts. It makes using dial and cleaning hub surface very difficult. The star shape they use for rear wheels makes it even more difficult. Some brands like bmw use bolts.
 

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Hate bolts, Hamed….murder trying to fit a bolt in a hole unless there is a decent centre hanging rim. Studs give an immediate hang point.
 
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